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ILOG JViews 5.5 Graph Layout User's Manual

1. LL anm NO ORDERING ORDER BY HEIGHT ORDER BY INDEX r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 227 Bus LAYOUT Bus Node To represent bus topologies the algorithm reshapes a special node called the bus node and gives it a serpent form This bus node must be an instance of the IlvPolyPointsInterface class Usually you use its subclass IlvPolyline Before performing the layout you must create this object and add it to the grapher as a node The number of points in the object you create is not important Then you must specify the node as bus node using the methods void setBus IlvPolyPointsInterface bus IlvPolyPointsInterface getBus If none is specified the Bus layout automatically tries to find an appropriate node that can be used as bus object The bus object must implement the interface 11vPolyPointsInterface andit must allow the insertion and removal of points see the methods al lowsPoint Insertion and allowsPointRemoval defined by the interface The initial number of points is not significant When a bus object is specified or automatically discovered in an 11vGrapher the appropriate link connector is automatically installed on it By default the link connector i
2. 17 Layout Parameters and Features in llvGraphLayout 20 Chapter 3 Getting Started with Graph 37 Basic Steps for Using Layout Algorithms A Summary 38 Sample Java Application sseeeseeeeeeee RR m nh 38 Chapter 4 Layout Algorithms REIR y Ib a aa 43 Determining the Appropriate Layout Algorithm 44 Typical Ways for Choosing the Layout 49 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL iii TABLE OF CONTENTS Chapter 5 Chapter 6 Generic Features and Parameters Support 51 Layout Characteristics llle hh hn 52 Topological Mesh Layout TML 54 Spring Embedder Layout 72 Uniform Length Edges Layout 81 Tree Layout fe eaa Pe ag lae e RI EROR nea ee ARR SNR Var wean 94 Hierarchical Layout 0 0 cece ehh n hh hh hh hn 134 Linki Layout UCM 185 Random Layout eee eee 217 amp eee EI PIE TCI T 222 Circular Layout sosem ios dev cul kl ux bk va rema e ae ed erue wr 238 Grid Layout
3. ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 11 ILOG JViEWS GRAPH LAYOUT MODULE IN USER INTERFACE APPLICATIONS 12 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Basic Concepts m 07 v O 5 a In this chapter you will learn about some basic concepts and background information that will help you when using the ILOG JViews Graph Layout module The following topics are covered Graph Layout A Brief Introduction Graph Layout in ILOG JViews The Base Class IlvGraphLayout Basic Operations with IlvGraphLayout 9 Layout Parameters and Features in IlvGraphLayout ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 13 GRAPH LAYOUT A BRIEF INTRODUCTION Graph Layout A Brief Introduction This section provides some background information about graph layout in general not specifically related to the ILOG JViews Graph Layout module Simply speaking a graph is a data structure which represents a set of entities called nodes connected by a set of links node can also be referred to as a vertex A link can also be referred to as an edge or a connection In practical applications graphs are frequently used to model a very wide range of things computer networks software program structures project management diagrams and so on Graphs are powerful models because they permit applications to benefit from the results of graph theory research For instance efficient
4. ae nc we eden Bile 255 Recursive Layouts 2 re ane ae a de A TOR s 265 Multiple Layout 2 cece eee eee eee eee eee eh hh hh mrt 282 Using Advanced 291 Using a Layout Report 0 0 cece eee n hh hh hn 292 Using Event Listeners 2 a eee eens 294 Redrawing the Grapher after Layout 296 Using the Graph Model sunat nnn nnn 297 Laying Out a Non JViews Grapher 303 Laying Out Connected Components of a Disconnected Graph 304 Laying Out Nested lt 306 Saving Layout Parameters and Preferred Layouts 315 Using the Filtering Features to Lay Out a Part of an IlvVGrapher 321 Choosing the Layout Coordinate Space 323 Releasing Resources Used During the Layout 328 Defining a New Type of Layout 329 Questions and Answers about Using the Layout Algorithms 333 Automatic Label 1 339 Getting Started with Labeling 340
5. IlvDirection Left IlvDirection Top which is the same as IlvDirection TopLeft meaning the left or the top side o gt 1 3 You can specify the value 0 for the allowed side if all sides should be allowed Full Positioning at a Link The most powerful constructor of a descriptor for a label that should be placed at a link is the following IlvAnnealingPolylineLabelDescriptor Object label Object link Object source Object target int anchor float maxDistFromLink float preferredDistFromLink int preferredSide int allowedSide int sideAssociation float topOverlap float bottomOverlap float leftOverlap float rightOverlap It combines all previously mentioned possibilities you can specify the anchor the side association and the allowed and preferred sides You must pass the link as well as the source node and the target node of the link The label does not need to touch the link If you want to allow the label to be placed at a short distance from the link then specify the maximal distance by maxDistFromLink and the preferred distance by preferredDistFromLink Conversely you may want to allow the link to partially overlap the label You specify this by setting topOverlap bottomOverlap leftOverlap Or rightOverlap to a value larger than O This is illustrated in Figure 6 11 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 367 THE ANNEALING LABEL LAYOUT
6. gt 3 void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 79 SPRING EMBEDDER LAYOUT 80 The link connection box interface is used only when link clipping is enabled by setting a link clip interface If no link clip interface is specified the link connection box interface has no effect An example of the combined effect is shown in Figure 4 19 Clipping at the node bounding box Clipping at a specified connection box Figure 4 19 Combined Effect of Link Clipping Interface and Link Connection Box If the links are clipped at the green irregular star node Figure 4 19 left they do not point towards the center of the star but towards the center of the bounding box of the node This can be corrected by specifying a link connection box interface that returns a smaller node box than the bounding box Figure 4 19 right Alternatively the problem could be corrected by specifying a link connection box interface that returns the bounding box as the node box but with additional tangential offsets that shift the virtual center of the node ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UNIFORM LENGTH EDGES LAYOUT Uniform Length Edges Layout In this section you will learn about the Uniform Length Edges Layout algorithm from the ILOG JViews Graph Layout module class IlvUniformLengthEdgesLayout from the package ilog views graphlayout unifor
7. gt 3 You can force the layout algorithm to compute the same shape for all the links having common origin and destination nodes The links will have parallel shapes When this option is disabled the layout is free to compute different shapes for links connecting the same pair of nodes Generally different shapes are chosen to avoid some overlaps ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 209 LINK LAYOUT Same Shape Option Disabled Same Shape Option Enabled Figure 4 99 Self link Style Options To enable this option use the method layout getShortLinkLayout setSameShapeForMultipleLinks true The default value is false Link Crossing Penalty The computation of the shape of the links is driven by the objective to minimize a cost function which is proportional to the number of link to link crossings and link to node crossings By default these two types of crossings have equal weights of 1 You can increase the weight of the link to node crossings for instance to a value of 5 by calling layout getShortLinkLayout setLinkToNodeCrossingPenalty 5 f This increases the possibility of obtaining a layout with no link to node crossings or with only a few crossings with the expense that there may be more link to link crossings You can alternatively increase the weight of the link to link crossings for instance to a value of 3 by calling layout getShortLinkLayout setLinkToLinkCross
8. For instance to make sure that manager coordinates are used during layout call layout setCoordinatesMode IlvLabelLayout MANAGER COORDINATES This does not change the coordinates mode of the labeling model until layout is started Most of the time however it is recommended that you use the same coordinates mode for the default labeling model and the layout instance so you call it twice defaultLabelingModel setCoordinatesMode IlvLabelLayout MANAGER COORDINATES layout setCoordinatesMode IlvLabelLayout MANAGER COORDINATES Reference View and Reference Transformer To specify the reference view use the method void setReferenceView IlvManagerView view If no reference view is explicitly specified the first manager view is used The default labeling model needs only to know the transformer of the reference view Alternatively you can specify the reference transformer directly Use the method void setReferenceTransformer IlvTransformer transformer The mechanism of how the reference view and reference transformer are used is similar to that in the 11vGrapherAdapter class of the Graph Layout module For details see the sections Reference Transformers on page 324 and Reference Views on page 325 Note The reference transformer is used only if the coordinates mode is IlvLabelLayout VIEW COORDINATES or IlvhLabelLayout INVERSE VIEW COORDINATES If you change the reference transformer the layout is no longer
9. To obtain the current choice use the method int getLinkStyle Using a Link Clipping Interface By default the Circular Layout does not place the connection points of links It relies on the link connectors of the nodes to determine the connection points If no link connectors are installed at the nodes the default behavior is to connect to a point at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correct the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 124 252 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT without clipping with clipping Figure 4 124 Effect of Link Clipping Interface You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface Note The link clip interface requires link connectors at the nodes of an 11vGrapher that allow connector pins to be placed freely at the node border It is recommended that you use IlvRelativeLink
10. Fill in the grapher with nodes and links here Create the bus node the number of points and the coordinates are not important IlvPoint points new IlvPoint 10 10 IlvPolyline bus new IlvPolyline points grapher addNode bus false Fill in the grapher with links between each node and the bus here r lt c gt e gt 3 IlvBusLayout layout new IlvBusLayout layout attach grapher Specify the bus node layout setBus bus ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 223 Bus LAYOUT try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vBusLayout class supports the following generic parameters defined in the IlvGraphLayout class Allowed Time Layout of Connected Components Layout Region Link Clipping Preserve Fixed Links Preserve Fixed Nodes Save Parameters to Named Properties 9 9 9 Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass Allowed Time The layout algorithm stops if the allowed time setting has elapsed For a description of this layout parameter in the 11vGraphLayout class see A
11. HorizontalGridO HorizontalMinOffset Orthogonal links IncrementalMode false InputCheckE nabled true LayoutMode Short links LinkOffset 2 0 MinBusyT ime 50 ILOG JVIEWS GRAPH LAYOUT BEANS MinFinalS amp gmentLenath 10 0 MinNodeCormerOffset 3 0 Adding a Swing Bean You are now going to add a Swing Bean to the applet This Bean will allow you to launch the layout process on the graph 1 On the Beans toolbar click the Swing tab to display the Swing Beans 2 On the Swing Beans toolbar click the JButton Bean icon and drag it to the Form Designer Place this button below the IlvJScrol1lManagerView bean 3 Make sure that the JButton Bean is selected in the Form Designer Its properties should be displayed in the Property List 4 Inthe Property List window click the value field of the Text property Change jbutton to Perform Layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 403 sue g 1noAeq c 2 2 o O gt CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Form Designer JApplet1 Wappel Mod Ff Adding User Interaction You are now going to define the action that will be performed when the user clicks the Perform Layout button 1 With the right mouse button click the JButton Bean in the Form Designer 2 From the pop up menu that appears select Add int
12. Save the settings to named properties adapterA savePreferredLayouts provider true false true Save the nested grapher to an ivl file grapherA write abcd ivl Loading Layout Parameters from ivl Files The following example shows how to load and recover the parameters of the three layout instances when the layout settings are stored in an iv1 file Read the IVL file This reads all named properties as well grapher read abcd ivl IlvGrapherAdapter adapterl IlvGrapherAdapter layoutl getGraphModel IlvGrapherAdapter adapter2 IlvGrapherAdapter layout2 getGraphModel IlvGrapherAdapter adapter3 IlvGrapherAdapter layout3 getGraphModel Transfer the parameter settings from the named properties to the layouts adapter3 loadParametersFromNamedProperties layout3 adapter2 loadParametersFromNamedProperties layout2 adapterl loadParametersFromNamedProperties layoutl just to be sure that no named layout properties remain in the memory adapterl removeParametersFromNamedProperties adapter2 removeParametersFromNamedProperties adapter3 removeParametersFromNamedProperties When reading an ivi file you usually do not know how many named layout properties are stored in the file In the previous example if there are less than three sets of named layout properties stored in the iv1 file any unsuccessful call of loadParametersFromNamedProperties has simply no effect that is it does not ch
13. Specific Parameters The following parameters are specific to the IlvCircularLayout class Clustering Mode The Circular Layout algorithm has two clustering modes To select a clustering mode use the method void setClusteringMode int mode To obtain the current clustering mode call int getClusteringMode The valid values for mode are IlvCircularLayout BY CLUSTER IDS the default Cluster identifiers need to be explicitly provided for each node see Cluster Membership and Order of the Nodes on a Cluster on page 245 A tree like algorithm places the clusters ilvCircularLayout BY SUBGRAPHS The algorithm handles a nested graph including intergraph links It arranges the nodes of each subgraph on a circle so that the number of link crossings is small It respects the intergraph links and rotates the cluster so that the number of link crossings is small It assumes that all nodes are nearly square and that all nodes are in subgraphs but the subgraph nesting is only 1 Nodes that are inside subgraphs of subgraphs are not handled Note that in this mode each subgraph keeps its initial position The subgraphs can be placed either by a different layout algorithm or interactively r lt gt gt 3 Cluster Membership and Order of the Nodes on a Cluster This section applies only if he clustering mode is BY SUBGRAPHS Before performing the layout you must specify to whic
14. public IlvRect getBox IlvGraphModel graphModel Object node IlvRect rect graphModel boundingBox node if node instanceof IlvShadowRectangle need a rect that is 4 pixels smaller rect resize rect width 4 f rect height 4 f return rect public float getTangentialOffset IlvGraphModel graphModel Object node int nodeSide switch nodeSide IlvDirection Left IlvDirection Right return 10 shift up with 10 for both left and right side IlvDirection Top IlvDirection Bottom return 0 no shift for top and bottom side 30 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Some layout algorithms allow you to use the link connection box interface and the link clip interface in a combined way It is specific to each layout algorithm how the interfaces will be used and which connection points are the final result Memory Savings The computation of a layout on a large graph may require a large amount of memory Some layout algorithms optionally use two ways to store data one which gives the priority to speed this is the default case the other which consumes less memory and is usually slower The amount of memory savings depends of course on the implementation of the subclass of IlvGraphLayout No matter which option you choose for memory savings the resulting layout should be the same To specify your option use the following method void setMemorySavi
15. 9 9 9 Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass Layout Region The layout algorithm uses the layout region setting either your own or the default setting to control the size and the position of the graph drawing All three ways to specify the layout region are available for this subclass See Layout Region on page 25 Percentage Completion Calculation The layout algorithm calculates the estimated percentage of completion This value can be obtained from the layout report during the run of the layout For a detailed description of this features see Percentage Completion Calculation on page 31 and Layout Event Listeners on page 294 Preserve Fixed Links The layout algorithm does not reshape the links that are specified as fixed See Preserve Fixed Links on page 32 Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed See Preserve Fixed Nodes on page 32 r lt e gt gt 3 Random Generator Seed Value The Random Layout uses a random number generator to compute the coordinates You can specify a particular value to be used as a seed value See Random Generator Seed Value on page 33 For the default behavior the random generator is initialized using the current system clock Therefore different layouts are obtained if you perform the layout repeatedly o
16. If you call the first method the node belongs only to the cluster whose identifier is clusterId The second method allows you to specify that a node belongs to more than one cluster These methods have another version with an additional argument an integer value representing the index void setClusterId Object node IlvClusterId clusterId int index void addClusterId Object node IlvClusterId clusterId int index This value is used to order the nodes on the cluster If you specify these indices the algorithm sorts the nodes in ascending order according to the index values Note that the values of the index cannot be negative They do not need to be continuous only the order of the values is important To obtain the current index of a node on a given cluster use the method int getIndex Object node IlvClusterId clusterId If no index is specified for the node the method returns the value IlvCircularLayout NO INDEX Itis a negative value ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT To obtain an enumeration of the cluster identifiers for the clusters to which the node belongs use the method Enumeration getClusterIds Object node The elements of the enumeration are instances of a subclass of 11vClusterId To efficiently obtain the number of clusters to which a node belongs use the method int getClusterIdsCount Object node To remove a node from a cluster with a given identifier
17. One possible reason may be related to the different ways layout algorithms deal with the size of the nodes The Topological Mesh and Spring Embedder algorithms are not able to explicitly take into account the size of the nodes The Tree Hierarchical Bus and Grid algorithms always avoid overlapping nodes The Link algorithm does not move the nodes It only reshapes the links such that the crossings and overlaps are reduced The size of the nodes is taken into account The Uniform Length Edges algorithm with the option Respect Node Sizes enabled and the Circular algorithm in many cases succeed in avoiding overlapping nodes In any case if the layout algorithm supports the layout region mechanism see Layout Region on page 25 you should try to increase the size of the layout region For example if your graph contains hundreds of nodes it is not reasonable to use a small layout region such as 600x600 There will be not enough space for all the nodes You should try a larger layout region for example 5000x5000 The optimal size of the layout region depends of course not only on the number of nodes but also on their size If the nodes are relatively large with respect to the size of the layout region it may be necessary to adjust some of the parameters for instance the preferred link length for the Uniform Length Edges Layout 334 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL QUESTIONS AND ANSWERS ABOUT
18. Figure 7 1 shows the application panel that you will have created if you follow this short tutorial example Applet Viewer JApplet1 class OL x Applet IEEE sue g nofe c 2 o O gt Perform Layout Applet started Figure 7 1 Final JFC Swing Applet The example in this section shows how to create an ILOG JViews applet using a typical IDE procedure The procedures are the same however for other IDEs This section does not explain the concepts that underlie JavaBeans For this information refer to the Web site http java sun com products javabeans Furthermore it is assumed that you are familiar with the manipulation of JavaBeans within your IDE ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 393 CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Creating the Manager View To create the manager view do the following 1 Create a new project as a JFC Swing applet or application 2 On the Beans toolbar click the JViews tab to display the JViews Graphics Framework Beans 3 On the JViews Graphics Framework Beans toolbar click the IlvJScrollManagerView Bean icon and drag it to the Form Designer Note You will notice two scroll manager view icons on the toolbar Place the pointer over the icon to read the name and choose the one with J in its prefix IlvJScrollManagerView Note The Graphics Framework Swing Beans have the letter J in
19. ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Chapter 7 TABLE OF CONTENTS The Base Classes IlvLabelingModel and llvLabelLayout 346 The Annealing Label Layout 354 The Random Label Layout sos csee reser cee eee eee n nnn nnn 376 Using Advanced Features 379 Defining Your Own Labeling Model 384 Using Graph Layout Beans 391 Graph Layout Classes Available as lt 392 Creating a Simple Applet Using ILOG JViews Graph Layout Beans 393 ante eet bale Sine Sale wea Ee ee ea ae Yee Seale ete 411 eee de Stee betas Bhd PREG PER eee Fede eee es 419 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TABLE OF CONTENTS vi ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL About This Manual The ILOG JViews Component Suite provides special support for applications that need to display graphs or networks of nodes and links Any graphic object can be defined to behave like a node and can be connected to other nodes via links which themselves can have many different forms Used in conjunction with layout algorithms the ILOG JViews grapher is often used to display network topologies for telecommunications networks and systems manageme
20. ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 161 HIERARCHICAL LAYOUT detect the structure of the previous layout by examining the node coordinates For instance if two nodes are in the same level then they stay in the same level after an incremental layout If a node is in a higher level than another node it stays in the higher level Figure 4 77 on page 163 illustrates the difference between an incremental and nonincremental layout incremental layout Figure 4 77 Incremental and Nonincremental Layouts Incremental mode is disabled by default To enable incremental mode call layout setIncrementalMode true You can determine whether incremental mode is enabled by calling layout isIncrementalMode 162 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Phases of the Incremental Mode The layout algorithm analyzes the drawing in incremental mode in the following way 1 First it determines from the node coordinates which nodes must belong to the same level For instance if the flow direction is towards the bottom it tries to detect horizontal reference lines at those vertical positions where many nodes are placed along a line The specified vertical node offset helps to detect these lines because the horizontal reference lines should be approximately the vertical node offset apart See Figure 4 78 on page 164 nodes that touch the same reference line are assigned to the same le
21. Layout Constraints The Hierarchical Layout algorithm supports relative position constraints on nodes Such a constraint is a rule on how a particular node or a group of nodes must be placed with respect to the other nodes The constraints influence the relative positions For example you ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 169 HIERARCHICAL LAYOUT can force node A to be on the left side of node B so the position of A is expressed relative to the position of B It is theoretically possible to specify contradicting constraints if you specify that node A must be on the left side of B and B must be on the left side of A then these constraints are not solvable at the same time If A is on the left side of B then B must be on the right side of A The Hierarchical Layout algorithm tries to detect and resolve constraint conflicts automatically It ignores those constraints that are infeasible Since the automatic constraint resolution is time consuming it is recommended to specify nonconflicting constraints when possible Constraints should be used only if the incremental mode is switched off In fact the incremental mode is implemented by means of additional constraints that are added internally Hence if you use constraints during the incremental mode it is very likely that the system detects so many constraint conflicts that you get unexpected results Constraints should be used carefully The more constraints are specifie
22. Static layout The layout algorithm is completely redone scratch each time the graph is changed ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 15 GRAPH LAYOUT IN ILOG JVIEWS Incremental layout When the layout algorithm is performed a second time on a modified graph it tries to preserve the stability of the layout as much as possible The layout is not performed again from scratch The layout algorithm also tries to economize CPU time by using the previous layout as an initial solution Some layout algorithms and layout styles are incremental by nature For others incremental layout may be impossible Graph Layout in ILOG JViews 16 In ILOG JViews graphs are instances of the class IlvGrapher We call these instances graphers The nodes which are instances of 11vGraphic and the links which are instances of 11vLinkImage know how to draw themselves The nodes can have arbitrary coordinates or they can be placed interactively or by code All that needs to be done to lay out the grapher in order to obtain a readable drawing is to compute and to assign appropriate coordinates for the nodes In some cases the shape of the links may also need to be modified The main task of the Graph Layout module is to provide support for the operation of laying out a grapher that is drawing the graph The Graph Layout module of ILOG JViews benefits from its integration with the graph visualization and graph manipulation
23. orthogonal drawing path planar graph polyline drawing radial drawing ring seed value self link semiautomatic layout A drawing where each link is drawn as a polygonal chain of alternating horizontal and vertical segments A sequence of consecutive nodes leading from one node to another using the links of the graph It is the route along the links through the nodes in a graph The length of a path is the number of links traversed A graph that can be drawn with no links crossing other links 4 Fw a m A drawing where each link is drawn as a polygonal chain E A layout style where the nodes are placed radially around a root node A type of network topology where the nodes are arranged in a circular configuration The value that is used for the initialization of a random number generator Some layout algorithms use random numbers during the layout computation A link whose origin and destination nodes are the same node A layout process where the user makes manual improvements to the result of the automatic layout process 416 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL spanning tree star static layout straight line drawing subgraph GLOSSARY A minimal subgraph defined as follows A spanning tree S of a graph G is a subgraph of G containing all the nodes of the graph and whose links are a subset of the links of the graph The number of links of G that are not present in S must be
24. void move float x float y boolean redraw Layout algorithms that compute new coordinates for the nodes use the moveNode method Link layout algorithms that compute new shapes for the links call one of the reshapeLink methods Notification of Changes The following methods of the 11vGraphModel1 class allow a layout algorithm to be notified of changes in the graph void addGraphModelListener GraphModelListener listener void removeGraphModelListener GraphModelListener listener void fireGraphModelEvent GraphModelEvent event void fireGraphModelEvent Object nodeOrLink int type boolean adjusting void adjustmentEnd A change in the graph can be a structure change that is a node or a link was added or removed or a geometry change that is a node or a link was moved or reshaped The graph model event listener mechanism provides a means to keep the layout algorithms informed of these changes When the layout algorithm is restarted on the same graph it is able to detect whether the graph has changed since the last time the layout was successfully performed If necessary the layout can be performed again If there is no change in the graph the layout algorithm can avoid unnecessary work by not performing the layout To know whether the previous layout is still valid or it must be redone the layout algorithms call the following method of the model boolean isLayoutNeeded The graph model event
25. Flow to Bottom Flow to Top Flow to Left Figure 4 60 Flow Directions To specify the flow direction use the following method void setFlowDirection int direction The valid values for direction are IlvDirection Right the default IlvDirection Left IlvDirection Bottom IlvDirection Top To obtain the current choice use the following method int getFlowDirection Level Justification If the layout uses horizontal levels the nodes of the same level are placed approximately at the same y coordinate The nodes can be justified depending on whether the top border or the bottom border or the center of all nodes of the same level should have the same y coordinate r lt gt Q gt 3 If the layout uses vertical levels the nodes of the same level are placed approximately at the same x coordinate In this case the nodes can be justified to be aligned at the left border at the right border or at the center of the nodes that belong to the same level To specify the level justification use the following method void setLevelJustification int justification ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 143 HIERARCHICAL LAYOUT If the flow direction is to the top or to the bottom the valid values for justification are IlvDirection Top IlvDirection Bottom IlvDirection Center the default NDA Top Justification AL As Bottom Justifi
26. Global Alignment Parameters To set and retrieve the global alignment use the following methods void setGlobalHorizontalAlignment int alignment void setGlobalVerticalAlignment int alignment int getGlobalHorizontalAlignment int getGlobalVerticalAlignment The valid values for alignment are ILOG IlvGridLayout CENTER the default The node is horizontally and or vertically centered over its grid cell or row or column IlvGridLayout TOP The node is vertically aligned on the top of its cell s or row Not used if the layout mode is TILE TO COLUMNS IlvGridLayout BOTTOM The node is vertically aligned on the bottom of its grid cell s or row Not used if the layout mode is TILE TO COLUMNS IlvGridLayout LEFT The node is horizontally aligned on the left of its grid cell s or column Not used if the layout mode is TILE TO ROWS r lt gt gt 3 IlvGridLayout RIGHT The node is horizontally aligned on the right of its grid cell s or column Not used if the layout mode is TILE TO ROWS IlvGridLayout MIXED Each node can have a different alignment The alignment of each individual node can be set with the result that different alignments can occur in the same graph JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 259 GRID LAYOUT 260 ILO Alignment of Individual Nodes nodes have the same alignment unless the globa
27. H C HC HE H getl getIndex method IlvBusLayout class 226 IlvCircularLayout class 246 getInterGraphLinks method IlvGraphModel class 300 getInterGraphLinksCount method IlvGraphModel class 300 304 getL getLabelLayout method IlvMultipleLayout class 287 getLabelOverlap method IlvLabelingModel class 386 389 getLabels method IlvLabelingModel class 385 389 getLabelsCount method IlvLabelingModel class 385 ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge I Cf Cf CF E CF E CF E CF E CF CF E CF EJ CF E EF CF E CF Cf n H ct H I Layouts method LinksTo method Layers method lvDefaultLabelingModel class 379 lvLayoutGraphicFilter class 323 LayoutMode method lvGridLayout class 258 lvLinkLayout class 192 245 lvTreeLayout class 103 LayoutOfConnectedComponents method lvGraphLayout class 305 LayoutRegion method lvGraphLayout class 25 lvRandomLabelLayout class 379 lvGraphLayout class 308 LayoutTime method lvGraphLayoutReport class 294 lvLabelLayoutReport class 352 LeftMargin method lvGridLayout class 263 LevelAlignment method lvTreeLayout class 120 LevelJustification method lvHierarchicalLayout class 144 LevelOffset method lvCircularLayout class 251 LinkOffset method lvShortLinkLayout class 202 Link
28. ILOG JViews 5 5 Graph Layout User s Manual December 2002 Copyright 2002 by This document and the software described in this document are the property of ILOG and are protected as ILOG trade secrets They are furnished under a license or non disclosure agreement and may be used or copied only within the terms of such license or non disclosure agreement No part of this work may be reproduced or disseminated in any form or by any means without the prior written permission of ILOG S A Printed in France Table of Contents Preface About This Manual c c rmn vii Chapter 1 Introducing the Graph Layout 1 What is the Graph Layout Module of ILOG JViews 2 Composition of the ILOG JViews Graph Layout Module 2 The ILOG JViews Graph Layout Algorithms 4 Features of the ILOG JViews Graph Layout Module 8 ILOG JViews Graph Layout Module in User Interface Applications 10 Chapter 2 Basic Concepts eae eed ip ae eri rei 13 Graph Layout A Brief 1 14 Graph Layout ILOG JViews esee IRI 16 The Base Class IlvGraphLayout 17 Basic Operations with IlvGraphLayout
29. If no layers have been specified or all the specified layers have been removed all layers in the IlvManager are used In this case the get Layers method returns nu11 and isLayerAdded returns false for any layer Nonzoomable Labels and Obstacles Label layout algorithms have to deal with the geometry of the labels and obstacles The labels and obstacles of an ILOG JViews 11vManager can be any graphic objects that is any subclass of 11vGraphic Their position and size are given by their ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 379 USING ADVANCED FEATURES 380 boundingBox IlvTransformer t method and usually depend on the transformer used for their display Therefore when an 11vManager has to be laid out the geometry of the manager must be considered for a given value of the transformer The most natural transformer value that could be chosen is the identity transformer An identity transformer has no translation zoom or rotation factors In terms of ILOG JViews this would mean that the geometry of the 11vManager would be considered in the manager coordinates not in the manager view coordinates transformed coordinates However the special case of nonzoomable graphic objects must be taken into account For this case the idea of simply using the geometry of the grapher in manager coordinates is not pertinent A Special Case Nonzoomable Graphic Objects A graphic object is said to be zoomable if its bounding box
30. While tip over alignment can be specified explicitly for individual nodes the Tree Layout algorithm also has layout modes that automatically use tip over alignment when needed These are the tip over layout modes The tip over layout modes work as follows Several trial layouts are performed in free layout mode For each trial certain tip over alignments are set for individual nodes while the specified alignment of all other nodes is preserved The algorithm picks the trial layout that best fits the specified aspect ratio of the drawing area The aspect ratio can be set by one of the following methods see Aspect Ratio on page 122 in the Radial Layout Mode void setAspectRatio IlvManagerView view 126 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT void setAspectRatio IlvRect rect void setAspectRatio float aspectRatio The tip over modes are slightly more time consuming than the other layout modes For very large trees it is recommended that you set the allowed layout time to a high value for instance 60 seconds when using the tip over modes Use the following call layout setAllowedTime 60000 By using this call you avoid running short of algorithm Because it would be too time cons alignment use there are heuristics that check different strategies illustrated in Figure 4 51 Tip Leaves Over Tip Roots Over Tip Roots and Leaves Over Tip Over Fast Tip Leaves Over Figure 4 51
31. Yes Yes Yes Yes Yes ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 51 LAYOUT CHARACTERISTICS Layout Characteristics It is often useful to know how certain settings will affect the resulting layout of the graph after the layout algorithm has been applied Table 4 3 provides additional information about the behavior of the layout algorithms Table 4 3 Layout Characteristics of Layout Algorithms Do the initial positions of the How do get a different layout of the same graph gor nodes affect the layout when perform the layout a second time Topological Mesh No You can completely change the layout by using the Layout TML starting node outer cycle and fixed nodes parameters To change only the dimensions of the graph use the layout region parameter Spring Embedder No This is the default behavior when using the default Layout parameter settings the random generator is initialized differently each time To change only the dimensions of the graph use the layout region and spring constant parameters Uniform Length Edges Yes You can completely change the layout by changing Layout the initial positions of the nodes To change only the dimensions of the graph use the preferred length of the links or size of the layout region Tree Layout Yes if incremental mode is In incremental mode you can change the layout by switched on changing the ini
32. barycentric algorithms are implemented for Step 2 of TML You can specify the algorithm using the method void setNodesPlacementAlgorithm int option The valid values for opt ion IlvTopologicalMeshLayout SLOW_GOOD This option provides more uniformity of the nodes distribution inside the outer cycle but is slightly slower IlvTopologicalMeshLayout QUICK_BAD This option provides less uniformity of the nodes distribution but is slightly quicker ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ToPOLOGICAL MESH LAYOUT TML To obtain the current choice use the method int getNodesPlacementAlgorithm In most cases both algorithms are fairly quick We recommend that you use the SLOW_GOOD version which is the default value Compare the layouts of the same graph in Figure 4 3 and Figure 4 4 to get an idea of the difference between these algorithms Figure 4 3 Nodes Placement Algorithm SLOW_GOOD ii ES r lt Lad gt gt 3 Figure 4 4 Nodes Placement Algorithm QUICK BAD ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 63 ToPOLOGICAL MESH LAYOUT TML Starting Node Step 1 of TML needs a starting node parameter TML produces a different layout depending on the choice of the starting node TML works on different cycles of the graph depending on the starting node To specify the starting node use the method void setStartingNode Object
33. float getBranchOffset float getTipOverBranchOffset For Experts Additional Spacing Parameters The spacing parameters normally specify the minimal offsets between the node borders Hence the layout algorithm places the nodes such that they do not overlap You can also specify that the layout should ignore the node sizes by setting layout setRespectNodeSizes false In this case the spacing parameters are interpreted as the minimum distances between the node centers and the node sides are not taken into account during the layout However if the specified offset parameters are now smaller than the node size the nodes and links will overlap This often happens with orthogonal links in particular It makes sense to use this option only if all nodes have approximately the same size all links are straight and the spacing parameters are larger than the largest node If the link style is orthogonal the shape of the links from the parent to its children looks like a fork see Figure 4 33 on page 107 The position of the bend points in this shape can be influenced by the orthogonal fork percentage a value between 0 and 100 This is a percentage of the parent child offset If the orthogonal fork percentage is 0 the link shape forks directly at the parent node If the percentage is 100 the link shape forks at the child node A good choice is between 25 and 75 This percentage can be set and obtained by the following methods void
34. import ilog views graphlayout labellayout annealing IlvTreeLayout treeLayout new IlvTreeLayout IlvLinkLayout linkLayout new IlvLinkLayout IlvAnnealingLabelLayout labelLayout new IlvAnnealingLabelLayout IlvMultipleLayout multipleLayout new IlvMultipleLayout treeLayout linkLayout labelLayout IlvGrapher grapher layout attach grapher Fill in code to set the layout parameters of treeLayout linkLayout and labelLayout X linkLayout setIntergraphLinksMode true By constructing a Multiple Layout instance in this way the Tree Layout Link Layout and Label Layout become sublayouts of the Multiple Layout instance Attaching the Multiple Layout will automatically attach its sublayouts 282 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL MULTIPLE LAYOUT The Multiple Layout has two slots for graph layouts and one slot for the label layout Not all slots need to be used You can pass nu11 as the sublayout for unused slots If you need more slots you can compose a Multiple Layout that contains another Multiple Layout as a sublayout To perform the composed layout you use either a Simple Layout Recursive Layout Simple Layout You can perform the composed layout on a flat grapher one which contains no submanagers in the following way try IlvMultipleLayoutReport layoutReport IlvMultipleLayoutReport multipleLayout performLayout int code layoutReport getCode System
35. 4 Initialize the random generator Random random isUseSeedValueForRandomGenerator new Random getSeedValueForRandomGenerator new Random For information on the seed value parameter see Random Generator Seed Value on page 33 5 Get an enumeration of the nodes getNodes on the graph model instance Enumeration nodes graphModel getNodes 6 Browse the nodes skipping fixed nodes isFixed node on the layout instance if asked by the user isPreserveFixedNodes on the layout instance while nodes hasMoreElements Object node nodes nextElement For details on fixed nodes see Preserve Fixed Nodes on page 32 7 Move each node to the newly computed coordinates inside the layout region graphModel moveNode graphModel moveNode node x y redraw 8 Notify the listeners on layout events that a new node was positioned callLayoutStepPerformedIfNeeded on the layout instance This allows the user to implement for example a progress bar if a layout event listener was registered on the layout instance callLayoutStepPerformedIfNeeded For details on event listeners see Using Event Listeners on page 294 9 Finally set the code in the layout report layoutReport setCode IlvGraphLayoutReport LAYOUT DONE soJnjeoaJj e 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 331 DEFINING A NEW OF LAYOUT 332
36. 5 gt 2 lt E 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 305 LAYING OUT NESTED GRAPHS region parameter is set by default to the rectangle 0 0 800 800 Its layout mode parameter is set to I1vGridLayout TILE TO ROWS Note The Tree Hierarchical and Circular layouts contain built in support for disconnected graphs For the Tree and Hierarchical layouts the result can be different from the result of the generic mechanism the layout of connected components feature provided by the base class 11vGraphLayout Depending your particular needs you can use either the generic mechanism or the built in support Laying Out Nested Graphs The IlvGrapher class provided by the ILOG JViews Graphic Framework allows nested graphs to be represented for details see the chapter Nested Managers and Nested Graphers in the ILOG JViews Graphics Framework User s Manual An example of a nested graph is given in Figure 5 3 INetwork2 1 INetwork2 2 ATE LI OG Figure 5 3 Example of a Recursive Layout of a Nested Graph In this example there is a topmost graph which contains only two nodes named Part1 and Part2 connected by a link Each of these two nodes is another graph composed of three nodes connected by links Finally each of these nodes is another graph composed of some icons connected by links 306 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYING OUT NESTED GRAPHS Such nested graphs ar
37. 5 o a Nodes or links were moved or reshaped The value of a layout parameter was modified The transformer of a manager view I1vManagerView of the grapher has changed Users often do not want the layout to be computed again if no changes occurred If there were no changes the method performLayout returns without performing the layout Note that if the argument force is passed as t rue the verification is no longer performed The argument redraw determines whether a redraw of the graph is requested For details see Redrawing the Grapher after Layout on page 296 The protected abstract method 1ayout boolean redraw is then called This means that the control is passed to the subclasses that are implementing this method The implementation computes the layout and moves the nodes to new positions and or reshapes the links The performLayout method returns an instance of IlvGraphLayoutReport or of a subclass that contains information about the behavior of the layout algorithm It tells you whether the algorithm performed normally or whether a particular predefined case occurred For a more detailed description of the layout report see Using a Layout Report on page 292 Note that the layout report that is returned can be an instance of a subclass of IlvGraphLayoutReport depending on the particular subclass of IlvGraphLayout you are using For example it will be an instance of I1vTopologicalMeshLayoutReport if
38. Bus Layout No except in incremental mode You change the dimensions of the graph by using the various dimensional parameters Circular Layout No You can completely change the layout by using clustering settings and the root clusters parameter You can change the dimensions of the graph by using the dimensional parameters Grid Layout No except in incremental mode You can change various dimensional parameters layout mode and so on Recursive Layout Depends on the behavior of the sublayouts applied to the subgraphs Depends on the behavior of the sublayouts applied to the subgraphs You can change the parameters of the sublayouts individually Multiple Layout Depends on the behavior of the sublayout that is applied first Depends on the behavior of the sublayouts of the Multiple Layout instance You can change the parameters of the sublayouts individually All of the layout classes provided in ILOG JViews except the Link Layout support the fixed nodes mechanism This means that you can specify nodes that cannot be moved during the layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 53 r lt e gt gt 3 o TOPOLOGICAL MESH LAYOUT TML Topological Mesh Layout TML In this section you will learn about the Topological Mesh Layout TML algorithm from the ILOG JViews Graph Layout module class IlvTopologicalMeshLayout from the
39. For Experts Additional Features The following features are available in both layout modes Using a Node Side Filter Some applications require that links are not connected to specific sides of certain nodes The Link Layout algorithm allows you to restrict which node side a link can connect to by using a node side filter A node side filter is any class that implements the interface IlvNodeSideFilter This interface defines the following method public boolean accept IlvGraphModel graphModel Object link boolean origin Object node int side This method allows you to permit the input 1 ink to connect its origin or destination to the input side of the input node As an example assume that the application requires that for end nodes of type IlvShadowRectangle links can connect their origin only at the top and bottom side For G JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL LINK LAYOUT end nodes of type IlvReliefRectangle links can connect their destination only at the left and right side The following node side filter accomplishes this class MyFilter implements IlvNodeSideFilter public boolean accept IlvGraphModel graphModel Object link boolean origin Object node int side if node instanceof IlvShadowRectangle amp amp origin return side IlvDirection Top side IlvDirection Bottom if node instanceof IlvReliefRectangle amp amp origin return side IlvDirection Left side IlvDirectio
40. IlviinkLayout DIRECT STYLE ilviinkLayout NO RESHAPE STYLE that is the link is not reshape in any manner Note The link style of a Link Layout graph requires links in an 11vGrapher that can be reshaped Links of type 11vLinkImage IlvOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage cannot be reshaped You should use the class T1vPolylineLinkImage or IlvSplineLinkImage instead 196 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT End Points Mode Normally the layout algorithm is free to choose the termination points of each link However if fixed link connectors are used for instance T1vPinLinkConnector user can specify that the current fixed termination pin of a link should be used The layout algorithm provides two end point modes You can set the end point mode globally in which case all end points have the same mode or locally on each link in which case different end point modes occur in the same drawing Global End Point Mode To set the global end point mode the following methods are provided void setGlobalOriginPointMode int mode void setGlobalDestinationPointMode int mode The valid values for mode are IlvLinkLayout FREE MODE the default The layout is free to choose the appropriate position of the connection point on the origin destination node 1ilvLinkLayout FIXED MODE
41. It is recommended that you use IlvRelativeLinkConnector or IlvClipLinkConnector for link connectors to be used in combination with 11vGrapher objects The clip link connector updates the clipped connection points automatically during interactive node movements The special bus node is an exception it always uses the bus link connector r lt e gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 237 CIRCULAR LAYOUT Circular Layout In this section you will learn about the Circular Layout algorithm from the ILOG JViews Graph Layout module class 11vCircularLayout from the package ilog views graphlayout circular Samples Here are sample drawings produced with the Circular Layout Figure 4 115 Ring and Star Topology Drawing Produced with the Circular Layout 238 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT rnt Figure 4 116 Large Ring and Star Topology Drawing Produced with the Circular Layout What Types of Graphs Graphs representing interconnected ring and or star network topologies Application Domains Application domains of the Circular Layout include ILOG Telecom and networking LAN diagrams Business processing organization charts r lt gt gt 3 Database and knowledge engineering sociology genealogy The World Wide Web Web hyperlink neighborhood
42. This method reads the named properties stored in the file and sets the preferred layout if any has been stored on the Layout Provider using its method set PreferredLayout The following example shows how to load and recover the preferred layouts with their parameters when the preferred layout settings are stored in an iv file IlvGrapher grapher new IlvGrapher Create the grapher adapter for the topmost graph IlvGrapherAdapter adapter new IlvGrapherAdapter grapher ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 319 soinjeo4 e 5 gt 2 lt 5 o SAVING LAYOUT PARAMETERS AND PREFERRED LAYOUTS 320 Load the graphers from the ivl file grapher read abcd ivl Create the layout provider IlvDefaultLayoutProvider provider new IlvDefaultLayoutProvider Load the preferred layouts into the provider layout parameters are also read adapter loadPreferredLayoutsFromNamedProperties provider true true Now the provider can be used to perform the recursive layout adapter performLayout provider true true true Detach the layouts when the provider is no longer needed provider detachLayouts adapter true Dispose the topmost adapter when no longer needed adapter dispose Additional Information for Expert Users This section contains useful information for expert users Interface Parameters Some layout classes allow an interface as inpu
43. distance from link Figure 6 11 Distance and Overlap at Link Full Positioning at a Polyline Obstacle left overlap If the label should be placed at a polyline that is not a link then the most powerful constructor is the following IlvAnnealingPolylineLabelDescriptor Object label Object relatedObstacle IlvPoint referencePoints float lineWidth float minPercentageFromStart float maxPercentageFromStart float prefPercentageFromStart float maxDistFromPath float preferredDistFromPath int preferredSide int allowedSide int sideAssociation float topOverlap float bottomOverlap float leftOverlap float rightOverlap It combines all previously mentioned possibilities If the label should be placed at a polyline obstacle then pass this as the related obstacle If the label should be placed at an imaginary polyline then pass the polyline with the points parameter and the width of the polyline with the 1inewidth parameter Instead of an anchor you can pass the area where the label is placed by the minimal maximal and preferred percentage values relative to the polyline length The minimal and maximal percentages are strictly obeyed while the preferred percentage is only a recommendation for the layout 368 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT For instance if you want to specify that the label can be placed anywhere but you prefer the center of the polyline speci
44. limitations 56 link clipping parameter 60 69 link connection box parameter 60 70 link style parameter 61 nodes placement algorithm 62 nodes placement allowed time parameter 62 nodes placement iterations parameter 62 optimization allowed time parameter 62 optimization iterations parameter 62 outer cycle parameter 64 refining a layout 66 sample drawings 54 specific parameters 61 starting node parameter 64 using fixed nodes parameter to refine 66 using layout region parameter to refine 68 using outer cycle parameter to refine 68 Tree Layout adding an invisible root node radial mode 124 algorithm description 97 alternating radial mode 122 applicable graph types 95 application domains 95 aspect ratio parameter tip over mode 126 aspect ration parameter 122 calculating link shapes 98 calculating node positions 98 calculating the spanning tree 97 code sample 98 compass directions 103 connector style parameter 111 evenly spaced first circle radial mode 124 features 95 flow direction parameter 104 free layout mode 104 generic parameters 99 global link style parameter 110 individual link style parameter 110 interactive editing 132 layout modes 103 level alignment parameter 119 level layout mode 118 limitations 96 link clipping parameter 100 114 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 447 INDEX link connection box parameter 100 113 link style parameter 109 making in
45. lt Lad gt gt 3 Spacing Parameters The spacing of the layout is controlled mainly by three spacing parameters the distance between a parent and its children the minimal distance between siblings and the minimal distance between nodes of different branches For instance if the flow direction is to the top ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 115 TREE LAYOUT or bottom the offset between parent and children is vertical while the sibling offset and the branch offset are horizontal For tip over alignment an additional spacing parameter is provided the minimal distance between branches starting at a node with tip over alignment This offset is always orthogonal to the normal branch offset If the flow direction is to the top or bottom the tip over branch offset is vertical Parent Child Offset i Parent Child Sibling Offset Sibling Offset Branch Offset Sibling Offset Tip Over Branch Offset Tip Over Branch Offset Figure 4 41 Spacing Parameters The spacing parameters can be set by the following methods void setParentChildOffset float offset void setSiblingOffset float offset void setBranchOffset float offset 116 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT void setTipOverBranchOffset float offset The current settings can be obtained by the corresponding methods float getParentChildOffset float getSiblingOffset
46. 5 USER S MANUAL RECURSIVE LAYOUT In specified provider mode there is no reference layout You allocate the Recursive Layout using the constructor with your layout provider as argument IlvRecursiveLayout IlvLayoutProvider specifiedProvider You can access the current layout provider by IlvLayoutProvider getLayoutProvider You should implement your layout provider in a way so that it delivers a different layout instance for each subgraph The delivered layout instance must be attached to the graph model of the corresponding subgraph Notice since there is no reference layout global layout parameters are independent for each subgraph It is recommended that the implementation of the layout provider takes care of the setting of global and local layout parameters Theoretically you can use the method IlvGraphLayout getLayout Object subgraph which will return the layout instance that the specified layout provider delivers for the graph model of the input subgraph If you pass nu11 as subgraph you get the layout instance of the top level graph However the effect of this method depends on the implementation of the layout provider that was passed to the constructor of Recursive Layout The layout instances of the subgraphs used during recursive layout should be attached by the layout provider They are usually not automatically detached when the Recursive Layout is detached Unless you use one of the predefined providers of cla
47. BackgroundPattem PS Bounds 2 2 207 159 Cursor DEFAULT_CURSOR DefaultGhostColor Wg black DefaultORColor white DoubleBuffering true Enabled true Grid Default Inherit Background true Interactor Default Keeping4spectRatic true Default v MaximumSize MinimumSize igen it ilvGraphert Name m ptimizedT ranslation true Once this operation is done the 11vManagerView can display the contents of the IlvGrapher Bean You could create several I1vManagerView Beans and associate them with the same I1vGrapher Bean This allows you to have several views of the same graph Loading an ivl File into the Grapher You are now going to load an ivi file into the 11vGrapher Bean so that the contents of the ivl file are displayed in the manager view To load an ivi file do the following 1 In the Form Designer select the 11vGrapher Bean so that its properties appear in the Property List 2 Click the value field of the FileName property and then click the button The FileName Editor dialog box appears FileName Editor x Enter URL Es ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 399 sue g noke c 2 2 o O gt CREATING A SIMPLE APPLET USING ILOG JVIEWS GRAPH LAYOUT BEANS 3 To specify the ilv file click the button in the FileName Editor The Choose URL dialog box appears 4 Go to the ins
48. Create a grapher object 11vGrapher and fill it with nodes and links 2 Create an instance of the layout algorithm any subclass of ilog views graphlayout IlvGraphLayout 3 Declare a handle for the corresponding layout report The layout report is an object in which the layout algorithm stores information about its behavior For details see Using a Layout Report on page 292 4 Attach the grapher to the layout instance 5 Modify the default settings for the layout parameters if needed 6 Call the performLayout method inside t ry block H Read and display information from the layout report Catch the exceptions 0 2 00 When the layout instance is no longer needed detach the grapher from the layout instance An application that illustrates these steps is provided in Sample Java Application on page 38 Sample Java Application You can use this application as an example to get started with the layout algorithms of the Graph Layout module The example uses the Orthogonal Link Layout but the principles are mostly the same for any of the other layouts The source code of the application is named Layout Sample1 java and be found at the location installdir doc usermansrc graphlayout LayoutSamplel java To compile and run the example do the following 1 Goto the graphlayout directory at the above path On Windows 98 2000 ME NT XP you must open a DOS Console 38 ILOG JVIEWS GRAPH LAYOUT 5 5
49. Generic Features and Parameters The IlvAnnealingLabelLayout class supports the following generic parameters defined in TlvLabelLayout class Allowed Time Percentage Completion Calculation Random Generator Seed Value Save Parameters to Named Properties Stop Immediately 99 Use Default Parameters The following comments describe the particular way in which these parameters are used by this subclass Allowed Time The label layout algorithm stops if the allowed time setting has elapsed This feature works similarly as in IlvGraphLayout see Allowed Time on page 22 If the layout stops early because the allowed time has elapsed the result code in the layout report is IlvLabelLayoutReport STOPPED AND VALID if the labels were moved to some better but not yet optimal positions 1ilvLabelLayoutReport STOPPED AND INVALID if the time elapsed even before that Percentage Completion Calculation The label layout algorithm calculates the estimated percentage of completion This value can be obtained from the label layout report during the run of the layout For a detailed description of this feature see Percentage Completion Calculation on page 31 and Layout Events and Listeners on page 352 Random Generator Seed Value The Annealing Label Layout is a randomized heuristic It uses a random number generator to control the movements For the default behavior the random generator is ini
50. JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 239 CIRCULAR LAYOUT Features Displays network topologies composed of interconnected rings and or stars Provides two clustering modes see Clustering Mode on page 245 The first mode lays out clusters as circles and places the clusters This mode is designed for rings stars that are interconnected in a tree structure but it can produce acceptable results even if the graph contains cycles The second mode lays out the clusters as circles of nodes minimizing the link crossings while keeping the clusters at their initial position See also Brief Description of the Algorithm on page 240 Takes into account the size of the nodes so that no overlapping occurs Limitations Link crossings cannot always be avoided Brief Description of the Algorithm Ring and star topologies are similar in several ways Take a look at Figure 4 117 and Figure 4 118 to get an idea of their similarities Figure 4 117 Ring Topology Figure 4 118 Star Topology 240 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT Both topologies are composed of nodes drawn on a circle For the Circular Layout algorithm the only difference between the ring and star topologies is that the star has a special node called the star center that is drawn in the center of the circle The user must specify the node that is the star center See Star Center on page 247 for information on how to spe
51. Label Layout may ask the label descriptor to place the label at the position 1 to 8 For the Annealing Label Layout these positions are just numbers between 0 and maxPathLocation The task of the label descriptor is to translate these numbers into the correct positions as shown in the upper part of the figure E Label ES EN c LE a ssuasasa susuesueu sus see path 1 2 T oom x z f K ocation pat location Figure 6 13 Path Locations at a Triangle Label Descriptor The base class IlvAnnealingLabelDescriptor has two protected data members actPathLocationis the current path location of the label maxPathLocation is the maximal value of the path location To create a new label descriptor you need to implement a method that initializes the path constructor at the beginning of layout You should calculate the maximal path location maxPathLocation and initialize the actPathLocation here The method is called only once during layout void initialize IlvLabelingModel labelingModel In the example of Figure 6 13 the maximal path location for an equilateral triangle is 3 sidelength 2 labelwidth 2 labelheight In each iteration step the layout calls the method setPosition and provides an actual value of the path location The method setPosition should store the value into actPathLocation and translate the path location into appropriate x y coordinates Then it should ca
52. Layout on B 3 Label Layout on B 4 Tree Layout on A 5 Link Layout on A 6 Label Layout on A This means that all layouts of subgrapher have finished before the layout of grapher A starts This is the correct order for a recursive layout If you do not combine the three component layouts into a Multiple Layout you can only apply them sequentially treeLayout performLayout true true true linkLayout performLayout true true true labelLayout performLayout true true true The effect of these three statements is slightly different than the effect of the Multiple Layout The layouts are now applied in the following order 1 Tree Layout on B 2 Tree Layout on A 3 Link Layout on B 4 Link Layout on A 5 Label Layout on B 6 Label Layout on A This order is not usually suitable for the layout of nested graphers because the Tree Layout of grapher A is started too early The Label Layout on grapher B in Step 5 may change the position of grapher B within grapher A invalidating the result of the Tree Layout in Step 2 Hence it is recommended that you combine multiple layout algorithms into one Multiple Layout object and apply this object as a whole to a nested grapher 284 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL MULTIPLE LAYOUT Features Allows composing two graph layout algorithms and one label layout algorithm into one layout object Should be used to achieve the correct layout order when dealing wit
53. Once the descriptor is passed to the layout instance it should normally not be changed If you need to change it later you must pass it to the layout instance again ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 363 THE ANNEALING LABEL LAYOUT Figure 6 8 Potential Label Positions With Rectangular Shape at a Point Polyline Label Descriptor If you want to place labels at straight lines polylines or links you should use the IlvAnnealingPolylineLabelDescriptor The allowed area for labels at a polyline is different from the rectangular or elliptic area at a reference point A polyline has two sides where the label can be placed along a path This is known as the polyline labeling problem Note The polyline label descriptor is not suitable for placing labels at splines or spline links Because splines have a complex geometric shape the automatic placement of labels at splines is currently not supported Simple Positioning at a Link This specification can be used if the label must be placed at a straight or polyline link Here is an example layout setLabelDescriptor label new IlvAnnealingPolylineLabelDescriptor label link IlvAnnealingPolylineLabelDescriptor CENTER The label is placed near the center of the link such that one border of the label just touches the link If the link is moved or reshaped the next label layout call will update the position of the label automatically to follow the link The example uses
54. Recursive Layout is stopped If the Recursive Layout stops early because the allowed time has elapsed the result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID r lt gt gt 3 Percentage Completion Calculation The Recursive Layout calculates the percentage of completion This value can be obtained from the layout report during the run of the layout The value is however a very rough estimation If the layouts on the subgraphs do not support the calculation of the percentage completion the Recursive Layout can report the percentage based only on the information how many layouts of subgraphs are already finished For instance if the entire nesting ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 271 RECURSIVE LAYOUT 272 structure contains five nested graphs the mechanism reports 2046 after the layout of the first subgraph has finished 40 after the layout of the second subgraph has finished and so on If the layouts of the subgraphs support the calculation of the percentage completion the Recursive Layout calculates a more detailed percentage In most cases the calculated percentage is only a very rough estimation that does not always grow linearly over time For a detailed description of this feature see Percentage Completion Calculation on page 31 and Layout Listeners on page 279 Save Parameters to Named Properties The Recursive Layout instance can s
55. Tip Over Strategies ILOG JViEWS GRAPH LAYOUT 5 5 time for sufficient iterations of the layout uming to check all possibilities of tip over only certain trials according to the following TEREE gt lt S 2 To 9 Tip Roots Over 5 D Tip Roots and Leaves Over USER S MANUAL 127 TREE LAYOUT Tip Leaves Over To use this tip over strategy set the layout mode as follows layout setLayoutMode IlvTreeLayout TIP LEAVES OVER The heuristic first tries the layout without any additional tip over options Then it tries to tip over the leaves then the leaves and their parents then additionally the parents of these parents and so on As a result the nodes closest to the root use normal alignment and the nodes closest to the leaves use tip over alignment Tip Roots Over To use this tip over strategy set the layout mode as follows layout setLayoutMode IlvTreeLayout TIP ROOTS OVER The heuristic first tries the layout without any additional tip over options Then it tries to tip over the root node then the root and its children then additionally the children of these children and so on As a result the nodes closer to the leaves use normal alignment and the nodes closer to the root use tip over alignment Tip Roots and Leaves Over To use this tip over strategy set the layout mode as follows layout setLayoutMode IlvTreeLayout TIP ROOTS AND LEAVES OVER The heuristic first tries the layo
56. algorithm description 189 bypass distance parameter 210 features 187 link box connection interface 211 link crossing penalty parameter 210 link offset parameter 202 minimum final segment parameter 203 number of optimization iterations 209 same shape for multiple links parameter 209 self link style parameter 208 spacing parameters 201 side association 366 side by side constraints Hierarchical Layout 176 simulated annealing 356 spacing parameters Hierarchical Layout 159 Link Layout long link mode 203 orthogonal fork percentage Tree Layout 117 overlap percentage Tree Layout 117 Tree Layout free mode 115 117 Tree Layout radial mode 123 specified provider mode Recursive Layout 269 274 specifying a reference transformer 326 spring constant parameter Spring Embedder Layout 78 Spring Embedder Layout 77 applicable graph types 73 application domains 73 code sample 74 description 74 features 74 generic parameters 75 limitations 74 link clipping parameter 76 78 link connection box parameter 76 79 sample drawings 72 specific parameters 77 spring constant parameter 78 star center parameter Circular Layout 247 star topology Circular Layout 241 starting node parameter Topological Mesh Layout 64 static layout 15 stop immediately parameter Bus Layout 225 Circular Layout 245 Grid Layout 258 Hierarchical Layout 142 Link Layout 192 Multiple Layout 286 Random Layout 220 Recursive Layout 272 Spri
57. along the x axis and y axis Creating a Grapher and Associating a Manager View You are now going to create an I1vGrapher Bean and associate a manager view with it The IlvGrapher Bean provides the data structure that contains the grapher you want to display To create the IlvGrapher Bean and associate a manager view with the grapher do the following ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 397 CREATING A SIMPLE APPLET USING ILOG JVIEWS GRAPH LAYOUT BEANS 1 On the JViews Graphics Framework Beans toolbar click the IlvGrapher 9 icon and drag it into the Form Designer The 11vGrapher class is not a graphical Bean so it is not managed the same way by the various IDEs The following figure shows the grapher as a small object inside the Form Designer Form Designer JApplet1 IlvGrapher Bean Japen Mde 4 2 To associate the manager view with the grapher select the 11vManagerView Bean so that its properties appear in the Property List You now need to set the Manager property of the IlvManagerView Bean to the new IlvGrapher Bean Keep in mind that the 11vGrapher class is a subclass of IlvManager 3 In the Property List window click the value column of the Manager property Change Default to ilvGrapherl 398 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Property List J amp pplet1 il ManagerViewl X
58. and polyline graphics it is not able to place labels precisely at smooth curves such as spline graphics 11vSpline or spline links I1vSplineLinkImage IlvOneSplineLinkImage IlvDoubleSplineLinkImage The algorithm handles labels as upright rectangles It is for instance not able to rotate a label to fit the flow of a link Brief Description of the Algorithm The algorithm uses simulated annealing This is a general randomized optimization technique that simulates a thermodynamic particle system Each label is moved to a new random position within the limits given by its label descriptor The quality of the new position is calculated and compared to the quality of the old position If the quality has not improved the label is moved back to the old position The amount of movement is 356 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT controlled by a conceptual temperature when the system is hot the labels can move long distances producing potentially large global quality improvements When the system cools down the move distances become smaller and hence focus on local fine tuning of the position Each label has its own label descriptor The label descriptor describes the path on which the label can move If a label must be placed at a city in a geographic map then its label descriptor makes sure that the label is always placed close to the graphics that represent the city If a label must be
59. and the offsets between the link borders are different In the drawing on the right the thick links have more space available than do the thinner links The offset between the link border at the segments that connect to the left node is constant because the link width is considered in the calculation of the connection points LinkWidthUsed false LinkWidthUsed true Figure 4 69 Using the Link Width To enable the connector calculation to respect the link width use the following call layout setLinkWidthUsed true The link width setting is disabled by default The link width has no effect if the connector styles CENTERED_PINS Or CLIPPED PINS are used Port Sides Parameter The Hierarchical Layout algorithm produces a layout where the majority of the links flow in the same direction If the flow direction is towards the bottom usually the incoming links are connected to the top side of the node and the outgoing links are connected to the bottom side of the node It is also possible to specify on which side a link connects to the node To simplify the explanations of the port sides we use the compass directions north south east and west The specified link flow direction is always towards south and the first level is towards north If the flow direction is towards bottom north is at the top south at the bottom east on the right and west on the left side of the drawing If the flow direction is toward
60. automatically You can affect how the nodes are positioned within each level by specifying the position index of some nodes The nodes are placed at the specified position within their level To specify the position index of a node use the following method void setSpecNodePositionIndex Object node int index The default value is 1 If the default value is used if a node is set to a negative position index or if a node is set to a position index that is larger than the number of nodes of its level the layout automatically calculates an appropriate position index during the crossing reduction step To obtain the current position index of a node use the following method int getSpecNodePositionIndex Object node Relative Position Constraints r lt fe gt e gt 3 Working with absolute node position indices is inconvenient in certain situations For instance if two nodes belong to the same level you may want to force one node to a position with a lower index than the other node without fixing the absolute positions of the nodes You can achieve this by using a relative position constraint layout addConstraint new IlvRelativePositionConstraint nodeA nodeB priority ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 175 HIERARCHICAL LAYOUT This forces nodeA to a lower position than nodeB If the flow direction is towards the bottom the nodes are in horizontal levels hen
61. be saved in IVL files For details see Saving Layout Parameters and Preferred Layouts on page 315 Code Sample The following code sample illustrates the use of the class I1vDefaultLayoutProvider IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher Fill the graphers with nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create a grapher adapter for the topmost graph IlvGrapherAdapter adapterA new IlvGrapherAdapter grapherA Get a grapher adapter for the subgraph IlvGraphModel adapterB adapterA getGraphModel grapherB Create the layout provider IlvDefaultLayoutProvider provider new IlvDefaultLayoutProvider Specify the preferred layouts for each grapher this automatically attaches the layouts provider setPreferredLayout adapterA new IlvTreeLayout provider setPreferredLayout adapterB new IlvGridLayout Create a recursive layout in specified provider mode IlvRecursiveLayout layout new IlvRecursiveLayout provider Perform the layout try IlvRecursiveLayoutReport layoutReport IlvRecursiveLayoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e r lt c p gt gt 3 System err println e getMessage d
62. cannot use these mechanisms You must use a same level constraint gt r lt c p gt O mi gt 3 layout addConstraint new IlvSameLevelConstraint nodel node2 This forces node1 and node2 to be placed into the same level but it does not constrain them to any particular level Figure 4 82 illustrates the placement of nodes on the same level ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 173 HIERARCHICAL LAYOUT penas pee Jones ies Figure 4 82 All Nodes Fixed at Same Level Group Spread Constraint An alternative way to force a group of nodes to the same level is by specifying a group spread constraint with a spread size of zero 0 In general the group spread constraint forces a group of nodes to subsequent levels The number is the spread size It does not select the lowest or highest level index of the group but only requires that the nodes be placed no more than k levels apart Hence if k 0 all nodes of the group are placed at the same level The following example illustrates the general group spread constraint IlvNodeGroup nodeGroup new IlvNodeGroup nodeGroup add nodeA nodeGroup add nodeB nodeGroup add nodeC layout addConstraint new IlvGroupSpreadConstraint nodeGroup 2 The constraint is satisfied if the highest level index for nodeA nodeB and nodeC is no more than two levels apart from the smallest level index of
63. checks whether a set of valid constraints are in conflict with each other Thus constraint resolution is a complex process on a network of multiple related constraints Constraint resolution decides which constraints can be solved and which cannot But the constraint resolution does not remove conflicting constraints from the layout instance it just delivers a solution that may ignore some constraints For Experts More Indices The Hierarchical Layout allows you to specify the level index and the position index of a node How these indices are used depends on the graph topology and the additional constraints It is also possible to obtain the indices of nodes that were calculated during layout Calculated Level Index The layout algorithm allows you to access the level index that was calculated for a node by a previous layout To do this use the following method int getCalcNodeLevelIndex Object node If the node was never laid out this method returns 1 Otherwise it returns the previous level index of the node The method can be used to specify the level index for the next layout in the following way int index layout getCalcNodeLevelIndex node layout setSpecNodeLevelIndex node index When this is done it ensures that the node is placed at the same level as in the previous layout r lt gt e gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 183 HIERARCHICAL L
64. class 232 isFixed method IlvGraphLayout class 32 33 isForceFitToLayoutRegion method IlvUniformLengthEdgesLayout class 88 isInterGraphLink method IlvGraphModel class 300 isLabel method IlvLabelingModel class 385 389 isLayerAddedmethod IlvGrapherAdapter class 322 isLayoutNeeded method IlvGraphModel class 301 isLayoutOfConnectedComponentsEnabled method IlvGraphLayout class 305 isLayoutOfConnectedComponentsEnabledByDe fault method IlvGraphLayout class 305 isLayoutTimeElapsed method IlvGraphLayout class 22 isLink method IlvGraphModel class 299 isLinkBetween method IlvGraphModel class 300 isMemorySavings method IlvGraphLayout class 91 isNode method IlvGraphModel class 299 isObstacle method IlvLabelingModel class 385 389 isPolylineObstacle method IlvLabelingModel class 385 isPreserveFixedLinks method IlvGraphLayout class 32 isPreserveFixedNodes method IlvGraphLayout class 93 isRespectNodeSizes method IlvUniformLengthEdgesLayout class 88 isRootPosition method IlvTreeLayout class 103 isStarCenter method IlvCircularLayout class 247 isSubgraph method IlvGraphModel class 300 INDEX IsTree static method IlvGraphLayoutUtil class 49 isUseDefaultParameters method IlvGraphLayout class 36 isUseSeedValueForRandomGenerator method IlvGraphLayout class 34 IVL files 315 compatibility issues 320 J Java application sample code 342 Java application sample code 38 L label 340 aut
65. criteria because many of the criteria are mutually contradictory Time consuming trade offs may be necessary In addition it is not a trivial task to assign weights to each criteria Multicriteria optimization is in most cases too complex to implement and much too time consuming For these reasons layout algorithms are often based on heuristics and may provide less than optimal solutions with respect to one or more of the criteria Fortunately in practical terms the layout algorithms will still often provide reasonably readable drawings m 07 2 O O 5 o a Methods for Using Layout Algorithms Layout algorithms can be employed in a variety of ways in the various applications in which they are used The most common ways of using an algorithm are the following Automatic layout The layout algorithm does everything without any user intervention except perhaps the choice of the layout algorithm to be used Sometimes a set or rules can be coded to choose automatically and dynamically the most appropriate layout algorithm for the particular type of graph being laid out Semiautomatic layout The end user is free to improve the result of the automatic layout procedure by hand At times the end user can move and nodes at desired locations and perform the layout again In other cases a part of the graph is automatically set as read only and the end user can modify the rest of the layout
66. definition very similar to the corresponding methods of the 11vGrapher class The main difference is that the arguments of the 11vGraphModel methods are java lang Object instead of IlvGraphic or IlvLinkImage The methods can be divided into several categories that provide information on the structure of the graph the geometry of the graph modification of the graph geometry and notification of changes in the graph Information on the Structure of the Graph The following methods of the 11vGraphMode1 class allow the layout algorithms to retrieve information on the structure of the graph Enumeration getNodesAndLinks Enumeration getNodes int getNodesCount Enumeration getLinks int getLinksCount boolean isNode Object obj boolean isLink Object obj Enumeration getLinks Object node int getLinksCount Object node Enumeration getLinksFrom Object node int getLinksFromCount Object node soJnjeoaJj Enumeration getLinksTo Object node 2 o 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 299 USING THE GRAPH MODEL int getLinksToCount Object node Enumeration getNeighbors Object node int getNodeDegree Object node Object getFrom Object link Object getTo Object link Object getOpposite Object link Object node boolean isLinkBetween Object nodel Object node2 The following methods are provided for use with neste
67. directly by the following method void setSpecNodeLevelIndex Object node int index You pass a single node as the first argument not a node group The default index value is 1 If the default value is used or if a node is set to a negative level index the level index is considered to be unspecified In this case the layout algorithm automatically calculates an appropriate level index during the leveling phase of the algorithm To obtain the specified level index for a node use the following method int getSpecNodeLevelIndex Object node However this method returns the value that was set by set SpecNodeLevel Index If the level index was specified by allocating a corresponding level range constraint that has the same meaning get SpecNodeLevel Index still returns 1 Warning Using arbitrarily large level indices is not recommended For instance if you set the level index of a node to 100000 the layout algorithm creates 100 000 levels even if the graph has far fewer nodes This causes the layout algorithm to become unnecessarily slow Same Level Constraints If you want to force several nodes to the same level with fixed index you can set the level index parameter of these nodes accordingly see Level Index Parameter on page 174 or use a level range constraint see Level Range Constraints on page 173 However if you want to force several nodes to the same level without forcing them to a specific level index you
68. end points of the links are placed in the center of the border where the links are attached IlvTreeLayout CLIPPED PINS Each link pointing to the center of the node is clipped at the node border The connector pins are placed at the points on the border where the links are clipped This style affects straight links It behaves like centered connector pins for orthogonal links 112 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT IlvTreeLayout EVENLY_SPACED_PINS The connector pins are evenly distributed along the node border This style works for straight and orthogonal links IlvTreeLayout AUTOMATIC PINS The connector style is selected automatically depending on the link style and the layout mode In the nonradial modes the algorithm always chooses centered pins In the radial layout modes it chooses clipped pins To obtain the current choice use the following method int getConnectorStyle Note The connector style parameter requires link connectors at the nodes of an IlvGrapher fhat allow connector pins to be placed freely at the node border It is recommended that you use 11vRelativeLinkConnector for link connectors to be used in combination with 11vGrapher objects Using a Link Connection Box Interface By default the connector style determines how the connection points of the links are distributed on the border of the bounding box of the nodes symmetrically with respect to the m
69. final segments of the links incident to a given side of a node equally on the node border Long Link Layout Algorithm The Long Link Layout algorithm first treats each link individually For each link it first calculates the connection points at the end nodes that are on the grid and orders them according to a penalty value Connection points on used grid points have a very high penalty and therefore are very unlikely to be used r lt gt gt 3 For the orthogonal links see Figure 4 88 on page 187 the Long Link Layout algorithm then uses a grid traversal to search a route over free grid points from the start connection point to the end connection point Therefore in contrast to the short link mode orthogonal links can have any shape with a large number of bends if this is necessary to bypass obstacle nodes to avoid overlappings For the direct links see Figure 4 87 on page 187 it shortens the search by using a direct segment between the connection points ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 189 LINK LAYOUT 190 ILO After all links are placed a crossing reduction phase examines pairs of links and eliminates link crossings by exchanging parts of the routes between both links The Long Link Layout algorithm relies on the fact that links fit to the grid spacing and parts of the routes between different links can be exchanged Therefore the Long Link Layout algorithm does
70. float getMarginOnBus Using a Link Clipping Interface By default the Bus Layout does not place the connection points of links at the nodes At the bus node it installs a bus link connector that is responsible for the connection points At the other nodes it relies on their link connectors to determine the connection points If no link connectors are installed at these nodes the default behavior is to connect to a point at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correct the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 114 without clipping with clipping Figure 4 114 Effect of Link Clipping Interface You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface 236 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT Note The link clip interface requires link connectors at the nodes of an 11vGrapher that allow connector pins to be placed freely at the node border
71. forces the two nodes to be placed side by side However it does not specify which node is at the lower node position and which node is at the higher node position If the group consists of more than two nodes it forces the nodes to be placed at consecutive positions such that all nodes are clustered together A node that does not belong to the group cannot be placed between the nodes of the group For instance assume that the group contains the three nodes A C The constraint is satisfied if the position indices of A B and C are 3 4 5 or 9 7 8 However if node D is placed between A and B say D has position 4 A has position 3 and C has position 5 then the constraint is not satisfied because D does not belong to the same group The side by side constraint has an effect only if the nodes actually belong to the same level To achieve this you can for instance use a same level constraint in addition Side by side constraints have priorities that decide how to resolve constraint conflicts The higher the priority the more likely the constraint is satisfied You can use side by side constraints to create nested clusters For example IlvNodeGroup groupl new IlvNodeGroup groupl add nodeA groupl add nodeB groupl add nodeC 176 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT groupl add nodeD layout addConstraint new IlvSideBySideConstraint groupl 10 0f IlvNodeGroup group2 new IlvN
72. graph The layout should not change very much when compared to the layout of the original graph r lt gt gt 3 The first layout results in a drawing with minor deficiencies You want to solve these deficiencies manually and perform a second layout to clean up the drawing The second layout probably should not change very much the parts of the graph that were already acceptable after the first layout The Hierarchical Layout supports sequences of layout that do not change very much It allows you to preserve the level index of a node and the position index of the node within the level By doing this the relative position of a node compared to a previous layout does not ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 263 GRID LAYOUT change The algorithm calculates new coordinates for the nodes and new routings for the links to adjust the absolute positions of the objects in order to clean up the drawing The relative order such as node A is in a level above node B or node A is left of node B can be preserved if you use the combination of specified and calculated level index and position index This is described in the following two sections 264 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL RECURSIVE LAYOUT Recursive Layout In this section you will learn about the Recursive Layout class from the ILOG JViews Graph Layout module class 11vRecursiveLayout from the package
73. grapher addLink link3 false grapher addLink link4 false grapher addLink link5 false set some nice colors setLinkColors link1 link2 link3 link4 link5 Add labels objects Since we perform layout later play a role Labels are neither nodes nor links hence add them as the initial position doesn t IlvPoint p new IlvPoint 0 0 IlvZoomableLabel labell new IlvZoomableLabel p Labell ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 343 GETTING STARTED WITH LABELING 344 IlvZoomableLabel label2 new IlvZoomableLabel p Label2 IlvZoomableLabel label3 new IlvZoomableLabel p Label3 IlvZoomableLabel label4 new IlvZoomableLabel p Label4 IlvZoomableLabel label5 Il Il grapher addObject labell false grapher addObject label2 false grapher addObject label3 false grapher addObject label4 false grapher addObject label5 false grapher addObject label6 false Declare a handle for the layout instance IlvAnnealingLabelLayout layout new IlvAnnealingLabelLayout Declare a handle for the layout report IlvLabelLayoutReport layoutReport null Attach the manager to the layout instance layout attach grapher new IlvZoomableLabel p Start Label IlvZoomableLabel label6 new IlvZoomableLabel p End Label For each label set a label descriptor that specifies labell belongs to linkl label2 belongs to link2 and so on link5 has 2 labe
74. graphic objects 418 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL A absolute level position range 167 absolute level position tendency 167 accept method IlvLayoutGraphicFilter class 922 accessing all sublayouts 275 addClusterId method IlvCircularLayout class 246 addGraphLayoutEventListener method IlvGraphLayout class 295 addGraphModelListener method IlvGraphModel class 301 adding layout constraints 171 addLabelingModelListener method IlvLabelingModel class 387 addLayer method IlvDefaultLabelingModel class 379 IlvLayoutGraphicFilter class 922 addLineObstacle method IlvLongLinkLayout class 214 addNode method IlvGrapher class 841 addOb ject method IlvManager class 341 addRectObstacle method IlvLongLinkLayout class 214 adjustmentEnd method Index IlvGraphModel class 301 alignment options Grid Layout 259 Tree Layout free mode 106 allowed time parameter Bus Layout 224 Grid Layout 257 Hierarchical Layout 140 Link Layout 191 Multiple Layout 285 Recursive Layout 271 Spring Embedder Layout 75 Topological Mesh Layout 59 Tree Layout 99 Uniform Length Edges Layout 85 angle layout criteria 15 animation parameter Link Layout 191 Spring Embedder Layout 75 Topological Mesh Layout 59 Uniform Length Edges Layout 85 Annealing Label Layout 354 allowed time parameter 358 automatic update 372 code sample 357 description 356 expert parameters 372 features 356 generic param
75. ilog views graphlayout recursive Application Domain The 11vGrapher class provided by the ILOG JViews Graphic Framework allows nested graphs to be represented for details see the chapter Nested Managers and Nested Graphers in ILOG JViews Graphics Framework User s Manual An example of a nested graph is given in Figure 4 130 INetwork1 Network1 2 Figure 4 130 Example of a Recursive Layout of a Nested Graph In this example there is a topmost graph which contains two nodes named Part 1 and Part2 connected by a link Each of these two nodes is another graph composed of three nodes connected by links Finally each of these nodes is another graph composed of some icons connected by links m r lt gt gt 3 Such nested graphs are often used to represent the hierarchical decomposition of a network into subnetworks more generally to mix connectivity information for several levels of detail in the same drawing In Figure 4 130 a layout algorithm the Tree Layout has been used for each of the graphs ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 265 RECURSIVE LAYOUT The Recursive Layout class is not a layout algorithm but rather a facility to apply another layout algorithm recursively on a nested graph It traverses the nesting structure starting from the graph that is attached to the Recursive Layout itself and recursively applies a layout on all subgrap
76. in IlvGraphLayoutUtil fo automatically replace inappropriate links This can be done before layout or when the 11vInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 To obtain the current choice use the following method int getLinkStyle Spring Constant The spring constant is an important parameter because it controls the force characteristics in the spring model Changing the value of the spring constant can cause large variations in the layout Recommended values range from 6 to 18 A better range is 12 to 16 To specify the spring constant use the method void setSpringConstant float constant To obtain the current value use the method float getSpringConstant Using a Link Clipping Interface By default the Spring Embedder Layout does not place the connection points of links It relies on the link connectors of the nodes to determine the connection points If no link connectors are installed at the nodes the default behavior is to connect to a point at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correc
77. is not done if the coordinates mode is specified as view coordinates If no view is attached the method returns nu11 The layout algorithms call a different method IlvRect getCalcLayoutRegion This method first tries to use the layout region specification by calling the method get SpecLayoutRegion If this method returns a non null rectangle this rectangle is returned Otherwise the method tries to estimate an appropriate layout region according to the number and size of the nodes in the attached graph If no graph is attached or the attached graph is empty it returns a default rectangle 0 0 1000 1000 To indicate whether a subclass of IlvGraphLayout supports the layout region mechanism the following method is provided boolean supportsLayoutRegion The default implementation returns false A subclass can override this method in order to return true to indicate that this mechanism is supported Note The implementation of the method void layout boolean redraw is solely responsible for whether the layout region is taken into account when calculating the layout and in which manner For details refer to the documentation of the layout algorithms 26 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Link Clipping Some layout algorithms try to calculate the specific connection points of links at the border of nodes and require instances of I1vRelativeLinkConnecto
78. is specified for a graph G and no preferred layout is set for its subgraphs then the graph G and all its subgraphs are laid out using the same layout algorithm L copies of it are used for the subgraphs Note You must call the method detachLayouts IlvGraphModel graphModel boolean traverse when you no longer need the layout provider instance otherwise some objects may not be garbage collected 312 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYING OUT NESTED GRAPHS The settings of the preferred layout made using the class IlvDefaultLayoutProvider can be saved in IVL files For details see Saving Layout Parameters and Preferred Layouts on page 315 Code Sample The following code sample illustrates the use of the class I1vDefaultLayoutProvider IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher Fill the graphers with nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create a grapher adapter for the topmost graph IlvGrapherAdapter adapterA new IlvGrapherAdapter grapherA Get a grapher adapter for the subgraph IlvGraphModel adapterB adapterA getGraphModel grapherB create the layout provider IlvDefaultLayoutProvider provider new IlvDefaultLayoutProvider specify the preferred layouts for each grapher this automatically attaches the layouts provider setPreferredLayout adapterA new IlvTreeLayout pr
79. it has been disposed When a layout provider an instance of IlvDefaultLayoutProvider instantiated by your code is no longer useful call the method detachLayouts model true on it passing as arguments the graph models that have been used for performing a recursive layout with this provider 328 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL DEFINING A NEW OF LAYOUT Defining a New Type of Layout If the layout algorithms provided in ILOG JViews do not meet your needs you can develop your own layout algorithms by subclassing 11vGraphLayout When a subclass of 11vGraphLayout is created it automatically fits into the generic layout framework of ILOG JViews and benefits from its infrastructure generic parameters see Layout Parameters and Features in IlvGraphLayout on page 20 notification of progress see Using Event Listeners on page 294 capability to lay out any graph object using the generic graph model see Using the Graph Model on page 297 capability to apply the layout separately for the connected components of a disconnected graph see Laying Out Connected Components of a Disconnected Graph on page 304 capability to lay out nested graphs see Laying Out Nested Graphs on page 306 and so on Sample Code To illustrate the basic ideas for defining a new layout the following simple example shows a possible implementation of the simplest layout algorithm the Random Layout The new layout class is called MyRandomLay
80. keep the layout algorithms informed of these changes When the layout algorithm is restarted on the same graph it is able to detect whether the data structures have changed since the last time the layout was successfully performed If necessary the layout can be performed again If there was no change the layout algorithm can avoid unnecessary work by not performing the layout The labeling model event listener is defined by the Label ingModelListener interface receive the events that is instances of the LabelingModelEvent class a class must implement LabelingModelListener interface and must register itself using the addLabelingModelListener method of the T1vLabelingModel class Note The label layout algorithms register themselves as listeners to the labeling model via the functionality in 3X1vLabelLayout Therefore there is usually no need to manipulate these listeners directly Storing and Retrieving Object Properties The following methods of the 11vLabelingModel class allow a layout algorithm to store data objects for each label or obstacle void setProperty Object labelOrObstacle String key Object value ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 387 DEFINING YOUR OWN LABELING MODEL Object getProperty Object labelOrObstacle String key void setProperty String key Object value Object getProperty String key The layout algorithm may need to associate a set of prop
81. labeling model Before you attach the graph model you call the method set LabelingModel in the following way multipleLayout setLabelingModel myLabelingModel multipleLayout attach myGraphModel You must specify the labeling model in this way if your nodes links and labels are not stored in an I1vGrapher but in your own data structures because the default labeling model is designed to handle only anIlvGrapher If the Multiple Layout instance is detached from the graph model all sublayouts are automatically detached as well ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 287 MULTIPLE LAYOUT Combining Multiple and Recursive Layout Often the Multiple Layout is used inside a Recursive Layout For convenience ILOG JViews provides a layout algorithm that combines both mechanisms the Recursive Multiple Layout This is a Recursive Layout see Recursive Layout on page 265 that uses an instance of Multiple Layout for each subgraph In order to apply a Tree Layout a Link Layout and an Annealing Label Layout recursively on a nested graph you can use IlvRecursiveMultipleLayout layout new IlvRecursiveMultipleLayout new IlvTreeLayout new IlvLinkLayout new IlvAnnealingLabelLayout This is in principle the same as a Recursive Layout that has a Multiple Layout as a reference layout IlvRecursiveLayout layout new IlvRecursiveLayout new IlvMultipleLayout new IlvTreeLayout new IlvLinkLayout new Ilv
82. layout algorithms whether or not they use the JViews grapher 11o0g views IlvGrapher However to make things very simple for the common case of applications that manipulate an I1vGrapher it is not mandatory to work directly with the graph model except for some advanced features such as filtering see Using the Filtering Features to Lay Out a Part of an IlvGrapher on page 321 so1njeoaJj e 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 297 USING THE GRAPH MODEL The Graph Model Concept With a graph model you can use already built graphs nodes and links that have been developed without ILOG JViews and apply the layout algorithms of ILOG JViews The graph model provides the basic generic operations for performing the layout A subclass must be written to adapt the graph model to specific graph node and link objects This subclass plays the role of an adapter or bridge between the application objects and the graph model This often makes it much easier to add graph features to existing applications Figure 5 1 shows the relationship between the graph model and graph layout algorithms ILOG JViews graphers non JViews graphers and manager views Graph Model Layout Algorithm Nan diis IlvGraphModel IlvGraphLayout SE Lew optional Filter IlvLayoutGraphicFilter optional Custom Adapter subclass of IlvGraphModel Adapter IlvGrapherAdapter Custom
83. layout getLongLinkLayout getCalcFallbackLinks For instance you can iterate over these links and apply your own specific fallback mechanism instead of the default fallback mechanism of the Long Link Layout algorithm 216 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL RANDOM LAYOUT Random Layout In this section you will learn about the Random Layout algorithm from the ILOG JViews Graph Layout module class IlvRandomLayout from the package ilog views graphlayout random Sample Here is a sample drawing produced with the Random Layout Figure 4 104 Graph Drawing Produced with the Random Layout What Types of Graphs Any type of graph Connected and disconnected graphs Planar and nonplanar graphs r lt gt gt 3 Features Random placement of the nodes of a grapher inside a given region ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 217 RANDOM LAYOUT 218 Limitations The algorithm computes random coordinates for the upper left corner of the graphic objects representing the nodes In some cases this may not be appropriate To ensure that the nodes do not overlap the margins of the layout region the algorithm computes the coordinates randomly inside a region whose width and height are smaller than the width and height of the layout region The difference is the maximum width and the maximum height of the nodes respectively In some c
84. layout region If several manager views are attached the first attached view is used If no manager view is attached the layout region is automatically estimated on the basis of the number and size of the nodes Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 85 UNIFORM LENGTH EDGES LAYOUT This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to the border of the node shapes See Using a Link Clipping Interface on page 91 for details of the link clipping mechanism Link Connection Box The layout algorithm can use a link connection box interface see Link Connection Box on page 29 in combination with the link clip interface If no link clip interface is used the link connection box interface has no effect For details see Using a Link Clipping Interface on page 91 Preserve Fixed Links The layout algorithm does not reshape the links that are specified as fixed See Preserve Fixed Links on page 32 See also Link Style on page 86 Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed Moreover the algorithm takes into account the fixed nodes when computing the position of the nonfixed nodes See Preserve Fixe
85. link priorities is important in combination with ports Links with from ports on the south side and to ports on the north side are preferably laid out opposite to the flow direction Such a feedback link may cause parts of the drawing to tip over Figure 4 74 shows an example The red link is a feedback link with port specifications To obtain the correct result as shown in the drawing on the right side of Figure 4 74 you would set the priority of the feedback link to a very low value 158 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT MNT Link D gt B has a lower priority than the other links All links have the same priority Figure 4 74 Using Link Priorities and Ports Spacing Parameters The spacing of the layout is controlled by three kinds of spacing parameters the minimal offset between nodes the minimal offset between parallel segments of links and the minimal offset between a node border and a bend point of a link or a link segment that is parallel to this border The offset between parallel segments of links is at the same time the offset between bend points of links All three kind of parameters occur in both directions horizontally and vertically Horizontal Link Offset Horizontal Horizontal Node Link Node Offset Offset Vertical Node Offset Horizontal Node Link Offset rc lt gt Q e gt 3 Figure 4 75 Spacin
86. methods are available for finding the shortest path between two nodes the minimum cost path and so on Graph layout is used in graphical user interfaces of applications that need to display graph models To lay out a graph means to draw the graph so that an appropriate readable representation is produced Essentially this involves determining the location of the nodes and the shape of the links For some applications the location of the nodes may be already known based on the geographical positions of the nodes for example However for other applications the location is not known a pure logical graph or the known location if used would produce an unreadable drawing of the graph In these cases the location of the nodes must be computed But what is meant by an appropriate drawing of a graph In practical applications it is often necessary for the graph drawing to respect certain quality criteria These criteria may vary depending on the application field or on a given standard of representation It is often difficult to speak about what a good layout consists of Each end user may have different subjective criteria for qualifying a layout as good However one common goal exists behind all the criteria and standards the drawing must be easy to understand and provide easy navigation through the complex structure of the graph These topics are pursued in the following sections What is a Good Layout Methods for Using L
87. modes void setParentChildOffset float offset void setSiblingOffset float offset void setBranchOffset float offset Note that the sibling and branch offsets are minimal distances tangential to the circles or ellipses while the parent child offset is a minimal distance radial to the circles or ellipses Figure 4 47 shows the spacing parameters in radial layout mode Sibling Offset Sibling Offset ta bun Offset Parent Child Offset Branch Offset Shing toe r lt gt gt 3 Figure 4 47 Spacing Parameters Radial Layout Mode ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 123 TREE LAYOUT For Experts Adding an Invisible Root to the Layout If the graph contains several trees that are disconnected from each other the layout places them individually next to each other Each connected component has its own radial structure with circular layers However sometimes it is appropriate to fit all connected components into a single circular layer structure Conceptually this is done by adding an invisible root at the center and connecting all disconnected trees to this root Figure 4 48 shows the effect of using an invisible root This works only if the generic mechanism to lay out connected components is switched off using the following method layout setLayoutOfConnectedComponentsEnabled false To use an invisible root to combine disconnected components use the
88. node To obtain the current choice for the starting node use the method Object getStartingNode If you do not specify a starting node an arbitrary node of the graph is used If you specify a starting node but want to reset the setting and return to the default behavior that is having an arbitrary node automatically chosen as the starting node call the set Start ingNode method with a nu11 argument Outer Cycle Step 1 of TML computes a set of cycles that can be used as the outer cycle in Step 2 By default the longest cycle is actually used that is the cycle containing the largest number of nodes However you may find it useful to try a different outer cycle In this case you can use the method void setExteriorCycleId int cycleId The valid values for 1 range from zero to the number of cycles computed by Step 1 minus one This number is returned by the method int getNumberOfPossibleExteriorCycles If the number is not in this range the value zero is used To obtain the current choice for the starting node use the method int getExteriorCycleId You can use these methods only after having successfully performed the layout Otherwise no outer cycle is defined When the layout is performed again with a new outer cycle only Step 2 of TML is performed and not the time consuming Step 1 This is true if the topology of the graph has not been changed that is no nodes or links were added o
89. not take the link width into account because it would be too difficult to find the parts of two links that can be exchanged It is recommended to set the grid spacing larger than the largest link width Code Sample Below is a code sample using the 11vLinkLayout class import ilog views import ilog views graphlayout import ilog views graphlayout link IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher Fill in the grapher with nodes and links here IlvLinkLayout layout new IlvLinkLayout layout attach grapher Specify the layout mode layout setLayoutMode IlvLinkLayout SHORT LINKS try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vLinkLayout class supports the following generic parameters as defined in the class IlvGraphLayout Allowed Time Animation Automatic Layout G JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT Preserve Fixed Links Save Parameters to Named Properties Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass Allowed Time The layout algorithm stops if the allowed time setting has e
90. obstacles need to be removed while a layout instance is attached that is before detach is called and you use a default labeling model class IlvDefaultLabelingModel the cleaning of properties for the removed labels and obstacles is done automatically The default labeling model fires labeling model events to the layout when objects are removed from the manager The layout listens to these events and calls cleanLabel and cleanObstacle automatically Notice that this also holds when you attach the layout directly to the manager by calling attach IlvManager manager because in this case the default labeling model is always created and used internally ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 383 DEFINING YOUR OWN LABELING MODEL Iflabels or obstacles need to be removed while a layout instance is attached and you use your own subclass of 11vLabelingModel see Defining Your Own Labeling Model on page 384 the cleaning is done automatically only if your labeling model fires labeling model events whenever an object gets removed If no events are fired you must call the methods cleanLabel or cleanObstacle yourself after removing any label or obstacle from the manager to perform the cleaning for it When a labeling model instantiated by your code is no longer useful call the method dispose it to ensure that the resources it has used are released Note that a labeling model must not be used once it has been disposed of S
91. of ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 289 MULTIPLE LAYOUT 290 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL Using Advanced Features This chapter describes advanced features for using the Graph Layout module of ILOG JViews The following topics are covered 9 99 9 9 FF 9 o o ILOG Using a Layout Report Using Event Listeners Redrawing the Grapher after Layout Using the Graph Model Laying Out a Non JViews Grapher Laying Out Connected Components of a Disconnected Graph Laying Out Nested Graphs Saving Layout Parameters and Preferred Layouts Using the Filtering Features to Lay Out a Part of an IlvGrapher Choosing the Layout Coordinate Space Releasing Resources Used During the Layout Defining a New Type of Layout soinjeo4 Questions and Answers about Using the Layout Algorithms e 5 gt 2 lt o 5 o JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 291 USING A LAYOUT REPORT Using a Layout Report 292 Layout reports are objects used to store information about the particular behavior of a layout algorithm After the layout is completed this information is available to be read from the layout report Layout Report Classes Each layout class instantiates a particular class of ilog views graphlayout IlvGraphLayoutReport each time the layout is performed Table 5 1 shows the layout classes and their corresponding layout reports Table 5 1 Layout Repo
92. of IlvGraphLayout The class ITlvGraphLayout is an abstract class It has no constructors You will instantiate a subclass as shown in the following example IlvLinkLayout layout new IlvLinkLayout If you want to use the layout report that is returned by the layout algorithm you need to declare a handle for the appropriate layout report class as shown in the following example IlvGraphLayoutReport layoutReport For more information on the layout report see Using a Layout Report on page 292 Attaching a Grapher You must attach the grapher before performing the layout The following method defined on the class IlvGraphLayout allows you to specify the grapher you want to lay out void attach IlvGrapher grapher For example IlvGrapher grapher new IlvGrapher Add nodes and links to the grapher here layout attach grapher The attach method does nothing if the specified grapher is already attached Otherwise it first detaches the grapher that is already attached if any You can obtain the attached grapher using the method getGrapher If the grapher is attached in this way a default graph model is created internally For details on the graph model see Using the Graph Model on page 297 The attached graph model can be obtained by IlvGraphModel graphModel layout getGraphModel Warning Notice that such an internally created model is not allowed to be attached to any other layout instance nor to be us
93. of events layout events and parameter events Layout Event Listeners The layout event listeners mechanism provides a way to inform the end user of what is happening during the layout At times a layout algorithm may take a long time to execute especially when dealing with large graphs In addition an algorithm may not converge in some cases No matter what the situation the end user should be informed of the events that occur during the layout This can be done by implementing a simple progress bar or by displaying appropriate information such as the percentage of completion after each iteration or step The layout event listener is defined by the GraphLayoutEventListener interface To receive the layout events delivered during the layout a class must implement the 294 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING EVENT LISTENERS GraphLayoutEventListener interface and must register itself using the addGraphLayoutEventListener method of the IlvGraphLayout class When you implement the GraphLayoutEventListener interface you must implement the layout StepPerformed method The layout algorithm will call this method on all the registered layout event listeners passing the layout report as an argument In this way you can read information about the current state of the layout report For example you can read this information after each iteration or step of the layout algorithm The following example shows how
94. out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage The statement with multipleLayout performLayout in this case has the same effect as the sequence of the three statements treeLayout performLayout linkLayout performLayout labelLayout performLayout Recursive Layout If you perform the Multiple Layout on a grapher that contains submanagers there is a difference in the order of the layout see Order of Layouts in Recursive Layouts on page 307 You apply a recursive layout on the grapher and its submanagers in the following way IlvRecursiveLayout recursiveLayout new IlvRecursiveLayout multipleLayout try r lt o c gt e gt 3 IlvGraphLayoutReport layoutReport recursiveLayout performLayout catch IlvGraphLayoutException e System err println e getMessage or alternatively in the following way both ways are equivalent try ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 283 MULTIPLE LAYOUT IlvMultipleLayoutReport layoutReport IlvMultipleLayoutReport multipleLayout performLayout true true true catch IlvGraphLayoutException e System err println e getMessage Assume the attached grapher A contains a subgrapher B The combined Multiple Layout applies its sublayouts in postorder as follows 1 Tree Layout on B 2 Link
95. over its children taking the center of the children into account IlvTreeLayout BORDER CENTER The parent is centered over its children taking the border of the children into account If the size of the first and the last child varies the border center alignment places the parent closer to the larger child than to the default center alignment IlvTreeLayout EAST The parent is aligned with the border of its easternmost child For instance if the flow direction is to the bottom east is the direction to the right If the flow direction is to the 106 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT top east is the direction to the left See Using Compass Directions for Situating Layout Parameters on page 103 for details IlvTreeLayout WEST The parent is aligned with the border of its westernmost child For instance if the flow direction is to the bottom west is the direction to the left If the flow direction is to the right west is the direction to the bottom See Using Compass Directions for Situating Layout Parameters on page 103 for details IlvTreeLayout TIP OVER The children are arranged sequentially instead of in parallel and the parent node is placed with an offset to the children For details see Tip over Alignment on page 108 i1ilvTreeLayout TIP OVER BOTH SIDES The children are arranged sequentially instead of in parallel Whereas the alignment TI
96. package ilog views graphlayout topologicalmesh Samples Here are some sample drawings produced with TML Figure 4 1 Small Cyclic Graph Drawing Produced with TML 54 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TOPOLOGICAL MESH LAYOUT TML Figure 42 Large Cyclic Graph Drawing Produced with TML What Types of Graphs Cyclic 2 connected graphs Preferably without cut nodes or cut edges otherwise manual adjustments are necessary Cyclic 2 connected graphs plus only a few branches You may need to make manual adjustments for the branches Both planar and nonplanar graphs Application Domains Application domains of the Topological Mesh Layout include Database and knowledge engineering semantic networks qualitative reasoning and other artificial intelligence diagrams r lt gt fe gt 3 Features Most of the time produces planar drawings of planar graphs and drawings with a small number of link crossings for nonplanar graphs Produces a nice layout for most small and medium size graphs relatively quickly The maximum cyclomatic number of the graph is about 30 50 but the number of nodes and links can be a lot higher ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 55 ToPOLOGICAL MESH LAYOUT TML Most of the time produces symmetrical drawings of symmetrical graphs The computation time for one iteration depends on th
97. placed freely at the node border It is recommended that you use IlvRelativeLinkConnector or IlvClipLinkConnector for link connectors to be used in combination with 11vGrapher objects The clip link connector updates the clipped connection points automatically during interactive node movements If a node has an irregular shape the clipped links sometimes should not point towards the center of the node bounding box but to a virtual center inside the node You can achieve this by additionally providing a class that implements the IlvLinkConnectionBoxInterface example for the implementation of a link connection box interface is in Link Connection Box on page 29 To set a link connection box interface call void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface The link connection box interface is used only when link clipping is enabled by setting a link clip interface If no link clip interface is specified the link connection box interface has no effect ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UNIFORM LENGTH EDGES LAYOUT An example of the combined effect is shown in Figure 4 26 x NM need Clipping at the node bounding box Clipping at a specified connection box Figure 4 26 Combined Effect of Link Clipping Interface and Link Connection Box If the links are clipped at the green irregular star node Figure 4 26 left they do not point towards the center of the star but towards the center of the bou
98. placement of labels e ilog views graphlayout labellayout annealing For close label positioning e ilog views graphlayout labellayout random For random placement ilog views graphlayout swing Swing components useful for creating applications mixing ILOG JViews Graph Layout and Swing ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 3 THE ILOG JViEWS GRAPH LAYOUT ALGORITHMS The ILOG JViews Graph Layout Algorithms The Graph Layout module of ILOG JViews provides numerous ready to use layout algorithms They are shown below with sample illustrations In addition new layout algorithms can be developed using the generic layout framework of the ILOG JViews Graph Layout module Topological Mesh Layout TML Spring Embedder Layout 4 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ILOG JViEWS GRAPH LAYOUT ALGORITHMS THE 1 Introducing the Graph Layout Module Uniform Length Edges Layout use aa th Circular Layout Ring Star USER S MANUAL ILOG JVIEWS GRAPH LAYOUT 5 5 THE ILOG JViEWS GRAPH LAYOUT ALGORITHMS Hierarchical Layout Link Layout 6 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ILOG JViEWS GRAPH LAYOUT ALGORITHMS Tree Layout 1 Q E 2 lt p Random Layout Bus Layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 7 FEATURES OF THE ILOG JViEWS GRAPH LAYOUT MODULE Gri
99. set of nodes also called vertices connected by a finite set of links also called edges or connections In ILOG JViews an instance of the class IlvGrapher More generally a Java object that is used to manage a collection of nodes and links The process that applies a layout algorithm to a graph Also the graph drawing that results from the layout process In the ILOG JViews Graph Layout framework a Java class that defines a suitable generic API for graphs or an instance of the class IlvGraphModel A drawing where nodes and link bends have discrete integer coordinates A layout process where the result of a previous layout is used as the starting point for applying the layout algorithm a second time to a modified graph in order to minimize the changes A link node connection link is incident to a node if the node is at one end of the link A node is incident to a link if that link is incident to the node In ILOG JViews the storage area of a manager in which graphic objects are placed A manager uses multiple layers referenced by index numbers Objects in a higher numbered layer are displayed in front of objects in a lower numbered layer The process that computes new coordinates for nodes and or new shapes for links in order to obtain a suitable representation of a graph In the ILOG JViews Graph Layout module the rectangle where the graph drawing will be placed when the graph is laid out 414 ILOG JViEWS GRAPH LA
100. setOrthForkPercentage float percentage float getOrthForkPercentage If the link style is not orthogonal links may overlap neighboring nodes This happens only in a very few cases for instance when a link starts at a very small node that is neighbored by a very large node This deficiency can be fixed by increasing the branch offset However this influences the layout globally affecting nodes without that deficiency To avoid a global change you can change the overlap percentage instead which is a value between 0 and 100 This value is used by an internal heuristic of the layout algorithm that considers a node to be smaller by this percentage The default percentage is 30 This usually results in better usage of the space However if very small nodes are neighbored to very large nodes it is recommended to decrease the overlap percentage or to set it to 0 to switch this heuristic off to avoid links overlapping nodes The overlap percentage can be set and obtained by the following methods r lt gt 2 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 117 TREE LAYOUT void setOverlapPercentage float percentage float getOverlapPercentage Note It is recommended that you always set the orthogonal fork percentage to a value larger than the value of the overlap percentage Overlap Percentage 60 96 Overlap Percentage 0 Figure 4 42 Effect of Using the Overlap Per
101. tCalcNodePositionIndex method 184 tConnectorStyle method 148 156 tDestinationPointMode method 149 tFlowDirection method 143 tFromPortIndex method 156 tFromPortSide method 155 tGlobalDestinationPointMode method 149 tGlobalLinkStyle method 146 tGlobalOriginPointMode method 149 HorizontalLinkOffset method 160 HorizontalNodeLinkOffset method 160 HorizontalNodeOffset method 160 LevelJustification method 144 LinkPriority method 158 LinkStyle method 146 NumberOfPorts method 156 tOriginPointMode method 149 Toce check g ge ge ge ge ge tSpecNodeLevelIndex method 173 tSpecNodePositionIndex method 175 tToPortIndex method 156 tToPortSide method 155 tVerticalLinkOffset method 160 tVerticalNodeLinkOffset method 160 ILOG JViEWS GRAPH LAYOUT 5 5 ge INDEX tVerticalNodeOffset method 160 provided as a Bean 392 se se se se se se se se se se se se se se se se se se S tConnectorStyle method 147 tDestinationPointMode method 149 tFlowDirection method 143 tFromPortIndex method 156 tFromPortSide method 154 156 tGlobalDestinationPointMode method 148 tGlobalLinkStyle method 145 tGlobalOriginPointMode method 148 HorizontalLinkOffset method 160 HorizontalNodeLinkOffset method 160 HorizontalNodeOffset method 160 IncrementalMode method 162 LevelJustification method 143 LinkPriority method 158 LinkStyle method 146 LinkWidthUsed method 153 umberOfPorts method 155 tOriginPoint
102. the child that should be in the leftmost position to the coordinate 0 0 and the child that should get the ith relative position in order from left to right to the coordinate W 1 i 0 Ifthe flow direction is to the left or to the right determine the maximal height H of all nodes Move the child that should be in the topmost position to the coordinate 0 0 and the child that should get the ith relative position in the order from top to bottom to coordinate 0 H 1 i Inthe radial layout modes determine the maximal diagonal w2 Hof all nodes If the position of the parentis x y before the layout move the child that should be the first in the circular order to the coordinate x y D and the child that should get the ith relative position in the circular order to coordinate x D i If you want to specify a relative order for all nodes in radial layout mode you must do this for the parents before you do it for the children In this case moving the children can be performed easily during a depth first traversal from the root to the leaves The layout that is performed after moving the children arranges the children with the desired relative order ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 133 r lt e gt gt 3 HIERARCHICAL LAYOUT Hierarchical Layout In this section you will learn about the Hierarchical Layout algorithm from the ILOG JViews G
103. the following constructor IlvAnnealingPolylineLabelDescriptor Object label IlvLinkImage link int anchor 364 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT The options for the anchor are IlvAnnealingPolylineLabelDescriptor CENTER place the label near the center of the link that is in the middle third of the link path IlvAnnealingPolylineLabelDescriptor START place the label near the source node of the link that is in the first third of the link path IlvAnnealingPolylineLabelDescriptor END place the label near the target node of the link that is in the last third of the link path o gt o r IlvAnnealingPolylineLabelDescriptor FREE place the label anywhere on the link Start Label Figure 6 9 Anchors for Label Positions at a Link Simple Positioning at a Polyline Obstacle This specification can be used if the label must be placed at a polyline obstacle an instance of I1vLine or IlvPolyline in the default labeling model The polyline obstacle does not need to be a link of a grapher Here is an example layout setLabelDescriptor label new IlvAnnealingPolylineLabelDescriptor label polyline IlvAnnealingPolylineLabelDescriptor FREE IlvDirection Left IlvDirection TopLeft IlvAnnealingPolylineLabelDescriptor GLOBAL The label is placed a
104. the minimum number for which there are no cycles in S The spanning tree is shown by the red links in the following illustration A type of network topology where the nodes are arranged on a circle with each node being connected to a center node A layout process where the layout algorithm is completely redone each time the graph is changed A drawing where each link is drawn as a straight line segment G is a subgraph of G if its node and link sets are included in the node and link sets of G ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 417 GLOSSARY tree topology undirected graph vertex view A connected acyclic graph that is a graph that does not contain any cycles The structure of a graph Two drawn graphs have the same topology if you can obtain one drawing from the other by moving the nodes and reshaping the links A graph in which every link is associated with an unordered pair of nodes A dot in a graph A graph consists of a finite set of vertices connected by a finite set of edges also called links or connections A vertex is also called a node In this documentation the term node is primarily used for the term vertex In ILOG JViews the AWT component where graphic objects are displayed To display graphic objects contained in the different layers of a grapher you create at least one view and often multiple views The grapher lets you connect as many views as you require to display
105. the nodes and links could be created by code try grapher read fileName catch Exception e System out println could not read fileName return ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 39 SAMPLE JAVA APPLICATION Attach the grapher to the layout instance layout attach grapher try Perform the layout and get the layout report IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode Print information from the layout report optional System out println layout done in layoutReport getLayoutTime millisec code code layoutReport codeToString code Catch the exceptions catch IlvGraphLayoutException e System out println e getMessage Detach the grapher from the layout instance layout detach further methods The sample Java application produces the graph shown in Figure 3 1 40 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL SAMPLE JAVA APPLICATION Figure 3 1 Output from Sample Java Application peueis Pune O 0 gt lt p ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 41 SAMPLE JAVA APPLICATION 42 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL Layout Algorithms This chapter describes the layout algorithms of the ILOG JViews Graph Layout module The following topics are covered Determining the Appropriate
106. the same drawing Global End Point Mode To set the global end point mode the following methods are provided void setGlobalOriginPointMode int mode void setGlobalDestinationPointMode int mode The valid values for mode are IlvLinkLayout FREE MODE the default 148 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT The layout is free to choose the appropriate position of the connection point on the origin destination node 1ilvLinkLayout FIXED MODE The layout must keep the current position of the connection point on the origin destination node IlvLinkLayout MIXED_MODE Each link can have a different end point mode The connection points are automatically considered as fixed if they are connected to grapher pins To obtain the current choice use the following methods int getGlobalOriginPointMode int getGlobalDestinationPointMode Individual End Point Mode All links have the same end point mode unless the global end point mode is IlvLinkLayout MIXED_MODE Only when the global end point mode is set to MIXED MODE can each link have an individual end point mode To set and retrieve the mode of an individual link use the following methods void setOriginPointMode Object link int mode int getOriginPointMode Object link void setDestinationPointMode Object link int mode int getDestinationPointMode Object li
107. these features are used by this subclass Allowed Time r lt c gt e gt 3 The layout algorithm stops if allowed time setting has elapsed For a description of this layout parameter in the 11vGraphLayout class see Allowed Time on page 22 If the layout stops early because the allowed time has elapsed the nodes and links are not moved from their positions before the layout call and the result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 99 TREE LAYOUT Layout of Connected Components The layout algorithm can utilize the generic mechanism to layout connected components For more information about this mechanism see Layout of Connected Components on page 25 It has however a specialized internal mechanism to layout connected components and therefore the generic mechanism is switched off by default The generic connected component layout mechanism has the disadvantage that it moves connected components completely Fixed nodes within a component do not preserve their old position and the resulting layout may be unstable on incremental changes depending on which layout instance is used for the component layout If the generic connected component layout mechanism is disabled the algorithm uses its own specialized internal mechanism instead of the generic mechanism to lay out each component as a separate tre
108. to a value smaller than the preferred length of the links Using a Link Clipping Interface By default the Uniform Length Edges Layout does not place the connection points of links It relies on the link connectors of the nodes to determine the connection points If no link connectors are installed at the nodes the default behavior is to connect to a point at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correct the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 25 r lt gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 91 UNIFORM LENGTH EDGES LAYOUT 92 p without clipping with clipping Figure 4 25 Effect of Link Clipping Interface You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface Note The link clip interface requires link connectors at the nodes of an 11vGrapher that allow connector pins to be
109. to implement a layout event listener class LayoutIterationListener implements GraphLayoutEventListener public void layoutStepPerformed GraphLayoutEvent event IlvGraphLayoutReport layoutReport event getLayoutReport System out println percentage of completion layoutReport getPercentageComplete Then register the listener on the layout instance as follows layout addGraphLayoutEventListener new LayoutIterationListener Parameter Event Listeners The layout parameter event listeners mechanism provides a way to inform the end user that any layout parameter has changed This is useful when the layout parameter values are displayed in a dialog box that needs to be updated to indicate parameter changes The parameter event listener is defined by the GraphLayoutParameterEventListener interface To receive the layout parameter events a class must implement the GraphLayoutParameterEventListener interface and must register itself using the addGraphLayoutParameterEvent Listener method of the IlvGraphLayout class When you implement the GraphLayoutParameterEventListener interface you must implement the parametersUpToDate method The layout class will call this method on all the registered layout parameter event listeners The layout parameter event contains a flag accessible by the isParametersUpToDate method It returns t rue if the event occurs at the end of a run of the layout wh
110. use the method void removeClusterId Object node IlvClusterId clusterId To remove a node from all the clusters to which it belongs use the method void removeAllClusterIds Object node Star Center To specify whether a node is the center of a star call the method void setStarCenter Object node boolean starCenter By default a node is not the center of a star To know whether a node is the center of a star use the method boolean isStarCenter Object node This parameter has no effect if the clustering mode is Bv SUBGRAPHS Root Clusters The algorithm arranges the clusters of each connected component of the graph of clusters around a root cluster By default the algorithm can choose this cluster Optionally you can specify one or more root clusters one for each connected component using the methods void setRootClusterId IlvClusterId clusterId To obtain an enumeration of the identifiers of the clusters that have been specified as root clusters use the method Enumeration getRootClusterIds r lt gt gt 3 This parameter has no effect if the clustering mode is BY SUBGRAPHS Area Minimization For very large graphs the radius of the concentric circles on which the clusters are placed can become very large Therefore the Circular Layout provides an optional mode that reduces the total area of the layout To reduce the total area the cluste
111. usually source node unless ports are specified into a lower level than its target node To force the source node into a higher level than the target node you need to create a constraint with a higher priority than the link For instance to ensure that the constraints are satisfied even if there are many links you can use link priorities between 0 and 10 and constraint priorities between 1000 and 10 000 You can also create a relative level constraint between groups of nodes layout addConstraint new IlvRelativeLevelConstraint nodeGroupl nodeGroup2 priority Position Index Parameter In Step 2 of the layout algorithm the crossing reduction phase the nodes are ordered within the levels All nodes that belong to the same level get a position index starting from 0 For instance when the flow direction is to the bottom the node with the position index 0 is placed in the leftmost position within its level The nodes with a larger position index are placed farther to the right than the nodes with a smaller position index in the same level The nodes of different levels are independent The node of the first level with the position index 0 is to the left of the node of the first level with the position index 1 but not necessarily to the left of a node of another level with position index 0 Note that long links crossing a level also obtain a position index see Figure 4 59 on page 139 The layout algorithm calculates these position indices
112. void setDisconnectedGraphOffset float offset To obtain the current value use the method float getDisconnectedGraphOffset This parameter has no effect if the clustering mode is Bv SUBGRAPHS Get the Contents the Position and the Size of the Clusters At times you might need to know the position and the size of the circle on which the nodes for each cluster are drawn This may be the case if you want to perform some reshaping operations on the links To do this you can obtain a vector containing all the cluster identifiers after the layout is performed Use the following method Vector getClusterIds The vector contains instances of a subclass of 11vClusterrd By browsing the elements of this Vector you can get the necessary information for each cluster float getClusterRadius int clusterIndex IlvPoint getClusterCenter int clusterIndex Vector getClusterNodes int clusterIndex r lt gt gt 3 The getClusterNodes method returns the nodes that make up the cluster The argument clusterIndex represents the position of the cluster in the vector returned by the method getClusterIds These methods should not be used if the clustering mode is BY SUBGRAPHS ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 251 CIRCULAR LAYOUT Link Style When the layout algorithm moves the nodes straight line links such as instances of IlvLinkImage will automatically fol
113. you click the Fit to content icon the applet window appears as shown in the following image 408 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS E JApplet1 class DE X Applet OCICS Perform Layout Applet started 3 To lay out the graph click the Perform Layout button As the layout is being performed you should see the progress indicated in the progress bar at the bottom of the window When the layout is completed the applet window should appear similar to the window in the following image ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 409 sue g nofe c 2 o O gt CREATING A SiMPLE APPLET UsiNG ILOG JViEWS GRAPH LAYOUT BEANS Applet Viewer JApplet1_class This completes the Graph Layout Beans example For information on how to save your project along with the type of files that are generated when saving refer to the documentation for your IDE 410 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 2 connected graph acyclic graph automatic layout biconnected graph bus topology connected component connected graph Glossary Also known as a biconnected graph A connected graph that will remain a connected graph if a discretionary node is removed In other words a graph in which at least two distinct paths exist between every two nodes
114. you to compare the same graph laid out with the additional repulsion disabled Figure 4 23 and then enabled Figure 4 24 You can see that the star configuration where many nodes are connected to the same central node is better displayed when the additional repulsion is enabled r lt gt gt 3 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 89 UNIFORM LENGTH EDGES LAYOUT Figure 4 23 Additional Repulsion Disabled Produced with the Uniform Length Edges Layout Figure 4 24 Additional Repulsion Enabled Produced with the Uniform Length Edges Layout 90 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UNIFORM LENGTH EDGES LAYOUT Sometimes for large graphs better results are obtained if the layout is performed once without the additional force this may help for the convergence of the algorithm then a second time with the additional force as a refinement step Node Distance Threshold The additional repulsion force between two nodes not connected by a link is computed only when their distance is smaller than a predefined distance This distance can be set and retrieved using the following methods void setNodeDistanceThreshold float threshold float getNodeDistanceThreshold Note that this additional force is computed only if the additional node distance weight is set to a value larger than 0 which is the default It is recommended that this threshold be set
115. 0 getFromPortIndex method I lvHierarchicalLayout class 156 getFromPortSide method I lvHierarchicalLayout class 155 getG getGlobalAlignment method vBusLayout class 232 vTreeLayout class 107 getGlobalDestinationPointMode method Ll lvHierarchicalLayout class 149 vLinkLayout class 197 getGlobalHorizontalAlignment method I lvGridLayout class 259 getGlobalLinkStyle method Il Tl I4 I Il vHierarchicalLayout class 146 iinkLayout class 195 TreeLayout class 110 getGlobalOriginPointMode method HierarchicalLayout class 149 vLinkLayout class 197 getGlobalSelfLinkStyle method lvShortLinkLayout class 209 211 getGlobalVerticalAlignment method I lvGridLayout class 259 UsER S MANUAL INDEX getGraphLayout method IlvGraphLayout class 269 311 getGraphModel method IlvGraphModel class 300 getH HorizontalAlignment method lvGridLayout class 260 HorizontalGridBase method lvLongLinkLayout class 205 HorizontalGridOffset method lvGridLayout class 262 lvLongLinkLayout class 205 HorizontalLinkOffset method lvHierarchicalLayout class 160 HorizontalMinOffset method lvLongLinkLayout class 205 HorizontalNodeLinkOffset method lvHierarchicalLayout class 160 HorizontalNodeOffset method lvHierarchicalLayout class 160 getHorizontalOffset method lvBusLayout class 235 Q 0 H ct Hct HH CO
116. 1 m m m m om 1 Dd extremity extremity of level 2 of level 2 ES ud e oe oe south extremity direction level 2 la Figure 4 84 Sketch of Extremity Constraints Swim Lane Constraint Swim lanes are rectangular areas orthogonal to the levels 178 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Ifthe link flow direction is towards the bottom or top the levels are horizontal rows and the swim lanes are vertical columns Ifthe flow direction is towards the left or right the levels are vertical columns and the swim lanes are horizontal rows Swim lanes can be used if the nodes are partitioned into groups to indicate which nodes belong to a certain group The nodes of the same swim lane are placed so that it is possible to draw a surrounding rectangle around them Swim lanes allow you to organize the graph in a table like manner For instance you may have a workflow diagram where nodes represent actions then the swim lanes could represent the departments that perform these actions Each node can belong to only one swim lane In order to specify that a group of nodes belong to the same swim lane call layout addConstraint new IlvSwimLaneConstraint new IlvNodeGroup nodeVector nodes of the node vector will be placed in the same swim lane rectangle If a graph has many swim lane rectangles
117. 1 and draws it as a regular polygon Then it iteratively moves each node except those on the regular polygon at the barycenter of its neighbors the nodes to which it is connected This procedure always converges and the final result is a graph drawing where the number of link crossings is dependent only on the choice of the outer cycle ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 57 TOPOLOGICAL MESH LAYOUT TML 58 Code Sample Below is a code sample using the 11vTopologicalMeshLayout class import ilog views import ilog views graphlayout import ilog views graphlayout topologicalmesh IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher fs Fill in the grapher with nodes and links here IlvTopologicalMeshLayout layout new IlvTopologicalMeshLayout layout attach grapher try IlvTopologicalMeshLayoutReport layoutReport IlvTopologicalMeshLayoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters TML supports the following generic parameters defined in the 11vGraphLayout class Allowed Time Animation Layout of Connected Components Layout Region Link Clipping Link Connection Box Memory Savings Preserve Fixed Links Preserve Fixed No
118. 103 PreferredLayout method lvDefaultLayoutProvider class 280 312 PreferredLinksLength method lvUniformLengthEdgesLayout class 87 88 PreferredPathLocation method lvAnnealingLabelDescriptor class 375 tProperty method IlvGraphModel class 302 IlvLabelingModel class 388 Ek CU p vet CC getR ReferenceTransformer method lvLayoutGraphicFilter class 326 ReferenceView method lvLayoutGraphicFilter class 325 RightMargin method lvGridLayout class 263 RootClusterId method lvCircularLayout class 247 getRootModel method lvGraphModel class 300 ge H ct g H Q 0 H tHe H getS getSecondGraphLayout method IlvMultipleLayout class 287 getSeedValueForRandomGenerator method IlvGraphLayout class 34 get Short LinkLayout method IlvLinkLayout class 208 getSiblingOffset method IlvTreeLayout class 117 get SpecNodeLevel Index method IlvHierarchicalLayout class 173 getSpecNodePositionIndex method IlvHierarchicalLayout class 175 getSpecRoots method IlvTreeLayout class 102 getSpringConstant method IlvSpringEmbedderLayout class 78 426 ge ge ge tStartingNode method IlvTopologicalMeshLayout class 64 tSubgraphs method IlvGraphModel class 300 tSubgraphsCount method IlvGraphModel class 300 304 getT ge ge ge ge ge ge tTangentialOffset method IlvLinkConnectionBoxInterface class 29 212 tTipOverBranch
119. 230 Figure 4 108 Bus Width Adjusting Disabled and Bounded Number of Nodes per Level r lt gt fe gt 3 Figure 4 109 Bus Width Adjusting Enabled and Bounded Number of Nodes per Level To enable or disable the bus width adjusting use the method void setBusWidthAdjustingEnabledM boolean enable ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 231 Bus LAYOUT To get the current value use the method boolean isBusWidthAdjustingEnabled The bus width adjusting is disabled by default Alignment Parameters The alignment options control how a node is placed above its row bus level The alignment can be set globally in which case all nodes are aligned in the same way or locally on each node with the result that different alignments occur in the same drawing Global Alignment Parameters To set and retrieve the global alignment use the following methods void setGlobalVerticalAlignment int alignment int getGlobalVerticalAlignment The valid values for alignment are IlvBusLayout CENTER the default The node is vertically centered over its row bus level IlvBusLayout TOP The node is vertically aligned on the top of its row bus level IlvBusLayout BOTTOM The node is vertically aligned on the bottom of its row bus level IlvBusLayout MIXED Each node can have a different alignment The alignment of each individua
120. 5 UsER s MANUAL 61 TOPOLOGICAL MESH LAYOUT TML 62 Optimization Iterations and Allowed Time The iterative computation performed in Step 1 is stopped if the number of iterations exceeds the allowed number of iterations for optimization or the time exceeds the allowed time for optimization or of course if the general layout time has elapsed To specify the parameters use the following methods void setAllowedOptimizationTime long time void setAllowedNumberOfOptimizationIterations int iter The t ime is in milliseconds The default value is 28000 28 seconds To obtain the current values use the following methods long getAllowedOptimizationTime int getAllowedNumberOfOptimizationIterations Nodes Placement Iterations and Allowed Time The iterative computation performed in Step 2 is stopped if the number of iterations exceeds the allowed number of iterations or the time exceeds the allowed time for nodes placement or of course if the general layout time has elapsed ILOG JViews allows you to specify these parameters using the methods void setAllowedNodesPlacementTime long time void setAllowedNumberOfNodesPlacementIterations int iter The time is in milliseconds The default value is 28000 28 seconds To obtain the current values use the following methods long getAllowedNodesPlacementTime int getAllowedNumberOfNodesPlacementIterations Nodes Placement Algorithm Two
121. 5 5 USER S MANUAL 361 THE ANNEALING LABEL LAYOUT Positioning at a Point Here is an example of positioning a label at a specific point layout setLabelDescriptor label new IlvAnnealingPointLabelDescriptor label null new IlvPoint 25 75 5f 15f IlvDirection Right This specification can be used if the label must be placed close to a specific point in this example at 25 75 independent of any obstacle The label must be at least 5 coordinate units and at most 15 coordinate units away from the point see Figure 6 7 The preferred position is at the right side of the point Figure 6 7 Potential Label Positions Between 5 and 15 Units Away From a Point The example uses the following constructor IlvAnnealingPointLabelDescriptor Object label Object relatedObstacle IlvPoint referencePoint float minDist float maxDist int preferredDirection The label is placed close to the reference point It does not take the actual position of the related obstacle into account If the related obstacle is moved the label does not follow the obstacle on the next call of layout but stays at the reference point If a related obstacle is given the label is not pushed away from the related obstacle However it is pushed away from all other obstacles to avoid overlaps You can set the relatedObstacle parameter to nu11 if the label is independent of all obstacles The parameters minDist and maxDist are the minimal and maximal dista
122. 6 123 setTipOverBranchOffset method 117 setWestEastNeighboring method 130 ge se ct IlvU IlvUniformLengthEdgesLayout class getAllowedNumberOfIterations method 87 getLinkStyle method 87 getPreferredLinksLength method 87 88 isForceFitToLayoutRegion method 88 isRespectNodesSizes method 88 provided as a Bean 392 setAllowedNumberOfIterations method 87 setForceFitToLayoutRegion method 88 setLinkStyle method 87 setPreferredLinksLength method 87 setRespectNodeSizes method 88 IlvUniformLengthEdgesLayoutReport class 294 continued incremental layout 16 incremental mode parameter Bus Layout 234 Grid Layout 260 Link Layout 198 individual end point mode parameter Hierarchical Layout 149 Link Layout 197 individual link style parameter Hierarchical Layout 146 Link Layout 195 Tree Layout free mode 110 individual node alignment parameter Bus Layout 233 Grid Layout 260 Tree Layout free mode 107 initialize method IlvAnnealingLabelDescriptor class 374 instantiating a subclass 18 interface parameters 320 intergraph link routing 199 internal provider mode Recursive Layout 267 269 273 isAnimate method IlvGraphLayout class 28 isAreaMinimizationEnabled method IlvCircularLayout class 248 isBoundingBoxDependent method IlvLabelingModel class 387 isBusWidthAdjustingEnabled method 434 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL IlvBusLayout
123. 6 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TOPOLOGICAL MESH LAYOUT TML ls 8 p pu Figure 4 9 The Original TML Layout To correct the problem you can perform the following steps 1 Move nodes 0 9 and 10 to a place in the free space inside the outer cycle by hand as shown in Figure 4 10 Figure 4 10 The Layout with Nodes Moved r lt Lad gt gt 3 2 Specify nodes 0 9 and 10 as fixed using the set Fixed method 3 Usethe setPreserveFixedNodes method to specify that the fixed nodes will not be moved when the layout is performed 4 Perform the layout again Only Step 2 will be performed The fixed nodes attract the other nodes which are distributed in the larger area inside the outer cycle as shown in Figure 4 11 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 67 TOPOLOGICAL MESH LAYOUT TML Figure 4 11 The Final Layout Using the Outer Cycle Parameter By default Step 2 of TML produces a layout using the longest outer cycle computed in Step 1 The length of a cycle is the number of nodes that compose the cycle Sometimes a better layout can be obtained using a different choice of the outer cycle This process of changing the outer cycle parameter and performing the layout again see Outer Cycle on page 64 is a manual refinement procedure that can also be used to avoid overlapping nodes Note that performing the layo
124. A possible step by step procedure may be the following 1 2 3 Create each graph manually with a graph editor or by code Try different layout algorithms and choose the best for each graph Apply manual refinements to the layout if needed Store the result of the layout by saving the graphers in iv1 files Provide these files with the application When the application is used these files will simply be loaded There will be no need to perform the layout again since it is already done Procedure for Hard coding when Layout is Applied at Run Time If the choice of the layout algorithm is hard coded but the layout must be performed at run time because the graphs are not known at programming time one possible step by step procedure for the choice of the appropriate layout algorithm may be the following 1 2 Look at sample graphs for your domain Try to determine some generalities about the properties of the structure and the size of the graph Is the graph cyclic Is the graph a tree Is the graph a combination of the two What is the number of nodes and links in the graph Pick one of the corresponding layout algorithms from Table 4 1 on page 45 Try out the algorithm on one or more samples 50 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL GENERIC FEATURES AND PARAMETERS SUPPORT Generic Features and Parameters Support The generic features and parameters of the Graph Layout module allow you to customize the be
125. ATE The even rows bus levels are left aligned and the odd rows are right aligned Maximum Number of Nodes Per Level By default the layout places as many nodes on each level as possible given the size of the nodes and the dimensional parameters layout region and margins If needed the layout can additionally respect a specified maximum number of nodes per level see Figure 4 108 on page 231 and Figure 4 109 on page 231 To set and retrieve the maximum number of nodes per level use the methods void setMaxNumberOfNodesPerLevel int nNodes int getMaxNumberOfNodesPerLevel The default value is Integer MAX VALUE that is the number of nodes placed in each level is only bounded by the size of the nodes and the dimensional parameters The specified value must be at least 1 230 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT Bus Width Adjusting By default the width of the bus object that is the difference between the maximum and minimum x coordinates depends on the width of the layout region and the other dimensional parameters see Figure 4 113 Bus Layout with Bottom Vertical Alignment on page 234 Optionally the width of the bus object can be automatically adjusted to the total width of the nodes plus the offsets and the margins This option can be particularly useful in conjunction with the customization of the maximum number of nodes per level see Maximum Number of Nodes Per Level on page
126. AYOUT If the graph is detached from the layout algorithm the calculated level index of a node is set back to 1 Note You should be aware of the difference between the methods getCalcNodeLevelIndex and getSpecNodeLevelIndex The first one returns the level index calculated by the previous layout The second one returns the specified level index even if there was no previous layout For instance consider two nodes A and B Node A has no specified level index and node B has a specified level index 5 Before the first layout the method getCalcNodeLevellndex returns 1 for both nodes because the levels have not been calculated yet However getSpecNodeLevelIndex returns 1 for A and 5 for B After the first layout node may be placed at level 4 Now getCalcNodeLevelIndex returns 4 for node A and 5 for node B and get SpecNodeLevelIndex still returns 1 for A and 5 for B Calculated Position Index The layout algorithm allows you to access the position index within a level that was calculated for a node by a previous layout To do this use the following method int getCalcNodePositionIndex Object node If the node was never laid out this method returns 1 Otherwise it returns the previous position index of the node within its level To ensure that the node is placed at the same level at the same relative position as in the previous layout use the following layout setSpecNodeLevel Index node layout getCalcNodeLeve
127. AnnealingLabelLayout The Recursive Multiple Layout has a first and second graph layout instance per subgraph and a label layout instance per subgraph You access these instances by the following methods IlvGraphLayout getFirstGraphLayout Object subgraph which returns the graph layout that is applied first to the subgraph IlvGraphLayout getSecondGraphLayout Object subgraph which returns the graph layout that is applied secondly to the subgraph IlvLabelLayout getLabelLayout Object subgraph which returns the label layout that is applied last to the subgraph If the subgraph parameter is nu11 in these methods the layout instances of the top level graph are returned For Experts The Reference Labeling Model The Recursive Multiple Layout must be used when the label layout should use a specified labeling model that is not the default labeling model IlvDefault LabelingModel see The Labeling Model on page 346 The Multiple Layout allows you to specify a particular labeling model by using the method set Label ingModel but when you encapsulate the Multiple Layout into a Recursive Layout this specification would need to be repeated for each layout instance of each subgraph This would be inconvenient However the Recursive Multiple Layout takes care of this mechanism automatically 288 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL MULTIPLE LAYOUT If you implement your own labeling model subclass
128. Connector or IlvClipLinkConnector for link connectors to be used in combination with 11vGrapher objects The clip link connector updates the clipped connection points automatically during interactive node movements If a node has an irregular shape the clipped links sometimes should not point towards the center of the node bounding box but to a virtual center inside the node You can achieve this by additionally providing a class that implements the IlvLinkConnectionBoxInterface An example for the implementation of a link connection box interface is inLink Connection Box on page 29 To set a link connection box interface call r lt Ld gt gt 3 void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface The link connection box interface is used only when link clipping is enabled by setting a link clip interface If no link clip interface is specified the link connection box interface has no effect An example of the combined effect is shown in Figure 4 125 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 253 CIRCULAR LAYOUT Clipping at the node bounding box Clipping at a specified connection box Figure 4 125 Combined Effect of Link Clipping Interface and Link Connection Box If the links are clipped at the green irregular star node Figure 4 125 left they do not point towards the center of the star but towards the center of the bounding box of the node This ca
129. Constraint Priorities 9 99 9 o For Experts Constraint Validation Adding and Removing Constraints To add a constraint to hierarchical layout you allocate a new constraint object and call on the IlvHierarchicalLayout instance void addConstraint IlvHierarchicalConstraint constraint You can add as many constraints as you want The constraints will be respected during the following calls of layout until you remove the constraints To remove the constraint that was most recently added call void removeConstraint To remove a specific constraint call void removeConstraint IlvHierarchicalConstraint constraint To remove all constraints that were previously added call void removeAllConstraints You can retrieve the constraints that were added to Hierarchical Layout Enumeration getConstraints Node Groups Some constraints affect single nodes Other constraints affect groups of nodes The class IlvNodeGroup is a convenient way to specify a group of nodes You can create a group of nodes in the following way r lt c gt e gt 3 group new IlvNodeGroup while group add node ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 171 HIERARCHICAL LAYOUT A node group has a similar functionality as a vector You can ask for the size and elements of the group remove elements from the group or check whether a node already belongs to the group You can al
130. Exception is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 Global Link Style To set the global link style the following method is provided void setGlobalLinkStyle int style The valid values for style ilvTreeLayout NO RESHAPE STYLE None of the links is reshaped in any manner IilvTreeLayout STRAIGHT LINE STYLE the intermediate points of the links if any are removed This is the default value See Figure 4 27 on page 94 and Figure 4 29 on page 95 as examples IlvTreeLayout ORTHOGONAL STYLE The links are reshaped in an orthogonal form alternating horizontal and vertical segments See Figure 4 28 on page 94 and Figure 4 35 on page 109 as examples IlvTreeLayout MIXED STYLE Each link can have a different link style The style of each individual link can be set to have different link shapes occurring on the same graph To obtain the current choice use the following method int getGlobalLinkStyle Individual Link Style All links have the same style of shape unless the global link style is IlvTreeLayout MIXED STYLE Only when the global link style is set to mixed can each link have an individual link style 110 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Ed EH Figure 4 36 Different Li
131. Expert Parameters of the Incremental Mode Each phase of the incremental mode can be parameterized These layout parameters have an effect only if incremental mode is switched on Minimizing Long Link Crossings As discussed in Phases of the Incremental Mode on page 163 the incremental layout tries to preserve the shape of long links that cross several levels This implies that link crossings between long links are not resolved If crossings of long links are not desired it may be better to reroute long links from scratch Figure 4 79 has four hierarchy trees with the original layout at the upper left The bottom right shows the result if long links are rerouted and the top right shows the result if the shape of long links are preserved ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT normal incremental layout io e iU AN KA uA incremental layout OR with crossing reduction KA Figure 4 79 Crossing Reduction During Incremental Layouts To reroute long links from scratch you must enable the crossing reduction mechanism for long links by the statement r lt gt e gt 3 layout setLongLinkCrossingReductionDuringIncremental true The crossing reduction of long links determines only the shape of the links It does not influence the order of the other nodes within the levels Minimizing All Link Crossings Optionally you can apply a cr
132. Figure 4 94 Routed Link in a Nested Graph when Layout is Performed for the Yellow Subgraph In order to route all links of a nested graph you need to apply the Link Layout recursively Details of the recursive layout mechanism are explained in Laying Out Nested Graphs on page 306 that discusses recursive layout For instance layout setInterGraphLinksMode true layout performLayout force redraw true routes the intergraph links recursively in all subgraphs If you use a layout provider a class that implements the interface I1vLayoutProvider you need to set the intergraph links mode for all subgraphs explicitly IlvLayoutProvider layoutProvider first set the intergraph mode for all layouts Enumeration e graphModel getLayouts layoutProvider true while e hasMoreElements IlvGraphLayout layout IlvGraphLayout e nextElement if layout instanceof IlvLinkLayout IlvLinkLayout layout setInterGraphLinksMode true 200 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT then perform layout recursively using the provider graphModel performLayout layoutProvider force redraw true If you want to recursively perform the intergraph link routing in combination with a layout that places the nodes or that arranges labels we recommend that you use an instance of the class IlvMultipleLayout to encapsulate the Link Layout and the other layouts and then perform the Multiple Layout recursively all a
133. Fill in the grapher with nodes and links here IlvHierarchicalLayout layout new IlvHierarchicalLayout layout attach grapher try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vHierarchicalLayout class supports the following generic features defined in the IlvGraphLayout class Allowed Time Layout of Connected Components Link Clipping Link Connection Box Percentage Completion Calculation Preserve Fixed Links Preserve Fixed Nodes Save Parameters to Named Properties 9 9 9 9 9 Stop Immediately The following paragraphs describe the particular way in which these parameters are used by this subclass Allowed Time The layout algorithm stops if the allowed time setting has elapsed For a description of this layout parameter in the 11vGraphLayout class see Allowed Time on page 22 If the layout stops early because the allowed time has elapsed the nodes and links are not moved from 140 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT their positions before the layout call and the result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID Layout of Connected Components The layout algorithm can utilize the gene
134. Graph ILOG JViews Grapher Object IlvGrapher Figure 5 1 Graph Model in the ILOG JViews Graph Layout Module You can see from this diagram that instead of using a concrete graph class such as IlvGrapher directly the layout algorithms interact with the graph via the graph model This is the key for achieving a truly generic graph layout framework Note that the use of an IlvManagerView to display the result of the layout is not mandatory 298 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING THE GRAPH MODEL The IlvGraphModel Class The 11vGraphModel class is an abstract Java class Because it does not provide a concrete implementation of a graph data structure a complete implementation must be provided by adapter classes The adapters extend the 11vGraphModel class and must use an underlying graph data structure A special adapter class called 11vGrapherAdapter is provided so that an IlvGrapher can be used as the underlying graph data structure Note If an application uses the 11vGrapher class the grapher can be attached directly to the layout instance without explicitly using a graph model See the IlvGraphLayout attach IlvGrapher method In this case the appropriate adapter IlvGrapherAdapter will be created internally This adapter can be retrieved using the 11vGraphLayout getGraphModel method which will return an instance of I1vGrapherAdapter Most of the methods defined in the 11vGraphModel class have a name and
135. GraphLink method 300 Ct ct ct ct ct ct ct ct ct ct ct ct ct ct ct p isLayoutNeeded method 301 isLink method 299 isLinkBetween method 300 isNode method 299 isSubgraph method 300 move method 301 moveNode method 301 removeGraphModelListener method 301 reshapeLink method 301 se tProperty method 302 IlvGridLayout class ge ge ge ge ge ge ge ge tBottomMargin method 263 tGlobalHorizontalAlignment method 259 GlobalVerticalAlignment method 259 HorizontalAlignment method 260 HorizontalGridOffset method 262 LayoutMode method 258 LeftMargin method 263 tMaxNumberOfNodesPerRowOrColumn method 260 ct ct ct ct ct 430 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ge ge ge ge tRightMargin method 263 tTopMargin method 263 tVerticalAlignment method 260 tVerticalGridOffset method 262 provided as a Bean 392 se se se Se se se se se se se se se BottomMargin method 263 GlobalHorizontalAlignment method 259 GlobalVerticalAlignment method 259 HorizontalAlignment method 260 HorizontalGridOffset method 262 IncrementalMode method 261 LayoutMode method 258 LeftMargin method 263 tRightMargin method 263 tTopMargin method 263 tVerticalAlignment method 260 tVerticalGridOffset method 262 ct ch ct cb cb cr IlvHierarchicalLayout class ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge tCalcNodeLevelIndex method 183
136. H LAYOUT 5 5 UsER s MANUAL HIERARCHICAL LAYOUT Step 4 Link Routing The shapes of the links are calculated such that the links bypass the nodes at the level lines In many cases this requires that a bend point be created whenever a link needs to cross a level line In a top to bottom layout these bend points have the same y coordinate as the level line they cross Note that these bend points also obtain a position index Figure 4 59 shows how the Hierarchical Layout algorithm uses the level and positions indices to draw the graph position 0 position 1 level 0 level 1 position 3 level 2 position 0 Figure 4 59 Level and Position Indices The steps of the layout algorithm can be affected in several ways For instance you can specify the desired level index that the algorithm should choose for a node in Step 1 or the desired relative node position within the level in Step 2 You can also specify the justification of the nodes within a level and the style of the links shapes r lt e gt gt 3 Code Sample Below is a code sample using the 11vHierarchicalLayout class ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 139 HIERARCHICAL LAYOUT import ilog views import ilog views graphlayout import ilog views graphlayout hierarchical IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher
137. IFORM LENGTH EDGES LAYOUT Layout of Connected Components Layout Region Link Clipping Link Connection Box Preserve Fixed Links Preserve Fixed Nodes Save Parameters to Named Properties 99 9 9 9 Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass Allowed Time The layout algorithm stops if the allowed time setting has elapsed See Allowed Time on page 22 Animation If animation is specified a redraw is automatically performed after each step of the layout algorithm See Animation on page 22 Layout of Connected Components The layout algorithm can utilize the generic mechanism to lay out connected components For more information about this mechanism see Layout of Connected Components on page 25 Layout Region The layout algorithm can use the layout region setting either your own or the default setting to control the size and the position of the graph drawing three ways to specify the layout region are available for this subclass See Layout Region on page 25 Note that by default the Uniform Length Edges Layout algorithm does not use the layout region For details see also Force Fit to Layout Region on page 88 r lt e gt gt 3 Remember that if you are using the default settings the visible area of the manager view an instance of IlvManagerView attached to the grapher is used as a
138. ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL DEFINING YOUR OWN LABELING MODEL overlap penalty if the label were placed at its passed bounding box and the obstacle were placed at its passed bounding box If the overlap methods return a positive nonzero penalty only when the speculative bounding boxes overlap then the following method can return t rue boolean isBoundingBoxDependent This method exists mainly for quadtree optimization purposes Notification of Changes o gt 1 3 r The following methods of the 11vLabelingModel class allow a layout algorithm to be notified of changes in the data structures void addLabelingModelListener LabelingModelListener listener void removeLabelingModelListener LabelingModelListener listener void fireLabelingModelEvent Object obstacleOrLabel int eventType boolean adjusting void fireLabelingModelEvent LabelingModelEvent event A change can be a structural change that is a label or obstacle was added or removed or a geometrical change that is a label or obstacle was moved or reshaped The event type is typically a bitwise Or of the bit masks defined in the class LabelingModelEvent For instance when a label was removed an event with type STRUCTURE CHANGED LABEL REMOVED is fired and the removed label is stored in the event The labeling model event listener mechanism provides a means to
139. ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 325 CHOOSING THE LAYOUT COORDINATE SPACE Specifying a Reference Transformer A reference transformer can be specified explicitly using the method void setReferenceTransformer IlvTransformer transformer The current reference transformer is returned by the method IlvTransformer getReferenceTransformer In most cases it is not necessary to specify a reference transformer because the last method automatically chooses it according the following rules Ifa reference transformer is specified the specified transformer is returned Ifa reference view has been specified the transformer of the reference view is returned Ifthe 11vGrapher attached to the IlvGrapherAdapter has at least one manager view the transformer of the first manager as returned by the method IlvManager getViews is returned The only cases where you may need to specify a reference transformer or a reference view are the following The IlvGrapher contains nonzoomable objects that is the layout cannot be correctly computed independently of the transformer used for drawing the graph and more than one manager view is attached to the grapher The IlvGrapher contains nonzoomable objects and you want to perform the layout without attaching a manager view to the grapher Therefore the default rule for choosing the current transformer of the first manager view as the reference transformer cannot be a
140. If no layers have been specified or all the specified layers have been removed all layers in the IlvGrapher are used In this case the get Layers method returns null When at least one layer is specified an 11vLayoutGraphicFilter is created internally if it has not already been specified using the setFilter method The default implementation of its accept method will automatically check whether a node or a link received as an argument belongs to one of the specified layers Filtering by Graphic Objects The nodes and links to be taken into account during the layout can also be filtered individually To do this a custom subclass of IlvLayoutGraphicFilter must be written The filtering rules have to be embedded in the overridden implementation of the accept method For example user properties could be used by an application to mark nodes and links that have to be accepted by the filter The filter class could then be written as follows public class LayoutFilter extends IlvLayoutGraphicFilter public LayoutFilter public boolean accept IlvGraphic obj Object prop obj getProperty markedObj if prop null return false accept a link only if its two end nodes are accepted if obj instanceof IlvLinkImage IlvLinkImage link IlvLinkImage obj return link getFrom getProperty markedObj null amp amp link getTo getProperty markedObj null return true Choosing the Layout Coordinat
141. LINK LAYOUT Using a Link Connection Box Interface By default the connection points of the links are distributed on the border of the bounding box of the nodes Sometimes it may be necessary to place the connection points on a rectangle that is smaller or larger than the bounding box For instance this can happen when labels are displayed below or above nodes You can modify the position of the connection points of the links by implementing a class that implements the 11vLinkConnectionBoxInterface This is a subinterface of IlvNodeBoxInterface see Using a Node Box Interface on page 207 It defines again the method public IlvRect getBox IlvGraphModel graphModel Object node This method allows you to return the effective rectangle on which the connection points of the links are placed Additionally the interface 11vLinkConnectionBoxInterface defines a second method public float getTangentialOffset IlvGraphModel graphModel Object node int nodeSide This method is used only in the short link mode For details see Using a Link Connection Box Interface on page 211 When using the Link Layout in long link mode just implement the method by returning the value 0 For Experts Special Options of the Short Link Layout The Link Layout algorithm utilizes the class IlvShortLinkLayout as a subalgorithm IlvShortLinkLayout is a subclass of T1vGraphLayout and can be used a stand alone as well To access the instance of 11vShortLink
142. Layout Algorithm Topological Mesh Layout TML Spring Embedder Layout Uniform Length Edges Layout Tree Layout Hierarchical Layout Link Layout Random Layout r lt e gt gt 3 Bus Layout Circular Layout Grid Layout Recursive Layout 9 9 9 9 9 9 o o Multiple Layout ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 43 DETERMINING THE APPROPRIATE LAYOUT ALGORITHM Determining the Appropriate Layout Algorithm When using the Graph Layout module you need to determine which of the ready to use layout algorithms is appropriate for your particular needs Some layout algorithms can handle a wide range of graphs Others are designed for particular classes of graphs and will give poor results or will reject graphs that do not belong to these classes For example a Tree Layout algorithm is designed for tree graphs but not cyclic graphs Therefore it is important to lay out a graph using the appropriate layout algorithm Table 4 1 can help you determine which of the layout algorithms is best suited for a particular type of graph Across the top of the table are various classifications of different types of graphs The layout algorithms appear on the left side of the table Table cells containing illustrations indicate when a layout algorithm is applicable for a particular type of graph By identifying the general characteristics of the graph you want to lay out you c
143. Layout Combination of 4 Trees Cyclic Graphs Cycles and Any Graph Representations Trees Hierarchical Layout Jm al ee 2 56 m pes pum ier mm oo T i ir E n mt y m HM a F E B Link Layout 13 gt Bus Layout E que TT gt a magy 1 Tritt E 3 7 For bus topologies ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 47 DETERMINING THE APPROPRIATE LAYOUT ALGORITHM Table 4 1 Layout Algorithms and Common Types of Graphs Continued Layout Domain Independent Graphs Trees Cyclic Graphs Combination of Cycles and Trees Any Graph Telecom Oriented Representations Circular Layout For interconnected ring star topologies Grid Layout Note that the algorithm does not take into account the links between the nodes Recursive Layout Nested graphs Multiple Layout Combination of multiple different layout algorithms on the same graph in particular for nested graphs 48 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TYPICAL WAYS FOR CHOOSING THE LAYOUT Typical Ways for Choosing the Layout Determining an appropriate algorithm for the graph can be done either by the end user at run time or by the programmer of the application This process can be semiautomatic where user intervention is involved or automatic where the applicatio
144. Layout that is used by the Link Layout algorithm call IlvShortLinkLayout getShortLinkLayout Using this accessor you can control many special features of the Short Link Layout that are not made available by the IlvLinkLayout class because these features are for experts only Self link Style Self links are links with the same origin and destination nodes The Short Link Layout provides two optional shapes for the self links 208 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL LINK LAYOUT Two bend Self link Style Three bend Self link Style Figure 4 98 Self link Style Options To set and retrieve the style of the self links use the following methods void setGlobalSelfLinkStyle int style int getGlobalSelfLinkStyle The valid values for style are 1ilvShortLinkLayout TWO BENDS ORTHOGONAL STYLE IilvShortLinkLayout THREE BENDS ORTHOGONAL STYLE Number of Optimization Iterations The link shape optimization is stopped if the time exceeds the allowed time see Allowed Time on page 192 or if the number of iterations exceeds the allowed number of iterations To set this number to 3 call layout getShortLinkLayout setAllowedNumberOfIterations 3 Note You may want to disable the link shape optimization by setting the number of iterations to zero in order to increase the speed of the layout process Same Shape for Multiple Links r lt gt
145. Link Style on page 109 100 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed For more information on node parameters in the IlvGraphLayout class see Preserve Fixed Nodes on page 32 Moreover the layout algorithm ignores fixed nodes completely and also does not route the links that are incident to the fixed nodes This can result in undesired overlapping nodes and link crossings However this feature is useful for individual disconnected components that can be laid out independently Save Parameters to Named Properties The layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to 71 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the nodes and links are not moved from their positions before the layout call and the result code in the layout report is I1vGraphLayoutReport STOPPED AND INVALID Specific Parameters All Tree Layout Modes The following parameters are specific to the 11
146. LinkOffset method 202 getMinFinalSegmentLength method 203 setAllowedNumberOfIterations method 209 setGlobalSelfLinkStyle method 209 211 setLinkOffset method 202 setLinkToLinkCrossingPenalty method 210 setLinkToNodeCrossingPenalty method 210 setMinFinalSegmentLength method 203 setSameShapeForMultipleLinks method 210 IlvSpringEmbedderLayout class getLinkStyle method 78 INDEX getSpringConstant method 78 provided as a Bean 392 setLinkStyle method 77 setSpringConstant method 78 livT IlvTerminationPointFilter class getPenalty method 214 TopologicalMeshLayout class tAllowedNodesPlacement Time method 62 tAllowedNumberOfNodesPlacementIterat ions method 62 getAllowedOptimizationTime method 62 ExteriorCycleId method 64 LinkStyle method 25 61 odesPlacementAlgorithm method 63 umberOfPossibleExteriorCycles method 64 Ch Gb Gh er getStartingNode method 64 provided as a Bean 392 tAllowedNodesPlacementTime method 62 tAllowedNumberOfNodesPlacementIterat ions method 62 tAllowedNumberOfOptimizationlteratio ns method 62 setAllowedOptimizationTime method 62 se tExteriorCycleId method 64 5 setLinkStyle method 24 61 odesPlacementAlgorithm method 62 setStartingNode method 64 IlvT IlvT opologicalMeshLayoutReport class 294 reeLayout class getAlignment method 108 ge ge ge ge ge ge ge ge ge ge ge tAspectRatio method 123 tBranchOffs
147. Mode method 149 cb Ge ce chet ct et ct ct se se se se se se IlvJ IlvJGraphLayoutProgressBar class 392 IlvJScrollManagerView class 394 livL IlvLabelingModel tSpecNodeLevelIndex method 173 tSpecNodePositionIndex method 175 tToPortIndex method 156 tToPortSide method 154 156 tVerticalLinkOffset method 160 tVerticalNodeLinkOffset method 160 tVerticalNodeOffset method 160 subclassing 389 IlvLabelingModel class 346 addLabelingModelListener method 387 boundingBox method 386 390 fireLabelingModelEvent method 387 getLabelOverlap method 386 389 getLabels method 385 389 getLabelsCount method 385 getObstacleOverlap method 386 390 USER S MANUAL 431 INDEX getObstacles method 385 389 getObstaclesCount method 385 getPolylineObstacleOverlap method 386 getPolylinePoints method 386 getPolylineWidth method 386 getProperty method 388 isBoundingBoxDependent method 387 isLabel method 385 389 isObstacle method 385 389 isPolylineObstacle method 385 method types 385 moveLabel method 386 389 removeLabelingModelListener method 387 setProperty method 387 388 IlvLabelLayout class 346 347 attach method 348 detach method 19 348 performLayout method 349 supportsSaveParametersToNamedPropertie s method 382 IlvLabelLayoutReport class method 352 getCode method 352 getPercentageComplete method 352 IlvLayoutGraphicFilter class accept method 322 addLayer method 322 getFil
148. NUAL Introducing the Graph Layout Module This chapter introduces you to the Graph Layout module of ILOG JViews The following topics are covered 9 ILOG What is the Graph Layout Module of ILOG JViews Composition of the ILOG JViews Graph Layout Module The ILOG JViews Graph Layout Algorithms Features of the ILOG JViews Graph Layout Module ILOG JViews Graph Layout Module in User Interface Applications JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 1 10 5 gt m lt S o 2 L WHAT IS THE GRAPH LAYOUT MODULE ILOG JVIEWS What is the Graph Layout Module of ILOG JViews Many types of complex business data can best be visualized as a set of nodes and interconnecting links more commonly called a graph or a network Examples of graphs include business organizational charts workflow diagrams telecom network displays and genealogical trees Whenever these graphs become large or heavily interconnected it becomes difficult to see the relationships between the various nodes and links the edges This is where ILOG JViews Graph Layout algorithms help The ILOG JViews Graph Layout module provides high level ready to use relationship visualization services It allows you to take any messy graph and apply a sophisticated graph layout algorithm to rearrange the positions of the nodes and links The result is a more readable and understandable pictur
149. NUAL RECURSIVE LAYOUT Features This subclass of 11vGraphLayout is not a usual layout algorithm but rather a facility to manage the layout of a nested grapher Three layout modes reference layout mode internal provider mode and specified provider mode Allows you to perform a layout algorithm recursively in a nested grapher Allows you to perform a recursive layout on a nested grapher while each subgrapher uses an individual layout style Layout features speed and quality depend on the features speed and quality of the sublayouts Generic Features and Parameters Depending on the support of its sublayouts Recursive Layout may support the following generic parameters defined in the 11vGraphLayout class Allowed Time Percentage Completion Calculation Save Parameters to Named Properties Stop Immediately The following paragraphs describe the particular way in which these parameters are used by this subclass Allowed Time The Recursive Layout can stop the entire layout of a nested graph after a certain amount of time If the allowed time setting has elapsed the Recursive Layout stops that means it stops the currently running layout of a subgraph and skips the subsequent layouts of subgraphs that have not yet been started If at the stop time point a sublayout is running on a subgraph that does not support the allowed time feature then this sublayout first runs to completion before the
150. OUT To specify that two nodes are east west neighbors use the following method void setEastWestNeighboring Object eastNode Object westNode You can also use the following method which is identical except for the reversed parameter order void setWestEastNeighboring Object westNode Object eastNode If the flow direction is to the bottom the latter method may be easier to remember because in this case west is to the left of east in the layout which is similar to the text flow of the parameters To obtain the node that is the east or west neighbor of a node use the following calls Object getEastNeighbor Object node Object getWestNeighbor Object node Note that each node can have maximally one east neighbor and one west neighbor because they are directly neighbored If more than one direct neighbor is specified it is partially ignored Cyclic specifications can cause conflict as well For instance if node B is the east neighbor of node A and node C is the east neighbor of B then node A cannot be the east neighbor of C Strictly speaking such cycles could be technically possible in some situations in the radial layout mode but nonetheless they are not allowed in any layout mode If B is the east neighbor of A then A is automatically the west neighbor of B On the other hand the east neighbor of A can itself have another east neighbor This allows creating chains of east west neighbors which is a co
151. Of course depending on the characteristics of the layout algorithm some of these steps may be different or unnecessary or other steps may be needed Depending on the particular implementation of your layout algorithm other methods of the IlvGraphLayout class may need to be overridden For instance if your subclass supports some of the generic parameters of the base class you must override the supports ParameterName method see Layout Parameters and Features in IlvGraphLayout on page 20 For further information about the API of the class IlvGraphLayout please refer to the Reference Manual of this class Note If you want to save the layout parameters of your new layout algorithm in iv1 files you should override the methods createLayoutGrapherProperty createLayoutNodeProperty createLayoutLinkProperty and subclass IlvGraphLayoutGrapherProperty IlvGraphLayoutNodeProperty and IlvGraphLayoutLinkProperty See Saving Layout Parameters and Preferred Layouts on page 315 for more explanation ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL QUESTIONS AND ANSWERS ABOUT USING THE LAYOUT ALGORITHMS Questions and Answers about Using the Layout Algorithms Table 5 2 provides some helpful suggestions for using the layout algorithms You may find some answers to questions that come up when using the Graph Layout module Table 5 2 Questions and Answers about the Layout Algorithms Question Answer perform the layout and One pos
152. Offset method IlvTreeLayout class 117 To method lvGraphModel class 300 TopMargin method lvGridLayout class 263 tToPortIndex method lvHierarchicalLayout class 156 tToPortSide method IlvHierarchicalLayout class 155 H ct HG H getV ge ge ge ge ge ge ge ge ge ge ILOG JViEWS GRAPH LAYOUT 5 5 tVerticalAlignment method IlvBusLayout class 233 IlvGridLayout class 260 tVerticalGridBase method IlvLongLinkLayout class 205 tVerticalGridOffset method IlvGridLayout class 262 PerformLayout class 311 tVerticallGridOffset method IlvLongLinkLayout class 205 tVerticalLinkOffset method IlvHierarchicalLayout class 160 tVerticalMinOffset method IlvLongLinkLayout class 205 tVerticalNodeLinkOffset method IlvHierarchicalLayout class 160 tVerticalNodeOffset method IlvHierarchicalLayout class 160 tVerticalOffsetToLevel method IlvBusLayout class 235 tVerticalOffsetToPreviousLevel method UsER S MANUAL IlvBusLayout class 235 getW getWestNeighbor method IlvTreeLayout class 130 G continued global alignment parameters Bus Layout 232 Grid Layout 259 Tree Layout free mode 106 global end point mode parameter Hierarchical Layout 148 Link Layout 197 global link style parameter Hierarchical Layout 145 Link Layout 194 Tree Layout free mode 110 global side association 366 graph layout choosing coordinate space 323 fields of application 10 filter
153. P OVER arranges all children at the same side of the parent this alignment arranges the children at both sides of the parent For details see Tip over Alignment on page 108 IlvTreeLayout MIXED Each parent node can have a different alignment The alignment of each individual node can be set with the result that different alignments can occur in the same graph To obtain the current setting use the following method int getGlobalAlignment Alignment of Individual Nodes nodes have the same alignment unless the global alignment is set to IlvTreeLayout MIXED Only when the global alignment is set to mixed can each node have an individual alignment style r lt gt gt 3 E ER EER eee Figure 4 33 Different Alignments Mixed in the Same Drawing To set and retrieve the alignment of an individual node use the following methods ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 107 TREE LAYOUT void setAlignment Object node int alignment int getAlignmen The valid values for a1ignment are 6 9 H Il Il Il Il t Object node R reeLayout CENTER the default TreeLayout BORDER_CENTE TreeLayout EAS TreeLayout WES reeLayout TIP_OVER TreeLayout TIP_OVER_BOTH_SIDES Tip over Alignment Normally the children of a node are placed in a parallel arrangement
154. PointAt method lvGraphModel class 300 304 LinkPoints method lvGraphModel class 300 LinkPointsCount method lvGraphModel class 300 LinkPriority method lvHierarchicalLayout class 158 Links method lvGraphModel class 299 LinksCount method lvGraphModel class 299 303 LinksFrom method lvGraphModel class 299 LinksFromCount method lvGraphModel class 299 304 lvGraphModel class 299 424 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL getLinksToCount method IlvGraphModel class 300 304 getLinkStyle method lvBusLayout class 229 lvCircularLayout class 252 lvHierarchicalLayout class 146 lvLinkLayout class 196 lvRandomLayout class 221 lvSpringEmbedderLayout class 78 lvTopologicalMeshLayout class 25 61 lvTreeLayout class 111 lvUniformLengthEdgesLayout class 87 getLinkWidth method IlvGraphModel class 300 getLongLinkLayout method IlvLinkLayout class 213 E A H HOHH HAH HOH getM getMargin method IlvBusLayout class 235 getMarginOnBus method IlvBusLayout class 235 getMaxChildrenAngle method IlvTreeLayout class 126 getMaxNumberOfNodesPerLevel method IlvBusLayout class 230 getMaxNumberOfNodesPerRowOrColumn method IlvGridLayout class 260 getMinFinalSegmentLength method IlvLongLinkLayout class 206 IlvShortLinkLayout class 203 getMinNodeCornerOffset method IlvLongLinkLayout class 206 getN getNeighbors method I
155. REFERRED LAYOUTS Now perform the recursive layout using the Layout Provider The node nodel will be considered as fixed by the layout applied to grapherB Nesting Several Layouts for Each Graph in the Nested Graph A more demanding task is to combine several layouts for each graph inside a nested graph For instance a node layout followed by a link layout and lastly by a label layout may be needed for each graph This case is covered by the section Recursive Layout on page 265 Saving Layout Parameters and Preferred Layouts Note To understand this section better read Using the Graph Model on page 297 first Layout parameters are stored in the layout classes directly not in the 11vGrapher The advantage of this is that the layout parameters are independent of the graph model However the disadvantage is that a layout parameter setting is lost whenever a graph is saved to an ivl file and reloaded later To overcome this disadvantage the 11vGrapherAdapter class allows you to transfer the graph layout settings to instances of I1vNamedProperty that can be stored in ivi files and to recover the settings from these named properties at a later time See Save Parameters to Named Properties on page 34 The following method indicates whether a layout class supports this mechanism supportsSaveParametersToNamedProperties It returns t rue if the layout class can transfer the parameter settings to named properties S
156. S MANUAL LINK LAYOUT a label a lab a label a label a label a label Default Settings Customized Settings Figure 4 101 Customization of the Link Connection Box For Experts Special Options of the Long Link Layout The Link Layout algorithm utilizes the class IlvLongLinkLayout as subalgorithm IlvLongLinkLayout is a subclass of I1vGraphLayout and can be used a stand alone as well To access the instance of 11vLongLinkLayout that is used by the Link Layout algorithm use the method IlvLongLinkLayout getLongLinkLayout Using this accessor you can control many special features of the Long Link Layout that are not made available by the IlvLinkLayout class because these features are for experts only Specifying Additional Obstacles The Long Link Layout algorithm considers nodes to be obstacles that cannot be overlapped and links to be obstacles that can be crossed at an angle of 90 degree approximately if the link style is direct but that cannot be overlapped r lt gt gt 3 Link Node Overlapping Link Crossing Link Overlapping Figure 4 102 Crossings and Overlappings If an application requires additional obstacles that are not links or nodes these can be specified by the following ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 213 LINK LAYOUT layout getLongLinkLayout addRectObstacle rect layout getLongLinkLayout addLineObstacle pointl point2 Rectangu
157. The default implementation returns alse A subclass can override this method to return true to indicate that this mechanism is supported Preserve Fixed Links At times you may want some links of the graph to be pinned that is to stay in their current shape when the layout is performed You need a way to indicate the links that the layout algorithm cannot reshape This makes sense especially when using a semiautomatic layout the method where the end user fine tunes the layout by hand after the layout is completed or when using an incremental layout the method where the graph and or the shape of the links is modified after the layout has been performed and then the layout is performed again ILOG JViews allows you to specify that a link is fixed using the method void setFixed Object link boolean fixed If fixed is true it means that the link is fixed To obtain the current setting for a link boolean isFixed Object link The default value is false To remove the fixed attribute from all links in the grapher use the method void unfixAllLinks Note The fixed attributes you may have set will be taken into consideration only if you call the method void setPreserveFixedLinks boolean option with a true argument You can read the current option using the method boolean isPreserveFixedLinks To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean
158. The layout must keep the current position of the connection point on the origin destination node ilvLinkLayout MIXED MODE Each link can have a different end point mode The connection points are automatically considered as fixed if they are connected to grapher pins To obtain the current choice use the following methods int getGlobalOriginPointMode int getGlobalDestinationPointMode Individual End Point Mode links have the same end point mode unless the global end point mode is IlvLinkLayout MIXED_MODE Only when the global end point mode is set to MIXED MODE can each link have an individual end point mode r lt gt gt 3 To set and retrieve the mode of an individual link use the following methods void setOriginPointMode Object link int mode int getOriginPointMode Object link void setDestinationPointMode Object link int mode ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 197 LINK LAYOUT 198 ILO int getDestinationPointMode Object link The valid values for mode are IlvLinkLayout FREE MODE the default r1ilvLinkLayout FIXED MODE The connection points are automatically considered as fixed if they are connected to grapher pins Note The layout algorithm may raise an 11vInappropriateLinkException if layout is performed an 11vGrapher but links are neither a subcl
159. To set a link connection box interface call void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface You implement the link connection box interface by defining a class that implements the IlvLinkConnectionBoxInterface This interface defines the following method m 07 0 O 5 o a public IlvRect getBox IlvGraphModel graphModel Object node This method allows you to return the effective rectangle on which the connection points of the links are placed A second method defined on the interface allows the connection points to be shifted tangentially in a different way for each side of each node public float getTangentialOffset IlvGraphModel graphModel Object node int nodeSide ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 29 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Label e without link connection box final result with link connection box 4 5 Py LS gt with connection box with connection box no tangential offset with positive tangential offsets Figure 2 2 Effect of Link Connection Box Interface For instance to set a link connection box interface that returns a link connection rectangle that is smaller than the bounding box for all nodes of type 11vShadowRectangle and shifts up the connection points on the left and right side of all the nodes call layout setLinkConnectionBoxInterface new IlvLinkConnectionBoxInterface
160. USER S MANUAL SAMPLE JAVA APPLICATION 2 Setthe CLASSPATH variable to the ILOG JViews library and the current directory On Windows 98 2000 NT XP lt installdir gt classes jviewsall jar On Unix Xinstalldir classes jviewsall jar 3 Compile the application javac LayoutSamplel java 4 Run the application java LayoutSamplel The LayoutSamplel java contains the following code the ILOG JViews Graphic Framework import ilog views the ILOG JViews Graph Layout Framework import ilog views graphlayout the ILOG JViews Link Layout import ilog views graphlayout link the Java AWT package import java awt public class LayoutSamplel public static final void main String arg Create the layout instance lvLinkLayout layout new IlvLinkLayout H Create the grapher instance H lvGrapher grapher new IlvGrapher Create the manager view instance Q 0 lt i p 1 H lvManagerView view new IlvManagerView grapher An AWT Frame to display Frame frame new Frame Layout Sample The name of the IVL file containing the graph data final String fileName SampleGraphl ivl Put the manager view inside an AWT Frame and show it frame add view frame setSize 600 600 frame setVisible true Fill the grapher with nodes and links from a JViews IVL file Alternatively
161. USING THE LAYOUT ALGORITHMS Table 5 2 Questions and Answers about the Layout Algorithms Continued Question Answer In some networks there are two or more subnetworks that are not connected How will this affect the layout algorithms provided in ILOG JViews This depends on the layout class you use IlvTopologicalMeshLayout It will work on the connected component of the graph that contains the starting node You can specify this node as a parameter If the starting node is not specified it is automatically chosen in an arbitrary way The nodes of the other connected components will not be moved You may want to perform the layout separately on each connected component using different layout regions and starting node settings This is what you get automatically when you enable the layout of connected components parameter See Layout of Connected Components on page 25 IlvSpringEmbedder IlvUniformLengthEdges These algorithms support disconnected graphs but usually itis better to rely on the automatic layout of connected components parameter See Layout of Connected Components on page 25 I1vBusLayout It will work on the connected component of the graph that contains the bus object You must specify the bus object as a parameter The other nodes that are not connected to the bus will not be moved You may need to perform the layout separately on each connected component This is what y
162. YOUT 5 5 USER S MANUAL link link connector link crossing listener loop manager manager view multiple links neighbor nodes node nonplanar graph NP complete GLOSSARY Another name for an edge in a graph In this documentation the term link is primarily used for edge See also edge In ILOG JViews the system that allows you to control the connections of links to nodes in a grapher Link crossings occur when links intersect at places other than an incident node Also called edge crossings Often layout algorithms are used to minimize the number of link crossings In ILOG JViews an interface allowing you to connect events that occur in the manager view with actions to be performed See cycle In ILOG JViews a holding place for grouping graphic objects and for coordinating their behavior and display in multiple layers and multiple views See view More than one link between the same origin and destination nodes The nodes that are connected to a given node by a link Another name for a vertex of a graph In this documentation the term node is primarily used for vertex A graph that cannot be drawn without any links crossing other links A class of computational problems for which no efficient solution algorithm has been found Many significant computer science problems including many graph layout problems belong to this class ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 415 GLOSSARY
163. a Aima y A graph that has no cycles A layout process where the layout algorithm does everything without any user intervention See 2 connected graph A type of network topology where a set of nodes is connected to a bus object A connected graph or subgraph A connected component of graph G is a maximal connected subgraph of G A graph where there is a path connecting each pair of nodes See also disconnected graph ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 411 GLOSSARY connection Another name for an edge of a graph See also edge cut edge An edge is a cut edge if the graph is no longer connected when the edge is removed from the graph In the following illustration the link between nodes 3 and 5 is a cut edge Note that its end points are cut nodes cut node A node is a cut node if the graph is no longer connected when the node is removed from the graph In the following illustration node 5 is a cut node cycle A path of a graph that begins and ends on the same node Also called a loop 412 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL cyclic graph cyclomatic number degree directed graph disconnected graph edge edge crossing fixed nodes GLOSSARY A graph that contains cycles A number equal to m 1 where m number of edges and n number of nodes In the following illustration the number of edges 10 the number of nodes 8 Therefore the cycl
164. a node covers the x coordinates 25 to 65 on a grid with offset 10 and base 0 the next grid lines used to bypass the node would normally be at 20 and 70 If we specify a minimal distance of 8 these grid lines are too close to the node and then the grid lines at 10 and 80 would be used The minimal distance can be set and obtained by the following methods void setHorizontalMinOffset float offset void setVerticalMinOffset float offset float getHorizontalMinOffset r lt gt gt 3 float getVerticalMinOffset Minimal Node Corner Offset Parameter The minimal corner offset is the minimal distance between a node corner and a link that connects to the node This parameter is used to avoid having a link that connects exactly to the corner or outside the border if the node see Figure 4 97 The minimal corner offset can be set and obtained by ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 205 LINK LAYOUT 206 ILO void setMinNodeCornerOffset float offset float getMinNodeCornerOffset minimal minimal corner offset corner offset Figure 4 97 Minimal Corner Offset Minimum Final Segment Length As with the short link mode the long link mode respects the minimum value for the length of the final connecting segments of the links This length can be set and obtained using the methods void setMinFinalSegmentLength float length float getMinFinalSegmentLength
165. a routine that automatically chooses the layout algorithm at run time The following simple rules could be applied r lt gt gt 3 1 If the nodes of the graph cannot be moved they are geo positioned use the Link Layout 2 Ifthe graph is a tree use the Tree Layout 3 Otherwise use one of the layout algorithms that are the less restricted to a given graph category especially the Uniform Length Edges Layout The preferred length of the links could also be computed with respect to the size of the nodes ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 49 TYPICAL WAYS FOR CHOOSING THE LAYOUT 4 If the graph is too large apply a divide and conquer strategy Cut the graph into several subgraphs and apply the layout separately to each subgraph If the graph is disconnected you can use the built in support provided by the layout library to perform this task automatically See Layout of Connected Components on page 25 If the graph is nested use the Recursive Layout algorithm that controls which subgraph is laid out by which flat sublayout Use step 1 4 above to determine the sublayouts for the subgraphs Procedure for Hard coding when Layout is Applied at Programming Time A special case occurs when the application will deal with only a small set of graphs that are known at the time the application is built In this case the layout can be performed at programming time
166. after each iteration or step JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL FEATURES OF THE ILOG JViEWS GRAPH LAYOUT MODULE e Fixed Nodes This parameter allows the layout algorithm to preserve the location of the specified nodes Certain nodes can be specified as fixed and will not be moved when the layout is performed The layout algorithm can specified nodes in place e Fixed Links This parameter allows the layout algorithm to preserve the shape of the specified links Certain links can be specified as fixed and will not be reshaped when the layout is performed The layout algorithm can specified links in place Q E 5 m lt e S o 2 e Filtering The layout algorithms are able to perform the layout using only the nodes and links that are on user defined layers of the grapher or to exclude nodes and links on an individual basis e Layout of Connected Components This parameter allows you to automatically lay out the connected components of a disconnected graph e Layout Region This parameter allows the layout algorithm to control the size of the graph drawing e Percentage Completion Calculation This parameter allows the layout algorithm to provide an estimation of how much of the layout has been completed e Random Generator Seed Value This parameter allows the layout algorithm to use randomly generated numbers that can be initialized with a us
167. al Parameters for the Grid Mode of the Grid Layout Algorithm r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 261 GRID LAYOUT Layout Region Width dM n CDD LL e pem SG a ee ans oe Top Margin Bottom Margin Third Row lt gt Left Margin Right Margin Layout Region Figure 4 129 Dimensional Parameters for the Row Column Mode of the Grid Layout Algorithm Grid Offset The grid offset parameters control the spacing between grid lines It is taken into account only by the grid mode layout modes TILE TO GRID FIXED WIDTH and TILE GRID FIXED HEIGHT The horizontal and vertical grid offset can be set and retrieved by the following methods void setHorizontalGridOffset float offset void setVerticalGridOffset float offset float getHorizontalGridOffset float getVerticalGridOffset The grid offset is the critical parameter for the grid mode If the grid offset is larger than the size of the nodes plus margins an empty space is left around the node If the grid offset is smaller than the size of the nodes plus margins the node will need to be placed on more 262 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL GRID LAYOUT than one grid cell The best choice for the grid offsets depends on the application It can be computed according
168. allows you to correct the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 67 without clipping with clipping Figure 4 67 Effect of Link Clipping Interface You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call r 2 lt c gt Q gt 3 void setLinkClipInterface IlvLinkClipInterface interface ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 151 HIERARCHICAL LAYOUT Note Additionally to the link clip interface the X1vC1ipLinkConnector can be used This special link connector updates the clipped connection points automatically during interactive node movements The connector style the link connection box interface and the link clip interface work together in the following way by respecting the connector style the proposed connection points are calculated on the rectangle obtained from the link connection box interface or on the bounding box of the node if no link connection box interface was specified Then the proposed connection point is passed to the link clip interface and the returned connection points are used to connect the link to the node An example of the combined effect is shown in Figure 4 68 Clipping at the node bounding
169. alue indicates that the layout algorithm should recalculate the root node preference using the heuristic If a root was specified by the setRoot method but this node should no longer be the root in subsequent layouts use the following call to clear the root node setting layout setRootPreference node qu This call also removes the node from the list of specified roots Position Parameters To set the position of the top left corner of the layout to 10 10 use the following call layout setPosition new IlvPoint 10 10 true 102 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT If the graph consists of only a single tree it is often more convenient to set the position of the root node instead This can be done by the same method passing false instead of t rue layout setPosition point false If no position is specified the layout keeps the root node at its previous position To obtain the current position use the following method IlvPoint getPosition This method returns nu11 if no position was specified If the method returns a point use the following method to query whether the specified position is the top left corner or the position of the first root node boolean isRootPosition Using Compass Directions for Situating Layout Parameters To simplify the explanations of the layout parameters we use the compass directions north south east and west The center of the root node of a tree is cons
170. an detachPrevious The layout instance specified as the preferred layout is stored in a property of the graph The current preferred layout is returned by the method getPreferredLayout IlvGraphModel graphModel The method returns nu11 if no layout has been specified for this graph When the method getGraphLayout is called on the default provider the previously specified preferred layout is returned if any Otherwise a new layout instance is allocated by a call to the method createGraphLayout IlvGraphModel graphModel This newly created layout is recorded as the preferred layout of this graph which is attached to the layout instance The default implementation of the method createGraphLayout copies the layout instance that is the preferred layout of the nearest parent graph of the given graph for which a preferred layout has been specified Therefore if a preferred layout L is specified for a graph G and no preferred layout is set for its subgraphs then the graph G and all its subgraphs are laid out using the same layout algorithm L copies of it are used for the subgraphs Note You must call the method detachLayouts IlvGraphModel graphModel boolean traverse when you no longer need the layout provider instance otherwise some objects may not be garbage collected 280 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL RECURSIVE LAYOUT The settings of the preferred layout made using the class IlvDefaultLayoutProvider can
171. an see from the table whether a layout algorithm is suited for that particular type of graph For example if you know that the structure of the graph is a tree you can look at the Domain Independent Graphs Trees column to see which layout algorithms are appropriate The Spring Embedder Layout Uniform Length Edges Layout Tree Layout and Hierarchical Layout could all be used Use the illustrations in the table cells to help you further narrow your choice The Recursive Layout can be used to control the layout of nested graphs containing subgraphs and intergraph links This is in particular useful if different layout styles should be applied to different subgraphs The other layout algorithms such as Spring Embedder Layout Tree Layout and Hierarchical Layout treat only flat graphs unless otherwise noted that is a specific layout instance is only able to lay out the nodes and links of the attached graph but not the nodes and links of its subgraphs The Recursive Layout allows you to specify which flat layout is used for which subgraph and it traverses the entire nested graph recursively when applying the layout As result the entire nested graph is laid out The Multiple Layout can be used to combine several different layouts into one instance In this case they become sublayouts of the Multiple Layout instance This is useful in particular for nested graphs when used in combination with the Recursive Layout The Multiple Layout ensures th
172. ance between the leftmost or rightmost node of the swim lane and the swim lane border The position index indicates the order of the swim lanes Just as nodes have position indices the swim lanes are placed sequentially at relative positions numbered from 0 to n In a top down layout the swim lane with position O is the leftmost swim lane and the swim lanes with higher position indices are placed farther to the right If the swim lanes have the position index 1 the layout algorithm determines the appropriate position automatically A swim lane constraint is always evaluated even if the incremental mode is enabled The constraint has a higher priority than the relative position constraint and the side by side constraint You can specify side by side constraints for a group of nodes that belong to the same swim lane but side by side constraints of nodes of different swim lanes are ignored You can specify relative position constraints between nodes of the same swim lane You can 180 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT also specify relative position constraints between one entire swim lane group and another swim lane group which effectively orders the swim lanes But relative position constraints are ignored if they would require breaking the swim lanes apart The swim lane constraint dominates the specified position indices and the extremity constraints that is if a swim lane constraint is used you cannot
173. and light trees there will be no difference from the normal radial mode Only for large graphs with a large number of children will the alternating radial mode have an effect The following statement sets the alternating radial layout mode layout setLayoutMode IlvTreeLayout ALTERNATING_RADIAL Figure 4 46 Radial Layout Mode right and Alternating Radial Layout Mode left Aspect Ratio If the drawing area is not a square arranging the levels as circles is not always the best choice You can specify the aspect ratio of the drawing area to better fit the layout to the drawing area In this case the algorithm uses ellipses instead of circles See Figure 4 29 on page 95 for an example 122 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT If the drawing area is a view a subclass of IlvManagerView you can use the following method void setAspectRatio IlvManagerView view If the drawing area is given only as a rectangle use the following void setAspectRatio IlvRect rect If neither a view nor a rectangle is specified you can calculate the aspect ratio from the width and height of the drawing area as aspectRatio width height and use the following method void setAspectRatio float aspectRatio To obtain the current aspect ratio call float getAspectRatio Spacing Parameters The spacing parameters of the radial layout mode are controlled by the same methods as used for the free and level layout
174. ange the parameters of the corresponding layout If there are more than three sets the final calls of the removeParametersFromNamedProperties method guarantee that no memory is wasted by the remaining unused layout properties As mentioned previously only one call of removeParametersFromNamedProperties is necessary if only one grapher adapter is attached to all three instances of layout Note that the parameters are loaded in the reverse order of that which they are stored This is not important if all three layout instances are different classes because a layout automatically loads only parameters that fit the layout class However if for example all three layouts are instances of IlvTreeLayout the last saved set of named properties for any Tree Layout is the first set of named properties that is loaded for a Tree Layout To load layout parameters use one of the following methods boolean loadParametersFromNamedProperties IlvGraphLayout layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL SAVING LAYOUT PARAMETERS AND PREFERRED LAYOUTS This method transfers a set of layout parameters from the named layout properties to the input layout It automatically determines which layout properties fit the input layout If several sets fit it transfers the set that was stored last removes this set of named layout properties from the grapher and returns t rue If no set fits and loading cannot be done it returns false boolean
175. arameter Bus Layout 235 vertical offset to previous level parameter Bus Layout 235 width adjusting Bus Layout 231 448 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL
176. are correctly released once they are no longer needed such obsolete objects can be garbage collected and memory leaks in the Java sense avoided the following rules must be respected 1 When a layout instance instantiated by your code is no longer useful call the method detach on it to ensure that no grapher or graph model is still attached to it Note that you can freely reuse a layout instance once the previously attached model has been detached 2 Layout parameters that are specific to a node or a link are cleaned when calling IlvGraphLayout detach This cleaning is done only for nodes and links that are still in the grapher when the detach method is called If per node or per link parameters have been specified and the node or the link needs to be removed before the detach method can be called you can call the methods cleanNode or cleanLink of the class 11vGraphLayout to perform the cleaning for the node or the link However you only need to do so if the removed node or link is reused by your code after removal Otherwise if your code does not keep any reference to it the node or link will be garbage collected anyway together with the property objects eventually stored by the layout 3 When a grapher adapter or other graph models instantiated by your code is no longer useful call the method dispose on it to ensure that the resources it has used are released Note that an adapter or graph model must not be used once
177. ases this may not be appropriate Brief Description of the Algorithm The Random Layout algorithm is not really a layout algorithm It simply places the nodes at randomly computed positions inside a user defined region Nevertheless the Random Layout algorithm may be useful when a random initial placement is needed by another layout algorithm or in cases where an aesthetic readable drawing is not important Code Sample Below is a code sample using the 11vRandomLayout class import ilog views import ilog views graphlayout import ilog views graphlayout random IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher Fill in here the grapher with nodes and links in IlvRandomLayout layout new IlvRandomLayout layout attach grapher try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL RANDOM LAYOUT Generic Features and Parameters The 11vRandomLayout class supports the following generic parameters defined in the IlvGraphLayout class Layout Region Percentage Completion Calculation Preserve Fixed Links Preserve Fixed Nodes Random Generator Seed Value Save Parameters to Named Properties
178. ass of IlvPolylineLinkImage nor of IlvSplineLinkImage or if connectors are not a subclass of 11vRelativeLinkConnector You can use the methods EnsureAppropriateLinkTypes EnsureAppropriateLinkConnectors or EnsureAppropriateLinks defined in IlvGraphLayoutUtil to automatically replace inappropriate links or link connectors before layout or when the IlvInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 Incremental Mode The Link Layout algorithm normally routes all links from scratch If the graph changes incrementally because you add or remove links or nodes the subsequent layout may differ considerably from the previous layout To avoid this effect and to help the user to retain a mental map of the graph the algorithm has an incremental mode To enable the incremental mode use the following call layout setIncrementalMode true In incremental mode the layout tries to minimize the changes to the layout A link is only rerouted if it is new if a link bend moved if its layout parameters have changed or if a node was moved such that it overlaps the link In short link mode if the next layout is incremental the links preserve the connection side and the general shape calculated by a previous layout except if one of their end nodes has been moved or resized In the long link mode a ne
179. at is not available for the labels A label should not overlap any obstacle or other label In fact this strict condition is unfeasible if there is not enough free space for the labels in this situation the Annealing Label Layout algorithm tries to reduce the amount of overlaps ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL GETTING STARTED WITH LABELING The ILOG JViews Label Layout framework is built on top of the ILOG JViews core library and can coexist with the ILOG JViews Graph Layout framework For details on the core library see the ILOG JViews Graphics Framework User s Manual Note The label layout framework allows you to add layout capabilities to applications that do not use the ILOG JViews manager For details see Creating a New Labeling Model on page 389 Basic Steps to Perform Label Placement o gt 1 3 m To use the Annealing Label Layout algorithm provided by the Graph Layout module of ILOG JViews you will usually perform the following steps 1 Create a manager object Il vManager and fill it with obstacles and labels For instance if you want to place labels at the links of a graph create a grapher and fill it with nodes and links the obstacles and additionally with the labels that should be placed at the links In this case the labels should be added using 11vManager addOb ject instead of IlvGrapher addNode because the labels should not be nodes at
180. at the normal layout the routing of the intergraph links and the layout of labels are applied in the correct order to a nested graph 44 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL DETERMINING THE APPROPRIATE LAYOUT ALGORITHM Table 4 1 Layout Algorithms and Common Types of Graphs Domain Independent Graphs Telecom Oriented Layout Combination of Trees Cyclic Graphs Cycles and Any Graph Representations Trees Topological Mesh Layout m Bi E i U Requires semi manual refinements Spring Embedder 5 u 5 5 s Layout H A a a Z H a E n 1i E a 4 Preferable to B avoid heavily interconnected 2 graphs large Q number of cycles E 9 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 45 DETERMINING THE APPROPRIATE LAYOUT ALGORITHM Table 4 1 Layout Algorithms and Common Types of Graphs Continued Uniform Length Edges Layout n os oe x Pa Ea Fini a l AA gp BE 1 lu Rn vi E i m Y E Preferable to avoid heavily interconnected graphs large number of cycles Tree Layout 46 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL DETERMINING THE APPROPRIATE LAYOUT ALGORITHM Table 4 1 Layout Algorithms and Common Types of Graphs Continued Domain Independent Graphs Telecom Oriented
181. ation on a subgrapher IlvTreeLayout treeLayout new IlvTreeLayout IlvAnnealingLabelLayout labelLayout new IlvAnnealingLabelLayout IlvGraphLayout multipleLayout new IlvMultipleLayout treeLayout null labelLayout Now set the parameters for tree layout and label layout Finally perform a recursive layout that handles tree layout and label layout together try multipleLayout performLayout true true true catch IlvGraphLayoutException e Thus the label layout does not provide a separate mechanism for a recursive layout on submanagers By incorporating the label layout into a multiple graph layout you can use all the graph layout facilities that are available for nested graphs see also Laying Out Nested Graphs on page 306 and Recursive Layout on page 265 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT Multiline Multiline Label Label gt E O 3 D pe o Figure 6 2 Nested Subgraphers with Labels The Label Layout Report The label layout report contains information about the particular behavior of a label layout algorithm After the layout is completed this information is available for reading from the label layout report The information can also be obtained during layout by using a layout listener as described in Layout Events and Listeners on page 352 The layout report is created aut
182. ave its layout parameters into named properties if all its sublayouts support this feature This can be used to save layout parameters to iv1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The Recursive Layout can be stopped at any time It stops the currently running layout of a subgraph after cleanup if the method stopImmediately is called and skips the subsequent layouts of subgraphs that have not yet been started If at the stop time point a sublayout is running on a subgraph that does not support the stop immediately feature then this sublayout first runs to completion before the Recursive Layout is stopped For a description of this method in 11vGraphLayout class see Stop Immediately on page 35 If the layout stops before completion the result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID Layout modes The Recursive Layout has three different layout modes The layout mode is determined by the constructor that you use The way how to set global layout parameters of the sublayouts that are applied to the subgraphs is slightly different for each layout mode You can query the current layout mode by using int getLayoutMode The possible return values are IlvRecursiveLayout REFERENCE LAYOUT MODE The same layout style with the same global layo
183. aving Layout Parameters to ivl Files The following example shows how to save the 11vGrapher including all layout parameter settings into an ivl file The example assumes that an I1vGrapher is attached to three instances layout1 layout2 and layout3 IlvGrapherAdapter adapterl IlvGrapherAdapter layoutl getGraphModel IlvGrapherAdapter adapter2 IlvGrapherAdapter layout2 getGraphModel IlvGrapherAdapter adapter3 IlvGrapherAdapter layout3 getGraphModel transfer the layout parameters to named properties if layoutl supportsSaveParametersToNamedProperties adapterl saveParametersToNamedProperties layoutl false if layout2 supportsSaveParametersToNamedProperties adapter2 saveParametersToNamedProperties layout2 false soJnjeoJj if layout3 supportsSaveParametersToNamedProperties 2 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 315 SAVING LAYOUT PARAMETERS AND PREFERRED LAYOUTS adapter3 saveParametersToNamedProperties layout3 false assume that adapterl adapter2 and adapter3 work on the same grapher save the grapher with all 3 sets of named layout properties to file grapher write abcd ivl remove the named layout properties because they are no longer needed adapterl removeParametersFromNamedProperties adapter2 removeParametersFromNamedProperties adapter3 removeParametersFromNamedProperties In this example different grap
184. ayout In order to do this use the method setCategorizingLinks in the following way layout setCategorizingLinks true now perform a layout layout performLayout now you can access the link categories r lt Lad gt gt 3 After the layout the link categories can be obtained by the following methods Enumeration getCalcForwardTreeLinks Enumeration getCalcBackwardTreeLinks Enumeration getCalcNonTreeLinks The link category data gets filled each time the layout is called unless you set the method setCategorizingLinks back to false ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 131 TREE LAYOUT Sequences of Layouts with Incremental Changes You can work with trees that have become out of date for example those that need to be extended with more children If you perform a layout after an extension you probably want to identify the parts that had already been laid out in the original graph The Tree Layout algorithm supports these incremental changes in incremental mode because it takes the previous positions of the nodes into account It preserves the relative order of the children in the subsequent layout In nonincremental mode the Tree Layout algorithm calculates the order of the children from the node order given by the attached graph model or grapher In this case the layout is independent from the positions of the nodes before layout It does not
185. ayout Algorithms What is a Good Layout To deal with the various needs of different applications many classes of graph layout algorithms have been developed A layout algorithm addresses one or more quality criteria depending on the type of graph and the features of the algorithm when laying out a graph The most common criteria are Minimizing the number of link crossings Minimizing the total area of the drawing 14 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL GRAPH LAYOUT A BRIEF INTRODUCTION Minimizing the number of bends in orthogonal drawings Maximizing the smallest angle formed by consecutive incident links Maximizing the display of symmetries How can a layout algorithm meet each of these quality criteria and standards of representation If you look at each individual criteria some can be met quite easily at least for some classes of graphs For other classes it may be quite difficult to produce a drawing that meets the criteria For example minimizing the number of link crossings is relatively simple for trees that is graphs without cycles However for general graphs minimizing the number of link crossings is a mathematical NP complete problem that is with all known algorithms the time required to perform the layout grows very fast with the size of the graph Moreover if you want to meet several criteria at the same time an optimal solution simply may not exist with respect to each individual
186. ayout algorithm by subclassing I1vLabelLayout you decide whether to use the features and the way in which you are going to use them The 11vLabelLayout class defines the following generic features Allowed Time Percentage Completion Calculation Random Generator Seed Value Save Parameters to Named Properties Stop Immediately Use Default Parameters For details of all generic features see Layout Parameters and Features in IlvGraphLayout on page 20 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 353 THE ANNEALING LABEL LAYOUT The Annealing Label Layout In this section you will learn about the Annealing Label Layout algorithm from the ILOG JViews Label Layout module class IlvAnnealingLabelLayout from the package ilog views graphlayout labellayout annealing Sample Here are some sample drawings produced with the Annealing Label Layout Figure 6 3 Label Placement At Nodes with the Annealing Label Layout 354 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT Label o gt 3 D ES Label Label Figure 6 4 Label Placement At Links with the Annealing Label Layout burg Duisburg Leipzig Yssen Dusse ldorf Kassel Cologne Dre 5 Bonn Wiesbaden eFrankfurt Stuttgart Munich Figure 6 5 Label Placement At Cities in a Map
187. ayout arranges nodes in horizontal or vertical levels such that the links flow in a uniform direction IlvLinkLayout reshapes the links of a graph without moving the nodes IlvRandomLayout moves the nodes of the graphs at randomly computed positions inside a user defined area IlvSpringEmbedderLayout can be used to lay out any type of graph IlvTopologicalMeshLayout can be used to lay out cyclic graphs IlvTreeLayout arranges the nodes of a tree horizontally or vertically starting from the root of the tree IlvUniformLengthEdgesLayout can be used to lay out any type of graph and allows you to specify a preferred length of the links IlvJGraphLayoutProgressBar a Swing JProgressBar toolbar that automatically displays the progress of the layout process The Beans listed in this section are classes of the ILOG JViews Graph Layout module The details of these classes are explained throughout this manual and in the ILOG JViews Graph Layout Reference Manual ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Creating a Simple Applet Using ILOG JViews Graph Layout Beans In this section you are going to create an ILOG JViews applet using ILOG JViews Graphics Framework Beans You are then going to add Graph Layout features using the Graph Layout Beans The applet is a simple JFC Swing applet that displays a graph and provides Graph Layout capabilities No coding will be necessary
188. ayout mode is IlvGridLayout TILE TO GRID FIXED WIDTH Or IlvGridLayout TILE TO GRID FIXED HEIGHT Incremental Mode The Grid Layout algorithm normally places all the nodes from scratch If the graph incrementally changes because you add remove or resize nodes the subsequent layout may differ considerably from the previous layout To avoid this effect and to help the user to retain a mental map of the graph the algorithm has an incremental mode In incremental mode the layout tries to place the nodes at the same location or in the same order as in the previous layout whenever it is possible G JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL GRID LAYOUT To enable the incremental mode call the method set IncrementalMode as follows layout setIncrementalMode true Note To preserve the stability the incremental mode can keep some regions free Therefore the total area of the layout can be larger than in nonincremental mode and in general the layout may not look as nice as in nonincremental mode Dimensional Parameters Figure 4 128 and Figure 4 129 illustrate the dimensional parameters used in the Grid Layout algorithm These parameters are explained in the sections that follow gt Left Margin gt Right Margin Top Margin gt Vertical Grid Offset Botton Margin gt Horizontal Grid Offset Grid Lines Figure 4 128 Dimension
189. ayout report 293 Recursive Layout USER S MANUAL accessing all sublayouts 275 advanced users 277 allowed time parameter 271 application domain 265 code sample different layout styles 267 code sample same layout style 266 code sample specified layout provider 269 combining multiple and recursive layout 288 convenience mechanism of reference layout mode 276 definition 266 features 271 generic parameters 271 internal provider mode 267 269 273 layout listeners 279 layout modes 272 layout providers for experts layout providers Recursive Layout 280 percentage completion parameter 271 reference layout mode 267 273 save to named properties 272 specific parameters 277 specified provider mode 269 274 stop immediately parameter 272 subgraph correction 278 recursive layout 307 applying the same layout 307 layout parameters 309 314 mixing different in nested graph 311 nesting for each graph in nested graph 315 nesting several layouts for each graph 315 simple 307 Recursive Multiple Layout 288 Reference Labeling Model 288 reference layout mode convenience mechanism Recursive Layout 276 Recursive Layout 267 273 reference transformer 324 325 326 reference views 325 refining a graph layout 66 using fixed nodes parameter 66 using layout region parameter 68 using outer cycle parameter 68 relative position constraints 169 relative position constraints Hierarchical Layout 175 INDEX releasing resources 328 removeAllC
190. ayout requires many long links that span several levels Therefore the layout process may become very time consuming for dense graphs the number of links is relatively high compared to the number of nodes or for graphs that require a large number of node levels Brief Description of the Algorithm This algorithm works in four steps Step 1 Leveling The nodes are partitioned into groups Each group of nodes forms a level The objective is to group the nodes in such a way that the links always point from a level with smaller index to a level with larger index Step 2 Crossing Reduction The nodes are sorted within each level The algorithm tries to keep the number of link crossings small when for each level the nodes are placed in this order on a line see Figure 4 59 This ordering results in the relative position index of each node within its level Step 3 Node Positioning From the level indices and position indices balanced coordinates for the nodes are calculated For instance for a layout where the link flow is from top to bottom the nodes are placed along horizontal lines such that all nodes belonging to the same level have approximately the same y coordinate The nodes of a level with a smaller index have a smaller y coordinate than the nodes of a level with a higher index Within a level the nodes with a smaller position index have a smaller x coordinate than the nodes with a higher position index 138 ILOG JViEWS GRAP
191. ayoutEventListener method 295 attach method 18 createLayoutReport method 292 detach method 20 getAllowedTime method 22 getGraphLayout method 269 311 get LayoutOfConnectedComponents method 305 getLayoutRegion method 25 getLayouts method 308 getSeedValueForRandomGenerator method 34 isAnimate method 23 isFixed method 32 33 isLayoutOfConnectedComponentsEnabled method 305 isLayoutOfConnectedComponentsEnabledBy Default method 305 isLayoutTimeElapsed method 22 isMemorySavings method 31 isPreserveFixedLinks method 32 isPreserveFixedNodes method 33 isUseDefaultParameters method 36 isUseSeedValueForRandomGenerator method 34 layout method 18 330 348 layoutReport method 18 layoutStepPerformed method 295 PerformLayout method 311 performLayout method 19 292 308 311 333 setAllowedTime method 22 setAnimate method 22 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 429 INDEX setAutoLayout method 23 setFixed method 32 33 setLayoutOfConnectedComponent s method 305 setLayoutOfConnectedComponentsEnabled method 305 LayoutRegion method 25 LinkClipInterface method 27 70 79 92 115 151 236 253 setLinkConnectionBoxInterface method 29 7O 79 92 113 150 253 setMemorySavings method 31 setSeedValueForRandomGenerator method 34 setUseDefaultParameters method 36 supportsAllowedTime method 22 31 36 supportsAnimation method 23 supportsLayoutOfConnectedComponents method 305 supportsLayoutR
192. ble for non incremental layout algorithms m 07 2 O 5 o a To perform layout automatically whenever the contents of grapher change use the following call layout setAutoLayout true Automatic layout works well if an 11vGrapher is not attached to other layouts If multiple layouts are used for the same I1vGrapher they may mutually affect each other In this case it is recommended to switch off automatic layout The following example shows how to perform multiple changes all at the same time in the IlvGrapher when automatic layout is switched on An automatic layout is performed only once at the end of all the changes layout attach grapher layout setAutoLayout true switch the notification of changes off grapher setContentsAdjusting true try perform multiple changes without any automatic layout finally now the grapher notifies layout about the changes therefore only one automatic layout is performed grapher setContentsAdjusting false ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 23 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT 24 For more information about automatic layout see the method performAutoLayout in the ILOG JViews Graph Layout Reference Manual Coordinates Mode The geometry that is the position and size of the graphic objects that are used to represent nodes and links in an 11vGrapher is subject to a transformer IlvTra
193. box Clipping at a specified connection box Figure 4 68 Combined Effect of Link Clipping Interface and Link Connection Box If the links are clipped at the red node in Figure 4 68 left they appear unsymmetric with respect to the node shape because the relevant part of the node here the triangle is not in the center of the bounding box of the node but the proposed connection points are calculated with respect to the bounding box This can be corrected by using a link connection box interface to explicitly specify a smaller connection box for the relevant part of the node Figure 4 68 right such that the proposed connection points are placed symmetrically at the triangle of the node For Experts Thick Links If evenly spaced pins are used as connector style the links can be evenly spaced with respect to the link center or with respect to the link border The difference is only visible when links that connect to the same node have different widths For instance when the link width indicates the cost or capacity of a flow in the application many different link width may occur Figure 4 69 shows the effect of using different link widths In the drawing on the left the center of the links are evenly distributed at the left node Each link has the same space 152 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT available at the node side Therefore the thick links appear closer to each other than do the thinner links
194. bstacle call defaultLabelingModel setObstacle graphic true Ifa graphic should be ignored by the labeling model call defaultLabelingModel setLabel graphic false defaultLabelingModel setObstacle graphic false This is useful particularly if you want to create graphics that act as background images and labels should be placed on top of the background images If the background images were obstacles the label layout algorithm would try to avoid the area covered by the background images o gt 1 3 m The overlap calculation of the default labeling model takes the bounding box of the obstacles into account This is a good approximation for the most objects For subclasses of IlvLine IlvPolyline and IlvLinkImage it takes the precise polyline shape into account However the default labeling model does not work well with spline obstacles The Label Layout Base Class The 11vLabelLayout class is the base class for all label layout algorithms This class is an abstract class and cannot be used directly Subclasses of llvLabelLayout There are currently two subclasses IlvRandomLabelLayout which randomizes the label positions for demonstration purpose IlvAnnealingLabelLayout which does a useful label arrangement You can also create your own subclasses to implement other label layout algorithms Despite the fact that only subclasses of 11vLabelLayout are directly
195. calLayout EVENLY_SPACED_PINS The connector pins are evenly distributed along the node border This style guarantees that the end points of the links do not overlap This is the best style for orthogonal links and works well for other link styles IlvHierarchicalLayout AUTOMATIC_PINS The connector style is selected automatically depending on the link style If any of the links has an orthogonal style or if any of the links has a port side specification the algorithm chooses evenly spaced connectors If all the links are straight it chooses centered connectors Otherwise it chooses clipped connectors To obtain the current choice use the following method int getConnectorStyle Note The connector style parameter requires link connectors at the nodes of an IlvGrapher fhat allow connector pins to be placed freely at the node border It is recommended that you use 11vRelativeLinkConnector for link connectors to be used in combination with 11vGrapher objects End Points Mode Normally the layout algorithm is free to choose the termination points of each link However if fixed link connectors are used for instance IlvPinLinkConnector the user can specify that the current fixed termination pin of a link should be used The layout algorithm provides two end point modes You can set the end point mode globally in which case all end points have the same mode or locally on each link in which case different end point modes occur in
196. cation Center Justification Figure 4 61 Level Justification for Horizontal Levels If the flow direction is to the left or to the right the valid values for justification are IlvDirection Left IlvDirection Right IlvDirection Center the default x Left Justification Figure 4 62 bi 7 Center Justification T 1 Ej E Right Justification Level Justification for Vertical Levels To obtain the current value use the following method int getLevelJustification Link Style The layout algorithm positions the nodes and routes the links To avoid overlapping nodes and links it creates bend points for the shapes of links The link style parameter controls the 144 ILOG JViEWS GRAPH LAYOUT 5 5 UsER S MANUAL HIERARCHICAL LAYOUT position and number of bend points The link style can be set globally in which case all links have the same kind of shape or locally on each link such that different link shapes occur in the same drawing Polyline Links Orthogonal Links Straight line Links Figure 4 63 Link Styles Note The layout algorithm may raise an 11vInappropriateLinkException if the layout is performed on an 11vGrapher but links are neither a subclass of IlvPolylineLinkImage nor of IlvSplineLinkImage or if connectors are not a subclass of 11vRelativeLinkConnector You can use the methods EnsureAppropriateLinkTypes EnsureAppropriateLinkConnectors or EnsureAppropria
197. ccording to the link style and alignment options Code Sample Below is a code sample using the 11vTreeLayout class import ilog views import ilog views graphlayout import ilog views graphlayout tree IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher Fill in the grapher with nodes and links here Suppose we have added rootNode as a node in the grapher IlvTreeLayout layout new IlvTreeLayout layout attach grapher Specify the root node orientation and alignment 98 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT layout setRoot rootNode layout setFlowDirection IlvDirection Right layout setGlobalAlignment IlvTreeLayout CENTER try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vTreeLayout class supports the following generic features defined in the IlvGraphLayout class Allowed Time Layout of Connected Components Link Clipping Link Connection Box Percentage Completion Calculation Preserve Fixed Links Preserve Fixed Nodes Save Parameters to Named Properties 9 9 9 9 9 Stop Immediately The following paragraphs describe the particular way in which
198. ce the constraint means that nodea is placed at the left side of nodeB If the flow direction is towards the right the nodes are in vertical levels hence the constraint means that nodeA is placed below nodeB The relative position constraint has an effect only if both nodes actually belong to the same level In order to achieve this you can for instance use a same level constraint in addition There is no way to influence the relative position of nodes that belong to different levels Similar to the relative level constraint the relative position constraint can be applied to node groups These constraints also have priorities that indicate which constraints dominate if a constraint conflict occurs The higher the priority the more likely the constraint is satisfied when resolving constraint conflicts Side By Side Constraints The relative position constraint see Relative Position Constraints on page 176 forces a specific order upon the nodes of a level but it does not specify which nodes are directly neighbored For instance a relative position constraint may force nodeA to be placed somewhere at a lower position than nodeB but there may be many nodes between nodeA and nodeB To force nodes to be directly neighbored use the side by side constraint on a group of type IlvNodeGroup see Node Groups on page 172 layout addConstraint new IlvSideBySideConstraint nodeGroup priority If the node group consists of just two nodes it
199. centage Level Layout Mode The level layout mode partitions the node into levels and arranges the levels horizontally or vertically The root is placed at level 0 its children at level 1 the children of those children at level 2 and so on In contrast to the free layout mode in level layout mode the nodes of the same level are justified with each other even if they are not siblings that is they do not have the same parent Figure 4 43 shows the same graph in free layout mode and in level layout mode The following statement sets the level layout mode layout setLayoutMode IlvTreeLayout LEVEL 118 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Free Layout Mode Level Layout Mode Figure 4 43 Free Layout Mode and Level Layout Mode General Parameters Most layout parameters that work for the free layout mode work as well for the level layout mode You can set the flow direction the spacing offsets the global or individual link style and the global or individual alignment See Free Layout Mode on page 104 for details The differences from the free layout mode are The tip over alignment does not work in level layout mode The parent child offset parameter controls the spacing between the levels In level layout mode it is the minimal distance between parent and its children while in free layout mode it is the exact distance between parent and its children The overlap percentage has no eff
200. ch connected component and then to position the connected components using a specialized layout algorithm usually 11vGridLayout Figure 5 2 shows an example of a graph containing four connected components Simply by enabling the layout of the connected components on the regular layout instance here I1vTopologicalMeshLayout the connected components are automatically identified and laid out individually Finally the four connected components are positioned using a highly customizable placement algorithm IlvGridLayout CUM T Figure 5 2 Automatic Layout of Connected Components on a Disconnected Graph 304 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYING OUT CONNECTED COMPONENTS OF A DISCONNECTED GRAPH To indicate whether a subclass of IlvGraphLayout supports this feature the following method is provided in the class IlvGraphLayout boolean supportsLayoutOfConnectedComponents The default implementation returns false A subclass can override this method in order to return true to indicate that this feature is supported ILOG JViews allows you to enable the layout of the connected components using the method void setLayoutOfConnectedComponentsEnabled boolean enable To obtain the current setting boolean isLayoutOfConnectedComponentsEnabled The default value is the value returned by the following method boolean isLayoutOfConnectedComponentsEnabledByDefault The default implementation of this met
201. choose the fixed nodes in a manual refinement procedure See Using Fixed Nodes on page 66 Layout of Connected Components The layout algorithm can use the generic mechanism to lay out connected components For more information about this mechanism see Layout of Connected Components on page 25 If the generic connected component layout mechanism is disabled the algorithm lays out only the connected component that contains the starting node Layout Region Step 2 of TML first draws the outer cycle computed in Step 1 as a regular polygon It uses the layout region setting either your own or the default setting to choose the size and the position of the polygon The remaining nodes are moved inside this polygon three ways to specify the layout region are available for this subclass See Layout Region on page 25 r lt gt gt 3 Remember that if you are using the default settings the visible area of the manager view an instance of IlvManagerView attached to the grapher is used as a layout region If several manager views are attached the first attached view is used If no manager view is attached the layout region is automatically estimated on the basis of the number and size of the nodes If TML produces a layout with overlapping nodes one possible way to correct the problem is to increase the size of the layout region For details see Using the Layout Region Parameter on pa
202. ciently To force a node to the first level you can specify layout addConstraint new IlvExtremityConstraint node IlvHierarchicalLayout NORTH ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 177 HIERARCHICAL LAYOUT To force a node to the last level you can specify layout addConstraint new IlvExtremityConstraint node IlvHierarchicalLayout SOUTH With compass directions as a convenient reference see Port Sides Parameter on page 153 the first level indicates the north pole and the last level indicates the south pole You can also specify extremity constraints for the east and west sides layout addConstraint new IlvExtremityConstraint nodel IlvHierarchicalLayout EAST layout addConstraint new IlvExtremityConstraint node2 IlvHierarchicalLayout WEST The west extremity constraint forces the node to the lowest position index within its level and the east extremity constraint forces the node to the highest position index within its level The position indices specify the relative position within the level For instance a node with west extremity constraint will be the leftmost node within its level if the flow direction is towards the bottom However this does not affect other levels there may be a node in another level that is still placed farther to the left Figure 4 84 illustrates some extremity constraints north extremity ma level
203. cific to a node or a link Such settings are copied anyway from the layout instance of the topmost grapher so such changes are erased just before the recursive layout runs ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYING OUT NESTED GRAPHS Mixing Different Layouts in the Same Nested Graph This section covers the layout of a nested graph in the case where at least one of the following conditions holds The layout algorithm to be applied on subgraphs is not the same as the algorithm needed for the topmost graph Different layouts need to be applied to different subgraphs The same layout algorithm but using different settings needs to be applied on different graphs Using the Layout Provider The ILOG JViews Graph Layout library provides a flexible mechanism for the choice of the layout instance to be applied to each subgraph in a nested graph This mechanism is based on the interface 11vLayoutProvider The interface has a unique method getGraphLayout IlvGraphModel graphModel This method must return the layout instance to be used for the graph model passed as the argument or nu11 if no layout is required for this graph An instance of a class implementing this interface can be passed to the following method of the class IlvGraphModel performLayout IlvGraphModel graphModel IlvLayoutProvider provider boolean force boolean redraw boolean traverse or equivalently to the following static method of the
204. cify the node For each ring or star generically called a cluster the Circular Layout algorithm in one of its modes see Clustering Mode on page 245 allows you to specify the order of the nodes on the circle this is discussed in Cluster Membership and Order of the Nodes on a Cluster on page 245 Otherwise an arbitrary order is automatically chosen In another mode the order is computed automatically such that the number of link crossings is small The network topology can be composed of more than one ring or star These rings and stars can be partially interconnected that is two or more clusters can have a common node as shown in Figure 4 119 They can also be interconnected by links between nodes of two different clusters as shown in Figure 4 120 Figure 4 119 Rings Interconnected by Common Nodes r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 241 CIRCULAR LAYOUT Figure 4 120 Rings Interconnected by Links The Circular Layout algorithm lays out the ring star topologies in a way that preserves the visual identity of each cluster and avoids overlapping nodes and clusters See the sample drawings in Samples on page 238 To understand how the layout is performed in the clustering mode Bv CLUSTER IDS consider a graph in which each node represents a ring or star cluster of a network topology Add a link between two nodes each time there is an interconnection bet
205. class 11vGraphLayout PerformLayout IlvGraphModel model IlvLayoutProvider provider boolean force boolean redraw boolean traverse When performing the recursive layout these methods get the layout instance to be used for each graph from the specified layout provider To implement the interface IlvLayoutProvider you must decide how the choice of the layout instance is done This can be based on some criteria such as the type of graph eventually known in advance or a choice already made by the end user and recorded for instance in a property of the graph A possible implementation of the getGraphLayout method is the following public IlvGraphLayout getGraphLayout IlvGraphModel graphModel Object prop graphModel getProperty layout type if none return null no layout needed for this graph if prop instanceof String return null soJnjeoaJj IlvGraphLayout layout null String name String prop e o 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 311 LAYING OUT NESTED GRAPHS if name equals tree layout new IlvTreeLayout else if name equals flow layout new IlvHierarchicalLayout else throw new RuntimeException unsupported layout choice name layout attach graphModel return layout Of course this is only an example among many possible implementations The implementation may decide to store the newly allocat
206. class 162 vLinkLayout class 198 vTreeLayout class 132 setIndex method Il vBusLayout class 226 setInvisibleRootUsed method LE vTreeLayout class 124 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 443 INDEX setL IlvUniformLengthEdgesLayout class 87 setLinkToLinkCrossingPenalty method setLabelLayout method IlvShortLinkLayout class 210 IlvMultipleLayout class 287 setLinkToNodeCrossingPenalty method setLayoutMode method IlvShortLinkLayout class 210 IlvGridLayout class 258 setLinkWidthUsed method IlvLinkLayout class 192 245 IlvHierarchicalLayout class 153 IlvTreeLayout class 103 104 118 121 122 128 setLayoutOfConnectedComponents method setM IlvGraphLayout class 305 setLayoutOfConnectedComponentsEnabled setMargin method method IlvBusLayout class 235 IlvGraphLayout class 305 setMarginOnBus method IlvTreeLayout class 124 IlvBusLayout class 235 setLayoutRegion method setMaxBacktrack method IlvGraphLayout class 25 IlvLongLinkLayout class 214 IlvRandomLabelLayout class 379 setMaxChildrenAngle method setLeftMargin method IlvTreeLayout class 126 IlvGridLayout class 263 setMemorySavings method setLevelAlignment method IlvGraphLayout class 31 IlvTreeLayout class 120 setMinFinalSegmentLength method setLevelJustification method IlvLinkLayout class 203 IlvHierarchicalLayout class 143 IlvLongLinkLayout
207. class 206 setLevelOffset method IlvShortLinkLayout class 203 IlvCircularLayout class 251 setMinNodeCornerOffset method setLinkClipInterface method IlvLongLinkLayout class 206 IlvGraphLayout class 27 70 79 92 115 151 236 253 setN setLinkConnectionBoxInterface method IlvGraphLayout class 70 79 92 113 150 253 setNodeSideFilter method setLinkConnnectionBoxInterface method IlvLinkLayout class 207 IlvGraphLayout class 29 setNodesPlacementAlgorithm method setLinkOffset method IlvTopologicalMeshLayout class 62 IlvShortLinkLayout class 202 setNumberCrossingReductionInterations setLinkPriority method method IlvHierarchicalLayout class 158 IlvLongLinkLayout class 215 setLinkStyle method setNumberOfPorts method IlvBusLayout class 228 IlvHierarchicalLayout class 155 IlvCircularLayout class 252 IlvHierarchicalLayout class 146 setO IlvLinkLayout class 196 IlvRandomLayout class 220 setOffset method IlvSpringEmbedderLayout class 77 IlvCircularLayout class 250 IlvTopologicalMeshLayout class 24 61 setOrdering method IlvTreeLayout class 111 IlvBusLayout class 226 444 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL setOriginPointMode method IlvHierarchicalLayout class 149 IlvLinkLayout class 197 setOrthForkPercentage method IlvTreeLayout class 117 setOverlapPercentage method IlvTreeLayout class 118 SetP tParentChildOffset method IlvTreeLayout class 116 123 Position method lvTreeLayout class 102 PreferredLayout method lvDefaul
208. class 216 tCalcForwardTreeLinks method lvTreeLayout class 131 tCalcNodeLevelIndex method lvHierarchicalLayout class 183 tCalcNodePositionIndex method lvHierarchicalLayout class 184 tCalcNonTreeLinks method lvTreeLayout class 191 tCalcRoots method lvTreeLayout class 102 tClusterCenter method I I I T I I I I I lvCircularLayout class 251 tClusterIds method Il tClusterIdsCount method lvCircularLayout class 247 tClusterNodes method lvCircularLayout class 251 tClusterRadius method lvCircularLayout class 251 tCode method lvGraphLayoutReport class 294 lvLabelLayoutReport class 352 tConnectorStyle method lvHierarchicalLayout class 148 156 lvTreeLayout class 113 tCoordinatesMode method lvGrapherAdapter class 328 vCircularLayout class 247 251 getD getDestinationPointMode method IlvHierarchicalLayout class 149 IlvLinkLayout class 198 getDisconnectedGraphOffset method IlvCircularLayout class 251 ILOG JViEWS GRAPH LAYOUT 5 5 INDEX getE getEastNeighbor method IlvTreeLayout class 130 getExteriorCycleId method IlvTopologicalMeshLayout class 64 getF getFilter I lvLayoutGraphicFilter class 322 getFirstGraphLayout method vMultipleLayout class 287 getFlowDirection method vBusLayout class 230 lvHierarchicalLayout class 143 vTreeLayout class 106 getFrom method vGraphModel class 30
209. class 276 312 dimensional parameters Bus Layout 234 Grid Layout 261 dimensional parameters Circular Layout 250 disconnected graph laying out connected components 304 disconnected graph offset parameter Circular Layout 251 E east west neighbors Tree Layout 129 end points mode parameter Hierarchical Layout 148 Link Layout 197 events label layout 352 extremity constraints Hierarchical Layout 177 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 421 INDEX F fallback mechanism Link Layout long link mode 215 features generic parameter descriptions 8 layout algorithms 4 fields of application for graph layouts 10 filtering features by graphic objects 323 by layers 322 for IlvGrapher 321 fireGraphModelEvent method IlvGraphModel class 301 fireLabelingModelEvent method IlvLabelingModel class 387 fixed links parameter Bus Layout 225 Circular Layout 244 Hierarchical Layout 141 Link Layout 191 Random Layout 219 Spring Embedder Layout 76 Topological Mesh Layout 60 Tree Layout 100 Uniform Length Edges Layout 86 fixed nodes parameter Bus Layout 225 Circular Layout 244 Grid Layout 258 Hierarchical Layout 141 Random Layout 219 Spring Embedder Layout 76 Topological Mesh Layout 60 Tree Layout 101 Uniform Length Edges Layout 86 using to refine a TML graph layout 66 flow direction parameter Bus Layout 229 Hierarchical Layout 142 Tree Layout free mode 104 force fit to layout region Un
210. close to the related obstacle according to the label descriptor For instance a link label is placed close to its link However if you move the link interactively the label normally stays at the old position which may be far away from the link after the movement The label loses the connection to the link and a new layout is necessary Because it is too time consuming to redo the layout after each single interactive move the Annealing Layout algorithm has a feature that automatically updates the labels on geometric changes that is the label follows the link when the link moves To enable this feature call layout setAutoUpdate true You can check whether this feature is enabled by testing layout isAutoUpdate If automatic update is enabled the algorithm does not perform a full layout of all labels during each interactive change It repositions only the label whose related obstacle has moved in one step Thus it may produce more overlaps than a full layout The automatic update mechanism is much faster however and hence better suitable for interactions Note The automatic update feature works only if the labeling model provides LabelingModelEvents on each obstacle movement The 11vDefaultLabelingModel provides these events If you implement your own labeling model you must provide these events in order to use the automatic update feature Expert Parameters To speed up the layout the Annealing Label Layout algorithm uses a
211. cremental changes 132 orthogonal fork percentage 117 overlap percentage parameter 117 position parameter 102 radial layout mode 120 respect node sizes 117 retrieving link categories 130 retrieving list of root nodes used by algorithm 102 retrieving list of specified root nodes 102 root node parameter 101 root node parameter options 102 sample drawings 94 setting a maximal children angle radial mode 125 setting a root node 101 spacing parameters free mode 115 spacing parameters radial mode 123 specific parameters 101 specifying east west neighbors 129 specifying root node preference 102 specifying the order of children 132 tip over alignment free mode 108 tip over layout modes 126 U unfixAllLinks method IlvGraphLayout class 32 unfixAllNodes method IlvGraphLayout class 93 Uniform Length Edges Layout additional node repulsion weight 89 applicable graph types 83 application domains 83 code sample 84 description 84 features 83 force fit to layout region parameter 88 generic parameters 84 limitations 83 link clipping parameter 85 91 link connection box parameter 86 92 link length weight 89 link style parameter 86 maximum allowed move per iteration 88 node distance threshold 91 number of iterations parameter 87 preferred length parameter 87 respect node size parameter 88 sample drawings 81 specific parameters 86 variable end point parameters Link Layout long link mode 214 vertical offset p
212. criterion is disabled and will no longer have any effect For Experts Implementing Your Own Label Descriptors The Annealing Label Layout is extensible The point label descriptor and the polyline label descriptor are designed to cover the majority of the cases In rare situations you may want to implement your own label descriptor by subclassing the base class IlvAnnealingLabelDescriptor This section describes the necessary steps A label descriptor basically specifies the path where the top left corner of a label can be placed For simplification it considers the path rolled out such that the path has only one dimension If the path is known the precise label position can be specified by just one value the path location The Annealing Label Layout proposes different path locations during the layout however it does not know what the path looks like The task of the label descriptor is to translate the path location into concrete x y coordinates of the label ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 373 THE ANNEALING LABEL LAYOUT As an example we want to create a label descriptor that is able to place labels precisely at a triangular obstacle We could use the point label descriptor as an approximation but it does not place the labels precisely at a triangular shape Figure 6 13 top shows the path around the triangle the dashed red and blue line Below that you see the same path rolled out in one dimension The Annealing
213. ctlnteractor ToolTipT ext View um ZoomlnButton vaila ZoomlnF actor j ZoomOutButton4 vat true Zoom utF actor ZoomViewButton v true ZoomViewlnteractor Default ilvM anagerview Note In this example you added interaction to the view using the control toolbar You could also set an interactor Bean such as the 11vSelectInteractor directly on the manager view by using the interactor property of the 11vManagerView Bean Adding a Graph Layout Bean You are now going to add the capability to apply a link layout to the graph displayed in your applet 1 ILOG On the Beans toolbar click the JViews Graph Layout tab to display the JViews Graph Layout Beans On the JViews Graph Layout Beans toolbar click the 11vLinkLayout Bean Ih icon and drag it to the Form Designer Place it under the 11vGrapher Bean You are now going to associate the 11vLinkLayout Bean with the 11vGrapher object Make sure that the 11vLinkLayout Bean is selected in the Form Designer Its properties should be displayed in the Property List In the Property List window click the value field of the Grapher property Change Default to ilvGrapherl This indicates to the layout Bean which grapher is to be laid out JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING Applet1 AllowedT ime 32000 Animate false AutoLayout true GlobalLinkStyle a Grapher HorizontalGridB ase
214. cy Automatic Update Expert Parameters Label Offset The label offset controls the desired minimal distance between two neighbored labels see Figure 6 12 on page 370 left To avoid labels being placed too close to each other you can increase the label offset This conceptually pushes the labels farther apart However depending on the available space the minimal distance between labels cannot always be maintained Set the label offset as in the following statement ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 369 THE ANNEALING LABEL LAYOUT layout setLabelOffset 25f To obtain the label offset call layout getLabelOffset Obstacle Offset The obstacle offset controls the desired minimal distance between a label and an unrelated obstacle The obstacle offset is usually more important than the label offset because if the obstacle offset is too small the label may be placed so close to an unrelated obstacle that it incorrectly appears to be assigned to that obstacle see Figure 6 12 on page 370 right does for example the green label belong to the upper yellow node or to the green node Increasing the obstacle offset conceptually pushes the label away from the obstacle However depending on the available space the minimal distance between label and obstacle cannot always be maintained Set the obstacle offset as in the following statement layout setObstacleOffset 25f To obtain the obstacle offset cal
215. d the more difficult it is to calculate a layout Therefore this resulting layout may have more link crossings and be less balanced than a graph with no constraints Each type of constraint is represented by a subclass of I1vHierarchicalConstraint The following constraint types are available IlvLevelRangeConstraint Forces a node into a range of certain levels IlvSameLevelConstraint Forces two nodes to the same level IlvRelativeLevelConstraint Forces a node to a lower higher level than another node IlvGroupSpreadConstraint Forces a group of nodes on levels that are no more than a specified spread value apart IlvRelativePositionConstraint Forces a node to a lower higher position than another node of the same level IlvSideBySideConstraint Forces two nodes of the same level to be placed side by side IlvExtremityConstraint Forces a node to the first or last level or to the first or last position within a level IlvSwimLaneConstraint Forces a group of nodes into the same rectangular swim lane area The uses of these classes are explained in the following topics Adding and Removing Constraints Node Groups Level Range Constraints Level Index Parameter 170 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Same Level Constraints Group Spread Constraint Relative Level Constraint Position Index Parameter Relative Position Constraints Side By Side Constraints Extremity Constraints
216. d Layout Lu Mmm m NI E NN E NE tem Features of the ILOG JViews Graph Layout Module The Graph Layout module provides the following features for using the layout algorithms Note that some of these features are not supported by all the algorithms provided with ILOG JViews 9 8 ILOG Capability to fit the layout into a manager view or a user defined rectangle Capability to take into account the size of the nodes when performing the layout to avoid overlapping nodes Capability to perform the layout using only the nodes and links that are on user defined layers of the graph Capability to perform the layout only on those parts of the graph that meet user defined conditions Capability to use non JViews graphers Layout reports providing information concerning the behavior of the layout algorithm Layout event listeners that can receive and report information during the graph layout A generic framework for customizing the layout algorithms The following generic features and parameters are defined Note that not all the layout algorithms provided with ILOG JViews support all these parameters Whether a generic parameter is supported depends on the particular layout algorithm e Allowed Time This parameter allows the layout algorithm to stop computation when a user defined time specification is exceeded e Animation This parameter allows the layout algorithm to redraw the graph
217. d Nodes on page 32 Save Parameters to Named Properties The layout algorithm is able to save its layout parameters into named properties This can be used to save layout parameters to 1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 I1vGraphLayoutReport STOPPED AND INVALID Specific Parameters The following parameters are specific to the IlvUniformLengthEdgesLayout class Link Style When the layout algorithm moves the nodes straight line links such as instances of IlvLinkImage will automatically follow the new positions of their end nodes If the grapher contains other types of links for example IlvPolylineLinkImage or IlvSplineLinkImage the shape of the link may not be appropriate because the intermediate points of the link will not be moved In this case you can ask the layout algorithm to automatically remove all the intermediate points of the links if any 86 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UNIFORM LENGTH EDGES LAYOUT To do this the following method is provided
218. d as a sample Java application with this release This section describes how to compile and run the application and provides the sample code The source code of the application is named Layout Sample2 java and can be found at the location installdir doc usermansrc graphlayout LayoutSample2 java To compile and run the example do the following 1 Goto graphlayout directory at the above path On Windows 98 2000 NT you must open a DOS Console 2 Setthe CLASSPATH variable to the ILOG JViews library and the current directory On Windows 98 2000 NT XP j lt installdir gt classes jviewsall jar On Unix Xinstalldir classes jviewsall jar 3 Compile the application javac LayoutSample2 java 4 Run the application java LayoutSample2 The LayoutSample2 java contains the following code the ILOG JViews Graphic Framework import ilog views import ilog views graphic the ILOG JViews Label Layout Framework import ilog views graphlayout labellayout the ILOG JViews Annealing Label Layout import ilog views graphlayout labellayout annealing the Java AWT package import java awt A very simple example for the use of a Layout Algorithm xy public class LayoutSample2 public static final void main String arg Create the manager instance subclass of IlvManager Since we want ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL GETTING STARTED WITH LABELING to plac
219. d graphs see also Laying Out Nested Graphs on page 306 IlvGraphModel getParentModel IlvGraphModel getRootModel IlvGraphModel getGraphModel Object subgraph IlvGraphModel createGraphModel Object subgraph Enumeration getSubgraphs int getSubgraphsCount boolean isSubgraph Object obj Enumeration getInterGraphLinks int getInterGraphLinksCount boolean isInterGraphLink Object obj Information on the Geometry of the Graph The following methods of the 11vGraphMode1 class allow the layout algorithms to retrieve information on the geometry of the graph IlvRect boundingBox Object nodeOrLink IlvRect boundingBox IlvPoint getLinkPoints Object link IlvPoint getLinkPointAt Object link int index int getLinkPointsCount Object link float getLinkWidth Object link The boundingBox method is called by a layout algorithm whenever it needs to get the position and the dimensions of a node or a link The other methods are used mainly by link layout algorithms 300 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL USING THE GRAPH MODEL Modification of the Geometry of the Graph The following methods of the 11vGraphModel class allow a layout algorithm to modify the geometry of the graph void moveNode Object node float x float y boolean redraw void reshapeLink Object link IlvPoint fromPoint IlvPoint points int startIndex int length IlvPoint toPoint boolean redraw
220. d using the coordinate space of the manager that is the I1vGrapher encapsulated by the adapter without applying any transformation This mode should be used if you visualize the graph at zoom level 1 or you do not visualize it at all or the grapher contains only fully zoomable objects In all these cases there is no need to take the transformer into account during the layout Note that in this mode the dimensional parameters of the layout algorithms are considered as being specified in manager coordinates The reference transformer and the reference view are not used IlvGraphLayout VIEW COORDINATES The geometry of the graph is computed in the coordinate space of the manager view More exactly all the coordinates are transformed using the current reference transformer This mode should be used if you want the dimensional parameters of the layout algorithms to be considered as being specified in manager view coordinates Il1vGraphLayout INVERSE VIEW COORDINATES The geometry of the graph is computed using the coordinate space of the manager view and then applying the inverse transformation using the reference transformer This mode is equivalent to the manager coordinates mode if the geometry of the graphic objects strictly obeys the transformer A small difference may exist because of the limited precision of the computations On the contrary if some graphic objects are either nonzoomable or semizoomab
221. d values for style are IilvRandomLayout NO RESHAPE STYLE None of the links is reshaped in any manner ilvRandomLayout STRAIGHT LINE STYLE the intermediate points of the links if any are removed This is the default value 220 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL RANDOM LAYOUT Note If the STRAIGHT LINE STYLE is selected the layout algorithm may raise an IlvInappropriateLinkException if layout is performed an 11vGraphez but links that cannot be given straight line shape are used Such links are 11vOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage You can use the method EnsureAppropriateLinkTypes orEnsureAppropriateLinks defined in IlvGraphLayoutUtil fo automatically replace inappropriate links This can be done before layout or when the 11vInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 To obtain the current choice use the following method int getLinkStyle r lt p gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 221 BUS LAYOUT Bus Layout In this section you will learn about the Bus Layout algorithm from the ILOG JViews Graph Layout module class 11vBusLayout from the package ilog views graphlayo
222. de but the tangential offset at all sides of the node is 0 Notice that the outgoing links are spaced according to the dashed rectangle which appears too wide for the blue node in this situation The picture on the right shows the effect of the connection box interface if in addition a positive tangential offset was specified for the bottom side and a negative offset was specified for the left side of the blue node Using a Link Clipping Interface By default the Tree Layout places the connection points of links at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correct the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 39 without clipping with clipping Figure 4 39 Effect of Link Clipping Interface 114 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface Note In additionally to the link clip interface t
223. define your own labeling model by creating a subclass of I1vLabelingModel The process is described in the following sections The IlvLabelingModel Class Subclassing the Default Labeling Model 384 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL DEFINING YOUR OWN LABELING MODEL Creating a New Labeling Model The IlvLabelingModel Class The methods defined in the 11vLabelingModel class can be divided into several categories those that provide information on the structure of the labels and obstacles on their geometry on their overlap penalty and notification of changes in the manager They are described in the following sections o gt 1 3 o r Information on the Structure of Labels and Obstacles Information on the Geometry of Labels and Obstacles Overlap Calculation Notification of Changes Storing and Retrieving Object Properties Information on the Structure of Labels and Obstacles The following methods of the 11vLabelingModel class allow the layout algorithms to retrieve information on the labels boolean isLabel Object obj Decides whether an object is a label Enumeration getLabels Enumerates all existing labels int getLabelsCount Returns the number of labels that exist The first method decides whether an object is a label The second method enumerates all existing labels The third method returns the number of labels that exist T
224. del graphModel Object node IlvRect currentNodeBox Object link IlvPoint proposedConnectionPoint IlvPoint auxControlPoint boolean origin This method allows you to return the corrected connection point when the layout algorithm tries to connect to the proposed connection point The auxcont rolPoint is the auxiliary control point of the link segment that ends at the proposed connection point The flag origin indicates whether the connection point is the start point or the end point of the link One strategy is to calculate the intersection between the ray starting at auxCont rolPoint and going through proposedConnectionPoint and the shape of the node If there is any intersection we return the one closer to auxCont rolPoint If there is no intersection clipping is not possible and we return the proposed connection point The following sample shows how to set a link clip interface that clips the connection points at the border of an ellipse or circle node layout setLinkClipInterface new IlvLinkClipInterface public IlvPoint getConnectionPoint IlvGraphModel graphModel Object node IlvRect nodeBox Object link IlvPoint proposedConnectionPoint IlvPoint auxControlPoint boolean origin get the intersections between the line through connect and control point and the ellipse at currentNodeBox IlvPoint intersectionPoints new IlvPoint 2 int numIntersections IlvGraphLayoutUtil LineIntersectsEllipse proposedConnectionPoi
225. der Layout 77 specific Topological Mesh Layout 61 specific Tree Layout 101 specific Uniform Length Edges Layout 86 supported by layout algorithms table 51 parameters of I1vGraphLayout allowed time 22 animation 22 automatic layout 23 coordinates mode 24 description of 20 layout region 25 link clipping 27 link connection box 29 memory savings 31 preserved fixed links 32 preserved fixed nodes 32 random generator seed value 33 save parameters to named properties 34 use default parameters 36 percentage completion parameter Hierarchical Layout 141 Multiple Layout 285 USER S MANUAL 439 INDEX Random Layout 219 Recursive Layout 271 Tree Layout 100 performLayout method IlvGraphLayout class 19 292 308 311 333 IlvLabelLayout class 349 point positioning at 362 point label descriptor 360 positioning at a point 362 positioning at an obstacle 360 positioning on multiple criteria 363 point labeling problem 360 polyline label descriptor full positioning at a link 367 full positioning at a polyline obstacle 368 simple positioning at a link 364 simple positioning at a polyline obstacle 365 global side association 366 local side association 366 side association 366 port index parameter Hierarchical Layout 155 port sides parameter Hierarchical Layout 153 position index parameter Hierarchical Layout 175 position parameter Tree Layout 102 preferred layout loading from ivl file 319 saving 315 saving to IVL file 317 pref
226. der by IlvLayoutProvider getLayoutProvider However in internal provider mode it is mostly not necessary to manipulate the layout provider directly Notice since there is no reference layout global layout parameters are independent for each subgraph Global and local layout parameters can be set by accessing the particular layout instance that is assigned to a specific subgraph After attaching the Recursive Layout to the top level grapher or graph model you can retrieve the layout instance of a specific subgraph by IlvGraphLayout getLayout Object subgraph If you pass nu11 as subgraph you get the layout instance of the top level graph The layout instances of the subgraphs used during recursive layout remain attached to the subgraphs or the graph models of the subgraphs respectively as long as the Reference Layout itself is attached When detaching the Reference Layout all layouts of subgraphs are automatically detached as well Specified Provider Mode Like the internal provider mode the specified provider mode can also be used if you want to perform graph layout on a nested graph but either you need individual global layout parameters for specific subgraphs or you want to layout different subgraphs by different styles However unlike the internal provider mode it is your own responsibility to manage the specified layout provider This is probably only necessary in very advanced applications 274 ILOG JViEWS GRAPH LAYOUT 5
227. des Save Parameters to Named Properties 9 9 9 9 o Stop Immediately ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ToPOLOGICAL MESH LAYOUT TML The following paragraphs describe the particular way in which these parameters are used by this subclass Note that all the methods allowing the modification of these parameters are overridden in this subclass This class keeps track of the changes for parameters that may affect the result of Step 1 separately from the parameters that may affect only Step 2 In this way Step 1 is not repeated The previous results are used if no parameters were modified since the last time the layout was successfully performed on the same graph using the same layout instance Allowed Time Step 1 of TML stops if the allowed time setting has elapsed In the same manner Step 2 of TML stops if the allowed time is exceeded See Allowed Time on page 22 You can specify separate time settings for each step Each step is stopped if its specified time limit is exceeded To learn how to do this see Optimization Iterations and Allowed Time on page 62 and Nodes Placement Iterations and Allowed Time on page 62 Animation In TML the animation parameter see Animation on page 22 is used only in Step 2 If specified a redraw will be automatically performed after each iteration of the step This is useful to better understand what is happening during the step and especially if you want to be able to
228. dividual global layout parameters for specific subgraphs or you want to layout different subgraphs by different styles In this case there is no reference layout You allocate the Recursive Layout using the constructor with no arguments IlvRecursiveLayout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 273 RECURSIVE LAYOUT Before you can perform a layout you need to specify which layout is used for which subgraph First you should attach the Recursive Layout to a graph Then in order to specify the layout of the top level graph call recursiveLayout setLayout null sublayout In order to specify the layout of a specific subgraph call recursiveLayout setLayout subgraph sublayout It is important that you assign a different layout instance for each subgraph You cannot share the same layout instance among different subgraphs We recommend that you allocate a new fresh layout instance for each subgraph If you pass nu11 as sublayout then no layout is performed for this particular subgraph To set the layout for a subgraph and recursively for all its subgraphs you can use setLayout Object subgraph IlvGraphLayout layout boolean traverse and pass the t rue argument for the traverse flag This sets the layouts to a clone of the input layout for each subgraph starting at the input subgraph Internally the Recursive Layout uses a layout provider of type IlvRecursiveLayoutProvider You can access the current layout provi
229. drawing grows relatively quickly with the size of the graph that is the number of nodes and links and the layout process may become time consuming for large graphs Overlapping nodes cannot always be avoided Nevertheless the layout algorithm often produces a drawing with no overlapping nodes Brief Description of the Algorithm This layout algorithm iteratively searches for a configuration of the graph where the length of the links is close to a user defined or a default value Code Sample Below is a code sample using the 11vUniformLengthEdgesLayout class import ilog views import ilog views graphlayout import ilog views graphlayout uniformlengthedges IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher A Fill in the grapher with nodes and links here IlvUniformLengthEdgesLayout layout new IlvUniformLengthEdgesLayout layout attach grapher try IlvUniformLengthEdgesLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vUniformLengthEdgesLayout class supports the following generic parameters defined in the 11vGraphLayovut class Allowed Time Animation 84 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UN
230. e Take a look at two sample drawings of the same graph Here no format layout algorithm was used Using one of the layout algorithms provided The nodes were placed randomly when the ILOG JViews the following drawing was graph was drawn obtained In the second drawing the layout algorithm has distributed the nodes quite uniformly avoiding overlapping nodes and showing the symmetries of the graph This drawing presents a much more readable layout than does the first drawing Composition of the ILOG JViews Graph Layout Module The ILOG JViews Graph Layout module is composed of the following packages ilog views graphlayout A high level generic framework for the graph layout services provided by ILOG JViews 2 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL COMPOSITION OF THE ILOG JViEWS GRAPH LAYOUT MODULE Layout algorithm packages e ilog views graphlayout bus layout algorithm designed to display bus network topologies that is a set of nodes connected to a bus node e ilog views graphlayout circular A layout algorithm that displays graphs representing interconnected ring and or star network topologies e ilog views graphlayout grid A layout algorithm that arranges the disconnected nodes of a graph in rows in columns or in the cells of a grid Bulonpos y L e ilog views graphlayout hierarchical A layout algorithm that arranges nodes in horizontal or vertical levels such that the links flo
231. e If the graph is a pure tree all links are chosen If the graph has cycles some links will not be included as part of the spanning tree These links are called non tree links while the links of the spanning tree are called tree links The non tree links are ignored in step 2 of the algorithm In Figure 4 27 Figure 4 28 and Figure 4 29 the root is the black node In the spanning tree each node except the root has a parent node All nodes that have the same parent are called children with respect to the parent and siblings with respect to themselves Nodes without children are called leaves Each child at a node starts a subtree also called a branch of the tree Figure 4 30 show an example of a spanning tree r lt gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 97 TREE LAYOUT root non tree link children of paren siblings x y non tree link branch Figure 4 30 Spanning Tree Step 2 Calculating Node Positions and Link Shapes The layout algorithm arranges the nodes according to the layout mode and the offset and alignment options In the free mode and level mode the nodes are arranged horizontally or vertically so that all tree links flow roughly in the same direction In the radial layout modes the nodes are arranged in circles or ellipses around the root so that all tree links flow radially away from the root Finally the link shapes are calculated a
232. e This is usually faster and more stable on incremental changes than the generic mechanism Furthermore it enables the user to set the position of the layout Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to the border of the node shapes See Using a Link Clipping Interface on page 114 for details of the link clipping mechanism Link Connection Box The layout algorithm can use a link connection box interface see Link Connection Box on page 29 in combination with the link clip interface If no link clip interface is used the link connection box interface has no effect For details see Using a Link Connection Box Interface on page 113 Percentage Completion Calculation The layout algorithm calculates the estimated percentage of completion This value can be obtained from the layout report during the run of layout For a detailed description of this feature see Percentage Completion Calculation on page 31 and Layout Event Listeners on page 294 Preserve Fixed Links The layout algorithm does not reshape the links that are specified as fixed For more information on link parameters in the 11vGraphLayout class see Preserve Fixed Links on page 32 and
233. e as illustrated in The Labeling Model on page 346 Some obstacles do not have a rectangular shape For simplicity and speed the overlap value is based on the bounding box of normal obstacles Hence the default labeling model may compute overlaps in situations where in fact there are no overlaps because the bounding box is usually a little larger than the area that is really covered by the obstacle You can correct 388 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL DEFINING YOUR OWN LABELING MODEL this by overriding the method getOverlapValue by implementing more precise but also more complex overlap test public double getObstacleOverlap Object label IlvRect labelBBox Object obstacle IlvRect obstacleBBox float minDist complex calulation of the overlap considering the precise shape of the obstacle If the label is closer than minDist to the obstacle it should be considered as overlap o gt 1 3 E r if hasOverlap return a value proportional to the overlap else return 0 0 Creating a New Labeling Model The default labeling model is suitable only if the underlying data structure is an IlvManager The case may arise where an application uses its own classes and where for some reason you do not want to replace these classes with ILOG JViews classes such as IlvManager and IlvLabel Here you cannot use the default labeling model To enable the label layout al
234. e 365 368 related 361 362 363 retrieving information on 385 386 setting immovable 347 obstacle parameters Link Layout long link mode 213 offset parameter Circular Layout 250 optimization allowed time parameter Topological Mesh Layout 62 optimization iterations parameter Topological Mesh Layout 62 order of nodes parameter Circular Layout 245 order parameter Bus Layout 226 orthogonal fork percentage parameter Tree Layout 117 outer cycle parameter Topological Mesh Layout description of 64 outer cycle parameter topological Mesh Layout using to refine a TML graph layout 68 overlap calculation 386 value 386 overlap percentage parameter Tree Layout 117 P parameters description of generic parameters 20 ILOG JViEWS GRAPH LAYOUT 5 5 INDEX generic Annealing Label Layout 358 generic Bus Layout 224 generic Circular Layout 243 generic Grid Layout 257 generic Hierarchical Layout 140 generic Link Layout 190 generic Multiple Layout 285 generic Random Label Layout 377 generic Random Layout 219 generic Recursive Layout 271 generic Spring Embedder Layout 75 generic Topological Mesh Layout 58 generic Tree Layout 99 generic Uniform Length Edges Layout 84 specific Bus Layout 226 specific Circular Layout 245 specific Grid Layout 258 specific Hierarchical Layout 142 specific Link Layout 192 specific Multiple Layout 286 specific Random Layout 220 specific Recursive Layout 277 specific Spring Embed
235. e Space Note To understand this section better read Using the Graph Model on page 297 first Graph layout algorithms have to deal with the geometry of the graph that is the position and shape of the nodes and links In addition they must deal with the layout of an 11vGrapher The nodes of an ILOG JViews 11vGrapher can be any graphic object that is any subclass of I1vGraphic The position and size of the nodes are given by their so1njeoaJj e o 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 323 CHOOSING THE LAYOUT COORDINATE SPACE boundingBox IlvTransformer t method and usually depend on the transformer used for their display Therefore when an 11vGrapher has to be laid out the geometry of the grapher must be considered for a given value of the transformer The most natural transformer value that could be chosen is the identity transformer An identity transformer has no translation zoom or rotation factors In terms of ILOG JViews this would mean that the geometry of the 11vGrapher would be considered in the manager coordinates not in the manager view coordinates transformed coordinates However the special case of nonzoomable graphic objects must be taken into account For this case the idea of simply using the geometry of the grapher in manager coordinates is not pertinent A Special Case Nonzoomable Graphic Objects A graphic object is said to be zoomable i
236. e bus object In the Hierarchical Layout algorithm you can specify node position indices and level indices as well as relative positioning constraints ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL QUESTIONS AND ANSWERS ABOUT USING THE LAYOUT ALGORITHMS Table 5 2 Questions and Answers about the Layout Algorithms Continued Question Answer If use ILOG JViews on different computers and or with different Java Virtual Machines JVM sometimes get different layouts for the same graph and with the same parameters Why There are two possible reasons 1 Different computers and JVMs may be slower or faster If the layout algorithm you use stops the computation when the specified allowed time has elapsed a slower computer or JVM will cause the computation to stop earlier That may be the cause of different results This may happen even with the same computer and JVM if the charge of the computer is increased You may need to increase the allowed time specification when running on a slower computer or JVM 2 f you use a layout algorithm that uses the random generator and if you use the default option for the seed value that is the system clock is used you get different results for each successive run of the layout on the same graph This allows you to obtain alternative results and to chose the one you prefer If you want to prevent different results for successive runs you can specify a constant seed
237. e cyclomatic number of the graph which is smaller than the number of nodes or links The user can obtain several layouts of the same graph easily and quickly by simply changing a parameter especially the starting node and the outer cycle or by applying manual refinements to the layout The best layout can then be selected from the resulting layouts Limitations The algorithm tries to minimize the number of link crossings which is generally an NP complete problem It is mathematically impossible to quickly solve this problem for any graph size Therefore the algorithm uses heuristics that cannot always obtain a layout with the theoretical minimum number of link crossings The computation time required to obtain an appropriate drawing grows relatively quickly with the cyclomatic number and the layout process may become very time consuming for large graphs Again this is because the minimization of the number of link crossings is mathematically NP complete in the general case The algorithm cannot automatically produce appropriate drawings of some types of graphs e For graphs containing branches and graphs containing cut nodes or cut edges manual adjustments are necessary See Refining a Graph Layout on page 66 e For disconnected graphs the connected component layout feature should be used See Layout of Connected Components on page 25 The layout algorithm often produces a drawing with no overlapping nodes Neverthele
238. e directed the algorithm automatically chooses the canonical root node If the links are undirected you can choose a root node Connected and disconnected graphs If the graph is not connected the layout algorithm treats each connected component separately Each component has exactly one root node In this case a forest of trees 15 laid out Application Domains Application domains of the Tree Layout include Business processing organizational charts Software management software re engineering UML diagrams call graphs r lt gt gt 3 Database and knowledge engineering decision trees The World Wide Web Web site maps Features Takes into account the size of the nodes so that no overlapping occurs ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 95 TREE LAYOUT 96 Optionally reshapes the links to give them an orthogonal form alternating horizontal and vertical line segments Various layout modes free levels radial or automatic tip over e Inthe free layout mode arranges the children of each node starting recursively from the root so that the links flow uniformly in the same direction e In the level layout mode partitions the nodes into levels and arranges the levels horizontally or vertically e In radial layout mode partitions the nodes into levels and arranges the levels in circles or ellipses around the root e In the t
239. e it is recommended to use layout providers that store the layout instances internally and return the same instance for the same graph model The predefines IlvDefaultLayoutProvider and IlvRecursiveLayoutProvider store the layout instances internally Convenience Mechanism of the Reference Layout Mode The class IlvGraphLayout contains a convenience method In order to perform a recursive layout recursively you can use int performLayout boolean force boolean redraw boolean traverse If the traverse flag is t rue it traverses the nested graph and performs the layout on each subgraph In fact this is just a shortcut for the reference mode of Recursive Layout The statement flatLayout performLayout force redraw true is equivalent to creating a Recursive Layout in reference mode that uses the flat Layout as reference layout IlvRecursiveLayout recursiveLayout new IlvRecursiveLayout flatLayout 276 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL RECURSIVE LAYOUT recursiveLayout performLayout force redraw Specific Parameters Besides some expert parameters Recursive Layout does not provide any specific layout parameters You can set specific layout parameters of the sublayouts individually by accessing them via get Layout Object IlvGraphLayout sublayout recursiveLayout getLayout subgraph sublayout setParameter parameter However Recursive Layout has some convenient methods that automatically t
240. e link labels IlvGrapher grapher we use a grapher in this example new IlvGrapher Create the manager view instance IlvManagerView view new IlvManagerView grapher view setBackground Color white An AWT Frame to display Frame frame new Frame Label Layout Sample Put the manager view inside Frame and show it o gt 1 3 r frame add view frame setSize 400 400 frame setVisible true Fill the grapher with nodes and links IlvReliefRectangle nodel new IlvReliefRectangle new IlvRect 0f Of 50f 50f IlvReliefRectangle node2 new IlvReliefRectangle new IlvRect 200f Of 50f 50f IlvReliefRectangle node3 new IlvReliefRectangle new IlvRect Of 200f 50f 50f IlvReliefRectangle node4 new IlvReliefRectangle new IlvRect 200f 200f 50f 50f grapher addNode nodel false grapher addNode node2 false grapher addNode node3 false grapher addNode node4 false set some nice colors setNodeColors nodel node2 node3 node4 IlvLinkImage 1 1 new IlvLinkImage nodel node2 true IlvLinkImage link2 new IlvLinkImage nodel node3 true IlvLinkImage link3 new IlvLinkImage node2 node4 true IlvLinkImage link4 new IlvLinkImage node4 node3 true IlvLinkImage link5 new IlvLinkImage nodel node4 true grapher addLink link1l false grapher addLink link2 false
241. e offset between parent and children However this affects the layout globally which means that nodes without the deficiency are also affected To avoid a global change such as this you can limit the maximal angle between the two rays from the parent if it is not the root to its two outermost children This increases the offset between parent and children only where necessary In Figure 4 50 you can see in the layout on the left that many of the links overlap other nodes In the layout on the right you can see how this problem was solved by setting a maximal children angle between two rays from a parent to the two outermost children r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 125 TREE LAYOUT Unrestricted Maximal Children Angle Maximal Children Angle 90 degrees Figure 4 50 Maximal Children Angle Use the following method to set and obtain the angle in degrees void setMaxChildrenAngle int angle int getMaxChildrenAngle Recommended values are between 30 and 180 Setting the value to 0 means the angle is unrestricted The calculation of the angle is not very precise above 180 degrees or if the aspect ratio is not 1 0 Tip Over Layout Modes As in radial layout mode drawing in free layout mode can be adjusted to the aspect ratio of the drawing area Free layout mode can also use tip over alignment to balance the drawing between the height and depth
242. e often used to represent the hierarchical decomposition of a network into subnetworks more generally to mix connectivity information for several levels of detail in the same drawing In Figure 5 3 a layout algorithm the Tree Layout has been used for each of the graphs Order of Layouts in Recursive Layouts Assume the grapher A contains a subgrapher B and the subgrapher B contains two subgraphers C and p The recursive layout needs to be applied in postorder as follows 1 Layouton 2 Layout on D 3 Layouton B 4 Layouton A This means that the layout of a graph is performed once all the layouts of its subgraphs have already been done In our example all layouts of subgrapher have finished before the layout of grapher A starts This is the correct order for a recursive layout This order ensures that the layout of a subgraph does not invalidate the layout of its parent graphs The correct order for a recursive layout is implemented by the different methods provided by the library presented in the following sections Applying the Same Layout Recursively Mixing Different Layouts in the Same Nested Graph Nesting Several Layouts for Each Graph in the Nested Graph Applying the Same Layout Recursively This section covers the layout of a nested graph in the case where both of the following conditions hold The same layout algorithm needs to be applied on the topmost graph and all its subgraphs The setting
243. e stopping point Often they have not yet been changed at all e NOT_NEEDED appears if the layout was not performed because no changes occurred in the grapher and parameters since the last time the layout was performed successfully soinjeo4 ge o 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 293 USING EVENT LISTENERS e EMPTY GRAPHER appears if the grapher is empty To read the code use the method int getCode Layout Time This field contains the total duration of the layout algorithm at the end of the layout To read the time in milliseconds use the method long getLayoutTime Percentage of Completion This field contains an estimation of the percentage of the layout that has been completed This can be used if the layout algorithm supports the generic percentage completion calculation feature See Percentage Completion Calculation on page 31 It is typically used inside layout event listeners that are described in the following section To access the percentage use the method int getPercentageComplete Additional information Additional information for particular layout algorithms is stored by the subclasses of IlvGraphLayoutReport For details see the Reference Manual for these classes e IlvTopologicalMeshLayoutReport e IlvUniformLengthEdgesLayoutReport Using Event Listeners layout classes support two kinds
244. e using the default settings the visible area of the manager view an instance of IlvManagerView attached to the grapher is used as a layout region If several manager views are attached the first attached view is used If no manager view is attached the layout region is automatically estimated on the basis of the number and size of the nodes Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to the border of the node shapes See Using a Link Clipping Interface on page 78 for details of the link clipping mechanism Link Connection Box The layout algorithm can use a link connection box interface see Link Connection Box on page 29 in combination with the link clip interface If no link clip interface is used the link connection box interface has no effect For details see Using a Link Clipping Interface on page 78 Memory Savings As with all classes supporting this parameter a certain amount of memory savings can be obtained by selecting this option See Memory Savings on page 31 Note that using this parameter will not change the resulting layout It will just slow down the computation Preserve Fixed Links The layout algorithm does not reshape the lin
245. eLinkImage cannot be reshaped You should use the class IlvPolylineLinkImage or IlvSplineLinkImage instead Connector Style The layout algorithm positions the end points of links the connector pins at the nodes automatically The connector style parameter specifies how these end points are calculated Centered Clipped Evenly Spaced Evenly Spaced Connector Pins Connector Pins Connector Pins Connector Pins with Orthogonal Links Figure 4 65 Connector Styles To set the connector style use the following method r lt gt gt 3 void setConnectorStyle int style The valid values for style IlvHierarchicalLayout CENTERED_PINS The end points of the links are placed in the center of the border where the links are attached This option is well suited for polyline links and straight line links It is less well suited for orthogonal links because orthogonal links can look ambiguous in this style ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 147 HIERARCHICAL LAYOUT IlvHierarchicalLayout CLIPPED_PINS Each link pointing to the center of the node is clipped at the node border The connector pins are placed at the points on the border where the links are clipped This option is particularly well suited for polyline links without port specifications It should not be used if a port side for any link is specified IlvHierarchi
246. ealingLabelLayout class 354 IlvAnnealingPointLabelDescriptor class constructor 361 362 363 IlvAnnealingPolylineLabelDescriptor class constructor 364 365 367 368 livB IlvBusLayout class ge ge ge ge ge ge ge ge ge ge ge ge ge is pro se se se se se se se se se se se se se Bus method 228 FlowDirection method 230 GlobalAlignment method 232 HorizontalOffset method 235 Index method 226 LinkStyle method 229 argin method 235 arginOnBus method 235 axNumberOfNodesPerLevel method 230 Ordering method 226 tVerticalAlignment method 233 tVerticalOffsetToLevel method 235 tVerticalOffsetToPreviousLevel method 235 BusWidthAdjust ingEnabled method 232 vided as a Bean 392 tBus method 228 tBusWidthAdjustingEnabled method 231 tFlowDirection method 230 260 tGlobalVerticalAlignment method 232 tHorizontalOffset method 234 tIncrementalMode method 234 tIndex method 226 tLinkStyle method 228 tMargin method 235 tMarginOnBus method 235 tOrdering method 226 tVerticalAlignment method 233 tVerticalOffsetToLevel method 235 CE Ce GRE GE cuc cL cb cr se IIvC tVerticalOffsetToPreviousLevel method 235 IlvCircularLayout class addClusterId method 246 getClusterCenter method 251 428 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL getClusterIds method 247 251 getClusterIdsCount method 247 getClusterNodes method 251 getClusterRadius me
247. ect in level layout mode Level Alignment gt lt gt fe gt 3 In level layout mode with flow direction to the top or bottom the nodes are organized in horizontal levels such that the nodes of the same level are placed approximately at the same y coordinate The nodes can be justified depending on whether the top border the bottom border or the center of all nodes of the same level should have the same y coordinate In flow direction to the left or right the nodes are organized in vertical levels approximately at the same x coordinate The nodes of the same level can be justified at the left border at the right border or at the center ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 119 TREE LAYOUT To distinguish the level alignment independently from the flow direction we use the directions north and south see Using Compass Directions for Situating Layout Parameters on page 103 The north border of a node is the border that is closer to the level where its parent is placed and the south border of a node is the border that is closer to the level where its children are placed If the flow direction is to the bottom the level alignment north means that the nodes are justified at the top border and south means that the nodes are justified at the bottom border If the flow direction is to the top it is converse north means the bottom border and south means the top border If the flow direc
248. ection rectangle that is smaller than the bounding box for all nodes of type 11vShadowRectangle and shifts up the connection points on the left and right side of all the nodes call layout setLinkConnectionBoxInterface new IlvLinkConnectionBoxInterface public IlvRect getBox IlvGraphModel graphModel Object node IlvRect rect graphModel boundingBox node if node instanceof IlvShadowRectangle need a rect that is 4 pixels smaller rect resize rect width 4 f rect height 4 f return rect public float getTangentialOffset IlvGraphModel graphModel Object node int nodeSide switch nodeSide case IlvDirection Left case IlvDirection Right return 10 shift up with 10 for both left and right side case IlvDirection Top case IlvDirection Bottom default return 0 no shift for top and bottom side 1 Figure 4 98 shows the effects of customizing the connection box the left is the result using the default settings the connection points are distributed on the bounding box of the node which includes the label and are symmetric with the middle of each node side including the label On the right is the result after specifying a link connection box interface On the bottom side of the nodes the links are now connected to the node passing over the label while on the left and right side the nodes are now symmetric to the middle of the node without the label 212 ILOG JViEWS GRAPH LAYOUT 5 5 USER
249. ed in any way once it has been detached from the layout instance For details see Using the IlvGrapherAdapter on page 302 After layout when you no longer need the layout instance you should call the detach method If the detach method is not called some objects may not be garbage collected This method also performs cleaning operations on the grapher properties that may have been added by the layout algorithm on the grapher s objects are removed 18 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL BASIC OPERATIONS WITH ILVGRAPHLAYOUT void detach Performing a Layout The performLayout method starts the layout algorithm using the currently attached grapher and the current settings for the layout parameters The method returns a report object that contains information about the behavior of the layout algorithm IlvGraphLayoutReport performLayout IlvGraphLayoutReport performLayout boolean force boolean redraw The first version of the method simply calls the second one with a false value for the first argument and a t rue value for the second argument If the argument force is false the layout algorithm first verifies whether it is necessary to perform the layout It checks internal flags to see whether the grapher or any of the parameters have been changed since the last time the layout was successfully performed A change can be any of the following Nodes or links were added or removed m 07 2 O
250. ed layout instance to avoid allocating a new one when the method is again called for the same graph The library provides a default implementation of this interface named IlvDefaultLayoutProvider In many cases it is simpler either to use this class as is or to subclass it rather than directly implementing this interface The class 11vDefaultLayoutProvider allows you to set the layout instance to be used for each graph called the preferred layout with the method setPreferredLayout IlvGraphModel graphModel IlvGraphLayout layout boolean detachPrevious boolean traverse The layout instance specified as the preferred layout is stored in a property of the graph The current preferred layout is returned by the method getPreferredLayout IlvGraphModel graphModel The method returns nu11 if no layout has been specified for this graph When the method getGraphLayout is called on the default provider the previously specified preferred layout is returned if any Otherwise a new layout instance is allocated by a call to the method createGraphLayout IlvGraphModel graphModel This newly created layout is recorded as the preferred layout of this graph which is attached to the layout instance The default implementation of the method createGraphLayout copies the layout instance that is the preferred layout of the nearest parent graph of the given graph for which a preferred layout has been specified Therefore if a preferred layout L
251. edder Layout and Trees Produced with the Spring 72 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL SPRING EMBEDDER LAYOUT Figure 4 17 Medium sized Graph Drawing Combination of Cycles and Trees Produced with the Spring Embedder Layout What Types of Graphs Any type of graph Connected and disconnected Planar and nonplanar graphs Application Domains Application domains of the Spring Embedder Layout include ILOG Telecom and networking WAN diagrams Software management software re engineering call graphs CASE tools dependency diagrams Database and knowledge engineering semantic networks database query graphs qualitative reasoning and other artificial intelligence diagrams and so on World Wide Web Web hyperlink neighborhood JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 73 r lt Lad gt gt 3 SPRING EMBEDDER LAYOUT Features Often provides a drawing with no link crossings or few crossings for small and medium size graphs The maximum number of nodes for which you can use this layout depends on the connectivity of the graph hundreds for trees dozens for cyclic graphs Limitations The computation time required to obtain an appropriate drawing grows relatively quickly with the size of the graph that is the number of nodes and links and the layout process may become very time consuming for large graphs O
252. een nodes see Figure 4 123 To specify the offset use the method void setOffset float offset To obtain the current value use the method float getOffset Level Offset If the clustering mode is BY SUBGRAPHS the level offset parameter controls the minimal offset between nodes that belong to the same cluster The following applies if the clustering mode is BY CLUSTER IDS As explained in Brief Description of the Algorithm on page 240 interconnected rings and or clusters are drawn on concentric circles around a root cluster The radius of each concentric circle is computed to avoid overlapping clusters In some cases you may want to increase this radius to obtain a clearer drawing of the network To meet this purpose the radius is 250 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT systematically increased with a level offset value see Figure 4 123 To specify this parameter use the method void setLevelOffset float offset To obtain the current value use the method float getLevelOffset The default value is zero This parameter has no effect if the clustering mode is BY SUBGRAPHS Disconnected Graph Offset As explained in Brief Description of the Algorithm on page 240 each connected component of the network is laid out separately and the drawing of each component is placed near the others see Figure 4 123 To specify the offset between each connected component use the method
253. egion method 26 334 supportsLinkClipping method 27 supportsLinkConnectionBox method 29 supportsMemorySavings method 31 supportsPreserveFixedLinks method 32 supportsPreserveFixedNodes method 25 33 34 supportsRandomGenerator method 34 supportsSaveParametersToNamedPropertie s method 315 unfixAllLinks method 32 unfixAllNodes method 33 IlvGraphLayoutReport class description 292 getCode method 294 getLayoutTime method 294 stored information 293 IlvGraphLayoutUtil class IsTree static method 49 IlvGraphModel class addGraphModelListener method 301 adjustmentEnd method 301 boundingBox method 300 createGraphModel method 300 description of 299 fireGraphModelEvent method 301 getFrom method 300 getGraphModel method 300 se se ct ct ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge ge is tInterGraphLinks method 300 tInterGraphLinksCount method 300 304 LinkPointAt method 300 304 LinkPoints method 300 LinkPointsCount method 300 Links method 299 LinksCount method 299 303 LinksFrom method 299 LinksFromCount method 299 304 ksTo method 299 LinksToCount method 300 304 LinkWidth method 300 Neighbors method 300 NodeDegree method 300 Nodes method 299 odesAndLinks method 299 odesCount method 299 303 tOpposite method 300 tParentModel method 300 tProperty method 302 tRootModel method 300 tSubgraphs method 300 tSubgraphsCount method 300 304 tTo method 300 Inter
254. el class 386 390 Bus Layout applicable graph types 222 application domains 222 bus node parameter 228 code sample 223 description 223 dimensional parameters 234 features 223 flow direction parameter 229 generic parameters 224 global alignment parameters 232 horizontal offset parameter 234 incremental mode parameter 234 individual node alignment parameter 233 link clipping parameter 225 link style parameter 228 margin on bus parameter 235 margin parameter 235 maximum nodes per level parameter 230 order parameter 226 ordering options table 227 sample drawing 222 specific parameters 226 vertical offset parameter 235 vertical offset to previous level parameter 235 width adjusting 231 bus node parameter Bus Layout 228 bypass distance parameter Link Layout short link mode 210 C calculated level index parameter Hierarchical Layout 183 calculated position index parameter Hierarchical Layout 184 calculating link shapes Tree Layout 98 calculating node positions Tree Layout 98 420 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL calculating the spanning tree Tree Layout 97 Circular Layout applicable graph types 239 application domains 239 area minimization parameter 247 cluster contents parameter 251 cluster membership parameters 245 cluster position parameter 251 cluster size parameter 251 clustering mode parameter 245 code sample 242 description 240 dimensional parameters 250 disconnected graph off
255. elong to different subgraphs of a nested graph Supports an incremental mode If new links are added to a drawing the next layout takes the shapes of the old links into account r lt gt gt 3 Two layout modes short links with a limited number of bends or long links with unlimited number of bends Short Link Mode e Links are placed freely in the space e Link to link and link to node crossings are reduced if this is possible with link shapes that have a maximum of 4 bends ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 187 LINK LAYOUT 188 e Links of different width are supported e Link bundles between the same pair of nodes are supported Optionally the algorithm can ensure that multiple links are bundled together by giving them parallel shapes e Automatically arranges the final segments of the links the segments near the origin or destination node to obtain a bundle of parallel links e Provides two optional shapes for the self links e Very fast algorithm with low memory footprint Long Link Mode e Links are placed on a grid e Link to node crossings of orthogonal links are avoided even if this introduces many bends e Orthogonal link segments do not overlap e Does not bundle the final segments Instead it distributes the links on the border of each end node according to which border has more free space e Fast algorithm speed and memory footpri
256. ely equal length links for small and medium size graphs having a small number of cycles The maximum number of nodes for which you can use the algorithm depends on the connectivity of the graph and is difficult to predict On demand the algorithm can take into account the size width and height of the nodes Otherwise they are more efficiently considered as points It is possible to specify specific desired lengths for each of the links Because it takes into account the initial configuration coordinates of the nodes the algorithm allows an incremental layout methodology Sometimes the layout algorithm is not able to find the optimal layout because it has been trapped by a local minimum of the cost function In this case the user can perform the layout once then move by hand one or more nodes to help the layout algorithm skip from the local minimum and then perform the layout again However the success of this procedure depends on the choice of the nodes to be moved In many cases the choice is quite intuitive r lt gt gt 3 Limitations The algorithm is not appropriate for all graphs In particular it will produce bad results on some highly connected cyclic graphs for which a planar drawing with equal length links may simply not exist ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 83 UNIFORM LENGTH EDGES LAYOUT The computation time required to obtain an appropriate
257. en labels are displayed below or above nodes You can modify the position of the connection points of the links by providing a class that implements the IlvLinkConnectionBoxInterface An example for the implementation of a link connection box interface is in Link Connection Box on page 29 To set a link connection box interface call void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface The link connection box interface provides each node with a link connection box and tangential shift offsets The Hierarchical Layout uses the link connection box but does not use the tangential offsets Figure 4 66 illustrates the effects of customizing the connection box On the left is the result without any connection box interface The picture on the right shows the effect if the connection box interface returns the dashed rectangle for the blue node 150 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL HIERARCHICAL LAYOUT EEG normal B y connection box specified Figure 4 66 Effect of Connection Box Interface Using a Link Clipping Interface By default the Hierarchical Layout places the connection points of links at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface
258. en the layout is considered up to date with respect to the layout parameters Itreturns false if the event occurs when any layout parameter has changed The following example shows how to implement a layout parameter event listener class LayoutParameterListener implements GraphLayoutParameterEventListener so1njeoaJj em o 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 295 REDRAWING THE GRAPHER AFTER LAYOUT public void parametersUpToDate GraphLayoutParameterEvent event if event isParametersUpToDate System out println Any layout parameter has changed Then register the listener with the layout instance as follows layout addGraphLayoutParameterEventListener new LayoutParameterListener Redrawing the Grapher after Layout When a layout algorithm is executed it moves the nodes and or reshapes the links of the graph If the graph is displayed on a screen its display must be updated to reflect the changes made by the layout Several scenarios for updating the display are possible one or another being preferable depending on the particular application ILOG JViews provides complete flexibility concerning the redraw operation When laying out an ILOG JViews grapher I1vGrapher the following scenarios are possible Automatic and selective redraw If you just want the grapher to be automatically redrawn after the layout simply call the following me
259. er defined seed value These seed values are then used during layout computations to produce different layouts of the graph e Save Parameters to Named Properties This parameter provides support for saving the layout parameters as named properties in ivl files e Stop Immediately This parameter allows the layout algorithm to stop layout computation immediately when an outside event occurs e Use Default Parameters This parameter allows the layout algorithm to return to using default parameter settings after the default settings have been modified ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 9 ILOG JViEWS GRAPH LAYOUT MODULE IN USER INTERFACE APPLICATIONS ILOG JViews Graph Layout Module in User Interface Applications 10 Many fields use graph drawings and graph layouts in user interface applications Therefore the ILOG JViews Graph Layout module is particularly well suited for these kinds of applications The following is a list of some of the fields where the graph layout capabilities of the ILOG JViews Graph Layout module can be used ILOG Telecom and Networking e LAN Diagrams Bus Layout Circular Layout e WAN Diagrams Spring Embedder Uniform Edge Length Electric Engineering e Logic Diagrams Hierarchical Layout e Circuit Block Diagrams Hierarchical Layout Link Layout Bus Layout Industrial Engineering e Industrial Process Charts Hierarchical Layout e Schematic Design Diagrams Link Layout Hi
260. eraction The Interaction Wizard appears Click Next on the first page of the wizard A In the Events area make sure that act ionPerformed is selected Click Next On the next page of the Interaction Wizard click Call a method In the Available objects area select I1vLinkLayoutl m In the Methods area select performLayout 404 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Interaction Wizard x What do you want to happen when JButton1 fires actionPerformed event Perform action Calla method C Set a property Available objects Methods notity notify AlIC e ilvGrapher1 ilv Manager view performLayout oll ilvScrollManagerview1 removeAllLayers removeGraphLayoutEventListener GraphLayoutEver removeLayer IlvManagerLayer setAllowedNumberOflterations int setAllowedTime long set amp nimate boolean set amp utolnstallLinkConnector boolean set amp utoLayout boolean setFixed Object boolean setGeometryLllpToDate boolean 4 b javadoc help is available x Back Next gt Finish Help 8 Click Finish to apply the interaction The Interaction Wizard closes i JButton1 sue g noke c 2 2 o O gt Now when the user clicks the Perform Layout button the layout is performed and the links of the graph are
261. erarchical Layout e Equipment Resource Control Charts Bus Layout Link Layout Business Processing e Workflow Diagrams Hierarchical Layout e Process Flow Diagrams Hierarchical Layout e Organization Charts Tree Layout Circular Layout e Entity Relation Diagrams Link Layout e PERT Charts Hierarchical Layout Software Management Software Re Engineering e UML Diagrams Hierarchical Layout Tree Layout e Flow Charts Hierarchical Layout e Data Inspector Diagrams Link Layout Hierarchical Layout e Call Graphs Spring Embedder Uniform Edge Length Layout Hierarchical Layout Tree Layout CASE Tools e Design Diagrams Link Layout Hierarchical Layout e Dependency Diagrams Spring Embedder Uniform Edge Length Layout JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL ILOG JViEWS GRAPH LAYOUT MODULE IN USER INTERFACE APPLICATIONS Data Base and Knowledge Engineering e Semantic Networks Uniform Edge Length Layout Spring Embedder Topological Mesh Layout e Decision Trees Tree Layout e Database Query Graphs Spring Embedder Uniform Edge Length Layout Hierarchical Layout e Qualitative Reasoning and other Artificial Intelligence Diagrams Topological Mesh Layout Spring Uniform Edge Length Layout The World Wide Web e Web Site Maps Tree Layout e Web Hyperlink Neighborhood Spring Embedder Uniform Edge Length Layout Circular Layout Bulonpos y L 10 E m lt
262. erarchical Layout 173 level justification parameter Hierarchical Layout 143 level layout mode Tree Layout description 118 general parameters 119 level alignment parameter 119 level offset parameter Circular Layout 250 library ILOG JViews core library 16 link box connection interface Link Layout short link mode 211 link categories retrieving Tree Layout 130 link clipping 27 link clipping parameter Bus Layout 225 Circular Layout 244 252 Hierarchical Layout 141 151 Spring Embedder Layout 76 78 Topological Mesh Layout 60 69 Tree Layout 100 114 Uniform Length Edges Layout 85 91 link connection box 29 link connection box interface feature Link Layout 208 link connection box parameter Circular Layout 244 253 Hierarchical Layout 141 150 Spring Embedder Layout 76 79 Topological Mesh Layout 60 70 Tree Layout 100 113 Uniform Length Edges Layout 86 92 link crossing penalty parameter Link Layout short link mode 210 link crossings layout criteria 14 Link Layout applicable graph types 186 application domains 187 bypass distance parameter short link mode 210 choosing the appropriate layout mode 193 code sample 190 description 189 end points mode parameter 197 fallback mechanism long link mode 215 features 187 generic parameters 190 global end point mode parameter 197 ILOG JViEWS GRAPH LAYOUT 5 5 INDEX global link style parameter 194 grid base parameter long link mode 205 grid offset parameter long
263. erations To obtain the current value use the method int getAllowedNumberOfIterations Preferred Length The main objective of this layout algorithm is to obtain a layout where all the links have a given length This is called the preferred length To specify the preferred length use the method r lt gt gt 3 void setPreferredLinksLength float length To obtain the current value use the method float getPreferredLinksLength ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 87 UNIFORM LENGTH EDGES LAYOUT It is also possible to specify a desired length for individual links using the method void setPreferredLength Object link float length To obtain the current value use the method float getPreferredLength Object link If a specific length is not specified for a link the global settings are used Respect Node Size By default the layout algorithm ignores the size width and height of the nodes For efficiency reasons the nodes are approximated with points place in the center of the bounding box of the nodes When dealing with large nodes the preferred length parameter can be increased in such a way that the nodes do not overlap However to improve the support for graphs with heterogeneous node sizes the algorithm provides a special mode in which the particular size of each node is taken into consideration To set and retrieve this mode use the foll
264. ergraph links mode is enabled you can select whether only the intergraph links are routed or whether the intergraph links and the normal links are routed at the same time If you call r lt gt gt 3 layout setCombinedInterGraphLinksMode false the next layout routes the intergraph links but does not reshape any normal links If you call layout setCombinedInterGraphLinksMode true the next layout routes both the normal links and the intergraph links ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 199 LINK LAYOUT When the intergraph links mode is enabled the layout cannot route the links incrementally see Incremental Mode on page 199 and the layout animation is disabled see Animation on page 22 Notice that the layout routes only those links that belong to the attached graph In a nested graph each subgraph is attached to a different layout instance Therefore when starting a normal nonrecursive layout for the top level graph of Figure 4 93 on page 200 not all links are routed that are shown in that figure but only those links that belong to the top level graph Figure 4 94 shows two situations the yellow subgraph indicates the subgraph where the nonrecursive layout is currently applied and color of the links indicate which links are currently routed Depending on the intergraph links mode the red and or blue links are routed but the grey links are not reshaped
265. ernally For simplicity the details of the mechanism are hidden and you select the choice of layout by using the method set Layout on the Recursive Layout instance Therefore this layout mode is called internal provider mode However you can also design your own layout provider and use it inside the Recursive Layout This is the specified provider mode of the Recursive Layout A layout provider is a class that implements the interface IlvLayoutProvider The interface has a unique method getGraphLayout IlvGraphModel graphModel This method must return the layout instance to be used for the graph model passed as the argument or nu11 if no layout is required for this graph When performing the Recursive Layout these methods get the layout instance to be used for each graph from the specified layout provider To implement the interface IlvLayoutProvider you must decide how the choice of the layout instance is done This can be based on some criteria such as the type of graph eventually known in advance or a choice already made by the end user and recorded for instance in a property of the graph A possible implementation of the get GraphLayout method is the following r lt fe c gt e gt 3 public IlvGraphLayout getGraphLayout IlvGraphModel graphModel Object prop graphModel getProperty layout type if none return null no layout needed for this graph if prop instanceof Stri
266. erred length parameter Uniform Length Edges Layout 87 preserve fixed links parameter Bus Layout 225 Circular Layout 244 Hierarchical Layout 141 Link Layout 191 Random Layout 219 Spring Embedder Layout 76 Topological Mesh Layout 60 Tree Layout 100 Uniform Length Edges Layout 86 preserve fixed nodes parameter Bus Layout 225 Circular Layout 244 Grid Layout 258 Hierarchical Layout 141 440 ILOG JViEWS GRAPH LAYOUT 5 5 Random Layout 219 Spring Embedder Layout 76 Topological Mesh Layout 60 Tree Layout 101 Uniform Length Edges Layout 86 R radial layout mode Tree Layout adding an invisible root node 124 alternating radial mode 122 aspect ratio parameter 122 description 120 evenly spaced first circle 124 setting a maximal children angle 125 spacing parameters 123 random generator seed value parameter Random Layout 219 Spring Embedder Layout 76 Random Label Layout 376 allowed time parameter 377 code sample 377 description 376 features 376 generic parameters 377 layout region parameter 379 percentage completion parameter 378 random generator seed value parameter 378 sample drawing 376 save parameters to named properties 378 specific parameters 378 stop immediately parameter 378 use default parameters 378 Random Layout applicable graph types 217 code sample 218 description 218 features 217 generic parameters 219 limitations 218 link style parameter 220 sample drawing 217 specific parameters 220 reading a l
267. erred position For this it calls the method setTowardsPreferredPosition pathLocation dist i with i from 1 to You should implement the method such that in each step you calculate a path location closer to the preferred location When i is it should be exactly at the preferred location You can call setPosition to move the label to the preferred x y position For instance public void setTowardsPreferredPosition double pathLocation float dist int i int maxI double offset pathLocation getPreferredPathLocation double newLocation pathLocation i offset maxI setPosition newLocation dist These methods take a distance as a parameter additional to the path location This is the distance from the path If the label must always be on the path you can assume this distance is 0 Only if your label descriptor allows the label to have a variable offset to the path should you include the distance from the path in the calculations ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 375 THE RANDOM LABEL LAYOUT The Random Label Layout In this section you will learn about the Random Label Layout algorithm from the ILOG JViews Label Layout module class IlvRandomLabelLayout from the package ilog views graphlayout labellayout random Sample Here is a sample drawing produced with the Random Label Layout e T el L abel gue e C e Lg Figure 6 14 Label Place
268. ertical grid offset can be set by the following methods void setHorizontalGridOffset float offset void setVerticalGridOffset float offset 204 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT They can be obtained by the corresponding methods float getHorizontalGridOffset float getVerticalGridOffset The grid offset is the critical parameter for the long link mode If the grid offset is too large there may be no grid lines between nodes even though some free space exists between the nodes In this case the link routings cannot use the free space However if the grid offset is too small the algorithm needs a long time to traverse the grid Grid Base Parameters Sometimes it is necessary to shift the whole grid by a small amount because the nodes are not aligned on the grid For instance to have grid lines at positions 3 13 23 33 and so on you can set the grid offset to 10 and the grid base to 3 The grid base can be adjusted and retrieved by the following methods void setHorizontalGridBase float coordinate void setVerticalGridBase float coordinate float getHorizontalGridBase float getVerticalGridBase Minimal Distance Parameters The minimal distance controls how closely a link can be placed to the border of a node that needs to be bypassed If the node border is not aligned to the grid the minimal distance specifies the next grid line close to the border that can be used For instance if
269. erties with the labels or obstacles or global properties Properties are a set of key value pairs where the key is a String object and the value can be any kind of information value Subclassing the Default Labeling Model The default labeling model 11vbefaultLabelingModel is a subclass of IlvLabelingModel It has certain properties that may not be suitable for your application Only objects of type 11vLabel and 11vZoomableLabel are considered labels Only objects of type IlvLine IlvPolyline and IlvLinkImage are considered polyline obstacles All other objects are considered rectangular obstacles It is easy to change these properties by subclassing 11vDefaultLabelingModel For instance if you use only labels of class MySpecialLabel you can override the method isDefaultLabelClass public boolean isDefaultLabelClass Object obj return obj instanceof MySpecialLabel If objects should be completely ignored you should make sure they are not considered as labels or obstacles To avoid considering objects of class IgnorableGraphic as obstacles you can override the method isObstacle public boolean isDefaultObstacleClass Object obj return super isDefaultObstacleClass obj amp amp obj instanceof IgnorableGraphic Note Instead of overriding isDefaultLabelClass and isDefaultObstacleClass you could also specify which objects are labels and obstacles by using the methods set Label and setObstacl
270. es by at least the amount specified by 1ayout setObstacleOffset Label Movement Policy The label movement policy is an easy way to define which labels should be moved by the label layout algorithm For instance the following code installs a label movement policy such that the layout moves only labels with a height larger than 100 layout setLabelMovementPolicy new IlvLabelMovementPolicy public boolean allowMove IlvLabelingModel labelingModel Object label return labelingModel boundingBox label height gt 100 Labels with smaller heights are not moved However they are also not completely ignored because the layout tries to position the movable labels so that they do not overlap the immovable labels and the label offset is respected between movable and immovable labels A more general useful example is a movement policy that prohibits moving labels that initially do not overlap anything This predefined movement policy is available through the class I1vOverlappingLabelMovementPolicy lt can be used in applications that have their own label positioning mechanism and use the Annealing Label layout only as postprocessing step to improve the positions of overlapping labels To install this policy call layout setLabelMovementPolicy new IlvOverlappingLabelMovementPolicy ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 371 THE ANNEALING LABEL LAYOUT Automatic Update After layout the labels are placed
271. est specified priority dominates the other constraints For Experts Constraint Validation Constraints may become invalid For instance if you add a constraint that node A must be to the left side of node B but you remove A from the graph then this constraint becomes invalid It simply does not make sense any more even though it does not conflict with any other constraint The layout instance automatically removes invalid constraints from time to time because they are a waste of memory The validation check is done during layout Forcing a validation check is normally not needed but if you want to perform it call layout validateConstraints ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT This removes all invalid constraints from the Hierarchical Layout and cleans up the memory The constraint validation does not check which constraints have conflicts The main effect of the validation is that the constraint system uses less memory afterwards Note A constraint is valid if it is meaningful Two valid constraints are conflicting if the system cannot satisfy them both at the same time Invalid constraints cannot be conflicting because they are meaningless Hence constraint validation and constraint resolution are different phases Constraint validation performs a quick local test It removes invalid constraints from the layout instance completely It does not affect conflicting constraints Constraint resolution
272. et method 117 tCalcBackwardTreeLinks method 131 tCalcForwardTreeLinks method 131 tCalcNonTreeLinks method 131 tCalcRoots method 102 tConnectorStyle method 113 tEastNeighbor method 130 tFlowDirection method 106 tGlobalAlignment method 107 tGlobalLinkStyle method 110 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 433 INDEX LayoutMode method 103 getLevelAlignment method 120 getLinkStyle method 111 getMaxChildrenAngle method 126 getOrthForkPercentage method 117 getOverlapPercentage method 118 getParentChildOffset method 117 getPosition method 103 getSiblingOffset method 117 getSpecRoots method 102 getTipOverBranchOffset method 117 getWestNeighbor method 130 isRootPosition method 103 provided as a Bean 392 setAlignment method 108 109 setAllowedTime method 127 setAspectRatio method 123 126 setBranchOffset method 116 123 setConnectorStyle method 112 setEastWestNeighboring method 130 setFlowDirection method 105 setGlobalAlignment method 106 108 setGlobalLinkStyle method 110 setIncrementalMode method 132 setInvisibleRootUsed method 124 setLayoutMode method 103 104 118 121 122 128 LayoutOfConnectedComponentsEnabled method 124 setLevelAlignment method 120 setLinkStyle method 111 setMaxChildrenAngle method 126 setOrthForkPercentage method 117 setOverlapPercentage method 118 setParentChildOffset method 116 123 setPosition method 102 setRoot method 102 setRootPreference method 102 setSiblingOffset method 11
273. etach the layouts when the provider is no longer needed provider detachLayouts adapterA true dispose the topmost adapter when no longer needed adapterA dispose ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 281 MULTIPLE LAYOUT Multiple Layout In this section you will learn about the Multiple Layout class from the ILOG JViews Graph Layout module class 11vMultipleLayout from the package ilog views graphlayout multiple Application Domain The Multiple Layout class is not a layout algorithm but rather a facility to compose multiple layout algorithms and treat them as one algorithm object This is necessary in particular when dealing with the recursive layout of nested submanagers see Recursive Layout on page 265 and Laying Out Nested Graphs on page 306 because performing the layouts recursively one after the other has a different effect than combining the layouts into one algorithm object and applying this object all at once Multiple Layout should also be used to combine a normal layout with a Link Layout that routes intergraph links This is illustrated in the following sample Code Sample You can for instance combine a Tree Layout a Link Layout and an Annealing Label Layout into one object of type IlvGraphLayout in the following way import ilog views import ilog views graphlayout import ilog views graphlayout multiple import ilog views graphlayout tree import ilog views graphlayout link
274. eter you may want the layout algorithm to use the default values You select the default values for all global parameters by layout setUseDefaultParameters true ILOG JViews keeps the previous settings when selecting the default values mode You can switch back to your own settings by layout setUseDefaultParameters false This setting affects only the global layout parameters The label descriptors have no default values so parameters of the label descriptors do not change depending on this flag Label Descriptors To specify where a label must be placed you must set a label descriptor for each label The algorithm places only those labels that have a label descriptor A label descriptor describes the locations that are allowed for the label For instance if you place a city name label in a geographic map you want the label to be positioned close to the graphic objects that represent the city Positions far away from the city are not reasonable for the label You need to allocate a new label descriptor for each label To set the descriptor for one label call layout setLabelDescriptor label descriptor You can retrieve the current label descriptor by layout getLabelDescriptor label ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 359 THE ANNEALING LABEL LAYOUT Subclasses of Label Descriptors There are two predefined subclasses of label descriptors the Point Label Descriptor Polyline Label Descripto
275. eters 358 global parameters 369 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 419 INDEX implementing your own label descriptors 373 label descriptors 359 subclasses 360 label movement policy 371 label offset parameter 369 limitations 356 obstacle offset parameter 370 percentage completion calculation parameter 358 point label descriptor 360 polyline label descriptor 364 random generator seed value parameter 358 sample drawings 354 save parameters to named properties 359 stop immediately parameter 359 use default parameters 359 area layout criteria 14 area minimization parameter Circular Layout 247 aspect ratio parameter Tree Layout radial mode 122 Tree Layout tip over mode 126 attach method IlvGraphLayout class 18 IlvLabelLayout class 348 attaching a grapher 18 automatic label placement 339 340 automatic layout description of 15 49 automatic layout parameter Link Layout 191 automatic update labels 372 B Beans associating objects 397 classes available as Beans 392 creating a graph layout Bean 402 creating a grapher 397 creating a toolbar 400 creating the manager view 394 editing properties 396 example applet 393 executing the applet 407 IlvJScrollManagerView class 394 IlvManagerView class 395 loading an iv1 file 399 setting properties of the manager view 396 testing the applet 407 bends layout criteria 15 boundingBox method 380 IlvGraphic class 924 IlvGraphModel class 300 IlvLabelingMod
276. evelPositionRange 100 This statement specifies that within the range of 100 coordinate units from the old position of the node the balance is the only criteria for the placement This means that a node whose optimal position is less than 100 coordinate units away from its previous position is placed exactly at its optimal position Nodes whose optimal position is farther away are placed at a position that is a compromise between previous position and optimal position This is illustrated in Figure 4 81 on page 170 right Set the absolute level position tendency as in the following example layout setIncrementalAbsoluteLevelPositionTendency 70 This statement specifies that positions of nodes whose optimal positions are far away from their previous position are 70 influenced by their previous position and 30 influenced by their optimal positions Imagine a rubber band that tries to pull a node to its previous position and another rubber band that tries to pull the same node to its optimally balanced position The level position tendency 70 means that one rubber band pulls with 70 of the force towards the previous position and the other rubber band pulls with 3096 towards the optimal position Increasing the tendency means that the node stays closer to its old position decreasing it means that the node moves closer to its optimal position If you set the tendency to 0 this has the same effect as disabling the incremental absolute level posi
277. ew IlvLevelRangeConstraint node 5 5 Alternatively you can call layout setSpecLevellIndex node 5 which has exactly the same meaning If you want to force the node to level 5 and above set UNSPECIFIED as the maximal level layout addConstraint new IlvLevelRangeConstraint node 5 IlvHierarchicalLayout UNSPECIFIED If you want to force the node to level 5 and below that is level 0 5 set UNSPECIFIED as the minimal level layout addConstraint new IlvLevelRangeConstraint node IlvHierarchicalLayout UNSPECIFIED 5 172 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT In this particular case you could also use zero 0 as the minimal level because the level indices start at 0 You can apply the constraint to a group of several nodes at once This has the same effect as specifying the constraint for each single node of the group but it is more memory efficient and convenient For instance if you want to force the group of nodes to the levels between 5 and 7 you can pass an I1vNodeGroup object see Node Groups on page 172 to the constraint in the following way layout addConstraint new IlvLevelRangeConstraint nodeGroup 5 7 Level Index Parameter The level index is a special case of a level range constraint see Level Range Constraints on page 173 It forces the node to one particular level For your convenience you can specify the level index of a node
278. example different global layout parameters for the Tree Layout of the top level graph and the Tree Layout of subgraph1 You access the layout instance of each individual subgraph in order to change global layout parameters for this subgraph as well as parameters of nodes and links of the subgraph For instance if node1 belongs to subgraph1 and node2 belongs to subgraph2 you can set individual global and local layout parameters in this way 268 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL RECURSIVE LAYOUT access the layout of the top level graph IlvTreeLayout treeLayoutl IlvTreeLayout layout getLayout null treeLayoutl setFlowDirection IlvDirection Bottom access the layouts of the subgraphs IlvTreeLayout treeLayout2 IlvTreeLayout layout getLayout subgraphl treeLayout2 setFlowDirection IlvDirection Left treeLayout2 setAlignment nodel IlvTreeLayout TIP OVER IlvBusLayout busLayout IlvBusLayout layout getLayout subgraph2 busLayout setOrdering IlvBusLayout ORDER BY HEIGHT busLayout setBus node2 IlvGridLayout gridLayout IlvGridLayout layout getLayout subgraph3 gridLayout setLayoutMode IlvGridLayout TILE TO COLUMNS Code Sample Using a Specified Layout Provider The ILOG JViews Graph Layout library provides a flexible mechanism for the choice of the layout instance to be applied to each subgraph in a nested graph the layout provider In the previous example an layout provider was used int
279. f its bounding box follows the zoom level Otherwise the object is nonzoomable To know whether a graphic object is zoomable use its boolean zoomable method or check its documentation If all the nodes and links of an IlvGrapher are zoomable graphic objects a layout obtained on the basis of the graph geometry in manager coordinates will look the same for any value of the transformer used for the display Simply speaking the drawing of the graph will just be zoomed or translated When at least one nonzoomable graphic object is used as a node in an I1vGrapher the geometry of the grapher in manager coordinates can no longer be used When drawn with different transformer values for instance at different zoom levels the same I1vGrapher can look very different Reference Transformers When grapher contains nonzoomable graphic objects it may not be appropriate to deal with the geometry of the 11vGrapher based on the graph objects bounding boxes systematically computed for an identity transformer manager coordinates To ensure that the drawing of the laid out graph is always correct including the case where nonzoomable graphic objects are present the transformer used for the display must be considered Generally speaking the layout of an 11vGrapher depends on the transformer Instead of dealing with the issue of zoomable nonzoomable objects and transformers at the level of the layout algorithms the ILOG JViews Graph Layou
280. features of the ILOG JViews core library This core library provides a wide range of very useful features to build powerful graphic interfaces easily Predefined extensible types of graphic objects for nodes and links A customizable mechanism to choose the contact points between links and nodes Grapher interactor classes Multiple views of the same grapher Management of multiple layers Support for nested graphs Selections management Events management Listeners on the contents of the grapher and or on the views Printing facilities User defined properties on nodes and links 9 9 9 9 9 9 9 oo o Input output operations ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE BASE CLASS ILVGRAPHLAYOUT For details on these features see ILOG JViews Graphics Framework User s Manual Note The Graph Layout module allows you to add layout capabilities to applications that do not use the ILOG JViews grapher For details see Laying Out a Non JViews Grapher on page 303 The Base Class llvGraphLayout The 11vGraphLayout class is the base class for all layout algorithms This class is an abstract class and cannot be used directly You must use one of its subclasses IlvTopologicalMeshLayout IlvSpringEmbedderLayout IlvUniformLengthEdgesLayout IlvTreeLayout IlvHierarchicalLayout IlvLinkLayout IlvRandomLayout IlvBusLayout IlvCircularLayout IlvGridLayout You can also create your own subclasses to implement other layo
281. ffect of Link Clipping Interface ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 69 TOPOLOGICAL MESH LAYOUT TML You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface Note The link clip interface requires link connectors at the nodes of an 11vGrapher that allow connector pins to be placed freely at the node border It is recommended that you use IlvRelativeLinkConnector or IlvClipLinkConnector for link connectors to be used in combination with 11vGrapher objects The clip link connector updates the clipped connection points automatically during interactive node movements If a node has an irregular shape the clipped links sometimes should not point towards the center of the node bounding box but to a virtual center inside the node You can achieve this by additionally providing a class that implements the IlvLinkConnectionBoxInterface An example for the implementation of a link connection box interface is in Link Connection Box on page 29 To set a link connection box interface call void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface The link connection box interface is used only when link clipping is enabled by setting a link clip interface If no l
282. flow direction is to the bottom the root node is placed topmost Each parent node is placed above its children which are normally arranged horizontally This tip over alignment is an exception If the flow direction is to the right the root node is placed leftmost Each parent node is placed to the left of its children which are normally arranged vertically To specify the flow direction use the following method r 2 lt c gt Q gt 3 void setFlowDirection int direction The valid values for direction are IlvDirection Right the default IlvDirection Left IlvDirection Bottom ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 105 TREE LAYOUT IlvDirection Top To obtain the current setting use the following method int getFlowDirection Alignment Parameter The alignment option controls how a parent is placed relative to its children The alignment can be set globally in which case all nodes are aligned in the same way or locally on each node with the result that different alignments occur in the same drawing in eum Center Alignment West Alignment Center Border Alignment East Alignment Figure 4 32 Alignment Options Global Alignment Parameters To set the global alignment use the following method void setGlobalAlignment int alignment The valid values for alignment are ER the default IlvTreeLayout CEN rj The parent is centered
283. following code layout setInvisibleRootUsed true NE Generic Layout of Connected Components Layout Using an Invisible Root Figure 4 48 Layout of Connected Components without and with an Invisible Root For Experts Even Spacing for the First Circle The radial mode is designed to optimize the space such that the circles have a small radius and the overall space for the entire layout is small To achieve this the layout algorithm may create larger gaps on the inner circles for better space usage of the outer circles This may produce unevenly spaced circles most notably for the first circle where all nodes have the same parent node To avoid this effect you can force the nodes to be evenly spaced on the entire first circle Depending on the structure of the graph this may cause the overall layout to waste more space on the other circles but may produce a more pleasing graph To enable this feature call layout setFirstCircleEvenlySpacing true 124 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Unevenly spaced first red circle Evenly spaced first red circle Figure 4 49 Evenly and Unevenly Spaced First Circle For Experts Setting a Maximal Children Angle If a node has a lot of children they may extend over a major portion of the circle and therefore are placed nearly 360 degrees around the node This can result in links overlapping some nodes The deficiency can be fixed by increasing th
284. follows the zoom level Otherwise the object is nonzoomable For instance the 11vLabe1 objects are nonzoomable while the 11vZoomableLabel objects are zoomable To determine whether a graphic object is zoomable use its boolean zoomable method or check its documentation If all the graphic objects of an 11vManager are zoomable a layout obtained on the basis of the graph geometry in manager coordinates will appear the same for any value of the transformer used for the display Simply speaking the drawing of the manager will just be zoomed or translated When at least one nonzoomable graphic object is used as a label or obstacle the geometry in manager coordinates can no longer be used When drawn with different transformer values for instance at different zoom levels the same 11vManager can look very different In this case you cannot use multiple manager views because only one of them can look correct other views will look wrong Coordinates Modes The default labeling model provides several coordinates modes The coordinates mode can be specified on the default labeling model and on the layout instance The coordinates mode of the layout instance is used during layout while the coordinates mode specified for the default labeling model is used on operations of the labeling model when layout is not currently performed To specify the coordinates mode use the following method It is available in the class IlvDefaultLabelingMode
285. fy 0 and 100 for the minimal and maximal percentages and 50 for the preferred percentage If there is not enough free space at the center the label will be placed elsewhere Butif you want to specify that the label must be placed close to the center even if there is not enough space then specify for instance 40 and 60 for the minimal and maximal percentages instead An alternative way to create a polyline label descriptor is to start with the empty descriptor o gt 1 3 r descriptor new IlvAnnealingPolylineLabelDescriptor Before the empty descriptor can be used it must be filled with information on how the label should be placed As a minimum you need to specify a related obstacle or reference points and line width For instance descriptor setRelatedObstacle polyline descriptor setMinPercentageFromStart 10f descriptor setMaxPercentageFromStart 90f descriptor setPreferredPercentageFromStart 50f At the end of all changes the descriptor must be passed to the layout instance layout setLabelDescriptor label descriptor Once the descriptor is passed to the layout instance it should normally not be changed If you need to change it later you must pass it to the layout instance again Specific Global Parameters The following global parameters are specific to the IlvAnnealingLabelLayout class Label Offset Obstacle Offset Label Movement Poli
286. g Parameters ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 159 HIERARCHICAL LAYOUT 160 The spacing parameters can be set for the horizontal direction by the following methods void setHorizontalNodeOffset float offset void setHorizontalLinkOffset float offset void setHorizontalNodeLinkOffset float offset The spacing parameters can be set for the vertical direction by the following methods void setVerticalNodeOffset float offset void setVerticalLinkOffset float offset void setVerticalNodeLinkOffset float offset The spacing parameters can be obtained by the corresponding methods Float getHorizontalNodeOffset float getHorizontalLinkOffset Float getHorizontalNodeLinkOffset float getVerticalNodeOffset float getVerticalLinkOffset Float getVerticalNodeLinkOffset For a layout with horizontal levels the flow direction is to the top or to the bottom the horizontal node offset is the minimal distance between nodes of the same level The vertical node offset is the minimal distance between nodes of different levels that is the minimal distance between the levels For non orthogonal link styles the horizontal link offset is basically the minimal distance between bend points of links The horizontal node link offset is the minimal distance between the node border and the bend point of a link For horizontal levels the vertical link offset and the vertical node link offset play a ro
287. g sublayout after cleanup if the method stopImmediately is called and skips the subsequent sublayouts that have not yet been started For a description of this method in 11vGraphLayout class see Stop Immediately on page 35 If the layout stops before completion the result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID Specific Parameters Multiple Layout does not provide any specific layout parameters However you can set the generic and specific layout parameters of the sublayouts individually For instance you can construct a Multiple Layout instance from two graph layouts Even though the Multiple Layout does not support setting fixed nodes on itself you can fix nodes for the sublayouts individually by applying set Fixed to the sublayout instances if the sublayouts support this feature IlvMultipleLayout multipleLayout new IlvMultipleLayout layoutl layout2 null multipleLayout attach grapher if layoutl supportsPreserveFixedNodes layoutl setFixed nodel true if layout2 supportsPreserveFixedNodes layout2 setFixed node2 true try perform a multiple layout nodel is fixed while layoutl runs and node2 is fixed while layout2 runs IlvMultipleLayoutReport layoutReport IlvMultipleLayoutReport multipleLayout performLayout true true true 286 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL MULTIPLE LAYOUT catch IlvGraphLayoutException e System err p
288. ge 68 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 59 ToPOLOGICAL MESH LAYOUT TML Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to the border of the node shapes See Using a Link Clipping Interface on page 69 for details of the link clipping mechanism in TML Link Connection Box The layout algorithm can use a link connection box interface see Link Connection Box on page 29 in combination with the link clip interface If no link clip interface is used the link connection box interface has no effect For details see Using a Link Clipping Interface on page 69 Memory Savings As with all classes supporting this parameter a certain amount of memory savings can be obtained by selecting this option Note that using this option does not change the resulting layout It just slows down the computation See Memory Savings on page 31 Preserve Fixed Links TML does not reshape the links that are specified as fixed See Preserve Fixed Links on page 32 See also Link Style on page 61 Preserve Fixed Nodes TML does not move the nodes that are specified as fixed Moreover the algorithm takes into account the fixed nodes when computing the posi
289. getMessage Generic Features and Parameters The 11vSpringEmbedderLayout class supports the following generic parameters defined in the T1vGraphLayout class Allowed Time Animation Layout of Connected Components Layout Region Link Clipping Link Connection Box Memory Savings Preserve Fixed Links Preserve Fixed Nodes Random Generator Seed Value Save Parameters to Named Properties 9 9 9 9 5 9 Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass If animation is specified a redraw is automatically performed after each step of the layout algorithm See Animation on page 22 gt Allowed Time 2 The layout algorithm stops if the allowed time setting has elapsed See Allowed Time on page 22 gt H H Animation El s 3 o Layout of Connected Components The layout algorithm can utilize the generic mechanism to lay out connected components For more information about this mechanism see Layout of Connected Components on page 25 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 75 SPRING EMBEDDER LAYOUT Layout Region The layout algorithm uses the layout region setting either your own or the default setting to control the size and the position of the graph drawing three ways to specify the layout region are available for this subclass See Layout Region on page 25 Remember that if you ar
290. gorithms to work with these data structures a custom labeling model that is a subclass of I1vLabelingModel must be written The custom labeling model must implement all the abstract methods of the IlvLabelingModel class The nonabstract methods of this class have a default implementation that is functional However they may not be optimal because they do not take advantage of the characteristics of the underlying graph implementation In this case they can be overridden as well The efficiency of the layout algorithm depends directly on the efficiency of the implementation of the labeling model and the underlying data structure The following is the minimal set of methods that must be implemented abstract Enumeration getLabels abstract boolean isLabel Object obj abstract void moveLabel Object label float x float y boolean redraw abstract double getLabelOverlap Object labell IlvRect bboxl Object label2 IlvRect bbox2 float minDist abstract Enumeration getObstacles abstract boolean isObstacle Object obj ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 389 DEFINING YOUR OwN LABELING MODEL abstract double getObstacleOverlap Object label IlvRect labelBBox Object obstacle IlvRect obstacleBBox float minDist abstract IlvRect boundingBox Object labelOrObstacle These methods are described in The IlvLabelingModel Class on page 385 390 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Using G
291. gt 3 The computation time depends on the number of nodes the number of levels and the number of links that cross several levels Most of the time the links are placed between adjacent levels which keeps the computation time small ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 137 HIERARCHICAL LAYOUT Limitations The algorithm tries to minimize the number of link crossings which is generally an NP complete problem It is mathematically impossible to solve this problem quickly for any graph size Therefore the algorithm uses a very fast heuristic that obtains a good layout but not always with the theoretical minimum number of link crossings The algorithm tries to place the nodes such that all links point uniformly in the same direction It is impossible to place cycles of links in this way For this reason it sometimes produces a graph where a small number of links are reversed to point into the opposite direction The algorithm tries to minimize the number of reversed links which again is an NP complete problem Therefore the algorithm uses a very fast heuristic resulting in a good layout but not always with the theoretical minimum number of reversed links The computation time required to obtain an appropriate drawing depends most significantly on the number of bends in the links Since the algorithm places one bend whenever a link crosses a level the number of bends can grow relatively quickly if the l
292. h cluster each node of the graph belongs To do this use a cluster identifier that is an instance of a subclass of the class IlvClusterId which is abstract Two subclasses are provided ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 245 CIRCULAR LAYOUT 246 IlvClusterNumber which uses integer numbers as cluster identifiers IlvClusterName which uses string names as cluster identifiers You can combine these two types of identifiers as any other subclass of 11vClusterId For example you can write create identifier for first cluster integer IlvClusterNumber clusterId1 new IlvClusterNumber 1 create identifier for second cluster string IlvClusterNumber clusterId2 new IlvClusterName R amp D network Then if node1 to node3 belong to the first cluster you can write layout setClusterId nodel clusterId1 layout setClusterId node2 clusterId1 layout setClusterId node3 clusterId1 Assume layout 15 an instance of I1vCircularLayout If you want the nodes to be drawn in a special order for example node1 node2 node3 you should also specify an index an integer value for each node layout setClusterId nodel clusterId1 0 layout setClusterId node2 clusterIdl 1 layout setClusterId node3 clusterIdl 2 Two methods allow you to specify the cluster to which a node belongs void setClusterId Object node IlvClusterId clusterId void addClusterId Object node IlvClusterId clusterId
293. h models for the subgraphs are created by calls to the get GraphModel method of the class IlvGraphLayout which in turn creates the graph model using the method createGraphModel these operations are done automatically in a completely transparent way you have to do is to call the performLayout with true for the traverse argument If needed you can get the layout instances applied on the subgraphs using the method getLayouts boolean preOrder Code Sample The following code sample illustrates how to apply a single layout algorithm to a nested graph IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher Fill the graphers with nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create the layout instance IlvTreeLayout layout new IlvTreeLayout Attach the topmost grapher to the layout layout attach grapherA Perform the recursive layout try int code layout performLayout true true true System out println Layout completed code code ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYING OUT NESTED GRAPHS catch IlvGraphLayoutException e System err println e getMessage Detach the grapher when layout no more needed layout detach An equivalent variant is the following IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher Fill the graphers with
294. h nested graphers Layout features speed and quality depend on the features speed and quality of the sublayouts Generic Features and Parameters Depending on the support of its sublayouts Multiple Layout may support the following generic parameters defined in the 11vGraphLayout class Allowed Time Layout of Connected Components Percentage Completion Calculation Save Parameters to Named Properties Stop Immediately The following paragraphs describe the particular way in which these parameters are used by this subclass Allowed Time A Multiple Layout instance supports this feature if all of its sublayouts support the feature If the allowed time setting has elapsed the Multiple Layout stops that means it stops the currently running sublayout and skips the subsequent sublayouts that have not yet been started If the layout stops early because the allowed time has elapsed the result code in the layout report is I1vGraphLayoutReport STOPPED AND INVALID Layout of Connected Components The Multiple Layout instance can use the generic mechanism to lay out connected components if the sublayouts of type 11vGraphLayout support this feature The sublayout of type IlvLabelLayout does not need special handling of connected components For more information about this mechanism see Layout of Connected Components on page 25 r lt p gt gt 3 Percentage Complet
295. havior of the layout algorithms to meet specific needs and to perform useful operations such as saving the layout parameters in a file Table 4 2 indicates the generic features and parameters that are supported by each layout algorithm These parameters are defined in the base class for all layout algorithms IlvGraphLayout Table 4 2 Generic Parameters Supported by Layout Algorithms 2 2 o x 2 ir S d 2 5 2 E EX essc Layout c 2 e o 5 9 i 9 amp amp E c S Algorithm E gt see Ge ze gt eos g Qe x E gt o gt 5 c x oe Go 2 iL iL ao e I a cw o o Topological Mesh Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Layout TML Spring Embedder Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Layout Uniform Length Yes Yes Yes Yes Yes Yes Yes Yes Yes Edges Layout Tree Layout Yes Yes Yes Yes Yes Yes Yes Yes Yes Hierarchical Yes Yes Yes Yes Yes Yes Yes Yes Yes gt Layout b Link Layout Yes Yes Yes Yes Yes Yes Random Layout Yes Yes Yes Yes Yes Yes Yes 2 Bus Layout Yes Yes Yes Yes Yes Yes Yes Circular Layout Yes Yes Yes Yes Yes Yes Grid Layout Yes Yes Yes Yes Yes Recursive Layout Yes Yes Yes Yes Multiple Layout
296. he 11vManagerView Bean You want to ensure that the double buffering mechanism will be used and that the zoom level of the manager views will always remain the same along the x axis and y axis 1 Make sure that the 11vManagerView Bean is selected in the Form Designer When the IlvManagerView Bean is selected in the Form Designer its properties are displayed in the Property List 396 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS false AutoFitToContents false Background 204 204 204 BackgroundPattern Bounds 2 2 303 267 Cursor DEFAULT_CURSOR DefaultGhostColor Wg black DefaultORColor white DoubleBuffering false ron Suc Enabled true o Grid Default 5 Inherit Background 07 el Interactor Default 9g Keeping4spectRatic false 2 Manager Default MaximumSize 32767 32767 MinimumSize 0 0 Name ilvManagerview OptimizedT ranslatio PreferredSize Transformer Transparent Visible 2 Click the value field of the DoubleBuf fering property Change the value from false to true This will ensure that the double buffering mechanism will be used 3 Click the value field of the KeepingAspectRatio property Change the value from false to t rue This will ensure that the zoom level remains the same
297. he 31vC1ipLinkConnector can be used This special link connector updates the clipped connection points automatically during interactive node movements The connector style the link connection box interface and the link clip interface work together in the following way by respecting the connector style the proposed connection points are calculated on the rectangle obtained from the link connection box interface or on the bounding box of the node if no link connection box interface was specified Then the proposed connection point is passed to the link clip interface and the returned connection points are used to connect the link to the node An example of the combined effect is shown in Figure 4 40 Clipping at the node bounding box Clipping at a specified connection box Figure 4 40 Combined Effect of Link Clipping Interface and Link Connection If the links are clipped at the red node in Figure 4 40 left they appear unsymmetric with respect to the node shape because the relevant part of the node here the upper rhombus is not in the center of the bounding box of the node but the proposed connection points are calculated with respect to the bounding box This can be corrected by using a link connection box interface to explicitly specify a smaller connection box for the relevant part of the node Figure 4 40 right such that the proposed connection points are placed symmetrically at the upper rhombus of the node r
298. he border of the node shapes See Using a Link Clipping Interface on page 252 for details of the link clipping mechanism Link Connection Box The layout algorithm can use a link connection box interface see Link Connection Box on page 29 in combination with the link clip interface If no link clip interface is used the link connection box interface has no effect For details see Using a Link Clipping Interface on page 252 Preserve Fixed Links The layout algorithm does not reshape the links that are specified as fixed See Preserve Fixed Links on page 32 Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed See Preserve Fixed Nodes on page 32 244 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT Save Parameters to Named Properties The layout algorithm is able to save its layout parameters into named properties This can be used to save layout parameters to 1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 IlvGraphLayoutReport STOPPED AND INVALID
299. he bypass distance according to the current value of the minimum final segment length This behavior is suitable in most cases However you can specify a non negative value in order to override the default behavior Using a Link Connection Box Interface By default the connection points of the links are distributed on the border of the bounding box of the nodes symmetrically with respect to the middle of each side Sometimes it may be necessary to place the connection points on a rectangle smaller or larger than the bounding box eventually in a nonsymmetric way For instance this can happen when labels are displayed below or above nodes r lt Lad gt gt 3 You can modify the position of the connection points of the links by implementing a class that implements the 11vLinkConnectionBoxInterface This interface defines the following method public IlvRect getBox IlvGraphModel graphModel Object node ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 211 LINK LAYOUT This method allows you to return the effective rectangle on which the connection points of the links are placed A second method defined on the interface allows the connection points to be shifted tangentially in a different way for each side of each node public float getTangentialOffset IlvGraphModel graphModel Object node int nodeSide For instance to set a link connection box interface that returns a link conn
300. he difference between normal tip over alignment and tip over at both sides is illustrated in Figure 4 35 Tip over alignment works very well with the orthogonal link style see Link Style on page 109 8 ER i gt See gt Bj gt Ej gt To Normal Tip Over Tip Over Both Sides o at Red Nodes at Red Nodes 3 o Figure 4 35 Tip over Alignment Link Style When using the Tree layout it is preferable to use link connectors of type IlvRelativeLinkConnector and links of type IlvPolylineLinkImage or IlvSplineLinkImage The links can be straight or have a specific shape with intermediate points You can specify that the links be reshaped into an orthogonal form You can set the ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 109 TREE LAYOUT link style globally in which case all links have the same kind of shape or locally on each link in which case different link shapes occur in the same drawing Note The layout algorithm may raise an InappropriateLinkException if layout is performed on an 11vGrapher but links are neither a subclass of IlvPolylineLinkImage nor of IlvSplineLinkImage or if connectors are not a subclass of I1vRelativeLinkConnector You can use the methods EnsureAppropriateLinkTypes EnsureAppropriateLinkConnectors Or EnsureAppropriateLinks defined in IlvGraphLayoutUtil to automatically replace inappropriate links or link connectors before layout or when the IlvInappropriateLink
301. he following methods allow the layout algorithms to retrieve information on the obstacles in a similar way boolean isObstacle Object obj boolean isPolylineObstacle Object obj Enumeration getObstacles int getObstaclesCount For optimization purposes the labeling model distinguishes between normal obstacles and polyline obstacles While normal obstacles cover the major part of their bounding box polyline obstacles have a line width and range over intermediate points thus they cover only a small part of their bounding box Since a polyline obstacle is an obstacle both isObstacle and isPolylineObstacle return true for a polyline obstacle ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 385 DEFINING YOUR OWN LABELING MODEL Information on the Geometry of Labels and Obstacles For labels and obstacles the label layout can retrieve the bounding box with the method IlvRect boundingBox Object labelOrObstacle For the special polyline obstacles the label layout can retrieve the precise shape of the polyline with the methods float getPolylineWidth Object polylineObstacle IlvPoint getPolylinePoints Object polylineObstacle The following method moves a label to the new position void moveLabel Object label float x float y boolean redraw Overlap Calculation A good label layout avoids overlaps Thus the calculation of overlap values is an important step of the algorithm The speed of the layout algorith
302. he geometry of the graph is computed using the coordinate space of the manager view and then applying the inverse transformation This mode is equivalent to the manager coordinates mode if the geometry of the graphic objects strictly obeys the transformer A small difference may exist because of the limited precision of the computations On the contrary if some graphic objects are either nonzoomable or semizoomable for example links with a maximum line width this mode gives different results than the manager coordinates mode These results are optimal if the grapher is visualized using the same transformer as the one taken into account during the layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Note that in this mode the dimensional parameters of the layout algorithms are considered as being specified in manager coordinates Fi n The default mode is I1vGraphLayout INVERSE VIEW COORDINATI To obtain the current choice use the following method long getCoordinatesMode See also Specifying the Coordinates Mode on page 327 Layout of Connected Components The base class 11vGraphLayout provides generic support for the layout of a disconnected graph composed of connected components For details see Laying Out Connected Components of a Disconnected Graph on page 304 To indicate whether a subclass of 11vGraphLayout supports this mechanism the follo
303. he links that is the segments near the origin and destination nodes using the method void setMinFinalSegmentLength float length To obtain the current value use the method float getMinFinalSegmentLength The default value is 10 Spacing Parameters in Long Link Mode The long link mode places the links on a grid Four parameters control the grid offsets and five parameters control the spacing of links in relation to other objects Figure 4 96 shows the spacing parameters used in the long link mode r lt e gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 203 LINK LAYOUT horizontal grid offset 5 2g ft e onm Q Im um 2 o ll Amm o 8 SIV 83 E La zs om 9 Iv 35 25 33 a S D ES RR ES VET fea SENE ye GER Qo EN eoueisip e91J9 horizontal minimal distance Figure 4 96 Spacing Parameters for the Long Link Mode Grid Offset Parameters The grid offset parameters control the spacing between grid lines Links are routed such that the center of the orthogonal link segments are on the grid lines The grid offsets should be set to a value larger than the largest link width value in order to avoid links that visually overlap The horizontal and v
304. her They dominate all other constraints even the specified level index The I1vLevelRangeConstraint and the direct level index specification has the second highest priority If two nodes are forced to the same level but have disjoint specified level ranges then the level range is ignored In the following example layout addConstraint new IlvSameLevelConstraint nodel node2 layout setSpecNodeLevelIndex nodel 5 layout setSpecNodeLevelIndex node2 10 r lt c gt e gt 3 both node1 and node2 will be placed at level 5 The conflicting specification layout setSpecNodeLevelIndex node2 10 is ignored The i1vRelativeLevelConstraint is dominated by the same level constraint by the level range constraint and by the direct specification of level indices If several relative level constraints conflict each other the one with the highest specified priority ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 181 HIERARCHICAL LAYOUT 182 dominates However note that all links are implicitly considered relative level constraints as well If links with high priority force a node to a certain level then a relative level constraint with lower priority will be ignored The IlvSwimLaneConstraint is always evaluated even if the incremental mode is enabled The constraint has a higher priority than the relative position constraint and the side by side constraint You can specify side by s
305. her adapters of the same I1vGrapher are supposed to be attached to 1ayout1 layout2 and layout3 If in fact the same grapher adapter more precisely grapher adapters that all work on the same set of nodes and links is attached to all three layout instances one call of the removeParametersFromNamedProperties method at the end is sufficient Take a look at the mechanism in detail String saveParametersToNamedProperties IlvGraphLayout layout boolean withDefaults This method creates named properties for the input layout and transfers the complete layout parameter settings to these properties The property name is an automatically generated unique string that is returned If the flag withDefaults is false the created layout properties are persistent only if they contain a setting that is not the default setting This means that the default values are not stored in the iv1 file and the file has a smaller size If the flag withDefaults is true the created properties are always persistent that is the default values are stored in the iv1 file as well The named properties that are created require additional memory Therefore it is recommended to remove them as soon as they are no longer needed To remove the named layout properties you can use one of the following methods void removeParametersFromNamedProperties This method removes all named layout properties from the grapher void removeParametersFromNamedProperties String pr
306. his mechanism the following method is provided boolean supportsStopImmediately Use Default Parameters the generic parameters have a default value After modifying parameters you may want the layout algorithm to use the default values Then you may want to return to your customized values ILOG JViews keeps the previous settings when selecting the default values mode You can switch between the default values mode and the mode for your own settings using the method void setUseDefaultParameters boolean option To obtain the current value boolean isUseDefaultParameters The default value is false This means that any setting you make will be taken into consideration and the parameters that have not been specified will have their default values ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Getting Started with Graph Layout This chapter provides information to get started using the Graph Layout module of ILOG JViews The following topics are covered Basic Steps for Using Layout Algorithms A Summary Sample Java Application 1 10 lt e ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 37 BASIC STEPS FOR USING LAYOUT ALGORITHMS A SUMMARY Basic Steps for Using Layout Algorithms A Summary To use the layout algorithms provided by the Graph Layout module of ILOG JViews you will usually perform the following steps 1
307. his value can be obtained from the layout report during the run of the layout For a detailed description of this features see Percentage Completion Calculation on page 31 and Layout Event Listeners on page 294 Preserve Fixed Links r lt gt gt 3 The layout algorithm does not reshape the links that are specified as fixed In fact fixed links are completely ignored For more information on link parameters in the 11vGraphLayout class see Preserve Fixed Links on page 32 and Link Style on page 109 Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed For more information on node parameters in the IlvGraphLayout class see Preserve Fixed Nodes on page 32 Moreover the layout algorithm ignores fixed nodes completely and also does ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 141 HIERARCHICAL LAYOUT not route the links that are incident to the fixed nodes This can result in undesired overlapping nodes and link crossings However this feature is useful for individual disconnected components that can be laid out independently Save Parameters to Named Properties The layout algorithm is able to save its layout parameters into named properties This can be used to save layout parameters to iv1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred La
308. hod in 11vGraphLayout returns false For some of the layout classes it is appropriate that this feature is enabled by default Therefore IlvSpringEmbedder and IlvUniformLengthEdgesLayout override this method to return t rue If enabled on a layout class that supports this feature the method performLayout of the class IlvGraphLayout cuts the attached graph model into connected components and lays out each connected component separately How does the layout of connected components feature work when this mechanism is enabled in the layout classes that support this feature Instead of directly calling the method layout to perform the layout on the entire graph the method performLayout first cuts the graph into connected components Then each connected component is laid out separately by a call of the method layout To do this the attached graph is temporarily changed into internally generated graphs corresponding to each of the connected components of the original graph Finally the layout instance returned by the method IlvGraphLayout getLayoutOfConnectedComponents is used to position the connected components To specify the layout instance that places the connected components use the following method void setLayoutOfConnectedComponents IlvGraphLayout layout If no layout instance is specified using this method the method get LayoutOfConnectedComponents returns an instance of I1vGridLayout Its layout soJnjeoaJj e o
309. hs You can tailor which sublayout must be applied to which subgraph There are basically two scenarios The same layout style must be applied to all subgraphs An individual layout style must be applied to each subgraph Code Sample Same Layout Style Everywhere First we assume you want to apply a Tree Layout to a nested graph Each subgraph should be laid out with the same global layout parameters The Tree Layout algorithm itself handles only flat graphs that is if applied to an attached graph it lays out only the nodes and links of the attached graph but not the nodes and links of the subgraphs that are nested inside the attached graph Hence we encapsulate the Tree Layout into a Recursive Layout The Recursive Layout traverses the entire nesting hierarchy of the attached graph while the encapsulated Tree Layout lays out each flat subgraph of the nesting hierarchy during the traversal import ilog views import ilog views graphlayout import ilog views graphlayout recursive import ilog views graphlayout tree IlvRecursiveLayout layout new IlvRecursiveLayout IlvTreeLayout IlvGrapher topLevelGrapher layout attach topLevelGrapher try IlvRecursiveLayoutReport layoutReport IlvRecursiveLayoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err pr
310. hs that are nested inside another grapher The instances can be shared between different instances of T1vRecursiveLayout Without subgraph correction subgraph position changed because contents of subgraph was laid out Result of IlvSubgraphCorrectionBoundsFixed Result of IlvSubgraphCorrectionBarycenterFixed Figure 4 132 Effect of Subgraph Correction Layout Listeners Layout event listeners are an advanced feature described in general in Using Event Listeners on page 294 You should come back to this section after you have understood the concept of layout listeners We mention here some specific details of the Recursive Layout related to layout listeners The application can listen to the layout events that the Recursive Layout sends or it can listen to the layout events that each sublayout sends individually For instance a progress bar that displays the progress of the entire nested layout should listen to the layout events that the Recursive Layout fires itself while an application that wants to detect when a specific sublayout of a subgraph is started or stopped should listen to the layout events of this particular sublayout r lt Lad gt e gt 3 In order to install a layout event listener at the Recursive Layout call usually recursiveLayout addGraphLayoutEventListener listener In order to install a layout listener that receives the layout events of all sublayouts of the Recur
311. ht line shape are used Such links are 11vOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage You can use the methods EnsureAppropriateLinkTypes orEnsureAppropriateLinks defined in IlvGraphLayoutUtil fo automatically replace inappropriate links This can be done before layout or when the 11vInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 To obtain the current choice use the following method long getLinkStyle Flow Direction The flow direction options control the horizontal alignment of each row bus level with respect to the left and right sides of the layout region The rows can be either all left aligned on the left border of the layout region or can alternate between the left and right alignment r lt gt gt 3 Figure 4 106 Bus Layout with Left to Right Flow Direction ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 229 BUS LAYOUT Figure 4 107 Bus Layout with Alternate Flow Direction To set and retrieve the flow direction use the methods void setFlowDirection int direction int getFlowDirection The valid values for direction are IlvBusLayout LEFT TO RIGHT the default the rows bus levels are left aligned IlvBusLayout ALTERN
312. ich subgraph and then you can perform the layout import ilog views import ilog views graphlayout import ilog views graphlayout recursive import ilog views graphlayout tree import ilog views graphlayout bus import ilog views graphlayout grid IlvRecursiveLayout layout new IlvRecursiveLayout IlvGrapher topLevelGrapher layout attach topLevelGrapher specify the layout of the top level graph layout setLayout null new IlvTreeLayout specify the layout of subgraphs layout setLayout subgraphl new IlvTreeLayout layout setLayout subgraph2 new IlvBusLayout layout setLayout subgraph3 new IlvGridLayout perform layout try IlvRecursiveLayoutReport layoutReport IlvRecursiveLayoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage detach the Recursive Layout when it is no longer needed layout detach In this scenario there is no reference layout layout parameters of different subgraphs are independent You need to specify new independent layout instances for each subgraph otherwise no layout will be performed for the corresponding subgraph The layout instances are attached to the subgraph as long as the Recursive Layout is attached to the top level graph You can specify in this
313. id detach Layout Parameters and Features in IlvGraphLayout 20 The 11vGraphLayout class defines a number of generic features and parameters These features and parameters can be used to customize the layout algorithms Although the 11vGraphLayout class defines the generic parameters it does not control how they are used by its subclasses Each layout algorithm that is each subclass of IlvGraphLayout supports a subset of the generic features and determines the way in which it uses the generic parameters When you create your own layout algorithm by subclassing I1vGraphLayout you decide whether you want to use the features and the way in which you are going to use them The 11vGraphLayout class defines the following generic features Allowed Time Animation Automatic Layout Coordinates Mode Layout of Connected Components 5 9 Layout Region ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Link Clipping Link Connection Box Memory Savings Percentage Completion Calculation Preserve Fixed Links Preserve Fixed Nodes Random Generator Seed Value Save Parameters to Named Properties Stop Immediately 9 9 9 9 5 5 o Use Default Parameters 07 v O 5 a ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 21 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Table 4 2 on page 51 provides a summary of the generic pa
314. iddle of each side Sometimes it may be necessary to place the connection points on a rectangle smaller or larger than the bounding box eventually in a nonsymmetric way For instance this can happen when labels are displayed below or above nodes You can modify the position of the connection points of the links by providing a class that implements the IlvLinkConnectionBoxInterface An example for the implementation of a link connection box interface is in Link Connection Box on page 29 To set a link connection box interface call void setLinkConnectionBoxInterface IlvLinkConnectionBoxInterface interface The link connection box interface provides each node with a link connection box and a tangential shift offset that defines how much the connection points are shifted tangentially depending on which side the links connect r lt gt gt 3 Figure 4 38 illustrates the effects of customizing the connection box when the connector style is evenly spaced ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 113 TREE LAYOUT mo 1 dashed connection box connection box specified specified no tangential tangential offset at bottom offset and left side Figure 4 38 Effect of Connection Box Interface On the left is the result without any connection box interface The middle picture shows the effect if the connection box interface returns the dashed rectangle for the blue no
315. ide constraints for a group of nodes that belong to the same swim lane but side by side constraints of nodes of different swim lanes are ignored You can specify relative position constraints between nodes of the same swim lane You can also specify relative position constraints between one entire swim lane group and another swim lane group which effectively orders the swim lanes But relative position constraints are ignored if they would require breaking the swim lanes apart The swim lane constraint dominates the specified position indices and the extremity constraints that is if a swim lane constraint is used you cannot specify position indices or east west extremity constraints for any node The IlvSideBySideConstraint is evaluated only if the corresponding nodes belong to the same level Typically you will use a same level constraint to force the nodes to the same level and then a side by side constraint to force the nodes to a certain ordering The side by side constraints dominate the relative position constraints If several side by side constraints are conflicting the one with the highest specified priority dominates the other constraints The IlvRelativePositionConstraint is also evaluated only if the corresponding nodes belong to the same level It is dominated by the side by side constraint however conflicts with side by side constraints are rare If several relative position constraints are conflicting the one with the high
316. idered the north pole In the nonradial layout modes the link flow direction always corresponds to south If the root node is placed at the top of the drawing north is at the top south at the bottom east to the right and west to the left If the root node is placed at the left border of the drawing north is to the left south to the right east at the top and west at the bottom In the radial layout modes the root node is placed in the center of the drawing The meaning of north and south depends on the position relative to the root the north side of the node is the side closer to the root and the south side is the side further away from the root The east direction is counterclockwise around the root and the west direction is clockwise around the root This is similar to a cartographic map of a real globe that shows the area of the north pole as if you were looking down at the top of the globe Compass directions are used to provide uniform naming conventions for certain layout options They occur in the alignment options the level alignment option and the east west neighboring feature which are explained later In Figure 4 31 and Figure 4 45 the compass icons show the compass directions in these drawings Layout Modes The tree layout algorithm has several layout modes To select a layout mode use the method r lt gt gt 3 void setLayoutMode int mode To obtain the current lay
317. iders the node or the link as part of the graph that needs to be laid out Otherwise it ignores the node or the link To specify a filter on an 11vGrapherAdapter use the following method of the IlvGrapherAdapter class void setFilter IlvLayoutGraphicFilter filter To remove the filter call the secFilter method with a null argument To obtain the filter that has been specified use the method IlvLayoutGraphicFilter getFilter Note All overridden implementations of the accept method must respect the following rule a link cannot be accepted by the filter if any of its end nodes origin or destination nodes are not accepted There are two ways to filter an 11vGrapher by layers or by graphic objects The two methods can be combined Filtering by Layers Inside an 11vGrapher nodes and links can be managed by layers See the ilog views IlvManagerLayer class J Views allows you specify that only nodes and links belonging to certain layers have to be taken into account when performing the layout Use the following methods of the 11vGrapherAdapter class void addLayer IlvManagerLayer layer boolean removeLayer IlvManagerLayer layer boolean removeAllLayers boolean isLayerAdded To get an enumeration of the manager layers to be taken into account during the layout use the method 322 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CHOOSING THE LAYOUT COORDINATE SPACE Enumeration getLayers
318. iform Length Edges Layout 88 fork link shapes Hierarchical Layout 156 free layout mode Tree Layout alignment parameter 106 description 104 flow direction 104 global alignment 106 global link style parameter 110 individual link style 110 individual node alignment 107 link style 109 orthogonal fork percentage 117 respect node sizes 117 spacing parameters 115 spacing parameters for experts 117 tip over alignment 108 getA getAlignment method IlvTreeLayout class 108 getAllowedNodesPlacementTime method IlvTopologicalMeshLayout class 62 getAllowedNumberOfIterations method IlvUniformLengthEdgesLayout class 87 getAllowedNumberOfNodesPlacementIteratio ns method IlvTopologicalMeshLayout class 62 getAllowedNumberOfOptimizationIterations method IlvTopologicalMeshLayout class 62 getAllowedOptimizationTime method IlvTopologicalMeshLayout class 62 getAllowedTime method IlvGraphLayout class 22 getAspectRatio method IlvTreeLayout class 123 getB getBottomMargin method IlvGridLayout class 263 getBox method IlvLinkConnectionBoxInterface class 29 208 211 IlvNodeBoxInterface class 207 getBranchOffset method IlvTreeLayout class 117 getBus method 422 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL IlvBusLayout class 228 getC ge ge ge I I I I I I tCalcBackwardTreeLinks method lvTreeLayout class 131 tCalcFallbackLinks method lvLongLinkLayout
319. ime when the redraw is performed You can use the following code grapher initReDraws try layout performLayout false true catch IlvGraphLayoutException e e printStackTrace finally grapher moveObject false some other changes in the grapher grapher reDrawViews Noredraw at all Sometimes the layout may need to be performed without any display of the grapher For instance this can be done to automatically produce iv1 files containing the result of the layout for future use To avoid any redraw during the layout just call the method performLayout With the value false for the redraw argument Note During animated layout for layouts supporting this option the grapher needs to be redrawn after each step to produce the animation effect Therefore you need to pass the value t rue for the redraw argument of the method performLayout boolean boolean In this case the initReDraw reDrawViews session is automatically used for each animation step Users should not add their own initReDraw reDrawViews session because this would prevent the graph from being redrawn during the animation Using the Graph Model The ilog views graphlayout IlvGraphModel class defines a suitable generic API for graphs that have to be laid out with ILOG JViews graph layout algorithms the layout algorithms provided in ILOG JViews are designed to lay out a graph model This allows applications to benefit from the graph
320. ing features by graphic objects 323 by layers 322 for IlvGrapher 321 in ILOG JViews 16 nonzoomable graphic objects 324 questions and answers 333 reference transformers 324 reference views 325 specifying a reference transformer 326 specifying the coordinates mode 327 Graph Layout module classes available as Beans 392 description of 2 features 4 features for using layout algorithms 8 packages 2 graph model concept of 298 description of 297 information on the geometry of the graph 300 INDEX information on the structure of the graph 299 modifying the geometry of the graph 301 notification of changes of the graph 301 retrieving data objects 302 storing data objects 302 grapher attaching 18 detaching 20 laying out a non JViews grapher 303 laying out connected components of a disconnected graph 304 laying out nested graphs 306 grapher adapter 302 GraphLayoutl EventListener interface 294 grid base parameter Link Layout long link mode 205 Grid Layout alignment options 259 applicable graph types 256 application domains 256 code sample 256 description 256 dimensional parameters 261 features 256 generic parameters 257 global alignment parameters 259 grid offset parameter 262 incremental mode parameter 260 individual node alignment parameter 260 layout modes 258 margin parameter 263 maximum nodes per row or column parameter 260 sample drawing 255 specific parameters 258 grid offset parame
321. ingPenalty 3 f This increases the possibility of obtaining a layout with no link to link crossings or with a only few crossings with the expense that there may be more link to node crossings Bypass Distance If the origin and destination nodes are too close there may not be enough space for routing the link directly between the end nodes Therefore by default if the end nodes are closer than a threshold distance the layout choses link shapes that bypass the interval between close nodes See Figure 4 100 210 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT a link label a link label End nodes distance larger than the End nodes distance smaller than the bypass distance bypass distance Figure 4 100 Nodes and Bypass Distance The bypass distance is the minimum distance between the origin and destination nodes for which a link shape going directly from one node to another is allowed The algorithm tries to avoid link shapes that connect directly the sides of the end nodes that are closer than the bypass value To set and retrieve the bypass distance use the following methods void setBypassDistance float dist float getBypassDistance The default value is a strictly negative value If the bypass distance is strictly negative the value of the minimum final segment length see Minimum Final Segment Length on page 206 parameter is used as the bypass distance This allows the automatic adjustment of t
322. ink Mode with Orthogonal Links What Types of Graphs Any type of graph where nodes are fixed and links need to be routed 186 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT Connected and disconnected graphs Planar and nonplanar graphs Nested graphs with intergraph links Application Domains Application domains of the Link Layout include Electrical engineering circuit block diagrams Industrial engineering schematic design diagrams equipment resource control charts Business processing entity relation diagrams Software management software re engineering data inspector diagrams Database and knowledge engineering sociology genealogy 9 5 9 CASE tools design diagrams Features Reshapes the links of a graph in either an orthogonal or a direct style without moving the nodes Orthogonal and direct style links can be combined in the same layout Allows you to specify which side of the node top bottom left or right a link can be connected to or to preserve the existing connection points of the links Supports self links that is links with the same origin and destination node Supports multiple links that is more than one link between the same origin and destination nodes Allows you to specify pinned fixed links that the layout algorithm cannot reshape Supports intergraph links of nested graphs An intergraph link is a link whose end nodes b
323. ink clip interface is specified the link connection box interface has no effect An example of the combined effect is shown in Figure 4 15 Clipping at the node bounding box Clipping at a specified connection box Figure 4 15 Combined Effect of Link Clipping Interface and Link Connection If the links are clipped at the green irregular star node Figure 4 15 left they do not point towards the center of the star but towards the center of the bounding box of the node This can be corrected by specifying a link connection box interface that returns a smaller node box than the bounding box Figure 4 15 right Alternatively the problem could be corrected 70 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ToPOLOGICAL MESH LAYOUT TML by specifying a link connection box interface that returns the bounding box as the node box but with additional tangential offsets that shift the virtual center of the node r lt gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 71 SPRING EMBEDDER LAYOUT Spring Embedder Layout In this section you will learn about the Spring Embedder Layout algorithm from the ILOG JViews Graph Layout module class 11vSpringl ilog views graphlayout springembedder EmbedderLayout from the package Samples Here are some sample drawings produced with the Spri Figure 4 16 Small Graph Drawing Combination of Cycles Embedder Layout ng Emb
324. ink will not be moved In this case you can ask the layout algorithm to automatically remove all the intermediate points of the links if any To do this the following method is provided void setLinkStyle int style The valid values for style are IlvTopologicalMeshLayout NO RESHAPE STYLE None of the links is reshaped in any manner Il1vTopologicalMeshLayout STRAIGHT LINE STYLE the intermediate points of the links except for links specified as fixed are removed This is the default value Note If STRAIGHT LINE STYLE is selected the layout algorithm may raise an IlvInappropriateLinkException when the layout is performed on an 11vGraphezr and links that cannot be given a straight line shape are used Such links are IlvOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage You can use the methods EnsureAppropriateLinkTypes orEnsureAppropriateLinks defined in IlvGraphLayoutUtil fo automatically replace inappropriate links This can be done before layout or when the 11vInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 To obtain the current choice use the following method r lt gt gt 3 7 long getLinkStyle ILOG JViEWS GRAPH LAYOUT 5
325. inks have to cross each other The link priority parameter controls which links should be selected if long reversed or crossing links are necessary Links with a low priority are more likely to be selected than links with a high priority This does not mean that low priority links are always longer reversed or crossed because the graph may have a structure such that no long reversed or crossing links are necessary To set or retrieve the link priority use the following methods void setLinkPriority Object link float priority float getLinkPriority Object link The default value of the link priority is 1 0 Negative link priorities are not allowed For an example of using the link priority consider a cycle A gt B gt C gt D gt E gt A It is impossible to lay out this graph without reversing any link Therefore the layout algorithm selects one link to be reversed To control which link is selected you can give one link a lower priority than the others This link will be reversed In Figure 4 73 the bottom layout shows the use of the link priority The link C gt D was given the priority 0 5 while all the other links have the priority 1 0 Therefore C D is reversed The top layout in Figure 4 73 shows what happens when all links have the same priority Link gt is reversed All links have the same priority Link C gt D has a lower priority than the other links Figure 4 73 Working with Link Priorities The use of
326. intln e getMessage detach the Recursive Layout when it is no longer needed layout detach 266 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL RECURSIVE LAYOUT This mode of the Recursive Layout is called reference layout mode In this case a Tree Layout is performed recursively to the top level graph and to each subgraph layouts are performed with the same global layout parameters Note Here we use the term global layout parameter for the parameters that do not depend on a specific node or link For instance Tree Layout has a global layout parameter set by setGlobalLinkStyle as well as a layout parameter set by setLinkStyle link style which is local to a link You can change the global layout parameters by accessing the reference layout of the Recursive Layout IlvTreeLayout treeLayout IlvTreeLayout layout getReferenceLayout treeLayout setFlowDirection IlvDirection Left Technically the reference layout instance is not applied to each subgraph because each subgraph needs an individual layout instance The reference layout instance is only applied to the top level graph Furthermore a clone of the reference instance is created for each subgraph This clone remains attached to the subgraph as long as the Recursive Layout is attached to the top level graph Before layout is performed the global layout parameters are copied from the reference layout instance to each cloned layout instance Sometimes yo
327. ion Calculation The Multiple Layout calculates the percentage of completion This value can be obtained from the layout report during the run of the layout The value is however a very rough estimation If the sublayouts do not support the calculation of the percentage completion the Multiple Layout can report the percentage based only on the information that the sublayout has already finished For instance if there are three sublayouts the mechanism reports 33 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 285 MULTIPLE LAYOUT after the first sublayout has finished 66 after the second sublayout has finished and 100 after all three sublayouts have finished If the sublayouts support the calculation of the percentage completion the Multiple Layout calculates a more detailed percentage For a detailed description of this feature see Percentage Completion Calculation on page 31 and Layout Event Listeners on page 294 Save Parameters to Named Properties The Multiple Layout instance can save its layout parameters into named properties if all its sublayouts support this feature This can be used to save layout parameters to iv1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The Multiple Layout instance supports this feature if all its sublayouts support this feature It stops the currently runnin
328. ioning feature is enabled by default but it can be disabled by calling layout setIncrementalAbsoluteLevelPositioning false With this statement the layout does not try to place the nodes close to the previous positions It places the nodes such that the layout is balanced However to create a perfect balance the layout may need to move a few nodes so far apart that you can no longer recognize the diagram after the layout from the node positions that were shown in the previous layout see Figure 4 80 bottom ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT with respecting previous positions _ without respecting previous positions 1 r lt gt gt 3 1j Uu Figure 4 80 Absolute Positioning During Incremental Layouts Setting Absolute Level Position Range and Tendency If absolute level positioning is enabled it competes with the aesthetic criteria to create a balanced layout Due to the fact that nodes must stay close to their previous positions the diagram after incremental layout may be somewhat unbalanced and unsymmetrical The ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 167 HIERARCHICAL LAYOUT 168 Hierarchical Layout algorithm uses a heuristic that you can influence by two parameters the absolute level position range and tendency Set the absolute level position range as in the following example layout setIncrementalAbsoulteL
329. ip over modes arranges the nodes in a similar way to the free layout mode but tries to tip over children automatically to better fit the layout to the given aspect ratio Provides several alignment and offset options Allows you to specify nodes that must be directly neighbored Provides incremental and nonincremental modes Incremental mode takes the previous position of nodes into account and positions the nodes without changing the relative order of the nodes in the tree so that the layout is stable on incremental changes of the graph Very efficient scalable algorithm Produces a nice layout quickly even if the number of nodes is huge Limitations ILOG If the orthogonal setting is not specified as the link style see Link Style on page 109 some links may in rare cases overlap nodes depending on the size of the nodes the alignment parameters and the offset parameters The layout algorithm first determines a spanning tree of the graph If the graph is not a pure tree some links will not be included as part of the spanning tree These links are ignored For this reason they may cross other links or overlap nodes in the final layout For stability in incremental mode the algorithm tries to preserve the relative order of the children of each node It uses a heuristic to calculate the relative order from the previous positions of the nodes The heuristic may fail if children overlap their old positions or are not aligned ho
330. is an advanced mechanism that is explained in detail in Saving Layout Parameters and Preferred Layouts on page 315 To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean supportsSaveParametersToNamedProperties 34 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Stop Immediately Several layout algorithms can stop computation when an external event occurs for instance when the user hits a Stop button To stop the layout you can call boolean stopImmediately This method is typically called in a multithreaded application from a separate thread that is not the layout thread The method returns t rue if the stop was initiated and false if the algorithm cannot stop The method returns immediately but the layout thread usually needs some additional time after initiating the stop to clean up data structures The following code fragment illustrates the usage You start the layout in a separate thread Thread layoutThread new Thread new GraphLayoutPerformer layout grapher layoutThread start The class GraphLayoutPerformer is an implementation of the interface Runnable that performs layout The following is a sketch of this class 07 2 O 5 o a class GraphLayoutPerformer implements Runnable public void run from now we are busy busy true try perf
331. keep the user aware of the evolution of the layout computation by showing intermediate results as a kind of progress bar However this increases the duration of the layout because additional redrawing operations need to be performed ILOG JViews allows you to specify that a redraw of the grapher must be performed after each iteration or step void setAnimate boolean option 22 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT To obtain the current value use the following method boolean isAnimate The default value is false To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean supportsAnimation The default implementation returns alse A subclass can override this method to return true to indicate that this mechanism is supported Automatic Layout For some layout algorithms it may be suitable to have the layout automatically reperformed after each change of the graph that is when a node or link moves is added or is removed Automatic layout is most useful for link layouts in a situation for example where the shape of the links remain optimal after each editing action of the end user It also works well with other layout algorithms that offer an incremental behavior that is for which a small change of the graph usually produces only a small change of the layout Automatic layout is generally not suita
332. ks 99 Preserve Fixed Nodes ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 243 CIRCULAR LAYOUT Save Parameters to Named Properties Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass Layout of Connected Components The layout algorithm can utilize the generic mechanism to layout connected components For more information about this mechanism see Layout of Connected Components on page 25 Layout Region This parameter has no effect if the clustering mode is BY SUBGRAPHS Itis not possible to allow the user to control the size of the layout by specifying a bounding box for the drawing The layout algorithm chooses the size in order to have enough space to avoid overlapping nodes and clusters The layout region setting either your own or the default setting is used only to choose the position of the center of the drawing This means that only the center of the layout region is taken into consideration All three ways to specify the layout region are available for this subclass See Layout Region on page 25 Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to t
333. ks are reshaped in an orthogonal form alternating horizontal and vertical segments See Figure 4 86 on page 186 and Figure 4 88 on page 187 as examples IlviinkLayout DIRECT STYLE The links are reshaped to a polygonal line composed of three segments a straight line segment that starts and ends with a small horizontal or vertical segment See Figure 4 87 on page 187 as an example IlviinkLayout MIXED STYLE Each link can have a different link style The style of each individual link can be set to have different link shapes occurring on the same graph To obtain the current choice use the following method int getGlobalLinkStyle Individual Link Style All links have the same style of shape unless the global link style is IlvlinkLayout MIXED STYLE Only when the global link style is set to MIXED STYLE can each link have an individual link style r lt gt gt 3 Figure 4 91 Different Link Styles Mixed in the Same Drawing Short Link Mode ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 195 LINK LAYOUT Figure 4 92 Different Link Styles Mixed in the Same Drawing Long Link Mode To set and retrieve the style of an individual link use the following methods void setLinkStyle Object link int style int getLinkStyle Object link The valid values for style are IlvLinkLayout ORTHOGONAL STYLE the default
334. ks that are specified as fixed See Preserve Fixed Links on page 32 Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed See Preserve Fixed Nodes on page 32 Random Generator Seed Value The Spring Embedder Layout algorithm uses some randomly generated parameters You can specify a particular value to be used as a seed value See Random Generator Seed Value on page 33 For the default behavior the random generator is initialized using the current system clock Therefore different layouts will be obtained if you perform the layout repeatedly on the same graph 76 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL SPRING EMBEDDER LAYOUT Save Parameters to Named Properties The layout algorithm is able to save its layout parameters into named properties This can be used to save layout parameters to 1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 IlvGraphLayoutReport STOPPED AND INVALID Specific Parameters The following parameters are specific to the IlvSpri
335. l layout getObstacleOffset The obstacle offset should not be set to an unreasonably large value such as Float MAX VALUE because this can cause computational problems inside quadtree operations Obstacle Sint Label Label Offset pre Ambiguous situation Label iab el obstacle offset Offset too small Obstac le Offset Label Figure 6 12 Label and Obstacle Offsets 370 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT The specified obstacle offset works globally for all labels It is also possible to specify a smaller obstacle offset for specific label obstacle pairs You need to install an obstacle offset interface that returns the obstacle offset for a given pair layout setObstacleOffsetInterface new IlvObstacleOffsetInterface public float getOffset IlvLabelingModel m Object label Object obstacle if label instanceof IlvZoomableLabel amp amp obstacle instanceof IlvIcon return 3f else use the global obstacle offset return Float MAX VALUE o gt 1 3 r The effective offset is the minimum of the value returned by the obstacle offset interface and the globally specified offset Hence the obstacle offset interface in the previous example means that labels of class 11vZoomableLabel can be placed up to 3 units near 11vIcon obstacles while they are placed away from all other obstacl
336. l alignment is set to IlvGridLayout MIXED Only when the global alignment is set to mixed can each node have an individual alignment style To set and retrieve the alignment of an individual node use the following methods void setHorizontalAlignment Object node int alignment void setVerticalAlignment Object node int alignment int getHorizontalAlignment Object node int getVerticalAlignment Object node The valid values for alignment are IlvGridLayout CENTER the default IlvGridLayout TOP IlvGridLayout BOTTOM IlvGridLayout LEE 9 9 IlvGridLayout RIGHT Maximum Number of Nodes Per Row or Column By default in IlvGridLayout TILE TO ROWSOr IlvGridLayout TILE TO COLUMNS mode the layout places as many nodes on each row or column as possible given the size of the nodes and the dimensional parameters layout region and margins If needed the layout can additionally respect a specified maximum number of nodes per row or column To set and retrieve the maximum number of nodes per row or column use the methods void setMaxNumberOfNodesPerRowOrColumn int nNodes int getMaxNumberOfNodesPerRowOrColumn The default value is Integer MAX VALUE that is the number of nodes placed in each row or column is bounded only by the size of the nodes and the dimensional parameters The specified value must be at least 1 The parameter has no effect if the l
337. l and the class I1vLabelLayout void setCoordinatesMode int mode Valid options of the coordinates mode are IilvLabelLayout MANAGER COORDINATES The geometry of obstacles and labels is computed using the coordinate space of the manager without applying any transformation This mode is suitable if the manager does not contain any nonzoomable labels ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING ADVANCED FEATURES 1ilvLabelLayout VIEW COORDINATES The geometry of obstacles and labels is computed in the coordinate space of the reference manager view This mode is suitable if the manager contains nonzoomable objects The layout will be correct with respect to the reference view but not correct with respect to any other view Dimensional layout parameters such as the label offset are specified in the coordinate space of the reference view IlvLabelLayout INVERSE VIEW COORDINATES This is the default The geometry of the graph is computed using the coordinate space of the reference manager view and then applying the inverse transformation This simulates the manager coordinate space This mode is also suitable if the manager contains nonzoomable objects The layout will be correct only with respect to the reference view Dimensional layout parameters such as the label offset are specified in the coordinate space of the manager o gt 1 3 o
338. l node can be set with the result that different alignments can occur in the same graph Figure 4 110 Bus Layout with Center Vertical Alignment 232 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT Figure 4 111 Bus Layout with Top Vertical Alignment Figure 4 112 Bus Layout with Bottom Vertical Alignment Alignment of Individual Nodes nodes have the same alignment unless the global alignment is set to IlvBusLayout MIXED Only when the global alignment is set to mixed can each node have an individual alignment style r lt gt fe gt 3 To set and retrieve the alignment of an individual node use the following methods void setVerticalAlignment Object node int alignment int getVerticalAlignment Object node The valid values for alignment of a node are IlvBusLayout CENTER the default IlvBusLayout TOP ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 233 BUS LAYOUT IlvBusLayout BOTTOM Incremental Mode The Bus Layout algorithm normally places all the nodes from scratch If the graph incrementally changes because you add remove or resize nodes the subsequent layout may differ considerably from the previous layout To avoid this effect and to help the user to retain a mental map of the graph the algorithm has an incremental mode In incremental mode the layout tries to place the nodes at the same location
339. lIndex node layout setSpecNodePositionIndex node layout getCalcNodePositionIndex node This example code works only if the generic connected component layout is disabled and the port sides EAST or WEST are not used in the layout If the graph is detached from the layout algorithm the calculated position index of a node is set back to 1 Note You should be aware of the difference between the methods getCalcNodePositionIndex and getSpecNodePositionIndex The first one returns the position index calculated by the previous layout and 1 if there was no previous layout The second one returns the specified position index even if there was no previous layout This behavior is similar to the behavior of the specified and calculated level index see section Calculated Level Index on page 184 184 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT Link Layout In this section you will learn about the Link Layout algorithm from the ILOG JViews Graph Layout module class 11vLinkLayout from the package ilog views graphlayout link Samples Here are sample drawings produced with the Link Layout Figure 4 86 Link Layout in Short Link Mode with Orthogonal Links r lt gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 185 LINK LAYOUT Figure 4 87 The Same Graph in Short Link Mode with Direct Links Figure 4 88 Link Layout Long L
340. lapsed For a description of this layout parameter in the 11vGraphLayout class see Allowed Time on page 22 If the layout stops early because the allowed time has elapsed some links may not be routed in the best possible way The result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID Animation The layout algorithm can show the temporary positions of the links during the routing in an animated way For a description of this layout parameter in the 11vGraphLayout class see Animation on page 22 Note If this option is enabled the layout of large graphs can be very time consumming Automatic Layout The Link Layout routes the links so that they bypass the nodes and cross each other as few times as possible It does not position any nodes However if the user moves adds or resizes nodes or adds or removes links the Link Layout drawing usually becomes invalid that is the links no longer look orthogonal overlap the moved nodes or cross other links Using the automatic layout feature of the 11vGraphLayout class the layout is reperformed whenever a change of the graph occurs For a description of this layout parameter in the IlvGraphLayout class see Automatic Layout on page 23 Preserve Fixed Links The layout algorithm does not reshape the links that are specified as fixed See Preserve Fixed Links on page 32 The fixed links are taken into account when computing the optimal layout of the nonfixed
341. lar obstacles behave like nodes links cannot overlap the rectangles Line obstacles behave like link segments other links can cross the line segments but cannot overlap the segments These obstacle settings can be removed by the following layout getLongLinkLayout removeAllRectObstacles layout getLongLinkLayout removeAllLineObstacles Penalties for Variable End Points If the termination points of the links are not fixed the algorithm uses a heuristic to calculate the termination points of each link It examines all free grid points that are close to the border of the start and end node and assigns a penalty to each grid point If a node side filter is installed the penalty depends on whether the node side is allowed or rejected A more precise way to affect how the termination points are chosen is the termination point filter This enables the user to specify the penalty for each grid point A termination point filter is a class that implements the interface IlvTerminationPointFilter that defines the following method public int getPenalty IlvGraphModel graphModel Object link boolean origin Object node IlvPoint point int side int proposedPenalty To select the origin or destination point of the input link the input point a grid point on the input side of the node is examined The proposedPenalty is calculated by the default heuristic of the algorithm You can return a changed penalty or you can return java lang Intege
342. le for example links with a maximum line width this mode gives different results than the manager coordinates mode These results are optimal if the grapher is visualized using the same transformer as the one taken into account during the layout Note that in this mode the dimensional parameters of the layout algorithms are considered as being specified in manager coordinates n The default mode is I1vGraphLayout INVERSE VIEW COORDINATI ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 327 so1njeoaJj em o 5 gt 2 lt E 5 o RELEASING RESOURCES UsED DURING THE LAYOUT To obtain the current choice use the following method long getCoordinatesMode The coordinates mode can also be specified directly on the layout instances For details see Coordinates Mode on page 24 Releasing Resources Used During the Layout Various objects need to be created during the layout process Most commonly these are layout instances subclasses of I1vGraphLayout and grapher adapters subclasses of IlvGrapherAdapter or other adapters subclasses of 11vGraphModel For recursive layout see Laying Out Nested Graphs on page 306 layout providers subclasses of IlvDefaultLayoutProvider may also be instantiated Finally some of the layout parameters are internally stored as property objects attached to the grapher object or to its nodes and links To ensure that all these allocated objects
343. le only if the link shapes are orthogonal Similarly for a layout with vertical levels the flow direction is to the left or to the right the vertical node offset controls node distances within the levels The horizontal node offset is the minimal distance between the levels In this case the vertical link offset and the vertical node link offset always play a role while the horizontal link offset and the horizontal node link offset affect the layout only with orthogonal links For orthogonal links the horizontal link offset is the minimal distance between parallel vertical link segments The vertical link offset is the minimal distance between parallel horizontal link segments However the layout algorithm cannot always satisfy these offset requirements If a node is very small but has many incident links it may be impossible to place the links orthogonally with the specified minimal link distance on the node border In this case the algorithm places some link segments closer than the specified link offset ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Link Offset Violation Caused by a Too Horizontal Small Node Node Link Offset q lt Vertical Link Horizontal Offset Link Offset Figure 4 76 Spacing Parameters for Orthogonal Links Incremental Mode In some circumstances you may need to use a sequence of layouts on the same graph For example You work with graphs that have become out
344. link mode 204 incremental mode parameter 198 individual end point mode parameter 197 individual link style parameter 195 intergraph link routing 199 layout mode parameter 192 limitations 188 link box connection interface short link mode 211 link connection box interface feature 208 link crossing penalty parameter short link mode 210 link offset parameter short link mode 202 link routing parameters long link mode 214 link style parameter 194 long link layout algorithm 189 minimal distance parameter long link mode 205 minimal node corner offset parameter long link mode 205 minimum final segment length parameter long link mode 206 minimum final segment parameter 203 node box interface feature 207 node side filter feature 206 number of optimization iterations short link mode 209 obstacle parameters long link mode 213 same shape for multiple links parameter short link mode 209 sample drawing 185 self link style parameter short link mode 208 short link layout algorithm 189 spacing parameters long link mode 203 spacing parameters short link mode 201 specific parameters 192 variable end point parameters long link mode 214 link offset parameter Link Layout short link mode 202 link priority parameter Hierarchical Layout 157 link routing parameters Link Layout long link mode 214 link style parameter Bus Layout 228 Circular Layout 252 Hierarchical Layout 144 Link Layout 194 Random Layout 220 Spring Embedder Lay
345. links r lt gt gt 3 Save Parameters to Named Properties The layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to 71 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 191 LINK LAYOUT Stop Immediately The layout algorithm stops if the method stopImmediately is called For a description of this method in the IlvGraphLayout class see Stop Immediately on page 35 If the layout stops early some links may not be routed in the best possible way The result code in the layout report is IlvGraphLayoutReport STOPPED AND INVALID Specific Parameters for Both Layout Modes The following parameters are specific to the IlvLinkLayout class Layout Mode The Link Layout algorithm has two layout modes To select a layout mode use the method void setLayoutMode int mode To obtain the current layout mode call int getLayoutMode The valid values for mode are IlvLinkLayout SHORT LINKS the default IlviinkLayout LONG LINKS Figure 4 89 shows a small sample graph in short and long link mode The short link mode bundles the links very well However due to the bundling some red links appear to be unconnected to the green nodes Furtherm
346. listener is defined by the GraphModelListener interface To receive the graph model events that is instances of the GraphModelEvent class a class so1njeaJj 2 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 301 USING THE GRAPH MODEL must implement the GraphModelListener interface and must register itself using the addGraphModelListener method of the 11vGraphModel class Note The creation of the graph model event listener is handled transparently by the IlvGraphLayout class Therefore there is usually no need to manipulate this listener directly Storing and Retrieving Data Objects Properties The following methods of the 11vGraphModel class allow a layout algorithm to store data objects for each node link or graph void setProperty Object nodeOrLink String key Object value Object getProperty Object nodeOrLink String key void setProperty String key Object value Object getProperty String key The layout algorithm may need to associate a set of properties with the nodes and links of the graph or with the graph itself Properties are a set of key value pairs where the key is String object and the value can be any kind of information value Note Creating a property and associating it with a node a link or a graph is handled transparently by the layout algorithm whenever it is necessary Therefore there is usually no need to manipulate the properties direc
347. ll the predefined method updatePosition x y with these coordinates 374 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT public void setPosition double pathLocation float distFromPath float x y make sure the position is between 0 and max while pathLocation maxPathLocation pathLocation maxPathLocation while pathLocation lt 0 pathLocation maxPathLocation store the actual position actPathLocation pathLocation translate the path location into x y if pathLocation labelwidth sidelength x float pathLocation y triangleBottom else if pathLocation labelwidth labelheight sidelength labelwidth sidelength y triangleBottom float pathLocation labelwidth sidelength else if other cases o gt 1 3 r finally update the internal data structures updatePosition x y The label may have a preferred position at the triangle The Annealing Layout checks a location close to the preferred position from time to time You should implement the following method to return the preferred path location double getPreferredPathLocation Furthermore you should implement a strategy on how to come close to the preferred location Towards the end of layout the algorithm performs a sequence of steps that have the task of getting the label from the current position closer to the pref
348. llowed Time on page 22 The result code in the layout report is I1vGraphLayoutReport STOPPED AND INVALID Layout of Connected Components The layout algorithm can utilize the generic mechanism to layout connected components For more information about this mechanism see Layout of Connected Components on page 25 224 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT Layout Region The layout algorithm uses the layout region setting either your own or the default setting to control the size and the position of the graph drawing All three ways to specify the layout region are available for this subclass See Layout Region on page 25 The size of the layout is chosen with respect to the layout region see Figure 4 113 on page 234 The height of the layout region is not taken into account The height of the layout will be smaller or larger depending on the number of nodes the size of the nodes and the other specified parameters Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to the border of the node shapes See Using a Link Clipping Interface on page 236 for details of the link clipping mechanism Preserve Fixed Links The layou
349. loadParametersFromNamedProperties IlvGraphLayout layout String propertyName This method transfers a set of layout parameters from the layout properties having the input property name to the input layout It returns t rue if successful and false otherwise IlvGraphLayout loadParametersFromNamedProperties IlvGraphLayout layout String propertyName This method transfers a set of layout parameters from the layout properties having the input property name to a newly created instance of 11vGraphLayout It returns the new instance It returns nu11 if no set of layout properties with the input name is found Loading Preferred Layouts from ivl Files The settings of the preferred layouts can be loaded from iv1 files using the method boolean loadPreferredLayoutsFromNamedProperties IlvDefaultLayoutProvider provider boolean withParameters boolean traverse The method takes the Layout Provider as an argument and several flags e withParameters if the flag is true the parameters of the preferred layout instances are loaded In this case it is not necessary to use the method loadParametersFromNamedProperties Otherwise after loading the 1 file the preferred layout will have in this case the default values for all its parameters e traverse if the flag is true the method applies recursively to the subgraphs Otherwise the method loads only the preferred layout of the grapher adapter on which the method is called
350. lobal Side Association Figure 6 10 Side Associations Local Side Association If the side association is local each polyline has two sides left and right The sides can be determined from the flow direction of the polyline from start point to end point Consider yourself standing on the polyline looking in the direction where the polyline continues towards the end point and then determine which is the left and which is the right side Hence the meaning of left and right in local side association is relative to the polyline The options for the preferred and allowed side are in this case IlvDirection Left IlvDirection Right You can also specify the value 0 for the allowed side which indicates that you do not want to restrict the side both sides are allowed Global Side Association If the side association is global the side specification is independent from the flow direction of the polyline and more like a compass direction north is top south is bottom west is left and east is right Here more options are possible top bottom left right and all combinations of these You specify the sides in the following way 366 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT IlvDirection Left IlvDirection Right IlvDirection Top IlvDirection Bottom You can also use combinations of these such as IlvDirection Left IlvDirection Right left or right but not top or bottom
351. low the new positions of their end nodes If the grapher contains other types of links for example IlvPolylineLinkImage or IlvSplineLinkImage the shape of the link may not be appropriate because the intermediate points of the link will not be moved In this case you can ask the layout algorithm to automatically remove all the intermediate points of the links if any To do this the following method is provided void setLinkStyle int style The valid values for style are 1ilvCircularLayout NO RESHAPE STYLE None of the links is reshaped in any manner 1ilvCircularLayout STRAIGHT LINE STYLE the intermediate points of the links if any are removed This is the default value Note If the STRAIGHT LINE STYLE is selected the layout algorithm may raise an IlvInappropriateLinkException if layout is performed on an 11vGraphez but links that cannot be given a straight line shape are used Such links are 11vOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage You can use the methods EnsureAppropriateLinkTypes orEnsureAppropriateLinks defined in IlvGraphLayoutUtil fo automatically replace inappropriate links This can be done before layout or when the 11vInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297
352. ls layout setLabelDescriptor labell new IlvAnnealingPolylineLabelDescriptor layout setLabelDescriptor label2 new IlvAnnealingPolylineLabelDescriptor layout setLabelDescriptor label3 new IlvAnnealingPolylineLabelDescriptor layout setLabelDescriptor label4 new IlvAnnealingPolylineLabelDescriptor layout setLabelDescriptor label5 new IlvAnnealingPolylineLabelDescriptor layout setLabelDescriptor label6 new IlvAnnealingPolylineLabelDescriptor label6 link5 IlvAnnealingPolylineLabelDescriptor Modify the layout parameters if needed layout setLabelOffset 10 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL labell 1 1 IlvAnnealingPolylineLabelDescriptor label2 link2 IlvAnnealingPolylineLabelDescriptor label3 link3 IlvAnnealingPolylineLabelDescriptor label4 link4 IlvAnnealingPolylineLabelDescriptor label5 link5 IlvAnnealingPolylineLabelDescriptor CENTER CENTER CENTER CENTER START END GETTING STARTED WITH LABELING layout setObstacleOffset 5 Perform the layout and get the layout report layoutReport layout performLayout Print information from the layout report optional System out println layout done in layoutReport getLayoutTime millisec code layoutReport getCode o gt 3 D r ES Fit the graph in the window view fitTransformerToConten
353. ltParameters false Specific Parameters The following parameter is specific to the IIvRandomLabelLayout class 378 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING ADVANCED FEATURES Layout Region The Random Label Layout algorithm places the labels randomly in a specified region You can set this region by setLayoutRegion IlvRect region You can obtain the current region by getLayoutRegion If no layout region is specified the default region 0 0 100 100 is used o gt 1 3 r Using Advanced Features This section describes advanced features for using the Label Layout module of ILOG JViews Filtering Manager Layers Inside an 11vManager the graphic objects can be managed by layers See the ilog views IlvManagerLayer class ILOG J Views allows you specify that only the labels and obstacles belonging to certain layers have to be taken into account when performing the layout Use the following methods of the IlvDefaultLabelingModel class void addLayer IlvManagerLayer layer boolean removeLayer IlvManagerLayer layer boolean removeAllLayers To get an enumeration of the manager layers to be taken into account during the layout use the method Enumeration getLayers To determine if a manager layer belongs to the layers to be taken into account during the layout use the method boolean isLayerAdded IlvManagerLayer layer
354. lue IlvBusLayout ORDER_BY_HEIGHT The nodes are arranged on the bus according to height starting at the upper left corner of the bus with the tallest node This option can save vertical space IlvBusLayout ORDER BY INDEX This option allows you to specify a particular order for the nodes The nodes are arranged on the bus according to their index values starting at the upper left corner of the bus with the node with the smallest index Nodes for which you do not specify an index are placed after the nodes for which an index is specified The 11vBusLayout ORDER BY INDEX option allows you to specify the order of the nodes according to physical geographical data for example If this option is chosen the algorithm sorts the nodes in ascending order according to their index values To obtain the current value use the method int getOrdering The index is an integer value associated with a node and is specified using the method void setIndex Object node int index The values of the indices cannot be negative To obtain the current index of a node use the method int getIndex Object node If no index is specified for the node the value 11vBusLayout NO INDEX is returned 226 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL Bus LAYOUT The ordering options for the Bus Layout are illustrated in Table 4 4 Table 4 4 Ordering Options the Nodes for the Bus Layout Algorithm
355. lusterIds method IlvCircularLayout class 247 removeAllLayers method IlvDefaultLabelingModel class 379 removeAllLayersmethod IlvLayoutGraphicFilter class 322 v v P removeAllLinkObstacles method IlvLongLinkLayout class 214 removeAllRectObstacles method IlvLongLinkLayout class 214 removeClusterId method IlvCircularLayout class 247 removeGraphModelListener method IlvGraphModel class 301 removeLabelingModelListener method IlvLabelingModel class 387 removeLayer method efaultLabelingModel class 979 IlvLayoutGraphicFilter class 322 removeParametersFromNamedProperties method IlvGrapherAdapter class 316 removing layout constraints 171 report classes for layout reports 292 creating a layout report 292 layout information 293 reading a layout report 293 using a layout report 292 reshapeLink method IlvGraphModel class 301 resources releasing 328 releasing after layout 383 respect node size parameter Uniform Length Edges Layout 88 respect node sizes parameter Tree Layout 117 ring topology Circular Layout 241 root clusters parameter Circular Layout 247 root node parameter additional options for Tree Layout 102 Tree Layout 101 J Ilv ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 441 INDEX S same shape for multiple links parameter Link Layout short link mode 209 save to named properties parameter Bus Layout 225 Circular Layout 245 Grid Layout 258 Hie
356. lvGraphModel class 300 getNodes method IlvGraphModel class 299 getNodesAndLinks method IlvGraphModel class 299 getNodesCount method IlvGraphModel class 299 303 INDEX getNodesDegree method IlvGraphModel class 300 getNodesPlacementAlgorithm method IlvTopologicalMeshLayout class 63 getNumberOfPorts method IlvHierarchicalLayout class 156 getNumberOfPossibleExteriorCycles method IlvTopologicalMeshLayout class 64 getO getObstacleOverlap method IlvLabelingModel class 386 390 getObstacles method IlvLabelingModel class 385 389 getObstaclesCount method IlvLabelingModel class 385 getOffset method IlvCircularLayout class 250 getOpposite method IlvGraphModel class 300 getOrdering method IlvBusLayout class 226 getOriginPointMode method IlvHierarchicalLayout class 149 IlvLinkLayout class 197 getOrthForkPercentage method IlvTreeLayout class 117 getOverlapPercentage method IlvTreeLayout class 118 getP getParentChildOffset method IlvTreeLayout class 117 getParentModel method IlvGraphModel class 300 getPenalty method IlvTerminationPointFilter class 214 getPercentageComplete method vLabelLayoutReport class 352 getPolylineObstacleOverlap method IlvLabelingModel class 386 getPolylinePoints method LabelingModel class 386 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 425 INDEX PolylineWidth method lvLabelingModel class 386 Position method lvTreeLayout class
357. m depends crucially on the speed of the overlap calculation The labeling model provides the following methods for overlap calculations double getLabelOverlap Calculates the Object labell IlvRect 1 overlap between two Object label2 IlvRect bbox2 labels float minDist double getObstacleOverlap Calculates the Object label IlvRect labelBBox overlap between a Object obstacle IlvRect obstacleBBox label and a normal float minDist obstacle double getPolylineObstacleOverlap Calculates the Object label IlvRect labelBBox overlap between a Object polylineObstacle label and a polyline IlvPoint pts float lineWidth float minDist Obstacle These methods return a positive penalty value that indicates how much the objects overlap The returned value is 0 if the objects do not overlap Asmaller overlap value designates less overlap than a larger overlap value The actual number is arbitrary and depends on the implementer of the labeling model For example if all objects are rectangles then it could be the size of the overlapping area of the rectangles Typically the overlap value is calculated before the label is moved It is calculated for a speculative label position not for the real label position Hence the speculative bounding box of the label is passed as an argument Similarly the bounding box or polyline shape of the obstacle is passed as an argument as well The meaning of the returned value is the 386
358. manner Note however that unlike fixed links the links are not ignored completely They are still used to calculate the leveling 1ilvHierarchicalLayout MIXED STYLE Each link can have a different link style The style of each individual link can be set such that different link shapes can occur in the same graph To obtain the current choice use the following method int getGlobalLinkStyle Individual Link Style All links have the same style of shape unless the global link style is MIXED_STYLE Only when the global link style is STYLE can each link have an individual link style Figure 4 64 Different Link Styles Mixed in the Same Drawing To set and retrieve the style of an individual line use the following methods void setLinkStyle Object link int style int getLinkStyle Object link 146 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT The valid values for style for local links are the same as for the global link style IlvHierarchicalLayout POLYLINE STYLE IlvHierarchicalLayout ORTHOGONAL STYLE IlvHierarchicalLayout STRAIGHT LINE STYLE IlvHierarchicalLayout NO RESHAPE STYLE Note The link style of a Hierarchical Layout graph requires links in an 11vGrapher that can be reshaped Links of type 11vLinklImage IlvOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplin
359. matically Reading a Layout Report To read a layout report all you need to do is store the layout report instance returned by the performLayout method and read the information as shown in the following example for the Spring Embedder Layout try IlvGraphLayoutReport layoutReport layout performLayout if layoutReport getCode IlvGraphLayoutReport LAYOUT DONE System out println Layout done else System out println Layout not done code layoutReport getCode catch IlvGraphLayoutException e System err println e getMessage Information Stored in a Layout Report The base class IlvGraphLayoutReport Stores the following information Code This field contains information about special predefined cases that may have occurred during the layout The possible values are the following e LAYOUT_DONE appears if the layout was performed successfully e STOPPED_AND_VALID appears if the layout was performed but was stopped before completion either because the layout time elapsed or because the method stopImmediately was called The positions of nodes and links are valid at the stopping point because the layout algorithm uses an iterative mechanism e STOPPED_AND_INVALID appears if a noniterative layout was performed but was stopped before completion either because the layout time elapsed or because the method stopImmediately was called The positions of nodes and links are not valid at th
360. ment Produced with the Random Label Layout Although each label belongs to a circle of the same color the random label placement does not show this Instead it places the labels randomly creating many overlaps The Random Label Layout can be used to shuffle the labels arbitrary in a given area Features Mainly for demonstration purposes Random placement of the labels inside a given region Brief Description of the Algorithm The Random Label Layout algorithm is not really a useful layout algorithm It simply places the labels at randomly computed positions inside a user defined region Nevertheless the Random Label Layout algorithm may be useful for demonstration purposes 376 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE RANDOM LABEL LAYOUT Code Sample Below is a code sample using the 11vRandomLabelLayout class import ilog views import ilog views graphlayout labellayout import ilog views graphlayout labellayout random IlvManager manager new IlvManager IlvManagerView view new IlvManagerView manager o gt S 3 r Fill in here code that fills the manager with labels and obstacles IlvRandomLabelLayout layout new IlvRandomLabelLayout layout attach manager layout setLayoutRegion new IlvRect 0 0 200 200 IlvLabelLayoutReport layoutReport layout performLayout if layoutReport getCode IlvLabelLayou
361. mlengthedges Samples Here are sample drawings produced with the Uniform Length Edges Layout Figure 420 Small Cyclic Graph Drawing Produced with the Uniform Length Edges Layout r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 81 UNIFORM LENGTH EDGES LAYOUT Figure 4 21 Medium Graph Drawing Combination of Cycles and Trees Produced with the Uniform Length Edges Layout a V PT cra e ni That ap Ma A E _ z ut sat 3 a4 xa y d d w 3 E ES EU N 2024 tq 4 T d SA ow Tun pos es Graph Drawing Combination of Cycles and Trees Produced with the Uniform Lengt ges Layout 82 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UNIFORM LENGTH EDGES LAYOUT What Types of Graphs Any type of graph Connected and disconnected graphs Planar and nonplanar graphs Application Domains Application domains of the Uniform Length Edges Layout include Telecom and networking WAN diagrams Software management software re engineering call graphs CASE tools dependency diagrams Database and knowledge engineering semantic networks database query graphs qualitative reasoning and other artificial intelligence diagrams and so on World Wide Web Web hyperlink neighborhood Features Often provides a drawing without any or with only a few link crossings and with approximat
362. mmon way to visualize lists of trees Two examples are shown in Figure 4 53 ns Figure 4 53 Chains of East West Neighbors to Visualize Lists of Trees Retrieving Link Categories The Tree Layout algorithm works on a spanning tree as mentioned in a Brief Description of the Algorithm on page 97 If the graph to be laid out is not a pure tree the algorithm ignores 130 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT some links To perform special treatment of such links you can obtain a list of non tree links Because there are parents and children in the spanning tree we distinguish the following link categories A forward tree link is a link from a parent to its child A backward tree link is a link from a child to its parent If the link is drawn as a directed arrow the arrow will point in the opposite direction to the flow direction Anon tree link is a link between two unrelated nodes neither one is a child of the other forward non tree tree link link non tree link backwar tree lin tre link Figure 4 54 Link Categories The layout algorithm uses these link categories internally but does not store them permanently for the sake of conserving time and memory efficiency If you want to perform special treatment on some link categories for example to call the Link Layout on the non tree links you must specify before the layout that you want to access the link categories after the l
363. n It chooses one of the cycles of the graph to be used in the second step In the second step called nodes placement the result of the first step is used to compute the coordinates of the nodes using a deterministic high speed barycenter algorithm Of course the problem still remains NP complete and large graphs cannot be processed In practice however you will often get better results for mesh graphs with TML than with many other algorithms Step 1 Topological Optimization Input The topology of the graph its connectivity or the neighborhood relationships between nodes Output set of possible outer cycles ordered decreasingly by their lengths The length of a cycle is the number of nodes in the cycle Explanation This step determines what cycles of the graph if used as an outer cycle for drawing the graph in Step 2 will allow a drawing with a minimum number of link crossings An optimization algorithm tries to minimize a heuristic cost function that estimates the number of link crossings for each solution based on pure topology graph connectivity Step 2 Nodes Placement Input The output of Step 1 and the graph Output set of coordinates for the nodes The coordinates are assigned to the nodes to obtain the graph drawing r lt gt gt 3 Explanation This step is a variant of the barycentric layout algorithm It takes a cycle from the output of Step
364. n Right return true To set this node side filter use the following call layout setNodeSideFilter new MyFilter To remove the node side filter use the following call layout setNodeSideFilter null Using a Node Box Interface Some applications require that effective area of a node is not exactly its bounding box For instance if the node has a shadow the shadow is included in the bounding box However the shadow may not be considered as an obstacle for the links In this case the effective bounding box of a node is smaller than the bounding box returned by IlvGraphic boundingBox You can modify the effective bounding box of a node by implementing a class that implements the 11vNodeBoxInterface This interface defines the following method public IlvRect getBox IlvGraphModel graphModel Object node This method allows you to return the effective bounding box For instance to set a node box interface that returns a smaller bounding box for all nodes of type IlvShadowRectangle call r lt c gt e gt 3 layout setNodeBoxInterface new IlvNodeBoxInterface public IlvRect getBox IlvGraphModel graphModel Object node IlvRect rect graphModel boundingBox node if node instanceof IlvShadowRectangle need a rect that is 4 units smaller rect resize rect width 4 f rect height 4 f return rect ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 207
365. n be corrected by specifying a link connection box interface that returns a smaller node box than the bounding box Figure 4 125 right Alternatively the problem could be corrected by specifying a link connection box interface that returns the bounding box as the node box but with additional tangential offsets that shift the virtual center of the node 254 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL GRID LAYOUT Grid Layout In this section you will learn about the Grid Layout algorithm from the ILOG JViews Graph Layout module class IlvGridLayout from the package ilog views graphlayout grid Sample Here are sample drawings produced with the Grid Layout E jwg EN Hs um m m m Figure 4 126 Drawing produced using the TO GRID FIXED WIDTH mode with CENTER horizontal and vertical alignment The red lines are drawn here to help the identification of the grid cells they are not drawn by the layout algorithm PLETE TTT TTTLIL Figure 4 127 Drawing produced using the TILE TO ROWS mode with CENTER vertical alignment r 2 lt c gt Q gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 255 GRID LAYOUT What Types of Graphs Any graph However the links are never taken into consideration This algorithm is designed for placing nodes independently on their eventual links Application Domai
366. n does everything with no user intervention Semiautomatic layout For applications using a semiautomatic layout the choice of the layout algorithm is done by the end user The application can provide a menu or some other way to select the layout algorithm In some cases this may be an iterative process The user may try different layout algorithms with different values for the parameters and or may apply manual refinements in order to find the best layout Eventually the application can provide some help using textual explanations or by automatically checking the graph to find out to which class it belongs For example to detect whether the graph that has been attached to a layout instance is a tree the 11vGraphLayoutUtil class provides the following method static boolean IsTree IlvGraphLayout layout Object startNode For details on this method see the corresponding section of the reference manual Automatic layout If an automatic layout is needed the choice of the layout algorithm can be e Dynamically chosen at run time using heuristics or rules to determine the appropriate layout algorithm depending on the structure and or size of the graph e Hard coded if the developer knows what types of graphs will be used and can determine the appropriate layout algorithm Procedure for Dynamically Choosing the Layout Algorithm If nothing is known about the graphs that the application will need to lay out the developer can write
367. n radial layout mode r lt gt fe gt 3 The orthogonal link style does not work in radial layout mode The clipped connector style is always used The parent child offset parameter controls the minimal distance between the circular levels However it is sometimes necessary to increase the offset between circular levels to obtain enough space on the circle to place all nodes of a level JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 121 TREE LAYOUT The level alignment north indicates alignment at the inner border of the circular level that is towards the root and the level alignment south indicates alignment at the outer border of the circular level that is away from the root The level alignments north and south sometimes result in overlapping nodes The overlap percentage has no effect in radial layout mode Alternating Radial Mode If levels of the graph contain many nodes it is sometimes necessary to increase the radius of the circular level to provide enough space on the circumference of the circle for all the nodes This may result in a considerable distance from the previous level To avoid this there is an alternating radial mode The alternating radial mode places the nodes of a level alternating between two circles instead of one circle resulting better usage of the space of the layout The alternating radial mode uses two circles only when necessary For many small
368. n the same graph ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 219 RANDOM LAYOUT Save Parameters to Named Properties The layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to 71 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 I1vGraphLayoutReport STOPPED AND INVALID Specific Parameters The following parameters are specific to the 11vRandomLayout class Link Style When the layout algorithm moves the nodes straight line links such as instances of IlvLinkImage will automatically follow the new positions of their end nodes If the grapher contains other types of links for example IlvPolylineLinkImage or IlvSplineLinkImage the shape of the link may not be appropriate because the intermediate points of the link will not be moved In this case you can ask the layout algorithm to automatically remove all the intermediate points of the links if any To do this the following method is provided void setLinkStyle int style The vali
369. nces from the reference point measured from the border of the label If you set the minimal and maximal distance to 0 the label will just touch the reference point To keep the circular area around the reference point free set the minimal distance accordingly Most of the time you probably 362 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT want to keep the label close to the reference point hence set the minimal and maximal distances to the same value The preferred position indicates whether the label should be placed to the left right top or bottom of the reference point This is a suggestion for the labeling algorithm as described for Positioning at an Obstacle on page 360 Positioning on Multiple Criteria The most powerful constructor combines all previously mentioned possibilities o gt 1 3 E r IlvAnnealingPointLabelDescriptor Object label Object relatedObstacle IlvPoint referencePoint int shape float halfWidth float halfHeight float maxDistFromPath float preferredDistFromPath int preferredDirection If a related obstacle is given and the reference point is nu11 the label is placed close to the related obstacle If a reference point is given the label is placed close to the reference point independently from the related obstacle position The shape of the free area around the point can be rectangular or elliptic The paramete
370. nding box of the node This can be corrected by specifying a link connection box interface that returns a smaller node box than the bounding box Figure 4 26 right Alternatively the problem could be corrected by specifying a link connection box interface that returns the bounding box as the node box but with additional tangential offsets that shift the virtual center of the node r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 93 TREE LAYOUT Tree Layout In this section you will learn about the Tree Layout algorithm from the ILOG JViews Graph Layout module class 11vTreeLayout from the package ilog views graphlayout tree Samples Here are some sample drawings produced with the Tree Layout Figure 4 27 Tree Layout in Free Layout Mode with Center Alignment and Flow Direction to the Right Figure 4 28 Tree Layout with Flow Direction to the Bottom Orthogonal Link Style and Tip Over Alignment at Some Leaf Nodes 94 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Figure 4 29 Tree Layout in Radial Layout Mode with Aspect Ratio 1 5 What Types of Graphs Primarily designed for pure trees It can also be used for non trees that is for cyclic graphs In this case the algorithm computes and uses a spanning tree of the graph ignoring all links that do not belong to the spanning tree Directed and undirected trees If the links ar
371. ng return null IlvGraphLayout layout null ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 269 RECURSIVE LAYOUT String name String prop if name equals tree layout new IlvTreeLayout else if name equals flow layout new IlvHierarchicalLayout else throw new RuntimeException unsupported layout choice name layout attach graphModel return layout Of course this is only an example among many possible implementations The implementation may decide to store the newly allocated layout instance to avoid allocating a new one when the method is again called for the same graph If you have implemented a layout provider you can use it in the Recursive Layout in the following way import ilog views import ilog views graphlayout import ilog views graphlayout recursive IlvLayoutProvider layoutProvider IlvRecursiveLayout layout new IlvRecursiveLayout layoutProvider IlvGrapher topLevelGrapher layout attach topLevelGrapher Perform the layout try IlvRecursiveLayoutReport layoutReport IlvRecursiveLayoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage detach the Recursive Layout when it is no longer needed layout detach 270 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MA
372. ng Embedder Layout 77 Topological Mesh Layout 60 Tree Layout 101 Uniform Length Edges Layout 86 subgraph correction Recursive Layout 278 sublayouts Recursive Layout 275 446 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL supportsAllowedTime method IlvGraphLayout class 22 31 36 supportsAnimation method IlvGraphLayout class 23 supportsLayoutOfConnectedComponents method IlvGraphLayout class 305 supportsLayoutRegion method IlvGraphLayout class 26 334 supportsLinkClipping method IlvGraphLayout class 27 supportsLinkConnectionBox method IlvGraphLayout class 29 supportsMemorySavings method IlvGraphLayout class 91 supportsPrserveFixedLinks method IlvGraphLayout class 32 supportsPrserveFixedNodes method IlvGraphLayout class 25 33 34 supportsRandomGenerator method IlvGraphLayout class 34 supportsSaveParametersToNamedProperties method IlvGraphLayout class 315 IlvLabelLayout class 382 swim lane constraint Hierarchical Layout 178 symmetries layout criteria 15 T time stop computation algorithms 22 tip over alignment Tree Layout free mode 108 tip over layout modes Tree Layout aspect ratio parameter 126 description 126 tip leaves over 128 tip over fast 128 tip roots and leaves over 128 tip roots over 128 Topological Mesh Layout applicable graph types 55 application domains 55 basic concepts 57 code sample 58 description of algorithm 56 features 55 INDEX generic parameters 58
373. ng if the specified manager is already attached Otherwise it first detaches the manager that is already attached if any You can obtain the attached manager using the method getManager If the manager is attached in this way a default labeling model is created internally The labeling model can be obtained by IlvLabelingModel labelingModel layout getLabelingModel Warning Notice that such an internally created model is not allowed to be attached to any other layout instance After layout when you no longer need the layout instance you should call the detach method If the det ach method is not called some objects may not be garbage collected This method also performs cleaning operations on the manager properties that may have been added by the layout algorithm on the manager s objects are removed void detach Performing a Layout The performLayout methods start the layout algorithm using the currently attached manager and the current settings for the layout parameters The method returns a report object that contains information about the behavior of the label layout algorithm 348 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT IlvLabelLayoutReport performLayout IlvLabelLayoutReport performLayout boolean force boolean redraw The first version of the method simply calls the second one with a a1se value for the first argument and a t r
374. ngEmbedderLayout class Link Style When the layout algorithm moves the nodes straight line links such as instances of IlvLinkImage will automatically follow the new positions of their end nodes If the grapher contains other types of links for example IlvPolylineLinkImage or IlvSplineLinkImage the shape of the link may not be appropriate because the intermediate points of the link will not be moved In this case you can ask the layout algorithm to automatically remove all the intermediate points of the links if any To do this the following method is provided void setLinkStyle int style The valid values for style are IlvSpringEmbedderLayout NO_RESHAPE_STYLE None of the links is reshaped in any manner r lt p gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 77 SPRING EMBEDDER LAYOUT 1ilvSpringEmbedderLayout STRAIGHT LINE STYLE All the intermediate points of the links if any are removed This is the default value Note If STRAIGHT LINE STYLE is selected the layout algorithm may raise an IlvInappropriateLinkException when the layout is performed on an 11vGraphezr and links that cannot be given a straight line shape are used Such links are IlvOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage You can use the method EnsureAppropriateLinkTypes orEnsureAppropriateLinks defined
375. ngs boolean option and to obtain the current value boolean isMemorySavings m 07 2 O Q 5 a The default value is false To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean supportsMemorySavings The default implementation returns false A subclass can override this method in order to return true to indicate that this mechanism is supported Percentage Completion Calculation Some layout algorithms can provide an estimation of how much of the layout has been completed This estimation is made available as a percentage value that is stored in the graph layout report When the algorithm starts the percentage value is set to 0 The layout algorithm calls the following method from time to time to increase the percentage value by steps until it reaches 100 void increasePercentageComplete int newPercentage The percentage value can be accessed from the layout report using the following int percentage layoutReport getPercentageComplete To see an example of how to read the percentage value during the running of a layout see Layout Event Listeners on page 294 To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean supportsPercentageComplete ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 31 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT
376. nk The valid values for mode are IlvLinkLayout FREE MODE the default IlvLinkLayout FIXED_MODE The connection points are automatically considered as fixed if they are connected to grapher pins r lt gt mi gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 149 HIERARCHICAL LAYOUT Note The layout algorithm may raise an 1X1vInappropriateLinkException if layout is performed an 11vGrapher but links are neither a subclass of IlvPolylineLinkImage nor of IlvSplineLinkImage or if connectors are not a subclass of 11vRelativeLinkConnector You can use the methods EnsureAppropriateLinkTypes EnsureAppropriateLinkConnectors Or EnsureAppropriateLinks defined in IlvGraphLayoutUtil to automatically replace inappropriate links or link connectors before layout or when the IlvInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 Using a Link Connection Box Interface By default the connector style determines how the connection points of the links are distributed on the border of the bounding box of the nodes symmetrically with respect to the middle of each side Sometimes it may be necessary to place the connection points on a rectangle smaller or larger than the bounding box For instance this can happen wh
377. nk Styles Mixed in the Same Drawing To set and retrieve the style of an individual link use the following methods void setLinkStyle Object link int style int getLinkStyle Object link The valid values for style are INE STYLE the default IlvTreeLayout STRAIGHT i1ilvTreeLayout NO RESHAPE STYLE IlvTreeLayout ORTHOGONAL STYLE Note The link style of a Tree Layout graph requires links in an 11vGrapher that can be reshaped Links of type 11vLinkImage IlvOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage cannot be reshaped You should use the class T1vPolylineLinkImage or IlvSplineLinkImage instead Connector Style r lt p gt gt 3 The layout algorithm automatically positions the end points of links the connector pins at the nodes The connector style parameter specifies how these end points are calculated for the outgoing links at the parent node ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 111 TREE LAYOUT Evenly Spaced Clipped Connector Pins Connector Pins Connector Pins Centered Evenly Spaced Connector Pins Connector Pins Figure 4 37 Connector Styles To set the connector style use the following method void setConnectorStyle int style The valid values for style are IlvTreeLayout CENTERED_PINS The
378. nnis G Tollis Algorithms for Drawing Graphs an Annotated Bibliography Computational Geometry Theory and Applications 4 1994 235 282 also available at http www cs brown edu people rt gd biblio html Journals The following are electronic journals Journal of Graph Algorithms and Applications http www cs brown edu publications jgaa Algorithmica http link springer ny com link service journals 00453 Computational Geometry Theory and Applications http www elsevier nl inca publications store 5 0 5 6 2 9 Journal of Visual Languages and Computing http www academicpress com jvlc The following journals occasionally publish papers on graph layout Information Processing Letters http www elsevier nl inca publications store 5 0 5 6 1 2 Computer aided Design http www elsevier nl inca publications store 3 0 4 0 2 IEEE Transactions on Software Engineering http www computer org tse Many papers are presented at conferences in Combinatorics and Computer Science Conferences An annual Symposium on Graph Drawing has been held since 1992 The proceedings are published by Springer Verlag in the Lecture Notes in Computer Science series For the 2001 edition see http link springer de link service series 0558 tocs t2265 htm For the 2003 Symposium to be held in Perugia Italy see http www gd2003 org ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ix ILOG JViEWS GRAPH LAYOUT 5 5 USER S MA
379. node1 contained in the subgraph grapherB of the topmost graph grapheraA needs to be declared as fixed see Preserve Fixed Nodes on page 32 the following code can be used IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher fill the graphers with nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create the layout instance IlvTreeLayout layout new IlvTreeLayout Attach the topmost grapher to the layout layout attach grapherA Ask the layout algorithm to not move the nodes specified as fixed This settings is automatically copied on the sublayouts Do not specify this global settings directly on the sublayout because it gets automatically the same settings as the topmost layout layout setPreserveFixedNodes true Search the layout instance used for grapherB IlvGraphLayout subLayout null Enumeration layouts layout getLayouts true while layouts hasMoreElements subLayout IlvGraphLayout layouts nextElement if subLayout getGraphModel getGrapher grapherB break Specify nodel contained in grapherB as fixed subLayout setFixed nodel true Now perform the recursive layout The node nodel will be considered as fixed by the layout applied to grapherB Note You should not try to change global settings of the layouts applied on the subgraphs that is settings that are not spe
380. nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create the layout instance IlvTreeLayout layout new IlvTreeLayout Create a grapher adapter for the topmost grapher IlvGrapherAdapter adapter new IlvGrapherAdapter grapherA Attach the adapter to the layout layout attach adapter Perform the recursive layout try perform the layout with argument traverse true int code layout performLayout true true true System out println Layout completed code code catch IlvGraphLayoutException e System err println e getMessage Detach the adapter when layout no more needed layout detach Dispose the adapter when no more needed adapter dispose Layout Parameters in Simple Recursive Layouts We have seen that when applying the same layout algorithm in a recursive way the layout instances for the subgraphs are obtained by cloning the layout instance attached to the topmost graph The layout parameters of the clone are the same as the parameters of the topmost layout except for parameters that are specific to a node or a link Such parameters ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 309 soJnjeoaJj em 5 gt 2 lt 5 o LAYING OUT NESTED GRAPHS 310 are not copied when cloning the layouts and need to be set separately for each layout instance For instance if a node
381. ns Any domain where a collection of isolated nodes needs to be laid out Features Arranges a collection of isolated nodes or connected components Takes into account the size of the nodes so that no overlapping occurs Provides several alignment options and dimensional parameters Provides full support for fixed nodes overlapping of nonfixed nodes with fixed nodes is avoided Provides an incremental mode which helps the retention of a mental map on incremental changes made to a collection of nodes Brief Description of the Algorithm The Grid layout has two main modes grid and row column In grid mode the layout arranges the nodes of a graph in the cells of a grid matrix If a node is too large to fit in one grid cell with margins it occupies multiple cells The size of the grid cells and the margins are parameters of the algorithm In row column mode the layout arranges the nodes of a graph either by rows or by columns according to the specified option The width of the rows is controlled by the width of the layout region parameter The height of the columns is controlled by the height of the layout region parameter The horizontal and vertical margins between the nodes are parameters of the algorithm Code Sample Below is a code sample using the 11vGridLayout class import ilog views import ilog views graphic import ilog views graphlayout import ilog views graphlayout g
382. nsformer By default the layout algorithms consider the geometry of the nodes and links of an IlvGrapher in a coordinate space that is appropriate for most cases In some situations it can be useful to specify a different coordinate space For details see Choosing the Layout Coordinate Space on page 323 To specify the coordinate space the following method is provided void setCoordinatesMode int mode The valid values for style are IlvGraphLayout MANAGER COORDINATES The geometry of the graph is computed using the coordinate space of the manager that is the attached 11vGrapher without applying any transformation This mode should be used if you visualize the graph at zoom level 1 or you do not visualize it at all or the grapher contains only fully zoomable objects In all these cases there is no need to take the transformer into account during the layout Note that in this mode the dimensional parameters of the layout algorithms are considered as being specified in manager coordinates IlvGraphLayout VIEW COORDINATES The geometry of the graph is computed in the coordinate space of the manager view More exactly all the coordinates are transformed using the current reference transformer This mode should be used if you want the dimensional parameters of the layout algorithms to be considered as being specified in manager view coordinates Il1vGraphLayout INVERSE VIEW COORDINATES T
383. nt auxControlPoint nodeBox intersectionPoints choose the result from the intersections return IlvGraphLayoutUtil BestClipPointOnRay proposedConnectionPoint auxControlPoint intersectionPoints numIntersections Note In addition to the link clip interface the IlvClipLinkConnector be used This special link connector clips the links at nonrectangular node shapes and updates the connection points automatically during interactive node movements 28 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT Link Connection Box If a layout algorithm calculates specific connection points then it places the connection points of links by default at the border of the bounding box of the nodes symmetrically with respect to the middle of each side Sometimes it may be necessary to place the connection points on a rectangle smaller or larger than the bounding box eventually in a nonsymmetric way For instance this can happen when labels are displayed below or above nodes see Figure 2 2 on page 30 This can be achieved by specifying a link connection box interface The link connection box interface allows you to specify for each node a node box different from the bounding box that is used to connect the links to the node To indicate whether a subclass of IlvGraphLayout supports the link connection box interface the following method is provided boolean supportsLinkConnectionBox
384. nt applications What Is in This Manual The ILOG JViews Graph Layout module provides high level ready to use graph drawing services that allow you to obtain readable representations easily This manual contains the following chapters Chapter 1 Introducing the Graph Layout Module describes the Graph Layout module of ILOG JViews and its features Chapter 2 Basic Concepts provides background information and basic concepts for using Graph Layout Chapter 3 Getting Started with Graph Layout provides information to get started quickly using Graph Layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL vii Chapter 4 Layout Algorithms describes the layout algorithms provided with the Graph Layout module Chapter 5 Using Advanced Features provides information on using a layout report using layout event listeners using a graph model laying out a non JViews grapher layout out disconnected graphs saving layout parameters to a file laying out a portion of a graph laying out graphs with nonzoomable objects and defining new types of layouts Chapter 6 Automatic Label Placement describes the label layout facilities provided with the Graph Layout module Chapter 7 Using Graph Layout Beans shows you how to use the ILOG JViews Beans and the Graph Layout Beans when creating an applet within an Integrated Development Environment IDE At the end of the manual you will find a Glossary containing definitions of the ba
385. nt depend on the grid spacing Limitations ILOG Since the Link Layout algorithm reshapes the links it works preferably with links of type IlvPolylineLinkImage and link connectors of type IlvRelativeLinkConnector When routing intergraph links the incremental mode cannot be used Due to the complexity of intergraph link routing more crossings and overlappings may occur than when routing normal links In short link mode crossings and overlapping of links with other links and nodes cannot always be avoided because the algorithm uses link shapes with a limited number of bends This happens in particular when there are many obstacles between the end points of a link In long link mode link crossings cannot always be avoided Segment overlappings of orthogonal links are always avoided unless there is no free space remaining on the border of the end nodes Any overlapping of nodes and links is always avoided unless one end nodes is inside an enclave An enclave is an area that is surrounded by other nodes such that the area cannot be reached from the other end node See Figure 4 103 on page 215 In long link mode segment overlapping or overlapping between nodes and links cannot always be avoided if the direct link style is used The long link mode is slower and uses more memory if the grid spacing is very small JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT Brief Description of the Algorithm The Link Lay
386. nywhere at the left or top side of the polyline obstacle with preference given to the left side The example uses the following constructor IlvAnnealingPolylineLabelDescriptor Object label Object relatedPolylineObstacle int anchor int preferredSide int allowedSide int sideAssociation Even though a polyline does not have a source node or a target node the anchor specification can be used in the same way as for links CENTER START END and FREE The first control point of the polyline is the start point Labels with anchor START are placed closer to the first control point and labels with anchor END are placed closer to the last control point of the polyline ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 365 THE ANNEALING LABEL LAYOUT The preferred side is a suggestion for the label layout algorithm on where to place the label If the area at the preferred side is occupied the label is placed elsewhere In contrast the allowed side is a strict constraint it is always obeyed even if the entire area at the allowed side is occupied and the label must overlap the obstacles in this area Side Association The orientation of the preferred and allowed sides depend on the side association Options for the side association are listed below and illustrated in Figure 6 10 IlvAnnealingPolylineLabelDescriptor LOCAL IlvAnnealingPolylineLabelDescriptor GLOBAL Rig Local Side Association G
387. o Release Resources IlvLabelLayout provides four methods that help to release all these objects once they no longer needed such obsolete objects can be garbage collected and memory leaks in the Java sense avoided o gt 1 3 r void detach void cleanLabelingModel IlvLabelingModel labelingModel void cleanLabel IlvLabelingModel labelingModel Object label void cleanObstacle IlvLabelingModel labelingModel Object obstacle The method cleanLabelingModel releases property objects that the layout instances stored globally for the labeling model or for the manager The methods c1eanLabel and cleanObstacle release property objects stored for the label or obstacle passed as an argument These three methods are automatically called when detach is called Rules for Releasing Resources The following rules must be respected When a layout instance instantiated by your code is no longer useful call the method IlvLabelLayout detach on it to ensure that no manager or labeling model is still attached to it Note that you can freely reuse a layout instance once the previously attached model has been detached Layout parameters or stored property objects that are specific to a label or an obstacle are cleaned when calling detach This cleaning is done only for labels and obstacles that are still in the manager when the detach method is called Iflabels or
388. od m 07 ps O 5 a boolean isPreserveFixedNodes To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean supportsPreserveFixedNodes The default implementation returns false A subclass can override this method in order to return true to indicate that this mechanism is supported Random Generator Seed Value Some layout algorithms use random numbers or randomly chosen parameters for which they accept a user defined seed value For example the Random Layout uses the random generator to compute the coordinates of the nodes The Spring Embedder uses the random generator to compute some internal variables Subclasses of IlvGraphLayout that are designed to support this mechanism allow the user to choose one of three ways of initializing the random generator With a default value that is always the same With a user defined seed value that can be changed when re performing the layout With an arbitrary seed value which is different each time In this case the random generator is initialized based on the system time The user chooses the initialization option depending on what happens when the layout algorithm is performed again on the same graph If the same seed value is used the same ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 33 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT layout is produced which ma
389. ode 360 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT gt E 3 D 7 r Figure 6 6 Potential Label Positions Around a Node The example uses the following constructor IlvAnnealingPointLabelDescriptor Object label Object relatedObstacle int shape int preferredDirection The relatedObstacle is the obstacle that gets the label The label is placed outside but close to this obstacle The related obstacle can be a node of a graph a city of a geographic map a Station of a railroad and so on whatever needs to have a label The shape of the related obstacle should be either an ellipse circle or rectangle You pass as the shape argument I IlvAnnealingPointLabelDescriptor ELLIPTIC for ellipses or circles IlvAnnealingPointLabelDescriptor RECTANGULAR for rectangles If the real shape of the related obstacle is neither of these then pass the shape that is the best approximation For instance if the obstacle is an 11vRoundRectangle this can be considered as a rectangular shape The preferred position is a suggestion for the label layout algorithm where the label should preferably be placed If the area at the preferred position is occupied the label will be placed elsewhere Options for the preferred position are IlvDirection Left IlvDirection Right IlvDirection Top IlvDirection Bottom ILOG JViEWS GRAPH LAYOUT
390. ode nodes nextElement skip fixed nodes if isPreserveFixedNodes amp amp isFixed node continue compute coordinates float x xMin xMax xMin random nextFloat float y yMin yMax yMin random nextFloat move the node to the computed position graphModel moveNode node x y redraw notify listeners on layout events callLayoutStepPerformedIfNeeded set the layout report code layoutReport setCode IlvGraphLayoutReport LAYOUT DONE Note that the layout method is protected which is the access type of the method in the base class This will not prevent a user outside the package containing the class from performing the layout because it is started using the public method performLayout Steps for Implementing the Layout Method In our example the Layout method is implemented using the following main steps 330 ILOG JViEWS GRAPH LAYOUT 5 5 UsER S MANUAL DEFINING A NEW OF LAYOUT 1 Obtain the graph model getGraphModel on the layout instance IlvGraphModel graphModel getGraphModel 2 Obtain the instance of the layout report that is automatically created when the performLayout method from the superclass is called get LayoutReport on the layout instance IlvGraphLayoutReport layoutReport getLayoutReport 3 Obtain the layout region parameter to compute the area where the nodes will be placed IlvRect rect getCalcLayoutRegion
391. odeGroup group2 add nodeB group2 add nodeC layout addConstraint new IlvSideBySideConstraint group2 10 0f The first constraint specifies that nodeA nodeB nodeC and nodeD must be clustered The second constraint specifies that nodeB and nodeC are clustered inside the larger cluster This means that no other node can be placed between the four nodes and furthermore neither nodeA nor nodeD can be placed between nodeB and nodec Figure 4 83 sketches four solutions that satisfy both constraints nodeA nodeD medem Rode nodec nodes Figure 4 83 Sketch of Solutions for Side By Side Constraints Extremity Constraints To force a node to the first level you can specify layout setSpecNodeLevelIndex node 0 However you cannot specify a level index for the last level because it is unknown at the beginning of layout how many levels will be created It is unwise to specify layout setSpecNodeLevelIndex node java lang Integer MAX VALUE because this will create many empty levels between the levels actually used and the last one Even though these empty levels are removed in postprocessing steps this influences the speed and quality of the layout In fact the algorithm will run out of memory if you set the specified level index unreasonably high r lt gt e gt 3 By using constraints you can achieve the same effect more effi
392. of 11vLabelingModel you must implement the method IlvLabelingModel createLabelingModel Object subgraph This method should return a new instance of your own labeling model for the input subgraph The Recursive Multiple Layout uses this method to generate all labeling models for all subgraph from a reference labeling model Before attaching the Recursive Multiple Layout instance you can set the reference labeling model in the following way recursiveMultipleLayout setReferenceLabelingModel myLabelingModel recursiveMultipleLayout attach myGraphModel gt r lt e mi gt 3 The reference labeling model is used for the label layout of the top level grapher Clones of the reference labeling model obtained by createLabelingModel are used for the label layouts of the subgraphers A simple way to perform a label layout recursively is the following IlvRecursiveMultipleLayout layout new IlvRecursiveMultipleLayout labelLayout layout setReferenceLabelingModel myLabelingModel layout attach topLevelGraph try IlvGraphLayoutReport layoutReport layout performLayout catch IlvGraphLayoutException e System err println e getMessage layout detach If the Recursive Multiple Layout instance is detached from the top level graph model all sublayouts are automatically detached as well and all labeling models of subgraphs including the reference labeling model are disposed
393. of Germany with Annealing Label Layout ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 355 THE ANNEALING LABEL LAYOUT Features 5 9 9 9 Places only labels Does not move any obstacles around Quality controlled randomized iterative heuristic Can place labels at points rectangles ellipses and polylines Can be used to place labels at nodes and links Can be used to place labels at cities in a geographic map Can place multiple labels at the same object point node link city and so on Tries to avoid overlaps among labels and between labels and obstacles by using the available free space Provides several anchor and preference options Easy extensible via subclassing of label descriptors Efficient scalable algorithm Produces nice label placements even if the number of labels is large Limitations The Annealing Label Layout algorithm as a randomized iterative heuristic does not guarantee that labels are placed without overlaps whenever possible However it produces a high quality layout with a high probability of minimum overlap The more iterations the higher the probability of high quality The algorithm is not able to create free space for labels by moving obstacles around It is recommended that you perform a graph layout algorithm with large spacing parameters to create the necessary free space before placing the labels While the algorithm is able to place labels at straight
394. of date and you need to extend the graph If you perform a layout on the extended graph you probably want to identify the parts that were already laid out in the original graph The layout should not change very much when compared with the layout of the original graph The first layout results in a drawing with minor deficiencies You want to solve these deficiencies manually and perform a second layout to clean up the drawing The second layout probably should not greatly change the parts of the graph that were already acceptable after the first layout The Hierarchical Layout normally works nonincrementally It performs a layout from scratch and moves all nodes to new positions and reroutes all links The previous positions of nodes have no influence on the result of the layout Hence even a small change can cause a large effect on the next layout r lt e gt vo gt 3 But Hierarchical Layout also supports incremental sequences of layout that do not change very much It can place the nodes close to their previous positions so that you can more easily identify the parts that had already been laid out in the original graph Incremental mode takes the previous positions of the nodes into account In this mode the algorithm preserves the relative order of the levels and the nodes within the levels in the subsequent layout It does not preserve the absolute positions of the nodes but it tries to
395. of the nodes for instance in Tree Layout and Hierarchical Layout In all these situations it is important that the subgraph remains at the old position even after its contents was laid out The implementation of IlvGrapher does not behave like this The solution is simply to move the subgraph back to its old position immediately after the subgraph was laid out just before the layout of the parent graph of the subgraph is started The Recursive Layout allows to install a subgraph correction interface that contains a correct method which is called exactly at this time point You install a subgraph correction interface in the following way layout setSubgraphCorrectionInterface new IlvSubgraphCorrectionBarycenterFixed Two default implementations of I1vSubgraphCorrectionInterface are available IlvSubgraphCorrectionBarycenterFixed corrects the subgraph so that after the layout of its contents the center of the subgraph remains the same Still the size of the bounding box of the subgraph may change due to the layout of the contents IlvSubgraphCorrect ionBoundsFixed corrects the subgraph so that after the layout of its contents the bounding box of the subgraph remains the same However in order to achieve this the zoom level of the subgraph is changed ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL RECURSIVE LAYOUT These implementation of the subgraph correction interface do not correct the top level graph but only subgrap
396. of the topmost graph grapherA IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher fill the graphers with nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create the grapher adapter for the topmost graph IlvGrapherAdapter adapterA new IlvGrapherAdapter grapherA Get a grapher adapter for the subgraph IlvGraphModel adapterB adapterA getGraphModel grapherB create the layout provider IlvDefaultLayoutProvider provider new IlvDefaultLayoutProvider specify the preferred layouts for each grapher this automatically attaches the layouts provider setPreferredLayout adapterA new IlvTreeLayout provider setPreferredLayout adapterB new IlvGridLayout Get the layout instance for grapherB from the provider of course in this example we already have it but we want to illustrate how to get layout instances from the provider IlvGrapherLayout subLayout provider getGraphLayout adapterB Specify nodel contained in grapherB as fixed subLayout setFixed nodel true Ask the sublayout to not move the fixed nodes This settings holds only to this layout The global settings of the topmost layout are not copied to the sublayouts once the sublayouts are instanciated subLayout setPreserveFixedNodes true 314 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL SAVING LAYOUT PARAMETERS AND P
397. ointCheckEnabled boolean enable For Experts Mechanisms for Advanced Users This section explains some mechanisms that are available for advanced users ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 277 RECURSIVE LAYOUT 278 How to correct the subgraphs during layout How to install layout event listeners efficiently Subgraph Correction In ILOG JViews the position of a subgrapher instance of 11vGrapher is always calculated from the positions of the contents of the subgrapher The position of the subgrapher is simply the position of the bounding box around its contents This mechanism has side effects when performing layout a subgraph will never appear fixed if its contents is laid out because by performing a layout on the contents of the subgraph the bounding box hence the position of the subgraph changes Depending on the applications this may be undesired Normally after the subgraph is laid out its parent graph gets laid out which will move the entire subgraph to its final position Therefore in most cases the undesired position of the subgraph is only temporary and you can ignore the entire problem However in a few situations you need to be aware of the effect Ifthe subgraph is specified as fixed for instance by using setFixed and hence should not move Ifthe parent graph is never laid out Ifthe parent graph is laid out in a layout style in an incremental mode that analyzes the positions
398. olyline links with these port sides sometimes have unnecessary bends Furthermore if port sides are specified the connector style CLIPPED should not be used Port Index Parameter Instead of asking the layout algorithm to decide at which point a link connects to the node border you can specify where the links connect to the node You cannot specify the exact location but you can specify the relative location compared to the connection points of the other links This is done by using a port index Figure 4 58 on page 136 shows a sample layout with ports at many nodes Links that have the same port index connect at the same point of the node The ports are evenly distributed at the node sides in a similar way as with the connector style EVENLY SPACED PINS The ports are ordered according to their indices On the north and south side of a node the port indices increase toward the east On the east and west sides of a node the port indices increase toward the south By using port indices in this way it is easier to rotate a graph by simply changing the flow direction without needing to update all the port specifications Figure 4 71 show how the port indices depend on the flow direction Ir fe Flow Direction ES ow E nA i L o gt 3 Figure 4 71 Index Numbering Conventions in Relation to Flow Direction Port numbers are normally used in c
399. omable objects and nonzoomable objects in the same way If the graphic object is zoomable the boundingBox Object nodeOrLink method ofthe IlvGrapherAdapter returns the bounding box in manager coordinates by calling IlvGraphic boundingBox null If the graphic object is nonzoomable the boundingBox Object nodeOrLink method computes the bounding box according to the reference transformer and returns a rectangle obtained by applying the inverse transformation to this rectangle See the IlvTransformer inverse IlvRect rect method The geometry of the 11vGrapher is computed in such a manner that the resulting drawing inside an 11 vManagerView using the reference transformer will look fine Reference Views Optionally an 11vManagerView can be specified as a reference view for the IlvGrapherAdapter If areference view is specified its current transformer at the moment when the layout is started is automatically used as the reference transformer Usually applications use the same manager view that is used for the display of the IlvGrapher as the reference view but this is not mandatory To specify the reference view use the following method void setReferenceView IlvManagerView view To get the current reference view use the method IlvManagerView getReferenceView If no view has been specified as the reference view the method returns nu11 soJnjeoJj e 5 gt 2 lt o 5 o
400. omatic number is 10 8 1 3 The number of neighbors of a node A graph in which every edge is associated with an ordered pair of nodes Also called an oriented graph A graph containing at least two nodes are not linked by a path In the following illustration node 5 is not linked by a path to any other node Nodes 3 and 4 are not linked by a path to any nodes other than nodes 3 and 4 al af A line connecting two vertices in a graph An edge is also called a link or a connection In this documentation the term link is primarily used for the term edge See link crossing If the user specifies a node as fixed layout algorithms are not allowed to move this node ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 413 GLOSSARY fixed links force directed layout graph grapher graph layout graph model grid drawing incremental layout incident layer layout algorithm layout region If the user specifies a link as fixed layout algorithms are not allowed to reshape this link A class of layout algorithms for creating straight line drawings of undirected graphs based on an iterative computation of the position of the nodes according to a set of attractive and repulsive forces These forces are computed in such a way that they tend to produce a layout with only a few link crossings or no link crossings The Spring Embedders are an example of force directed layout algorithms A finite
401. omatic placement 339 label descriptors 359 implementing your own 373 Label Layout advanced features 379 annealing 354 base class 347 basic steps 341 coordinates mode 380 creating a new labeling model 389 defining your own labeling model 384 events and listeners 352 filtering manager layers 379 geometry of labels and obstacles 386 getting started 340 IlvLabelLayout parameters 353 instantiating and attaching a subclass 348 labeling model class 346 loading layout parameters from IVL files 382 nonzoomable graphic objects 380 nonzoomable labels and obstacles 379 notification of changes 387 overlap calculation 386 perfoming a layout 348 performing a recursive layout on nested subgraphs 349 random 376 reference view and reference transformer 381 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 435 INDEX releasing resources 383 report 351 saving layout parameters to IVL files 382 storing and retrieving object properties 387 structure of labels and obstacles 385 using named properties to save layout parameters 382 label layout report 351 label movement policy labels 371 labeling model 346 defining your own 384 subclassing 388 layout algorithm basic procedure for using 38 choosing 44 setting the selection method 49 table of additional information 52 table of applicable graphs 45 table of generic parameters supported 51 layout constraints 169 adding 171 removing 171 layout criteria angle 15 area 14 bends 15 link crossing
402. omatically at the start of layout via the method createLayoutReport and is available as long as the manager is attached to the layout instance To read a layout report all you need to do is store the layout report instance returned by the performLayout method and read the information as shown in the following example IlvLabelLayoutReport layoutReport labelLayout performLayout if layoutReport getCode IlvLabelLayoutReport LAYOUT DONE System out println Label layout done else System out println Label layout not done code layoutReport getCode The class 11vLabelLayoutReport stores the following information The meaning is very similar to the information stored in an IlvGraphLayoutReport see Information Stored in a Layout Report on page 293 for details ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 351 THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT 352 Code This field contains information about special predefined cases that may have occurred during the layout The possible values are the following e IlvLabelLayoutReport LAYOUT DONE e IlvLabelLayoutReport STOPPED AND VALID E e IlvLabelLayoutReport STOPPED AND INVALID E e IlvLabelLayoutReport NOT NEEDED e IlvLabelLayoutReport NO LABELS I e IlvLabelLayoutReport EXCEPTION DURING LAYOUT To read the code use the method int getCode La
403. ombination with port sides Therefore you must specify how many ports are available on each side of a node To specify the number of ports use the following method void setNumberOfPorts Object node int side int numberOfPorts ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 155 HIERARCHICAL LAYOUT For example to use 4 ports on each side of a specific node use the following calls layout setNumberOfPorts node IlvHierarchicalLayout EAST 4 layout setNumberOfPorts node IlvHierarchicalLayout WEST 4 layout setNumberOfPorts node IlvHierarchicalLayout NORTH 4 layout setNumberOfPorts node IlvHierarchicalLayout SOUTH 4 The node side is specified again by EAST WEST NORTH and SOUTH To retrieve the retrieve the number of ports available at the node use the following method int getNumberOfPorts Object node int side After the number of ports per side is specified you can choose which port each link connects to You choose the port side and the port index for a link as follows To specify the connection at the source node use the following methods void setFromPortSide Object link int portSide void setFromPortIndex Object link int portIndex To specify the connection at the destination node use the following methods void setToPortSide Object link int portSide void setToPortIndex Object link int portIndex To obtain the current port index of a link use the following method
404. opertyName This method removes only the named layout properties that match the input property name void removeParametersFromNamedProperties Class layoutClass This method removes all named layout properties that fit the input layout class The named layout properties are subclasses of LlvGraphLayoutGrapherProperty IlvGraphLayoutNodeProperty and IlvGraphLayoutLinkProperty See the Reference Manual for details of these classes 316 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL SAVING LAYOUT PARAMETERS AND PREFERRED LAYOUTS Saving Preferred Layouts to ivl Files The class 11vDefaultLayoutProvider allows you to specify the layout instances to be used for each graph The layout provider can then be used for the recursive layout of a nested graph For details see Laying Out Nested Graphs on page 306 The settings of the preferred layouts done using the method set PreferredLayout of the class I1vDefaultLayoutProvider can be saved to iv1 files using the method boolean savePreferredLayoutsToNamedProperties IlvDefaultLayoutProvider provider boolean withParameters boolean withDefaults boolean traverse The method takes the Layout Provider as an argument and several flags e withParameters if the flag is true the parameters of the preferred layout instances are saved In this case it is not necessary to use the method saveParametersToNamedProperties Otherwise only the name of the class of the preferred la
405. or in the same order as in the previous layout whenever it is possible To enable the incremental mode call layout setIncrementalMode true Note To preserve the stability the incremental mode can keep some regions free Therefore the total area of the layout can be larger than in nonincremental mode and in general the layout may not look as nice as in nonincremental mode Dimensional Parameters Figure 4 113 illustrates the dimensional parameters used in the Bus Layout algorithm These parameters are explained in the sections that follow margin 6 10 15 vertipalOffsetToLewvel 2 7 4 5 14 layout marginOnBus 12 E 1 fence vertical Offs etT oPrevi ousLevel t FARIAM horizontalOffset margin Figure 4 113 Dimensional Parameters for the Bus Layout Algorithm Horizontal Offset This parameter represents the horizontal distance between two nodes To specify the horizontal offset use the method 234 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT void setHorizontalOffset float offset To obtain the current value use the method float getHorizontalOffset Vertical Offset to Level This parameter represents the vertical distance between a row of nodes and the next horizontal segment of the bus node To specify this parameter use the method void setVerticalOffsetToLevel float offset To obtain the current value use the method float getVe
406. ore the algorithm cannot find a route for the long red links without overlapping some nodes or without overlapping the green link The long link mode works on a grid It is specialized for long links and avoids overlapping any nodes or link segments It can connect to the green nodes by choosing connection points on different sides of the end nodes This advantage however is paid for by a less regular structure that does not bundle the links and a larger number of link crossings 192 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT Short Link Layout Mode Long Link Layout Mode Figure 4 89 Short and Long Link Modes with Orthogonal Links Choosing the Appropriate Layout Mode The short link mode should be used if any of the following conditions apply The majority of links is short and it is not fatal if long links overlap obstacles The link routes must be placed freely and cannot be restricted to a grid Itis important to limit the number of bends The long link mode should be used if any of the following conditions apply Many links are long and it is important that long links do not overlap obstacles There is a preferred routing because the nodes are already placed on the grid 1 15 important to have a guaranteed a minimal distance between link segments Anincreasing number of bends is acceptable if it avoids any overlappings Figure 4 90 shows how the long link mode can be used to find an orthogonal route wi
407. orm the layout layout performLayout true true catch IlvGraphLayoutException e handle the excepction finally we are not busy anymore busy false The Stop button operates outside the layout thread and simply calls the method stopImmediately of the running layout instance Button stopButton new Button Stop Layout stopButton addActionListener new ActionListener public void actionPerformed ActionEvent e if busy layout stopImmediately n ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 35 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT 36 Note A detail has been omitted from the previous code fragment A multitasking operation requires that the layout thread calls the yield or sleep t methods from time to time good place to do this is by using a graph layout event listener Event listeners are explained in Using Event Listeners on page 294 The consequences of stopping a layout process depends on the specific layout algorithm Some layout algorithms have an iterative nature Stopping the iteration process results in a slight loss of quality in the drawing but the layout can still be considered valid Other layout algorithms have a sequential nature Interrupting the sequence of the layout steps may not result in a valid layout Usually these algorithms return to the situation before the start of the layout process To indicate whether a subclass of 11vGraphLayout supports t
408. ossing reduction to all nodes within each level In this case the incremental layout determines from the node coordinates which nodes belong to the same level but it may reorder the nodes within the levels completely to avoid link crossings It ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 165 HIERARCHICAL LAYOUT 166 also reorders the long links in this case Figure 4 79 on page 166 bottom left shows the result Notice that the order of the nodes F and have changed to resolve the link crossings To enable the crossing reduction for all nodes call layout setCrossingReductionDuringIncremental true Setting Absolute Level Positioning As discussed in Phases of the Incremental Mode on page 163 the incremental layout tries to place the nodes in absolute positions that are close to the previous positions It tries to avoid nodes moving a large distance because even if the relative order of the nodes within the levels does not change large movement distances can be confusing for users It is much easier to keep a mental map of the diagram if the nodes remain close to the previous positions Figure 4 80 on page 168 illustrates node repositioning with and without taking the previous positions into account The incremental layout of the original graph at the top left results in the graph at the top right which is easier to recognize as the same graph than the graph at the bottom The absolute level posit
409. ou get automatically when you enable the layout of connected components parameter See Layout of Connected Components on page 25 IlvCircularLayout IlvHierarchicalLayout IlvTreeLayout They have built in support for disconnected graphs Alternatively you can use the automatic support from the base class See Layout of Connected Components on page 25 IlvLinkLayout IlvGridLayout IlvRandomLayout These algorithms support both connected and disconnected graphs Their behavior is the same for both categories of graphs ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL 335 so1njeoaJj e o 5 gt 2 lt E 5 o QUESTIONS AND ANSWERS ABOUT USING THE LAYOUT ALGORITHMS 336 Table 5 2 Questions and Answers about the Layout Algorithms Continued Question Answer There are some attributes of the network that we know about for instance we know what the core switch is and what the center should be Are such attributes taken into account by the layout algorithm It depends on the layout algorithm The Circular Layout is designed to allow you to specify information about the physical topology of the network You can specify which nodes belong to the same cluster ring or star the order of the nodes on the cluster and which node is the center of a star cluster In the Tree Layout you can specify the root node In the Bus Layout algorithm you can specify th
410. out The following shows the skeleton of the class public class MyRandomLayout extends IlvGraphLayout public MyRandomLayout public MyRandomLayout MyRandomLayout source super source source public IlvGraphLayout return new MyRandomLayout this protected void layout boolean redraw The constructor with no arguments is empty The copy constructor and the copy method are implemented they are used when laying out a nested graph see Laying Out Nested Graphs on page 306 Then the abstract method layout boolean of the base class is implemented as follows so1njeaJj e o 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 329 DEFINING A NEW OF LAYOUT protected void layout boolean redraw obtain the graph model IlvGraphModel graphModel getGraphModel x obtain the layout report H obtain the layout region lvRect rect getCalcLayoutRegion loat xMin rect x loat yMin rect y loat xMax rect x rect width Hh kh Fh Eh HON loat yMax rect y rect height initialize the random generator lvGraphLayoutReport layoutReport getLayoutReport Random random isUseSeedValueForRandomGenerator new Random getSeedValueForRandomGenerator new Random browse the objects in the grapher Enumeration nodes graphModel getNodes while nodes hasMoreElements Object n
411. out 77 USER S MANUAL 437 INDEX Topological Mesh Layout 61 Tree Layout free mode 109 Uniform Length Edges Layout 86 link width parameter Hierarchical Layout 152 listener layout event code example 295 description 294 GraphLayoutEventListener interface 294 listeners label layout 352 loading label layout parameters from IVL file 382 loadParametersFromNamedProperties method IlvGrapherAdapter class 318 319 loadPreferredLayoutsToNamedProperties method IlvGrapherAdapter class 319 local side association 366 long link mode Link Layout algorithm description 189 fallback mechanism 215 features 188 grid base parameter 205 grid offset parameter 204 link routing parameters 214 minimal distance parameter 205 minimal node corner offset parameter 205 minimum final segment length parameter 206 obstacle parameters 213 spacing parameters 203 variable end point parameters 214 margin on bus parameter Bus Layout 235 margin parameter Bus Layout 235 Grid Layout 263 markForIncremental method IlvLinkLayout class 199 maximum nodes per level parameter Bus Layout 230 Grid Layout 260 memory savings parameter Spring Embedder Layout 76 Topological Mesh Layout 60 minimal distance parameter Link Layout long link mode 205 minimal node corner offset parameter Link Layout long link mode 205 minimum final segment length parameter Link Layout long link mode 206 minimum final segment parameter Link Layo
412. out algorithm utilizes two sublayout classes IlvShortLinkLayout in short link mode IlvLongLinkLayout in long link mode Both implement different strategies to find the link shapes Short Link Layout Algorithm The Short Link Layout algorithm is based on a combinatorial optimization that chooses the optimal shape of the links in order to minimize a cost function This cost function is proportional to the number of link to link and link to node crossings For efficiency reasons the basic shape of each link is chosen from a set of predefined shapes These shapes are different for each link style option For the orthogonal link style the links are reshaped to a polygonal line of up to five alternating horizontal and vertical segments see Figure 4 86 on page 186 For the direct link style the links are reshaped to a polygonal line composed of three segments a straight line segment that starts and ends with small horizontal or vertical segments see Figure 4 87 on page 187 The shape of a link also depends on the relative position of the origin and destination nodes For instance when two nodes are very close or they overlap the shape of the link is chosen to provide the best visibility of the link The exact shape of a link is computed taking into account additional constraints The layout algorithm tries to do the following Minimize the number of crossings between the links incident to a given side of a node Space the
413. out class 148 IlvLinkLayout class 197 IlvGridLayout class 259 tGlobalLinkStyle method lvHierarchicalLayout class 145 lvLinkLayout class 194 H H IlvLayoutGraphicFilter class 922 IlvUniformLengthEdgesLayout class 88 IlvHierarchicalLayout class 154 156 tGlobalDestinationPointMode method tGlobalHorizontalAlignment method Il INDEX vTreeLayout class 110 setGlobalOriginPointMode method LI Il vHierarchicalLayout class 148 vLinkLayout class 197 setGlobalSelfLinkStyle method Il vShortLinkLayout class 209 211 setGlobalVerticalAlignment method Il Li vBusLayout class 232 vGridLayout class 259 SetH setH H se Cf 1 se se H ct rct se H ct o v v o lvHierarchicalLayout class 160 o v o v o v H ct ct setl orizontalAlignment method lvGridLayout class 260 orizontalGridBase method ongLinkLayout class 205 rizontalGridOffset method vGridLayout class 262 jongLinkLayout class 204 rizontalLinkOffset method rizontalMinOffset method jongLinkLayout class 205 rizontalNodeLinkOffset method HierarchicalLayout class 160 rizontalNodeOffset method HierarchicalLayout class 160 orizontalOffset method lvBusLayout class 234 setIncrementalMode method Il Td LI Ll Il vBusLayout class 234 vGridLayout class 261 vHierarchicalLayout
414. out mode call int getLayoutMode The available layout modes are the following E the default I IlvTreeLayout FR ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 103 TREE LAYOUT 104 IlvTreeLayout LEVEL IlvTreeLayout RADIAL IlvIreeLayout ALTERNATING RADIAL IlvTIreeLayout TIP OVER IlvTreeLayout TIP ROOTS OVER IlvTreeLayout TIP LEAVES OVER 9 9 9 IlvIreeLayout TIP ROOTS AND LEAVES OVER The following sections describe the characteristics and the layout parameters of each layout mode Free Layout Mode The free layout mode arranges the children of each node starting recursively from the root so that the links flow roughly in the same direction For instance if the link flow direction is top down the root node is placed at the top of the drawing Siblings nodes that have the same parent are justified at their top borders but nodes of different tree branches nodes with different parents are not justified The following statement sets the free layout mode layout setLayoutMode IlvTreeLayout FREE Flow Direction The flow direction parameter specifies the direction of the tree links The compass icons show the compass directions in these layouts ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Bottom Top Left Right Figure 4 31 Flow Directions If the
415. out option continue working for instance in order to declutter a Why particular part of the graph you may need to move one or several nodes in order to change the initial configuration The algorithm is dependent on the initial configuration soJnjeoJj e 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 333 QUESTIONS AND ANSWERS ABOUT USING THE LAYOUT ALGORITHMS Table 5 2 Questions and Answers about the Layout Algorithms Continued Question Answer After performing the layout the graph is laid out far from its initial position Why Most of the layout algorithms use a layout region parameter to control the size and position of the layout For details see Layout Region on page 25 Depending on the value of this parameter the nodes may be moved far from their initial positions To know whether a layout algorithm is designed to use a layout region parameter check the documentation to see if the layout class overrides the supportsLayoutRegion method of the base class order to return true Other algorithms have a different mechanism that allows you to specify the desired location of the layout It may happen that the default value of the location parameter is such that the graph is laid out far from its initial position When I use certain layout algorithms on certain graphs there are overlapping nodes Why and what can do
416. outMode The valid values for mode are 1IlvGridLayout TILE TO GRID FIXED WIDTH the default The nodes are placed in the cells of a grid matrix that has a fixed maximum number of columns This number is equal to the width of the layout region parameter divided by the horizontal grid offset IlvGridLayout TILE TO GRID FIXED HEIGHT The nodes are placed in the cells of a grid matrix that has a fixed maximum number of rows This number is equal to the height of the layout region parameter divided by the vertical grid offset IlvGridLayout TILE_TO_ROWS The nodes are placed in rows The maximum width of the rows is equal to the width of the layout region parameter The height of the row is the maximum height of the nodes contained in the row plus margins 258 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL GRID LAYOUT IlvGridLayout TILE TO COLUMNS The nodes are placed in columns The maximum height of the columns is equal to the height of the layout region parameter The width of the column is the maximum width of the nodes contained in the column plus margins Alignment The alignment options control how a node is placed over its grid cell or over its row or column depending on the layout mode The alignment can be set globally in which case all nodes are aligned in the same way or locally on each node with the result that different alignments occur in the same drawing
417. ovider setPreferredLayout adapterB new IlvGridLayout Perform the recursive layout try int code IlvGraphLayout PerformLayout adapterA provider true true true or equivalently int code adapterA performLayout provider true true true System out println Layout completed code code catch IlvGraphLayoutException e System err println e getMessage detach the layouts when the provider is no longer needed provider detachLayouts adapterA true dispose the topmost adapter when no longer needed adapterA dispose soJnjeoJj em 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 313 LAYING OUT NESTED GRAPHS Layout Parameters in Recursive Layouts Using the Layout Provider In the same way as for the simple recursive layouts see Layout Parameters in Simple Recursive Layouts on page 309 you must specify parameters that are specific to nodes or links directly on the layout instance that lays out the subgraph containing the nodes or the links The only thing slightly different is getting the layout instances for the subgraphs However a significant difference exists when using a Layout Provider you can specify different global settings that is settings that are not specific to a node or a link for each layout instance The following code shows how to specify as fixed a node node1 contained in the subgraph grapherB
418. owing methods void setRespectNodeSizes boolean respect boolean isRespectNodeSizes Force Fit to Layout Region For this layout algorithm it is more difficult than for others to choose an appropriate size for the layout region If the specified layout region is too small for a given graph the resulting layout will not be the best For this reason by default the Uniform Length Edges Layout algorithm does not use the layout region parameter It can use as much space as it needs to lay out the grapher To specify whether the layout algorithm must use the layout region use the following method void setForceFitToLayoutRegion boolean option To obtain the current value use the following method boolean isForceFitToLayoutRegion The default value of the parameter is alse For Experts Additional Features The following expert features are available Maximum Allowed Move Per Iteration At each iteration the layout algorithm moves the nodes a relatively small amount This amount should not be too large otherwise the algorithm may not converge But it should not 88 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL UNIFORM LENGTH EDGES LAYOUT be too small either otherwise the number of necessary iterations increases and the running time does also The maximum amount of movement at each iteration is controlled by a parameter that can be set and retrieved with the following methods void setMaxAllowedMo
419. pes There are two spacing parameters for the fork shape void setMinForkSegmentLength float length It sets the minimal length of the segment that is directly adjacent to the node void setPreferredForkAxisLength float length This method sets the preferred length of the fork axis per branch the second segment adjacent to the node If the fork has five branches the entire axis has the preferred length five times the specified parameter The preferred fork axis length is only a hint for the layout algorithm If enough space is available the algorithm will enlarge the fork axis to avoid unnecessary link bends If there is not enough space the algorithm may as well calculate a fork axis that is smaller than the preferred one r lt Lad gt e gt 3 Fork link shapes may sometimes look ambiguous in particular when a link starts at the same point where another link ends because in this case it is impossible to recognize whether the arrowhead belongs to one or the other link Link Priority Parameter The layout algorithm tries to place the nodes such that all links are short point in the flow direction and do not cross each other However this is not always possible Often links ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 157 HIERARCHICAL LAYOUT cannot have the same length If the graph has cycles some links must be reversed against the flow direction If the graph is nonplanar some l
420. placed at a specific point the IlvAnnealingPointLabelDescriptor can be used and describes an approximately elliptical path around the point If a label must be placed at a polyline the IlvAnnealingPolylineLabelDescriptor can be used and describes a boundary path at both sides of the polyline 2 gt S 3 Code Sample Here is a code sample using the 11vAnnealingLabelLayout class import ilog views import ilog views graphlayout labellayout import ilog views graphlayout labellayout annealing IlvManager manager new IlvManager IlvManagerView view new IlvManagerView manager Fill in here code that fills the manager with labels and obstacles IlvAnnealingLabelLayout layout new IlvAnnealingLabelLayout layout attach manager Assume labell should be placed at the right side of rectangular nodel layout setLabelDescriptor labell new IlvAnnealingPointLabelDescriptor labell nodel IlvAnnealingPointLabelDescriptor RECTANGULAR IlvDirection Right Fill in here code that sets descriptors for all other labels IlvLabelLayoutReport layoutReport layout performLayout if layoutReport getCode IlvLabelLayoutReport LAYOUT DONE System out println Layout done else System out println Layout not done code layoutReport getCode ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 357 THE ANNEALING LABEL LAYOUT
421. pplied If a grapher containing nonzoomable objects is displayed simultaneously in several views you can use the setRe erenceView method to indicate the view for which you want the drawing of the graph to be optimal If you specified a reference transformer but want to reset this setting and go back to the default behavior call the method setReferenceTransformer with a null argument Note that if you override the setReferenceTransformer method you must call super setReferenceTransformer to notify the IlvGrapherAdapter that the reference transformer has changed Note also that a call to the setReferenceView method overrides the effect of a call to the setReferenceTransformer method In the same way a call to the setReferenceTransformer method overrides the effect of a call to the setReferenceView method 326 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CHOOSING THE LAYOUT COORDINATE SPACE Specifying the Coordinates Mode By default IlvGrapherAdapter considers the geometry of the nodes and links of an IlvGrapher in a special coordinate space which is appropriate for most of the cases In some situations it can be useful to specify a different coordinate space To specify the coordinate space the class IlvGrapherAdapter provides the following method void setCoordinatesMode int mode The valid values for mode are Il1vGraphLayout MANAGER COORDINATES The geometry of the graph is compute
422. preserve the relative order of the children in subsequent layouts The incremental mode is enabled by default To disable the incremental mode call layout setIncrementalMode false Interactive Editing The fact that the relative order of the layout is preserved is particularly useful during interactive editing It allows you to correct the layout easily For instance if the first layout places a node A left to its sibling node B but you need to reverse the order you can simply move node A to the right of node B and start a new layout to clean up the drawing In the second layout A remains to the right of B and the subtree of A will follow node A oe After First Layout Move A to the Right of B After Second Layout Figure 4 55 Interactive Editing to Achieve a Specific Order of Children Specifying the Order of Children Some applications require a specific relative order of the children in the tree This means that for instance when the flow direction is to the bottom which child must be placed to the left of another child Even if the graph has never been laid out you can use the coordinates to specify a certain order of the children at a node You can use the following First make sure that the incremental mode is enabled 132 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT In free and level layout modes with flow direction to the bottom or top determine the maximal width w of all nodes Simply move
423. py of the rectangle that defines the specified layout region The dimensions of the rectangle are in the manager grapher coordinates Depending on the last method you called one of the following cases can occur IfsetLayoutRegion IlvRect was the last method called it returns a copy of the rectangle with no transformations IfsetLayoutRegion IlvManagerView IlvRect was the last method called it returns a copy of the rectangle transformed to the manager coordinates using the transformer of the view The transformation to manager coordinates is not done if the coordinates mode is specified as view coordinates For details see Coordinates Mode on page 24 IfsetLayoutRegion IlvManagerView was the last method called it returns a rectangle with the attributes x 0 y 0 and with the attributes width and height equal to the current width and height of the view transformed to manager coordinates using the current transformer of the view The transformation to manager coordinates is not done if the coordinates mode is specified as view coordinates None of the methods was called This is the default behavior If at least one manager view is attached to the grapher it returns a rectangle with the attributes x 0 y 0 and with the attributes width and height equal to the current width and height of the first attached view transformed to manager coordinates using the transformer of the view The transformation to manager coordinates
424. quadtree data structure The quadtree allows a check for overlaps to be done very efficiently The layout algorithm automatically detects from the graph model when the quadtree can be used You can switch it off explicitly by calling layout setUseQuadtree false Normally it is not useful to switch the quadtree off because it slows down the positioning of the labels However if you implement your own labeling model you may want to use this flag to verify that the labeling model is correct Simulated Annealing is an iterative mechanism In each iteration step all labels are tested for better positions Usually the algorithm is able to automatically detect when to stop The algorithm stops if The maximal number of iterations is reached After several iterations no better position was found for any label After several iterations the quality did not improve by a given percentage 372 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL THE ANNEALING LABEL LAYOUT In a few cases it may be necessary to limit the number of iterations which can be done by the statement layout setAllowedNumberOfIterations 100 As a general hint to obtain a reasonable layout the allowed number of iterations should not be considerably lower than the number of labels Simulated Annealing stops if after several iterations no better position was found for any label Because the search is randomized this does not necessarily mean that the best po
425. r Depending on the parameters passed during the construction these subclasses allow you to place a label e Close to a given point e Close to a specific rectangular or elliptic obstacle such as a node e Along an imaginary polyline e Close to a polyline obstacle for example 11vLine IlvPolyline e Close to a link You can also implement your own label descriptors by subclassing IlvAnnealingLabelDescriptor This is explained in the section For Experts Implementing Your Own Label Descriptors on page 373 Point Label Descriptor The 11vAnnealingPointLabelDescriptor can be used to place a label at a specific obstacle or point This is known as the point labeling problem Positioning at an Obstacle Here is an example of positioning a label at a specific obstacle layout setLabelDescriptor label new IlvAnnealingPointLabelDescriptor label node IlvAnnealingPointLabelDescriptor ELLIPTIC IlvDirection Right This specification can be used if the label must be placed at a node that has an elliptical or circular shape The label is placed in the free area around the node such that the border of the label just touches the border of the node shown in Figure 6 6 The preferred position is the right side of the node but this preferred position is used only if it does not create overlaps If the node is moved or reshaped the next call of label layout will update the position of the label automatically such that it follows the n
426. r halfWidth 18 the minimal distance of the label to the reference point in the horizontal direction The parameter halfHeight is the minimal distance of the label to the reference point in the vertical direction If the reference point is nu11 the parameters halfWidth and halfHeight are calculated from the bounding box of the related obstacle The parameter maxDelta specifies the maximal additional distance allowed for the label shown in Figure 6 8 The parameter preferredDelta specifies the preferred additional distance for the label It should be between 0 and maxDelta The preferred position indicates whether the label should be placed to the left right top or bottom of the reference point or related obstacle This is a suggestion for the labeling algorithm as described for Positioning at an Obstacle on page 360 An alternative way to create a point label descriptor is to start with the empty descriptor descriptor new IlvAnnealingPointLabelDescriptor Before the empty descriptor can be used it must be filled with information on how the label should be placed As a minimum you need to specify a related obstacle or a reference point For example descriptor setRelatedObstacle obstacle descriptor setShape IlvAnnealingPointLabelDescriptor ELLIPTIC descriptor setPreferredDirection IlvDirection Left At the end of all changes the descriptor must be passed to the layout instance layout setLabelDescriptor label descriptor
427. r MAX VALUE in order to reject the grid point If the grid point is rejected it is not chosen as termination point of the link The termination point filter can be set by the following layout getLongLinkLayout setTerminationPointFilter MyFilter Manipulating the Routing Phases As mentioned in Long Link Layout Algorithm on page 190 the algorithm first treats each link individually and the applies a crossing reduction phase to all links To find a route for an individual link the algorithm first checks whether a routing such as a straight line or with only one bend is possible If this kind of routing is not possible it uses a sophisticated but more time consuming grid search algorithm with backtracking to find a route with many bends To switch off the phase that finds a straight line or one bend routing use the following layout getLongLinkLayout setStraightRouteEnabled false The backtrack search for a route with many bends can be affected in the several ways You can specify the maximal number of backtrack steps by using the following 214 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL LINK LAYOUT layout getLongLinkLayout setMaxBacktrack 1000 The default maximal backtrack number is 30000 more convenient way is to specify the maximal time available to search for the route for each link layout getLongLinkLayout setAllowedTimePerLink 4000 The default allowed time per link is 2000 milliseconds 2
428. r attached to the nodes while other layout algorithms do not calculate any connection points but simply let the link connectors any subclass of 11vLinkConnector determine how the links connect to the nodes If a layout algorithm calculates specific connection points then it places the connection points of links by default at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want to place the connection points exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correct the calculated connection point so that it lies on the border of the shape Some examples are shown in Figure 2 1 UJ E e 5 2 Lad without clipping with clipping Figure 2 1 Effect of Link Clipping Interface To indicate whether a subclass of IlvGraphLayout supports the link clip interface the following method is provided boolean supportsLinkClipping To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 27 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT You modify the position of the connection points of the links by implementing a class that implements the 11vLinkClipInterface This interface defines the following method public IlvPoint getConnectionPoint IlvGraphMo
429. r removed and no parameters that affect Step 1 have been changed The following drawings show various layouts produced for the same graph when the cycleId parameter is changed 64 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL TOPOLOGICAL MESH LAYOUT TML r lt Lad gt gt 3 Figure 4 7 Layout Using 3rd Outer Cycle ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 65 TOPOLOGICAL MESH LAYOUT TML ig JIN A F Nae Figure 4 8 Layout Using 4th Outer Cycle Refining a Graph Layout After performing the layout on a graph you may want to improve the quality of the layout by making some manual refinements The following sections describe several ways to refine your layouts When the layout is performed again after the refinements have been applied only Step 2 of TML is redone The results of Step 1 are reused This is an important benefit of TML because the algorithm can recompute a layout using new parameters very quickly without performing the time consuming Step 1 again Using Fixed Nodes One reason for applying manual refinements is to avoid overlapping nodes To do this you can use the fixed nodes mechanism See Preserve Fixed Nodes on page 32 Take a look at the original layout shown in Figure 4 9 Several overlapping nodes exist in the original layout because the nodes are concentrated in a small region and do not use the available space inside the outer cycle 6
430. rameters supported by each layout algorithm If you are using one of the subclasses provided with ILOG JViews check the documentation for that subclass to know whether it supports a given parameter and whether it interprets the parameter in a particular way Allowed Time Several layout algorithms can be designed to stop computation when a user defined time specification is exceeded This may be done for different reasons as a security measure to avoid a long computation time on very large graphs or as an upper limit for algorithms that iteratively improve a current solution and have no other criteria to stop the computation ILOG JViews allows you to specify the allowed time void setAllowedTime long time To obtain the current value use the method long getAllowedTime If you subclass 11vGraphLayout use the following method to know whether the specified time was exceeded boolean isLayoutTimeElapsed The time is in milliseconds The default value is 32000 32 seconds To indicate whether a subclass of 11vGraphLayout supports this mechanism the following method is provided boolean supportsAllowedTime The default implementation returns false A subclass can override this method to return true to indicate that this mechanism is supported Animation Some iterative layout algorithms can optionally redraw the graph after each iteration or step This may create a pleasant animation effect and may be used to
431. raph Layout Beans sue g noke c 2 2 Q 10 gt The graph layout algorithm classes provided by ILOG JViews Graph Layout module are fully compliant with the JavaBeans standard This allows you to create an ILOG JViews application or applet from the visual programming environment of your favorite Integrated Development Environment IDE This chapter shows you how to use ILOG JViews Beans and the Graph Layout Beans when creating an applet within an IDE The following topics are covered Graph Layout Classes Available as Beans Creating a Simple Applet Using ILOG JViews Graph Layout Beans Before you can create an ILOG JViews application or applet within an Integrated Development Environment IDE you must install the ILOG JViews Beans into your IDE Complete installation instructions are given in the ILOG JViews Graphics Framework User s Manual ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 391 GRAPH LAYOUT CLASSES AVAILABLE AS BEANS Graph Layout Classes Available as Beans pun ds lo g NOR B gt 392 UE d SD A qs The following classes are provided as ILOG JViews Graph Layout Beans IlvBusLayout displays bus network topologies that is a set of nodes connected to a bus node IlvCircularLayout displays graphs representing interconnected ring and or star network topologies IlvGridLayout arranges disconnected nodes in rows or in columns or on a grid IlvHierarchicalL
432. raph Layout module class IlvHierarchicalLayout from the package ilog views graphlayout hierarchical Samples Here are some sample drawings produced with the Hierarchical Layout Figure 4 56 Sample Layout with Self Loops Multiple Links and Cycles 134 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT I Lg en Figure 4 57 Flowchart with Orthogonal Link Style r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 135 HIERARCHICAL LAYOUT Figure 4 58 Sample Layout with Ports and Orthogonal Link Style What Types of Graphs Any type of graph Preferably graphs with directed links The algorithm takes the link direction into account Connected and disconnected graphs Planar and nonplanar graphs Application Domains Application domains of the Hierarchical Layout include Electrical engineering logic diagrams circuit block diagrams 136 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Industrial engineering industrial process diagrams schematic design diagrams Business processing workflow diagrams process flow diagrams PERT charts Software management software re engineering UML diagrams flowcharts data inspector diagrams call graphs Database and knowledge engineering database query graphs CASE tools designs diagrams Features Organizes nodes withou
433. rarchical Layout 142 IlvGraphLayout 34 Link Layout 191 Multiple Layout 286 Random Layout 220 Recursive Layout 272 Spring Embedder Layout 77 Topological Mesh Layout 60 Tree Layout 101 Uniform Length Edges Layout 86 saveParametersToNamedProperties method IlvGrapherAdapter class 316 savePreferredLayoutsToNamedProperties method IlvGrapherAdapter class 317 saving label layout parameters to IVL file 382 layout parameters 315 preferred layout 315 self link style parameter Link Layout short link mode 208 semi automatic layout 49 semiautomatic layout 15 SetA setAlignment method IlvTreeLayout class 108 109 setAllowedNodesPlacementTime method IlvTopologicalMeshLayout class 62 setAllowedNuamberOfIterations method IlvShortLinkLayout class 209 setAllowedNumberOfIterations method IlvUniformLengthEdgesLayout class 87 setAllowedNumberOfNodesPlacementIteratio ns method IlvTopologicalMeshLayout class 62 setAllowedNumberOfOptimizationIterations 442 ILOG JViEWS GRAPH LAYOUT 5 5 method IlvTopologicalMeshLayout class 62 setAllowedOptimizationTime method IlvTopologicalMeshLayout class 62 setAllowedTime method IlvGraphLayout class 22 IlvTreeLayout class 127 setAllowedTimePerLink method IlvLongLinkLayout class 215 setAnimate method IlvGraphLayout class 22 setAreaMinimizationEnabled method IlvCircularLayout class 248 setAspectRatio method IlvTreeLayout class 123 126 setAutoLayo
434. rator is initialized using the current system clock Therefore different layouts are obtained if you perform the layout repeatedly on the same graph You can specify a particular value to be used as a seed value For example to specify the seed value 10 call layout setUseSeedValueForRandomGenerator true layout setSeedValueForRandomGenerator 10 Save Parameters to Named Properties The label layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to iv1 files For a detailed description of this feature see Using Named Properties to Save Layout Parameters on page 382 Stop Immediately The label layout algorithm stops after cleanup if the method stopImmediately is called This method works for the 11vLabelLayout class similarly to the corresponding method in the I1vGraphLayout class For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early in this way the result code in the layout report is I1vLabelLayoutReport STOPPED AND INVALID Use Default Parameters After modifying any label layout parameter you may want the layout algorithm to use the default values You select the default values for all parameters by layout setUseDefaultParameters true ILOG JViews keeps the previous settings when selecting the default values mode You can switch between back to your own settings by layout setUseDefau
435. raverse the nested graph recursively and set the corresponding parameter at each sublayout of a subgraph that supports this parameter This works in particular well in reference layout mode In internal or specified provider mode it takes only the current nesting structure into account If you change the specific layout of a subgraph or the nesting structure e g by adding a new subgraph after using such a convenience method the new layout of the new subgraph usually has a different setting so you may need to apply the conveniance method again The following methods traverse the nested graph recursively and set the corresponding parameter at all sublayouts see Layout Parameters and Features in IlvGraphLayout on page 20 and Chapter 5 Using Advanced Features for details setCoordinatesMode int mode void setUseDefaultParameters boolean option void setMinBusyTime long time void setInputCheckEnabled boolean enable void propagateLayoutOfConnectedComponentsEnabled boolean enable void propagateLayoutOfConnectedComponents IlvGraphLayout layout void propagateLinkConnectionBoxInterface IlvLinkConnectionBoxInterface linkConnectionBoxInterface propagateLinkClipInterface IlvLinkClipInterface linkClipInterface r lt gt gt 3 void checkAppropriateLinks void setLinkCheckEnabled boolean enable void setConnectionP
436. removeParametersFromNamedProperties The mechanism is the same as in the Graph Layout module See Saving Layout Parameters to ivl Files on page 315 Loading Layout Parameters from ivl Files The following example shows how to load and recover the parameters of the label layout when the layout settings are stored in an ivl file Read the IVL file This reads all named properties as well manager read abcd ivl IlvDefaultLabelingModel labelingModel IlvDefaultLabelingModel labelLayout getLabelingModel Transfer the parameter settings from the named properties to the layout At this time point the manager must be attached to the label layout labelingModel loadParametersFromNamedProperties labelLayout just to be sure that no named layout properties remain in the memory labelingModel removeParametersFromNamedProperties The mechanism is the same as in the Graph Layout Module See Loading Layout Parameters from ivl Files on page 318 382 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL USING ADVANCED FEATURES Releasing Resources Used During the Layout Various objects need to be created during the layout process Most commonly these are layout instances subclasses of I1vLabelLayout and labeling models subclasses of IlvLabelingModel Some of the layout parameters are internally stored as property objects attached to the labeling model to the manager or to its labels and obstacles Methods t
437. reshaped to orthogonal The links appear as alternating horizontal and vertical segments Adding a Progress Bar to the Applet In some cases a layout algorithm may take a long time to perform a layout and it may be useful to keep the user informed of the activity of the layout You are now going to add a progress bar to your applet Of course this step is not mandatory 1 On the Beans toolbar click the JViews Graph Layout tab to display the JViews Graph Layout Beans 2 the JViews Graph Layout Beans toolbar click the 11v3GraphLayoutProgressBar Bean Z icon and drag it to the Form Designer Place in under the IlvJScrollManagerView Bean next to the Perform Layout button ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 405 CREATING A SIMPLE APPLET USING ILOG JVIEWS GRAPH LAYOUT BEANS Form Designer JApplet1 You are now going to associate the I1vLinkLayout Bean with the IlvJGraphLayoutProgressBar object 3 Make sure that I1vJGraphLayoutProgressBar Bean is selected in the Form Designer Its properties should be displayed in the Property List 4 In the Property List window click the value field of the GraphLayout property Change Default to ilvLinkLayoutl 406 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Property List JAppletl p di ilvJGraphLayoutProgressB arl Border Default BorderPainted true Bounds 108 228 63 23 Cu
438. ric mechanism to layout connected components For more information about this mechanism see Layout of Connected Components on page 25 When using this mechanism each component is laid out in its own individual level structure Nodes of the first level of one component may be placed at a different position than nodes of the first level of another component The generic mechanism to layout connected components is however switched off by default In this case the layout algorithm can still handle disconnected graphs It merges all components into a global level structure Link Clipping The layout algorithm can use a link clip interface to clip the end points of a link See Link Clipping on page 27 This is useful if the nodes have a nonrectangular shape such as a triangle rhombus or circle If no link clip interface is used the links are normally connected to the bounding boxes of the nodes not to the border of the node shapes See Using a Link Clipping Interface on page 151 for details of the link clipping mechanism Link Connection Box The layout algorithm can use a link connection box interface see Link Connection Box on page 29 in combination with the link clip interface If no link clip interface is used the link connection box interface has no effect For details see Using a Link Connection Box Interface on page 150 Percentage Completion Calculation The layout algorithm calculates the estimated percentage of completion T
439. rid IlvGrapher grapher new IlvGrapher 256 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL GRID LAYOUT IlvManagerView view new IlvManagerView grapher Fill in the grapher with nodes and links here IlvGridLayout layout new IlvGridLayout layout attach grapher try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vGridLayout class supports the following generic parameters defined in the IlvGraphLayout class Allowed Time Layout Region Preserve Fixed Nodes Save Parameters to Named Properties Stop Immediately The following comments describe the particular way in which these parameters are used by this subclass Allowed Time The layout algorithm stops if the allowed time setting has elapsed For a description of this layout parameter in the 11vGraphLayout class see Allowed Time on page 22 The result code in the layout report is I1vGraphLayoutReport STOPPED AND INVALID r lt c p gt e gt 3 Layout Region The layout algorithm uses the layout region setting either your own or the default setting to control the size and the position of the graph drawing All three ways to specify
440. rintln e getMessage Accessing Sublayouts You can obtain the sublayouts of a Multiple Layout instance by the following methods IlvGraphLayout getFirstGraphLayout which returns the graph layout that is applied first 2 r lt o e gt 3 i1ilvGraphLayout getSecondGraphLayout which returns the graph layout that is applied second IlvLabelLayout getLabelLayout which returns the label layout that is applied last You can also change the sublayouts Of course you should not change the sublayouts while the Multiple Layout instance is attached to a graph You should detach the graph first To set the sublayouts the following methods are available void setFirstGraphLayout IlvGraphLayout layout void setSecondGraphLayout IlvGraphLayout layout void setLabelLayout IlvLabelLayout layout For Experts Attaching Graph and Labeling Models If a graph model is attached to the Multiple Layout instance the same graph model is automatically attached to the sublayouts of type 11vGraphLayout For the sublayout of type IlvLabelLayout a default labeling model is used when possible IlvDefaultLabelingModel see The Labeling Model on page 346 This works if the nodes links and labels are stored in an I1vGrapher If you implement your own labeling model subclass of 11vLabelingModel you can force the Multiple Layout to use this labeling model instead of the default
441. rizontally or vertically Despite preserving the relative order of the children in rare cases the layout is not perfectly stable in incremental radial layouts Subsequent layouts may rotate the nodes around the root although the relative circular order of the nodes within their circular levels is still preserved JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT The tip over layout modes will perform several trial layouts with different tip over alignment options according to various heuristics From these trial layouts the algorithm picks the layout that best fits the given aspect ratio This may not be the optimal layout for the aspect ratio but it is the best layout among the trials Calculating the absolute best fitting layout is not feasible computationally it is generally an NP complete problem Brief Description of the Algorithm The core algorithm for the free level and radial layout modes works in just two steps and is very fast The variations of the tip over layout mode perform the second step several times and pick the layout result that best fits the given aspect ratio the ratio between width and height of the drawing area For this reason the tip over layout modes are slower Step 1 Calculating the Spanning Tree If the graph is disconnected the layout algorithm chooses a root node for each connected component Starting from the root node it traverses the graph to choose the links of the spanning tre
442. root For Experts Additional Options for Root Nodes The layout algorithm manages a list of the root nodes that have been specified by the setRoot method To obtain the nodes in this list use the following method Enumeration getSpecRoots After layout you can also retrieve the list of root nodes that were actually used by the algorithm This list is not necessarily the same as the list of specified roots For instance it contains the chosen root nodes if none were specified or if too many were specified To obtain the root nodes that were used by the algorithm use the following method Enumeration getCalcRoots The following example shows how to iterate over the calculated root nodes and print the root node preferences Enumeration e layout getCalcRoots while e hasMoreElements node e nextElement System out println Preference layout getRootPreference node To directly manipulate the root node preference value of an individual node you can use the following method setRootPreference Object node int preference In this case the layout uses the specified value instead of the heuristically calculated preference for the node The normal preference value should be between 0 and 10000 Specifying a root node explicitly corresponds to setting the preference value to 10000 If you want to prohibit a node from becoming the root specify a preference value of zero 0 A negative preference v
443. rs are distributed more equally on the circle To enable or disable the area minimization mode use the following method ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 247 CIRCULAR LAYOUT void setAreaMinimizationEnabled boolean option The default value is a1se area minimization is disabled Deciding whether to enable the area minimization mode essentially depends on the size of the network We recommend the area minimization mode for very large networks To obtain the current choice use the method boolean isAreaMinimizationEnabled 248 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL CIRCULAR LAYOUT To get an idea of the difference between these modes compare the following layouts of the same network Figure 4 121 Area Minimization Disabled default r lt Lad gt gt 3 Figure 4 122 Area Minimization Enabled This parameter has no effect if the clustering mode is Bv SUBGRAPHS ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 249 CIRCULAR LAYOUT Dimensional Parameters Figure 4 123 illustrates the dimensional parameters used in the Circular Layout algorithm These parameters are explained in the sections that follow at offset 28 EON B7 ssp St d 53 esf 28 po PANEM Figure 4 123 Dimensional Parameters for the Circular Layout Algorithm Offset The layout algorithm tries to preserve a minimum distance betw
444. rsor DEFAULT_CURSOR DebugGraphicsO ptions Default Background true Default Font true Default Foreground true DoubleBuffered false Enabled true Font Dialog 12 Bold Foreground r fo lt 07 5 7 Maximum MinUpdateD elay Minimum z Model Name ilvJGraphLayoutProgressB Testing the Result Now that the applet has been created you can test the result 1 Execute the applet From the Project menu choose Execute Initially the resulting application should appear as shown in the following image the graph is not yet laid out ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 407 CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Applet Viewer JAppletl class X Applet Applet started 2 You can use the icons in the toolbar to manipulate the graph displayed in the manager view The toolbar contains the following icons e The Pan icon Eu to pan the content of a view e The Select arrow icon to select and edit objects in the view e The Interactive zoom icon 4 to drag a rectangle over an area that you want to Zoom e The Zoom in q and the zoom out amp icons to view the graph at different zoom levels e The Fit to content icon to size the graph so that it fits entirely in the manager view When
445. rt Classes Layout Class Layout Report Class IlvTopologicalMeshLayout IlvTopologicalMeshLayoutReport IlvSpringEmbedderLayout IlvGraphLayoutReport IlvUniformLengthEdgesLayout IlvUniformLengthEdgesLayoutReport IlvTreeLayout IlvGraphLayoutReport IlvHierarchicalLayout IlvGraphLayoutReport IlvLinkLayout IlvGraphLayoutReport IlvRandomLayout IlvGraphLayoutReport IlvBusLayout IlvGraphLayoutReport IlvCircularLayout IlvGraphLayoutReport IlvGridLayout IlvGraphLayoutReport IlvMultipleLayout IlvMultipleLayoutReport IlvRecursiveLayout IlvRecursiveLayoutReport Creating a Layout Report All layout classes inherit the performLayout method from the IlvGraphLayout class This method calls createLayoutReport to obtain a new instance of the layout report This instance is returned when performLayout returns The default implementation in the base layout class creates an instance of I1vGraphLayoutReport Some subclasses override this method to return an appropriate subclass Other classes such as 11vRandomLayout do not ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING A LAYOUT REPORT need specific information to be stored in the layout report and do not override createLayoutReport In this case the base class IlvGraphLayoutReport is used When using the layout classes provided with ILOG JViews you do not need to instantiate the layout report yourself This is done auto
446. rticalOffsetToLevel Vertical Offset to Previous Level This parameter represents the vertical distance between a row of nodes and the previous horizontal segment of the bus node To specify this parameter use the method void setVerticalOffsetToPreviousLevel float offset To obtain the current value use the method float getVerticalOffsetToPreviousLevel Margin This parameter represents the offset distance between the layout region and the bounding rectangle of the layout To specify this parameter use the method void setMargin float margin To obtain the current value use the method float getMargin Margin on Bus On the odd horizontal levels first third fifth and so on of the bus starting from the top this parameter represents the offset distance between the left side of the first node on the left and the left side of the bus object On the even horizontal levels second fourth sixth and so on of the bus starting from the top this parameter represents the offset distance between the right side of the last node on the right and the right side of the bus object See Figure 4 113 on page 234 for an illustration of the margin on bus parameter r lt gt gt 3 To specify this parameter use the method void setMarginOnBus float margin To obtain the current value use the method ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 235 BUS LAYOUT
447. s int getFromPortIndex Object link int getToPortIndex Object link Using the port side and port index specifications are additional constraints for the layout algorithm The more constraints are specified the more difficult it is to calculate a layout Therefore if too many links have a specified port index this resulting layout may have more link crossings and be less balanced Fork Link Shapes If several links start at the same position and are orthogonally routed it is sometimes preferred that the links share the first two link segments The shape of a link bundle of this kind looks like a fork In order to enable the fork shape mode for outgoing links call layout setFromFork true In order to enable the fork shape mode for incoming lins call layout setToFork true These statements have an effect only if the links are routed orthogonally The fork appears only at those links that start or end exactly at the same point Specifying setFromFork true by itself does not force the links to start at the same point In order to force links to start or end at the same point use the center connector style see Connector 156 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Style on page 147 or specify the same port for the links see Port Index Parameter on page 155 preferredFoxAxisLength Sl E E E E From Fork Shape minForkseamentLensth _ To Fork Shape Figure 4 72 Fork Link Sha
448. s 14 symmetries 15 layout listeners Recursive Layout 279 layout method IlvGraphLayout class 18 330 348 steps for implementing 330 layout methods types of automatic 15 49 incremental 16 semi automatic 49 semiautomatic 15 static 15 layout modes Grid Layout 258 Link Layout 192 Recursive Layout 272 Tree Layout 103 layout parameters loading from IVL file 318 saving 315 saving to IVL file 315 Layout Provider 311 layout region parameter Bus Layout 225 Circular Layout 244 Grid Layout 257 Random Layout 219 Spring Embedder Layout 76 Topological Mesh Layout 59 Uniform Length Edges Layout 85 using to refine a TML graph layout 68 layout report class table 292 creating 292 elapsed time 294 information stored in report 293 reading 293 using 292 layoutReport method IlvGraphLayout class 18 layouts 315 applying the same recursively 307 Bus Layout 222 Circular Layout 238 defining a new type 329 defining new type 320 Grid Layout 255 Hierarchical Layout 134 Link Layout 185 mixing different in nested graph 311 Multiple Layout 265 282 performing 19 procedure for implementing layout method 330 Random Layout 217 recursive 307 releasing resources 328 sample code for defining a new type 329 Spring Embedder Layout 72 Topological Mesh Layout 54 Tree Layout 94 Uniform Length Edges Layout 81 layoutStepPerformed method IlvGraphLayout class 295 436 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL level index parameter Hi
449. s of the layout algorithm that is the layout parameters need to be the same for the topmost graph as for all the subgraphs This situation is illustrated by the example in Figure 5 3 on page 306 where a Tree Layout is applied on the topmost graph as well as on all its subgraphs Moreover the settings of the Tree Layout algorithm are the same for all the graphs the application does not need for instance a different flow direction in the subgraphs than in the topmost graph soJnjeoaJj e 5 gt 2 lt o 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 307 LAYING OUT NESTED GRAPHS 308 Obtaining such recursive layouts is very easy The class 11vGraphLayout provides a special version of the performLayout method performLayout boolean force boolean redraw boolean traverse When the value t rue is passed for the last boolean argument the layout is applied not only on the graph attached to the layout instance but also in a recursive way to its subgraphs Internal Mechanism How does this work internally The mechanism is based on the principle that a given layout instance is used for only one graph and is not reused for its subgraphs Therefore the Tree Layout instance is automatically cloned using the copy method of the class IlvGraphLayout The same principle holds for the graph models a given graph model instance is used for only one graph and is not reused for subgraphs The grap
450. s of type IlvBusLinkConnector Usually the class IlvPolyline is used for the bus object The bus object must be added to the I1vGrapher as a node using the method addNode The links between the bus and the nodes connected to the bus must be created before performing the layout See the code provided in Code Sample on page 223 Link Style When the layout algorithm moves the nodes straight line links such as instances of IlvLinkImage will automatically follow the new positions of their end nodes If the grapher contains other types of links for example IlvPolylineLinkImage IlvSplineLinkImage the shape of the link may not be appropriate because the intermediate points of the link will not be moved In this case you can ask the layout algorithm to automatically remove all the intermediate points of the links if any To do this the following method is provided void setLinkStyle int style The valid values for style are IilvBusLayout NO RESHAPE STYLE None of the links is reshaped in any manner i1ilvBusLayout STRAIGHT LINE STYLE the intermediate points of the links if any are removed This is the default value 228 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT Note If the STRAIGHT LINE STYLE is selected the layout algorithm may raise an IlvInappropriateLinkException if layout is performed on an 11vGraphez but links that cannot be given straig
451. s right north is on the left south on the right east at the top and west at the bottom r lt Lad gt e gt 3 Figure 4 70 shows a drawing where the links connect to the larger middle node at the specified port sides A compass icon shows the compass directions in these drawings ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 153 HIERARCHICAL LAYOUT 154 m lt uonoeJiq MOJ Flow Direction S T UN Figure 4 70 Link Connections to Port Sides S Gp South N West 2 o z 9 LL Flow Direction To specify for a link at which side the link connects to its source node use the method void setFromPortSide Object link int side To specify for a link at which side the link connects to its destination node use the method void setToPortSide Object link The valid values for side are Il ILOG Il V M ierarchical ierarchical ierarchical ierarchical ierarchical int side Layout UNSPECIFI Layout NORTH Layout SOUTH jayout EAS Layout WES JVIEWS GRAPH LAYOUT 5 5 ED the default USER S MANUAL HIERARCHICAL LAYOUT To retrieve the current choice for a link use the following methods int getFromPortSide Object link int getToPortSide Object link The port sides east and west work particularly well with the orthogonal link style P
452. seconds Finally you can specify how many steps should be done during the crossing reduction phase by using layout getLongLinkLayout setNumberCrossingReductionIterations 5 You can disable the crossing reduction completely by using the following layout getLongLinkLayout setCrossingReductionEnabled false Fallback Mechanism The Long Link Layout algorithm may not be able to find a routing for a link if one end nodes is inside an enclave In Figure 4 103 the red node is inside an enclave In this case the backtrack search algorithm fails to find a routing without overlapping nodes The backtrack search algorithm may also fail if the situation is so complex that the search exceeds the allowed time per link Ei r lt gt e gt 3 Figure 4 103 Node Inside Enclave When the backtrack search algorithm fails to find a routing a simple fallback mechanism is applied that creates a routing with node overlappings This fallback mechanism can be disabled by using the following layout getLongLinkLayout setFallbackRouteEnabled false ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 215 LINK LAYOUT If the fallback mechanism is disabled these links are not routed at all and remain in the same shape as before the layout To retrieve the links that could not be routed in the usual way without the fallback mechanism you can use the following Enumeration e
453. set parameter 251 features 240 generic parameters 243 level offset parameter 250 limitations 240 link clipping parameter 244 252 link connection box parameter 244 253 link style parameter 252 offset parameter 250 order of nodes parameters 245 ring topology 241 root clusters parameter 247 sample drawings 238 specific parameters 245 star center parameter 247 star topology 241 cluster contents parameter Circular Layout 251 cluster membership parameters Circular Layout 245 cluster position parameter Circular Layout 251 cluster size parameter Circular Layout 251 clustering modes Circular Layout 245 compass directions Tree Layout 103 connected components parameter Bus Layout 224 Circular Layout 244 Hierarchical Layout 141 Multiple Layout 285 Spring Embedder Layout 75 Topological Mesh Layout 59 Tree Layout 100 Uniform Length Edges Layout 85 INDEX connector style parameter Hierarchical Layout 147 Tree Layout 111 coordinates mode Label Layout 380 specifying 327 core library of ILOG JViews 16 createGraphLayout method IlvDefaultLayoutProvider class 280 312 createGraphModel method IlvGraphModel class 300 createLayoutReport method IlvGraphLayout class 292 creating a layout report 292 D default labeling model subclassing 388 defining a new type of layout 329 detach method IlvGraphLayout class 20 IlvLabelLayout class 19 348 detaching a grapher 20 detachLayouts method IlvDefaultLayoutProvider
454. sible reason may be the layout algorithms nothing happens no node is provided in ILOG JViews all designed to do nothing by moved Why default if no change occurred in the graph since the last time the layout was performed successfully on the same graph A change means that a node was moved or a node or link was added removed or reshaped Note that you can force the layout to be performed again even if no change occurred by calling the IlvGraphLayout performLayout boolean force boolean redraw method with a true value for the force argument In the Composer demonstration you can choose this option in the Options menu Another possible reason may be an error or a special case occurred during the layout First you should check whether the performLayout method has thrown an exception If no exception was thrown call the get Code method on the instance of the layout report returned by the performLayout method Check this value with respect to the documentation of the appropriate layout report class For details see Using a Layout Report on page 292 With the Uniform Length The reason is probably that the first time you performed the Edges algorithm after having layout the algorithm reached the convergence When the performed the layout once layout is performed again it detects that the convergence don t see any movement even has been already reached and stops If you really want to if use the force lay
455. sic technical terms used in this manual Related Documentation The following documentation may provide helpful information when using ILOG JViews Graph Layout Books The first book dedicated to graph layout has been published Di Battista Giuseppe Peter Eades Roberto Tammassia and Ioannis G Tollis Graph Drawing Algorithms for the Visualization of Graphs Prentice Hall 1999 see http www cs brown edu people rt gdbook html or http www prenhall com books esm 0133016153 html Graph layout is closely related to graph theory for which extensive literature exists See Clark John and Derek Allan Holton A First Look at Graph Theory World Scientific Publishing Company 1991 For a mathematics oriented introduction to graph theory see Diestel Reinhard Graph Theory 2nd ed Springer Verlag 2000 A more algorithmic approach may be found in Gibbons Alan Algorithmic Graph Theory Cambridge University Press 1985 Gondran Michel and Michel Minoux Graphes et algorithmes 3rd ed Eyrolles Paris 1995 in French viii ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL Bibliographies A comprehensive bibliographic database of papers in computational geometry including graph layout can be found The Geometry Literature Database http compgeom cs uiuc edu jeffe compgeom biblios html The recommended bibliographic survey paper is the following Di Battista Giuseppe Peter Eades Roberto Tamassia and Ioa
456. sition was already found however it indicates that finding the best position would require too much layout time The number of ineffective iterations before stopping can be changed by D gt 1 3 r c layout setMaxNumberOfFailIterations maxNumber The default value is 20 If you set it to a higher value the layout slows down but may find better positions for the labels If you set it to a lower value the layout stops sooner but the label positions may be far from optimal In some cases the algorithm improves the quality in each step but the amount of improvement gets smaller in each step In this situation the previous fail iteration criteria does not work well because there is an improvment in each step but the amount of the improvement is so negligibly small that we want to stop Therefore it is also possible to require that the quality must improve in each step by a minimum percentage For example to specify that the algorithm must improve over ten rounds by at least 2 call layout setNumberIterationsForMinImprovement 10 layout setMinImprovementPercentageToContinue 2 By default the layout stops if the quality did not improve by 0 5 over five iterations If you set the required improvement percentage higher or the number of iterations lower the layout stops sooner but the label positions may be far from optimal If you set the required percentage to 0 this stop
457. sive Layout you can call ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 279 RECURSIVE LAYOUT recursiveLayout addSubLayoutEventListener listener Notice that in this case the listener is installed at the Recursive Layout instance not at the sublayout instances but receives the events from the sublayouts not from the Recursive Layout internal mechanism makes sure that the events are forwarded to the listener Alternatively you could traverse the nesting structure and install the same listener at all layouts of subgraphs However this would have two disadvantages it requires more memory and you need to reinstall or update the listener whenever you change the layout of a subgraph or the nesting structure by adding or removing subgraphs When you use addSubLayoutEventListener the update of the listener is not necessary in this case For Experts More on Layout Providers We illustrated above how to use the Recursive Layout when using a specified layout provider The library provides a default implementation of the interface IlvLayoutProvider named IlvDefaultLayoutProvider In many cases it is simpler either to use this class as is or to subclass it rather than directly implementing this interface The class 11vDefaultLayoutProvider allows you to set the layout instance to be used for each graph called the preferred layout with the method setPreferredLayout IlvGraphModel graphModel IlvGraphLayout layout boole
458. so convert a vector of nodes into a group group add node Adds a node to the group group remove node Removes a node from the group group contains node Checks whether a node is in the group group size Returns the number of nodes in the group group elements Returns the nodes of the group as an Enumeration group new IlvNodeGroup vector Creates a new group that contains the nodes stored in the input vector Level Range Constraints In Step 1 of the layout algorithm the leveling phase the nodes are partitioned into levels These levels are indexed starting from 0 For instance when the flow direction is to the bottom the nodes of the level index 0 are placed at the topmost horizontal level line and the nodes with larger level index are placed at a position lower than the nodes with smaller level index see Figure 4 59 on page 139 The layout algorithm calculates these level indices automatically You can affect how the levels are partitioned by specifying the range of the level index for some nodes The nodes are placed in those levels with index in the specified range You have to specify the minimal and maximal index of the desired level For instance layout addConstraint new IlvLevelRangeConstraint node 5 7 forces the node to be placed between minimal level 5 and maximal level 7 that is either in level 5 level 6 or level 7 If you want to place the node exactly at level 5 call layout addConstraint n
459. specify position indices or east west extremity constraints for any node Tip The automatic conflict resolution can handle conflicting constraints However to speed up the layout it is recommended that you specify constraints in such a way that there are no conflicts Constraint Priorities A set of constraints may cause conflicts This means that not all of the constraints can be satisfied at the same time For instance it is impossible to force two nodes into the same level by an 11vSameLevelConstraint while at the same time forcing one of the nodes to a higher level than the other node by an IlvRelativeLevelConstraint In this case one of the two constraints must be ignored during layout In general constraint conflicts are resolved by ignoring the constraints with the lowest priority while the constraints with the highest priority get satisfied The following rules explain the constraint priorities in detail The constraints that influence into which level a node is placed are applied before the constraints that influence the position of the node within a level The IlvExtremityConstraint is translated into a sequence of constraints with high priority For instance the extremity constraint with the south side is translated into several same level constraints and several relative level constraints The I1vSameLevelConstraint and the IlvGroupSpreadConstraint have the highest priority They are never in conflict with each ot
460. ss overlapping nodes cannot always be avoided When overlapping occurs you can try to increase the size of the layout region parameter or to change the outer cycle see the method setExteriorCycleId You can also use manual adjustments to correct the problem Brief Description of the Algorithm TML is an heuristical approach for the layout of cyclic 2 connected graphs either planar or nonplanar graphs TML is basically very simple to use However to use all the functionalities of TML you should understand its basic concepts 56 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL TOPOLOGICAL MESH LAYOUT TML TML Basic Concepts When laying out a general graph producing a drawing with a minimum number of link crossings is a mathematically NP complete problem The search space and time is exponentially combinatorial Traditionally most of the existing layout algorithms use node coordinates from the beginning searching for a coordinate set to minimize the cost function which is mainly the number of link crossings These coordinates can be constrained on a grid but the number of combinations to explore is still enormous In contrast TML uses a two step approach that drastically reduces the number of combinations to explore The first step of TML deals only with the pure topology that is the connectivity of the graph without taking into consideration the node coordinates This first step is called topological optimizatio
461. ss IlvDefaultLayoutProvider Or IlvRecursiveLayoutProvider you should traverse all layouts and detach them explicitely Accessing All Sublayouts When the Recursive Layout is attached you can conveniently access all layouts that will be used during layout This works in all layout modes Enumeration getLayouts boolean preOrder It returns an enumeration of instances of IlvGraphLayout If the preorder flag is true the layout of the parent graph occurs before the layout of its children in the enumeration If the preorder flag is false the layout of the parent graph occurs after the layout of its children For instance in the graph of Figure 4 131 on page 276 the call getLayouts true returns the layouts for the subgraphs in this order L1 L1 1 L1 1 1 L1 1 2 L1 2 The call getLayouts false returns the layouts for the subgraphs in this order L1 1 1 L1 1 2 L1 1 L1 2 L1 r lt gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 275 RECURSIVE LAYOUT L1 L1 1 11 2 11 1 1 1 1 2 z Figure 4 131 Nesting Structure in a Graph Note In specified provider mode the enumeration returned by get Layouts contains the instances that are delivered by the specified provider If the specified provider returns a different instance in each call of getGraphLayout IlvGraphModel then the enumeration does not contain the instances that are later used during layout Henc
462. st Neighbors You can specify that two unrelated nodes must be directly neighbored in a direction perpendicular to the flow direction In the level and radial layout modes both nodes are placed in the same level next to each other In the free layout and tip over modes both nodes are placed aligned at the north border Such nodes are called east west neighbors because one node is placed as the direct neighbor on the east side of the other node The other node becomes the direct neighbor on the west side of the first node See also Using Compass Directions for Situating Layout Parameters on page 103 Technically both nodes are treated as parent and child even if there may be no link in between Therefore one of the two nodes can have a real parent but the other node should not because its virtual parent is its east west neighbor The east west neighbor feature can be used for example for annotating nodes in a typed syntax tree occurring in compiler construction Figure 4 52 shows an example of such a tree Stat dark gray the syntax tree light gray the type annotations west neighbor east neighbor ArrayAccess float float Var a Array Bf int ArrayAccess float osf float Size 30 float array Bl int r lt Lad gt gt 3 Size 30 float Figure 4 52 Annotated Syntax Tree of Statement a 25 b 24 0 5 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 129 TREE LAY
463. supportsPreserveFixedLinks The default implementation returns alse A subclass can override this method in order to return t rue to indicate that this mechanism is supported Preserve Fixed Nodes At times you may want some nodes of the graph to be pinned that is to stay in their current position when the layout is performed You need a way to indicate the nodes that the layout algorithm cannot move This makes sense especially when using a semiautomatic layout the method where the end user fine tunes the layout by hand after the layout is completed or when using an incremental layout the method where the graph and or the 32 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT position of the nodes is modified after the layout has been performed and then the layout is performed again ILOG JViews allows you to specify that a node is fixed using the method void setFixed Object node boolean fixed If fixed is true it means that the node is fixed To obtain the current setting for a node boolean isFixed Object node The default value is false To remove the fixed attribute from all nodes in the grapher use the method void unfixAllNodes Note The fixed attributes you may have set will be taken into consideration only if you call the method void setPreserveFixedNodes boolean option with a true argument You can read the current option using the meth
464. t Redraw the grapher grapher reDraw Detach the grapher from the layout instance layout detach further methods The sample Java application produces the graph shown in Figure 6 1 Label4 Figure 6 1 Output from Sample Java Application ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 345 THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT The Base Classes IlvLabelingModel and IlvLabelLayout The base classes for automatic label placement are 11vLabelLayout the base class for labeling algorithms and 11vLabelingModel a base class for performing many of the generic operations common to all labeling algorithms Note Before reading this section you should be familiar with the IlvGraphLayout and IlvGraphModel classes see The Base Class IlvGraphLayout on page 17 and Using the Graph Model on page 297 Many of the concepts for the labeling layout mechanism and labeling model are similar and we mention the common features here without repeating all identical details The Labeling Model discusses how to use the IlvLabelingModel class The Label Layout Base Class introduces the 11vLabelLayout class The Labeling Model The ilog views graphlayout labellayout IlvLabelingModel class defines a suitable generic API to position labels automatically by an ILOG JViews label layout algorithm Its purpose is similar to the 11vGraphModel for the graph layout framework IlvLabelingModel is an abs
465. t algorithm does not reshape the links that are specified as fixed See Preserve Fixed Links on page 32 Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed See Preserve Fixed Nodes on page 32 Save Parameters to Named Properties The layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to iv1 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 I1vGraphLayoutReport STOPPED AND INVALID r lt gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 225 Bus LAYOUT Specific Parameters The following parameters are specific to the IlvBusLayout class Order Parameter The order parameter specifies how to arrange the nodes To specify the ordering option for the nodes use the method void setOrdering int ordering The valid values for ordering are IlvBusLayout NO_ORDERING The nodes are arranged on the bus in an arbitrary order This is the default va
466. t module delegates this task to the IlvGrapherAdapter Layout algorithms interact with the geometry of the graph using generic methods of the graph model 11vGraphModel such as boundingBox Object nodeOrLink The distinction between zoomable and nonzoomable objects and the notion of transformer 1IlvTransformer are outside this level of the layout framework The layout algorithms consider the geometry of the graph exactly as it is provided by the graph model From the point of view of the layout algorithms the problem of zoomable and nonzoomable objects is 324 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CHOOSING THE LAYOUT COORDINATE SPACE completely transparent Therefore when writing a layout algorithm you do not need to be concerned with that In the case of an I1vGrapher the IlvGrapherAdapter may need to compute the geometry of the graph for a given transformer This is what we call the reference transformer Usually the reference transformer is the transformer that is currently being used for the display of the IlvGrapher How a Reference Transformer is Used For a simple example of how a reference transformer is used consider the boundingBox Object nodeOrLink method This abstract method of the IlvGraphModel class is implemented in the IlvGrapherAdapter To compute the bounding box it calls the boundingBox IlvTransformer t method ofthe graphic object that it receives as an argument However it does not handle zo
467. t once For details see Recursive Layout on page 265 Spacing Parameters in Short Link Mode Since the short link mode places the links freely in the space only two parameters are necessary to control the spacing the minimal distance between links and the minimal length of the final segment Figure 4 95 shows the spacing parameters used in the short link mode r lt e gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 201 LINK LAYOUT gt MinFinalSegmentLength LinkOffse Figure 4 95 Spacing Parameters for the Short Link Mode Link Offset The layout algorithm computes the final connecting segments of the links that is the segments near the origin and destination nodes in order to obtain parallel lines spaced at a user defined distance In short link mode the algorithm takes into account the width of the links when computing the offset To specify the offset use the following method void setLinkOffset float offset To obtain the current value use the method float getLinkOffset 202 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT The offset is measured from the border of one link to the nearest border of the other link Therefore if the specified offset is zero the border of a link touches the border of its neighbor link Minimum Final Segment Length You can specify a minimum value for the length of the final connecting segments of t
468. t overlaps in horizontal or vertical levels Arranges the graph such that the majority of links are short and flow uniformly in the same direction from left to right from top to bottom and so on Reduces the number of link crossings Most of the time produces drawings with no crossings or only a small number of crossings Often produces balanced drawings that emphasize the symmetries in the graph Supports self links that is links with the same origin and destination node multiple links between the same pair of nodes and cycles Efficient scalable algorithm Produces a nice layout for most sparse and medium dense graphs relatively quickly even if the number of nodes is very large Provides several alignment and offset options Supports port specifications where links attach the nodes Allows you to specify which side of a node top bottom left right a link can be connected to or to specify which relative port position should be used for the connection Supports layout constraints Allows you to specify relative positional constraints for instance that a node is above another node or left of another node Incremental and nonincremental mode In incremental mode the previous position of nodes are taken into account Positions the nodes without changing the relative order of the nodes so that the layout is stable on incremental changes of the graph r lt gt
469. t parameter For instance the method setNodeBoxInterface sets an IlvNodeBoxInterface see IlvLinkLayout IlvShortLinkLayout and so on If an application uses a node box class that implements the node box interface this can only be stored to an iv file if the node box class also implements the IlvPersistentObject interface Otherwise the node box class is not saved to the iv1 file Compatibility Issues An ivl file that contains layout properties can be loaded only when the package ilog views graphlayout and its subpackages are available Defining a New Type of Layout If you develop your own layout algorithms by subclassing I1vGraphLayout and want to save the layout parameters of your own layout algorithm in ivi files you should subclass IlvGraphLayoutGrapherProperty IlvGraphLayoutNodeProperty and IlvGraphLayoutLinkProperty See Defining a New Type of Layout on page 329 You can find example code by referring to the classes in the Reference Manual You should also override the following methods of 11vGraphLayout to return your subclasses protected IlvGraphLayoutGrapherProperty createLayoutGrapherProperty String name boolean withDefaults return new MyOwnLayoutGrapherProperty name this withDefaults ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING THE FiLTERING FEATURES TO LAY OUT A PART OF AN ILVGRAPHER protected IlvGraphLayoutNodeProperty createLayoutNodeProperty String name IlvGraphic node boolean
470. t the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 18 78 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL SPRING EMBEDDER LAYOUT without clipping with clipping Figure 4 18 Effect of Link Clipping Interface You can modify the position of the connection points of the links by providing a class that implements the 11vLinkClipInterface An example for the implementation of a link clip interface is in Link Clipping on page 27 To set a link clip interface call void setLinkClipInterface IlvLinkClipInterface interface Note The link clip interface requires link connectors at the nodes of an 11vGrapher that allow connector pins to be placed freely at the node border It is recommended that you use IlvRelativeLinkConnector or IlvClipLinkConnector for link connectors to be used in combination with 11vGrapher objects The clip link connector updates the clipped connection points automatically during interactive node movements If a node has an irregular shape the clipped links sometimes should not point towards the center of the node bounding box but to a virtual center inside the node You can achieve this by additionally providing a class that implements the IlvLinkConnectionBoxInterface An example for the implementation of a link connection box interface is in Link Connection Box on page 29 To set a link connection box interface call r lt Lad gt
471. tLayoutProvider class 280 312 PreferredLinksLength method lvUniformLengthEdgesLayout class 87 Property method lvGraphModel class 302 lvLabelingModel class 387 388 se se H Cf se f se H ct se H SetR ReferenceTransformer lvLayoutGraphicFilter class 326 ReferenceTransformer method lvDefaultLabelingModel class 381 ReferenceView LayoutGraphicFilter class 325 ReferenceView method DefaultLabelingModel class 381 RespectNodeSizes method lvUniformLengthEdgesLayout class 88 RightMargin method lvGridLayout class 263 Root method lvTreeLayout class 102 RootClusterId method lvCircularLayout class 247 setRootPreference method lvTreeLayout class 102 se ox e se CT Cf 4 PA dt 4 f se D BE QU se H Cf se f H INDEX setS setSameShapeForMultipleLinks method IlvShortLinkLayout class 210 setSecondGraphLayout method IlvMultipleLayout class 287 setSeedValueForRandomGenerator method IlvGraphLayout class 34 setSiblingOffset method IlvTreeLayout class 116 123 setSpecNodeLevelIndex method IlvHierarchicalLayout class 173 setSpecNodePositionIndex method IlvHierarchicalLayout class 175 setSpringConstant method IlvSpringEmbedderLayout class 78 setStarCenter method IlvCircularLayout class 247 setStartingNode method IlvTopologicalMeshLayout class 64 setStraightRouteEnabled method IlvLongLinkLa
472. tReport LAYOUT DONE System out println Layout done else System out println Layout not done code layoutReport getCode Generic Features and Parameters The 11vRandomLabelLayout class supports the following generic parameters defined in the I1vLabelLayout class Allowed Time Percentage Completion Calculation Random Generator Seed Value Save Parameters to Named Properties Stop Immediately Use Default Parameters The following comments describe the particular way in which these parameters are used by this subclass Allowed Time The label layout algorithm stops if the allowed time setting has elapsed This feature works similarly as in IlvGraphLayout see Allowed Time on page 22 If the layout stops early because the allowed time has elapsed the result code in the layout report is IlvLabelLayoutReport STOPPED AND INVALID ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 377 THE RANDOM LABEL LAYOUT Percentage Completion Calculation The label layout algorithm calculates the estimated percentage of completion This value can be obtained from the label layout report during the run of the layout For a detailed description of this features see Percentage Completion Calculation on page 31 and Layout Events and Listeners on page 352 Random Generator Seed Value The Random Label Layout uses a random number generator to compute the coordinates For the default behavior the random gene
473. talldir data graphlayout link directory and select the samplel ivl file Click Open 5 Click OK in the FileName Editor dialog box The file is automatically displayed in the IlvManagerView Bean As you can see only a portion of the graph is visible in the manager view Form Designer JApplet1 Wappel Zz Adding a Control Toolbar Bean You are now going to add a toolbar and associate the toolbar with the manager view The toolbar allows the user to control the zoom level of the view and to pan the view Do the following 1 On the JViews Graphics Framework Beans toolbar click the IlvJManagerViewControlBar i icon and drag it to the Form Designer 400 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Form Designer JApplet1 sue g 1noAeq c 2 o O gt 2 Make sure that the TlvJManagerViewControlBar Bean is selected in the Form Designer so that its properties appear in the Property List 3 associate the toolbar with the manager view click the value field of the view property and select ilvManagerViewl ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 401 CREATING A SIMPLE APPLET USING ILOG JVIEWS GRAPH LAYOUT BEANS 402 Property List J amp pplet1 ilvyIManagerViewControlB art X Orientation HORIZONTAL PanButton amp vailable true Sele
474. teLinks defined in IlvGraphLayoutUtil to automatically replace inappropriate links or link connectors before layout or when the IlvInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 Global Link Style To set the global link style use the following method void setGlobalLinkStyle int style The valid values for style are IlvHierarchicalLayout POLYLINE STYLE r lt gt gt 3 links get a polyline shape A polyline shape consists of a sequence of line segments that are connected at bend points The line segments can be turned into any direction This is the default value ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 145 HIERARCHICAL LAYOUT IlvHierarchicalLayout ORTHOGONAL STYLE All links get an orthogonal shape An orthogonal shape consists of orthogonal line segments that are connected at bend points An orthogonal shape is a polyline shape where the segments can be turned only in directions of 0 90 180 or 270 degrees ilvHierarchicalLayout STRAIGHT LINE STYLE links get a straight line shape All intermediate bend points if any are removed This often causes overlapping nodes and links ilvHierarchicalLayout NO RESHAPE STYLE None of the links is reshaped in any
475. ted using IlvGraphLayout attach IlvGrapher you can use the method IlvGraphModel getOriginatingLayout This method returns a non nu11 object if the model has not been created using I1vGraphLayout attach IlvGrapher Additionally the 11vGrapherAdapter class provides a way to filter IlvGrapher By using the filtering mechanism you specify a particular set of nodes and links that have to be taken into account by the layout algorithm See Using the Filtering Features to Lay Out a Part of an IlvGrapher on page 321 The 11vGrapherAdapter class also allows you to specify the IlvTransformer that has to be used for computing the geometry of the graph See Choosing the Layout Coordinate Space on page 323 Note For details on how to write your own adapter see Laying Out a Non JViews Grapher on page 303 Laying Out a Non JViews Grapher Note To understand this section better read Using the Graph Model on page 297 first It is sometimes necessary to add graph layout features to an existing application If the application already uses ILOG JViews grapher 11og views IlvGrapher to manipulate and display graphs using the graph layout algorithms provided in ILOG JViews is a straightforward process No adapter has to be written However the case may arise where an application uses its own classes for nodes links and graphs and where for some reason you do not want to replace these classes with ILOG JViews classes To enable
476. ter Grid Layout 262 Link Layout long link mode 204 H Hierarchical Layout applicable graph types 136 application domains 136 calculated level index parameter 183 calculated position index parameter 184 code sample 139 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 427 INDEX connector style parameter 147 crossing reduction step 138 description 138 end points mode parameter 148 extremity constraints 177 features 137 flow direction parameter 142 fork link shapes 156 generic parameters 140 global end point mode parameter 148 global link style parameter 145 individual end point mode parameter 149 individual link style parameter 146 layout constraints 169 layout sequences 263 level index parameter 173 level justification parameter 143 leveling step 138 limitations 138 link clipping parameter 141 151 link connection box parameter 141 150 link priority parameter 157 link routing step 139 link style parameter 144 link width parameter 152 node positioning step 138 port index parameter 155 port sides parameter 153 position index parameter 175 relative position constraints 175 sample drawings 134 side by side constraints 176 spacing parameters 159 specific parameters 142 swim lane constraint 178 horizontal offset parameter Bus Layout 234 livA IlvAnnealingLabelDescriptor class getPreferredPathLocation method 375 initialize method 374 setTowardsPreferredPosition method 375 IlvAnnealingLabelLayout 347 IlvAnn
477. ter method 322 getLayers method 323 getReferenceTransformer method 326 getReferenceView method 325 removeAllLayers method 322 removeLayer method 322 setFilter method 322 setReferenceTransformer method 326 setReferenceView method 325 IlvLinkConnectionBoxInterface class getBox method 29 208 211 getTangentialOffset method 29 212 IlvLinkLayout class getDestinationPointMode method 198 getGlobalDestinationPointMode method 197 getGlobalLinkStyle method 195 getGlobalOriginPointMode method 197 getLayoutMode method 192 245 ChCP cb cr ge ge ge ge ma LinkStyle method 196 LongLinkLayout method 213 OriginPointMode method 197 ShortLinkLayout method 208 rkForIncremental method 199 ct ct ct ct provided as a Bean 392 se se se se se se se se tDestinationPointMode method 197 tGlobalDestinationPointMode method 197 tGlobalLinkStyle method 194 tGlobalOriginPointMode method 197 tIncrementalMode method 198 LayoutMode method 192 245 LinkStyle method 196 inFinalSegmentLength method 203 NodeSideFilter method 207 S se GE CCE act CU uct OriginPointMode method 197 IlvLongLinkLayout class ad ad ge ge ge ge ge ge ge ge ge dLineObstacle method 214 dRectObstacle method 214 CalcFallbackLinks method 216 HorizontalGridBase method 205 HorizontalGridOffset method 205 HorizontalMinOffset method 205 inFinalSegmentLength method 206 inNodeCornerOffset method 206 tVer
478. the graph layout algorithms to work with these graph objects a custom adapter that is a subclass of 11vGraphModel must be written The adapter must implement all the abstract methods of the 11vGraphModel class The nonabstract methods of this class have a default implementation that is really functional However they may not be optimal because they do not take advantage of the characteristics of the underlying graph implementation For better performance the following nonabstract methods can be overridden in the adapter class int getNodesCount int getLinksCount soJnjeoaJj int getLinksCount Object node em o 5 gt 2 lt E 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 303 LAYING OUT CONNECTED COMPONENTS OF A DISCONNECTED GRAPH int get int get int get tLinksFromCount Object node LinksToCount Object node LinkPointAt Object link int index int getSubgraphsCount int getInterGraphLinksCount The efficiency of the layout algorithm depends directly on the efficiency of the implementation of the adapter class and the underlying graph data structure Laying Out Connected Components of a Disconnected Graph ILOG JViews provides special support for the layout of a disconnected graph If a graph is composed of several connected components or contains isolated nodes nodes without any links it can be desirable to apply the layout algorithm separately on ea
479. the layout region are available for this subclass See Layout Region on page 25 The layout region is considered differently depending on the layout mode For details see Layout Modes on page 258 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 257 GRID LAYOUT Preserve Fixed Nodes The layout algorithm does not move the nodes that are specified as fixed See Preserve Fixed Nodes on page 32 Moreover nonfixed nodes are placed in such a manner that overlaps with fixed nodes are avoided Save Parameters to Named Properties The layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to 71 files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 I1vGraphLayoutReport STOPPED AND INVALID Specific Parameters The following parameters are specific to the 11vGridLayout class Layout Modes The Grid Layout algorithm has four layout modes To select a layout mode use the method void setLayoutMode int mode To obtain the current layout mode call int getLay
480. the nodes For instance the constraint is satisfied if the level indices for nodeA nodeB and nodec are 1 2 3 or if they are 7 8 9 or if they are 16 14 15 The constraint is also satisfied if all three nodes are placed at level 5 or if two of the nodes are placed at level 15 and the third node at level 13 The constraint is not satisfied if the level indices for nodeA nodeB and nodeC are 3 5 6 because in this case the highest index 6 is more than two levels away from the lowest index 3 Relative Level Constraint You can force a node into a higher level than another node If the flow direction is towards the bottom level 0 is topmost in the drawing In this layout you can specify by relative level constraints that a node be above or below another node If the flow direction is towards the right level 0 is leftmost in the drawing Here you can specify by relative level constraints that a node be left or right of another node For example layout addConstraint new IlvRelativeLevelConstraint nodeA nodeB priority This forces nodea to be placed at a level with a smaller index than nodeB Since relative level constraints compete with each other you must specify the priority of the constraint In 174 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT fact links also impose constraints on the system and the link priority has the same impact as the constraint priority A link with priority 10 forces its
481. the prefix of the Bean name You could also create the same type of application using only AWT controls To do so you would simply use the 11vScrollManagerView Bean that is an AWT control instead of the 11vJ8crollManagerView Bean However there is no equivalent of the I1vJGraphLayoutProgressBar Bean 4 Drag handles of the 11vJScrollManagerView Bean until it looks approximately like this 394 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CREATING A SIMPLE APPLET USING ILOG JVIEWS GRAPH LAYOUT BEANS Form Designer JApplet1 IIManagerView sue g nofe c 2 o O gt MAppel Mde S S A 5 On the JViews Beans toolbar click the 11vManagerView icon and drag it inside the I1vJScrollManagerView Bean The result is fairly similar to what you obtained in the previous step except that you can now select the manager view ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 395 CREATING A SIMPLE APPLET USING ILOG JViEWS GRAPH LAYOUT BEANS Form Designer JApplet1 pe oe llVManagerView Appen Mod f 4 Note If you were to compile and run the project at this point you would see that the IlvJScrollManagerView allows you to scroll through the contents of the IlvManagerView Bean At the moment the manager view is empty so there is nothing to scroll Setting the Properties of the Manager View You are now going to change two properties of t
482. the relative order of these swim lanes is determined automatically The size of the swim lane rectangle depends on the nodes that belong to the swim lane However you can specify the relative order relative size and the margins of the swim lane as well by using the constructor public IlvSwimLaneConstraint IlvNodeGroup group float relativeSize int positionIndex float minMargin r lt c gt e gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 179 HIERARCHICAL LAYOUT The red background rectangle indicates where the swim lane is Figure 4 88 Swim Lanes The relative size indicates how large this swim lane is compared to the other swim lanes Assume that the flow direction is towards the bottom In this case the relative size indicates the width of the swim lane All swim lanes with the same relative size will have the same width A swim lane with a relative size that is twice the value of another swim lane will have twice the width of the other swim lane The actual number of this parameter does not matter only how large the value is compared to the other swim lanes If you do not want to restrict the size of the swim lane set the value to O In this case the width of the swim lane will be independent of the other swim lanes The minimal margin is the margin of the swim lane in absolute coordinates If the flow direction 15 towards the bottom then it is the minimal horizontal dist
483. the same time 2 Create an instance of the Annealing Label Layout algorithm 3 Declare a handle for the corresponding layout report The layout report is an object in which the layout algorithm stores information about its behavior For details see The Label Layout Report on page 351 4 Attach the manager to the layout instance We assume that the labels are subclasses of IlvLabel or IlvZoomableLabel If they are not the label model can be extended as illustrated in The Labeling Model on page 346 5 Foreach label set a label descriptor The label descriptor describes the conditions for the placement of the label For instance if a label should be placed close to the source or destination node of a link use an I1vAnnealingPolylineLabelDescriptor with the corresponding options For details see Label Descriptors on page 359 Modify the default settings for the layout parameters if needed 7 Call the performLayout method 8 Read and display information from the layout report 9 When the layout instance is no longer needed detach the manager from the layout instance An application that illustrates these steps is provided in the section Sample Java Application on page 342 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 341 GETTING STARTED WITH LABELING 342 Sample Java Application You can use this application as an example to get started with the label layout algorithms of the Graph Layout module It is include
484. thod 251 getDisconnectedGraphOffset method 251 getIndex method 246 getLevelOffset method 251 getLinkStyle method 252 getOffset method 250 getRootClusterId method 247 isAreaMinimizationEnabled method 248 isStarCenter method 247 provided as a Bean 392 removeAllClusterIds method 247 removeClusterId method 247 setAreaMinimizationEnabled method 248 setClusterId method 246 setDisconnectedGraphOffset method 251 setLevelOffset method 251 setLinkStyle method 252 setOffset method 250 setRootClusterId method 247 setStarCenter method 247 t ct ct ct ct livD IlvDefaultLabelingModel class 346 addLayer method 379 getLayers method 379 removeAllLayers method 379 removeLayer method 379 setCoordinatesMode method 380 setReferenceTransformer method 381 setReferenceView method 381 IlvDefaultLayoutProvider class createGraphLayout method 280 312 detachLayouts method 276 312 getPreferredLayout method 280 312 setPreferredLayout method 280 312 IlvGrapher class 303 addNode method 341 boundingBox method 324 INDEX IlvGrapherAdapter class 302 getCoordinatesMode method 328 isLayerAdded method 322 loadParametersFromNamedProperties method 318 319 loadPreferredLayoutsToNamedProperties method 319 removeParametersFromNamedProperties method 316 saveParametersToNamedProperties method 316 savePreferredLayoutsToNamedProperties method 317 setCoordinatesMode method 327 IlvGraphLayout class 17 addGraphL
485. thod with the value t rue for the redraw argument IlvGraphLayoutReport performLayout boolean force boolean redraw When you do this an initReDraws reDrawViews session is initiated automatically When the nodes and the links are moved or reshaped the value t rue is passed for the redraw argument of the appropriate methods of IlvGrapher At the end of the layout the initReDraws reDrawViews session is ended This produces a selective redraw of the invalid regions of the views where the graph is displayed Nonautomatic and complete redraw If all the nodes are moved by the layout it may be more efficient to redraw the entire graph at the end of the layout instead of using the mechanism of the invalid regions provided by 11vGrapher In this case you can use the following code try layout performLayout false false argument redraw at false catch IlvGraphLayoutException e e printStackTrace finally redraw in the final clause to ensure that the redraw is performed even if an exception occurs grapher reDraw 296 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL USING THE GRAPH MODEL This completely redraws the grapher in all its visible views Alternatively you can call the method repaint on some of its views Delayed redraw After the layout you may want to perform other changes in the grapher before redrawing You can start the initReDraws reDrawViews session on your own to control the point in t
486. thout overlappings in a labyrinth of node obstacles r lt Lad gt gt 3 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 193 LINK LAYOUT Figure 4 90 Labyrinth Routing with the Long Link Mode Link Style The layout algorithm provides two link styles You can set the link style globally in which case all links have the same kind of shape or locally on each link in which case different link shapes occur in the same drawing Note The layout algorithm may raise an 11vInappropriateLinkException if layout is performed an 11vGrapher but links are neither a subclass of IlvPolylineLinkImage nor of IlvSplineLinkImage or if connectors are not a subclass of 11vRelativeLinkConnector You can use the methods EnsureAppropriateLinkTypes EnsureAppropriateLinkConnectors or EnsureAppropriateLinks defined in IlvGraphLayoutUtil to automatically replace inappropriate links or link connectors before layout or when the IlvInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 Global Link Style To set the global link style the following method is provided void setGlobalLinkStyle int style The valid values for style are IlvLinkLayout ORTHOGONAL_STYLE the default 194 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LINK LAYOUT The lin
487. tial positions of the nodes Furthermore you can change the layout by selecting a different root node To change only the dimensions of the graph use the various offset parameters Hierarchical Layout Yes if incremental mode is In incremental mode you can change the layout by switched on changing the initial positions of the nodes Furthermore you can use specified node level indices to change the level structure You can use specified node position indices to change the node order within the levels You can change the layout by changing the link priorities To change only the dimensions of the graph use the various offset parameters 52 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL LAYOUT CHARACTERISTICS Table 4 3 Layout Characteristics of Layout Algorithms Continued Layout Algorithm Do the initial positions of the nodes affect the layout How get a different layout of the same graph when perform the layout a second time Link Layout Yes Link Layout routes the links depending on the node positions It does not move the nodes You can change the link style option and the dimensional parameters such as the link offset and final segment length You can also specify the rules for computing the connection points of the links Random Layout No This is the default behavior when using the default parameter settings the random generator is initialized differently each time
488. tialized using the current system clock Therefore different layouts are obtained if you perform the layout repeatedly on the same graph You can specify a particular value to be used as seed value For example to specify the seed value 10 call layout setUseSeedValueForRandomGenerator true layout setSeedValueForRandomGenerator 10 358 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE ANNEALING LABEL LAYOUT Save Parameters to Named Properties The label layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to iv1 files For a detailed description of this feature see Using Named Properties to Save Layout Parameters on page 382 Stop Immediately The label layout algorithm stops after cleanup if the method stopImmediately is called This method works for the 11vLabelLayout class similarly to the corresponding method in the I1vGraphLayout class For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early in this way the result code in the layout report is o gt 1 3 IlvLabelLayoutReport STOPPED AND VALID if the labels were moved to some better but not yet optimal positions IilvLabelLayoutReport STOPPED AND INVALID if the layout stopped even before that Use Default Parameters After modifying any label layout param
489. tic Label Placement This chapter describes the label placement algorithms of the ILOG JViews Graph Layout module A label placement algorithm is not a graph layout algorithm in the sense that it does not use the IlvGraphModel and it is not a subclass of IlvGraphLayout However the labeling framework has many similarities to the graph layout framework and is included in this Graph Layout User s Manual The following topics are covered Getting Started with Labeling The Base Classes IlvLabelingModel and IlvLabelLayout The Annealing Label Layout The Random Label Layout Using Advanced Features 0 Defining Your Own Labeling Model ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 339 GETTING STARTED WITH LABELING Getting Started with Labeling 340 This section provides information to get started using the ILOG JViews Label Layout framework An Introduction explains the goal and the limitations of automatic label placement Asetof Basic Steps illustrates the basic steps to perform a label placement with the Annealing Label Layout algorithm The Sample Java Application included in the release is also discussed Introduction to Automatic Label Placement Usually a abel is a text or decoration that should be placed close to some graphic object because the label denotes the meaning of the graphic object The label should not be overlapped by obstacles because this would make it unreadable If there are man
490. ticalGridBase method 205 tVerticalGridOffset method 205 tVerticalMinOffset method 205 Cb Gh ach ct oct Ch removeAllLinkObstacles method 214 removeAllRectObstacles method 214 5 tAllowedTimePerLink method 215 se se se se se se se se se se se se se tCrossingReductionEnabled method 215 tFallbackRouteEnabled method 215 tHorizontalGridBase method 205 tHorizontalGridOffset method 204 tHorizontalMinOffset method 205 tMaxBacktrack method 214 tMinFinalSegment Length method 206 tMinNodeCornerOffset method 206 tNumberCrossingReductionIterations method 215 tStraightRouteEnabled method 214 tTerminationPointFilter method 214 tVerticalGridBase method 205 tVerticalGridOffset method 205 432 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL setVerticalMinOffset method 205 livM IlvManager class addOb ject method 341 IlvManagerView class 395 IlvMultipleLayout class 282 getFirstGraphLayout method 287 getLabelLayout method 287 getSecondGraphLayout method 287 setFirstGraphLayout method 287 setLabelLayout method 287 setSecondGraphLayout method 287 livN IlvNodeBoxInterface class getBox method 207 livR IlvRandomLabelLayout class 347 376 getLayoutRegion method 379 setLayoutRegion method 379 IlvRandomLayout class getLinkStyle method 221 provided as a Bean 392 setLinkStyle method 220 IlvS IlvShortLinkLayout class getGlobalSelfLinkStyle method 209 211 get
491. tion is to the right then north means the left border and south means the right border a a k North Justified South Justified Center Justified Figure 4 44 Level Alignment To specify the level alignment use the following method void setLevelAlignment int alignment To obtain the current value use the method int getLevelAlignment The valid values for a1ignment are IlvTreeLayout CENTER the default IlvTreeLayout NORTH IlvTreeLayout SOUTH Radial Layout Mode The radial layout mode partitions the node into levels and arranges the levels in circles around the root node Figure 4 45 shows an example of the radial layout mode The compass icons show the compass directions in this drawing 120 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Figure 4 45 Radial Layout Mode The following statement sets the radial layout mode layout setLayoutMode IlvTreeLayout RADIAL General Parameters Most layout parameters that work for the free and level layout mode work as well for the radial layout mode You can set the spacing offsets the level alignment the global or individual link style and the global or individual alignment See Free Layout Mode on page 104 and Level Layout Mode on page 118 for details The radial layout mode differs from the other layout modes as follows ILOG The tip over alignment does not work i
492. tion of the nonfixed nodes See Preserve Fixed Nodes on page 32 If TML produces a layout with overlapping nodes you can use the fixed nodes mechanism to correct the problem For details see Using Fixed Nodes on page 66 Save Parameters to Named Properties The layout algorithm can save its layout parameters into named properties This can be used to save layout parameters to ilv files For a detailed description of this feature see Save Parameters to Named Properties on page 34 and Saving Layout Parameters and Preferred Layouts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the result code in the layout report 15 I1vGraphLayoutReport STOPPED AND INVALID 60 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL ToPOLOGICAL MESH LAYOUT TML Specific Parameters The following parameters are specific to the IlvTopologicalMeshLayout class Link Style When the layout algorithm moves the nodes straight line links such as instances of IlvLinkImage will automatically follow the new positions of their end nodes If the grapher contains other types of links for example IlvPolylineLinkImage or IlvSplineLinkImage the shape of the link may not be appropriate because the intermediate points of the l
493. tioning see Figure 4 81 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT position tendency 90 om 3 position Le tendency 0 1 3 1 teed i PositionRange Le I 1 3 PositionTendency pPositionRange EN a 98 PositionRange Position Tendency PositionRange Figure 4 81 Absolute Positioning During Incremental Layouts Marking Nodes for Incremental Layout Incremental layout normally treats all nodes and links of the drawing in the same way However you may have added nodes and links to the drawing programmatically and the new nodes and links do not have meaningful coordinates yet Perhaps you have placed them all at the origin 0 0 or at random coordinates In this case you need an incremental layout that takes the coordinates of all nodes into account that were previously laid out while it ignores the coordinates of all new nodes The incremental mode of the Hierarchical Layout allows you to specify which nodes cannot be laid out incrementally by calling layout markForIncremental nodeOrLink If you call this statement the node or link is marked such that its coordinates are ignored during the next incremental layout The positions of marked nodes and links are calculated from scratch The mark is valid only until the next layout and is automatically cleared afterwards r lt Lad gt e gt 3
494. tly However if needed you can do this in your own subclass of 11vGraphLayout Using the IlvGrapherAdapter The IlvGrapherAdapter class is a concrete subclass of 11vGraphModel that allows an IlvGrapher to be laid out using the layout algorithms provided in ILOG JViews It provides an implementation for all the abstract methods of 11vGraphModel It also provides an overridden implementation of some nonabstract methods of 11vGraphModel to improve efficiency by taking advantage of the characteristics of the 11vGrapher If an application uses the 11vGrapher class the grapher can be attached directly to the layout instance without explicitly using the adapter See the method IlvGraphLayout attach IlvGrapher In this case an I1vGrapherAdapter is created internally by the layout class The adapter can be retrieved using the method IlvGraphLayout getGraphModel which will return an instance of IlvGrapherAdapter Notice that such an internally created adapter is not allowed to be attached to any other layout instance nor to be used in any way once the method 11vGraphLayout detach has been called on the layout instance 302 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL LAYING OUT A NON JVIEWS GRAPHER In case you need to be able to do any of the above operations directly create the instance of IlvGrapherAdapter and attach it using I1vGraphLayout attach IlvGraphModel To know whether a given 11vGraphModel instance has been crea
495. to either the maximum size of the nodes plus margins or the medium size and so on Of course if all the nodes have a similar size the choice is straight forward Margins The margins control the space around each node that the layout algorithm keeps empty The margins can be set and retrieved using the following methods void setTopMargin float margin void setBottomMargin float margin void setLeftMargin float margin void setRightMargin float margin float getTopMargin float getBottomMargin float getLeftMargin float getRightMargin The meaning of the margin parameters is not the same for the grid modes as for the row column modes In the grid modes they represent the minimum distance between the node border and the grid line see Figure 4 128 on page 261 In the row column modes they are used to control the vertical distance between the rows or the horizontal distance between the columns and the horizontal or vertical minimal distance between the nodes in the same row or column see Figure 4 129 on page 262 The default value for all the margin parameters is 5 Sequences of Graph Layout In some circumstances you may need to use a sequence of layouts on the same graph For example You work with graphs that have become out of date and need to extend the graph If you perform a layout on the extended graph you probably want to identify the parts that were already laid out in the original
496. tract base class that allows you to implement an adapter to your own data structures for the labeling algorithm see Defining Your Own Labeling Model on page 384 The labeling model of an attached layout can be obtained by layout getLabelingModel If labels and obstacles are contained in an 11vManager you do not need to implement an adapter You can use the default labeling model provided by ILOG JViews the class ilog views graphlayout labellayout IlvDefaultLabelingModel The default labeling model is suitable if the labels are upright rectangular objects and the overlap calculation considers their bounding boxes The default labeling model may not be suitable if the labels have a nonrectangular shape that leaves large parts of the label s bounding box empty because the overlap detection will wrongly assume that the empty space inside the bounding box causes overlaps The default labeling model considers subclasses of 11vLabel and I1vZoomableLabel as labels and all other objects as obstacles This is the most common case However you can redefine this meaning Ifa graphic should be treated as label even though it is not a subclass of 11vLabel and IlvZoomableLabel call defaultLabelingModel setLabel graphic true 346 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT Ifaninstance of I1vLabel IlvZoomableLabel should not be treated as a label but as an immovable o
497. tter read Using the Graph Model on page 297 first Applications sometimes need to perform the layout algorithm on a subset of the nodes and links of a graph If the graph is not an 11vGrapher the custom adapter should support the filtering of a graph See Laying Out a Non JViews Grapher on page 303 The methods that are related to the structure of the graph getNodes getLinks getNeighbors and so on as shown in Information on the Structure of the Graph on page 299 must behave just as if the graph has changed in some way They must take into account only the nodes and links that belong to the part of the graph that must be laid out soJnjeoaJj ge 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 321 USING THE FILTERING FEATURES TO LAY OUT A PART OF AN ILVGRAPHER For applications that use 11vGrapher the filtering feature is built into the IlvGrapherAdapter To do this the IlvGrapherAdapter needs a way to know for each node or link whether it must be taken into account during the layout This is the role of the filter class ilog views graphlayout IlvLayoutGraphicFilter The IlvLayoutGraphicFilter class implements the interface ilog views IlvGraphicFilter that is its method boolean accept IlvGraphic nodeOrLink If a filter is specified the 11vGrapherAdapter calls the accept method for each node or link whenever necessary If the method returns t rue the 11vGrapherAdapter cons
498. u can install a listener to these events at the layout instance by labelLayout addLabelLayoutParameterEventListener listener The listener must implement the LabelLayoutParameterEventListener interface and receives events when layout parameters change It also receives a special event at the end of a successful layout For example o gt 1 3 m class MyLabelLayoutParameterListener implements LabelLayoutParameterEventListener public void parametersUpToDate LabelLayoutParameterEvent event if levent isParametersUpToDate System out println Any label layout parameter has changed Layout Parameters and Features in IlvLabelLayout The 11vLabelLayout class defines a number of generic features and parameters These are a subset of the mechanism methods and parameters that are available for the IlvGraphLayout class Therefore we only list them here for detailed explanations refer to the particular section in Layout Parameters and Features in IlvGraphLayout on page 20 that describes the corresponding features for the 11vGraphLayout class Although the 11vLabelLayout class defines the generic parameters it does not control how they are used by its subclasses Each label layout algorithm that is each subclass of IlvLabelLayout supports a subset of the generic features and determines the way in which it uses the generic parameters When you create your own label l
499. u want to specify local layout parameters for individual nodes and links In this case you need to access the cloned layout instance that is attached to the subgraph that owns the node or link For instance to the the link style of an individual link use IlvTreeLayout treeLayout IlvTreeLayout layout getLayout link getGraphicBag treeLayout setLinkStyle link IlvTreeLayout ORTHOGONAL STYLE You cannot use the reference layout mode in the following cases The layout algorithm to be applied on subgraphs is not the same as the algorithm needed for the topmost graph the reference layout The same layout algorithm but using different global parameter settings needs to be applied on different subgraphs In this case you can use one of the following modes Code Sample Mixing Different Layout Styles r lt c gt gt 3 The following example shows the second scenario Each subgraph should be laid out by a different layout style or with individual global layout parameters In this case you use the internal provider mode of the Recursive Layout We assume that you have a graph with three subgraphs The top level graph and the first subgraph should be processed with Tree Layout the second subgraph with Bus Layout and ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 267 RECURSIVE LAYOUT the third subgraph with Grid Layout You have to specify which layout should be used for wh
500. ue value for the second argument If the argument force is false the layout algorithm first verifies whether it is necessary to perform the layout It checks internal flags to see whether the manager or any of the parameters have been changed since the last time the layout was successfully performed A change can be any of the following Obstacles or labels were added or removed o gt 1 3 E r Obstacles or labels were moved or reshaped The value of a layout parameter was modified The transformer changed while nonzoomable obstacles or labels were used Users often do not want the layout to be computed again if no changes occurred If there were no changes the method performLayout returns without performing the layout Note that if the argument force is passed as t rue the verification is skipped and layout is performed even if no changes occurred The argument redraw determines whether a redraw of the manager is requested This mechanism works in exactly the same way as in graph layout For details see Redrawing the Grapher after Layout on page 296 The protected abstract method 1ayout boolean redraw is then called This means that control is passed to the subclasses that are implementing this method The implementation computes the layout and moves the labels to new positions Performing a Recursive Layout on Nested Subgraphs The examples and explanations above ass
501. ume that you work with a flat manager ILOG JViews allows you to nest a grapher as a node into another grapher You can create a hierarchy of nested graphers see Figure 6 2 on page 351 see also Nested Managers and Nested Graphers in the ILOG JViews Graphics Framework User s Manual You can apply a recursive graph layout to this hierarchy by calling graphLayout performLayout true true true However it usually makes no sense to apply a label layout alone to nested graphers When labels are placed in a subgrapher this will likely change the bounds of the subgrapher hence the node positions in its parent grapher will no longer be up to date and a new graph layout will be necessary It makes sense to apply a label layout in combination with another graph layout to nested graphers 1 First the graph layout is applied to arrange the nodes and links nicely ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 349 THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT 350 2 Then the label layout is applied to position the labels according to the node and link positions 3 When this is finished for all subgraphers then it can be done for the parent grapher To perform a graph layout and a label layout together you can use the Multiple Layout class This is a subclass of 11vGraphLayout that allows combining graph layouts with a label layout The following sample shows how to apply a Tree Layout and an Annealing Label Layout in combin
502. ummary As a quick summary If you attach a manager directly by attach manager you need only make sure to call detach when the layout is no longer used Everything else is done automatically Ifyou allocate a default labeling model de aultLabelingModel yourself and call attach defaultLabelingModel you need to call detach on the layout as above and eventually de aultLabelingModel dispose when the model is no longer used Everything else is done automatically If you attach a labeling model that is not an I11vDefaultLabelingModel you need to call detach on the layout dispose on the labeling model and eventually cleanLabel or cleanObstacle whenever a label or obstacle gets removed while the layout is attached Defining Your Own Labeling Model Note Before reading this section you should be familiar with the IlvLabelingModel class see The Labeling Model on page 346 Itis sometimes necessary to add label layout features to an existing application If the application already uses ILOG JViews manager I1vManager to manipulate and display labels and obstacles using the label layout algorithms provided in ILOG JViews is a straightforward process You can use and adapt the default labeling model IlvDefaultLabelingModel Even if the application uses data structures that are independent from the ILOG JViews data structures it is possible to apply a label layout algorithm provided in ILOG JViews You have to
503. up to date A subsequent layout is necessary Hence changing the zoom level of the reference view also renders the layout out of date ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 381 USING ADVANCED FEATURES Using Named Properties to Save Layout Parameters The ILOG JViews Graph Layout module offers the facility to convert graph layout parameters into named properties of the 11vGrapher The same facility is available to convert label layout parameters into named properties of the 11vManager Named properties can be stored in ivi files The following method indicates whether a label layout class supports this mechanism supportsSaveParametersToNamedProperties It returns t rue if the layout class can transfer the parameter settings to named properties Saving Layout Parameters to ivl Files The following example shows how to save the 11vManager including all label layout parameter settings into an iv file IlvDefaultLabelingModel labelingModel IlvDefaultLabelingModel labelLayout getLabelingModel transfer the layout parameters to named properties if labelLayout supportsSaveParametersToNamedProperties labelingModel saveParametersToNamedProperties labelLayout false save the attached manager with the named layout properties to file labelingModel getManager write abcd ivl remove the named layout properties because they are no longer needed labelingModel
504. used to obtain the layouts it is still necessary to learn about this class because it contains methods that are inherited or overridden by the subclasses And of course you will need to understand it if you subclass it yourself Using llvLabelLayout The following sections describe the basic operations and generic parameters of IlvLabelLayout For more details on the T1vLabelLayout class see the ILOG JViews Graph Layout Reference Manual e Instantiating and Attaching a Subclass of IlvLabelLayout e Performing a Layout e Performing a Recursive Layout on Nested Subgraphs ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 347 THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT e The Label Layout Report e Layout Events and Listeners e Layout Parameters and Features in IlvLabelLayout Instantiating and Attaching a Subclass of IlvLabelLayout The class I1vLabelLayout is an abstract class It has no constructors You will instantiate a subclass as shown in the following example IlvAnnealingLabelLayout layout new IlvAnnealingLabelLayout In order to place labels a manager needs to be attached to the layout instance The following method defined on the class 11vLabelLayout allows you to specify the manager you want to lay out void attach IlvManager manager For example IlvManager manager new IlvManager Add obstacles and labels to the manager here layout attach manager The attach method does nothi
505. ut algorithms 07 2 O 5 o a Despite the fact that only subclasses of 11vGraphLayout are directly used to obtain layouts it is still necessary to learn about this class because it contains methods that are inherited or overridden by the subclasses And of course you will need to understand it if you subclass it yourself You can find more information about the class 11vGraphLayout in the following sections Basic Operations with IlvGraphLayout on page 17 tells you about the basic methods you need using the subclasses of IlvGraphLayout Layout Parameters and Features in IlvGraphLayout on page 20 contains the methods that are related to the customization of the layout algorithms Using Event Listeners on page 294 tells you about the layout event listener mechanism Defining a New Type of Layout on page 329 tells you how to implement new subclasses For details on 11vGraphLayout and other graph layout classes see the ILOG JViews Graph Layout Reference Manual Basic Operations with llvGraphLayout When subclassing IlvGraphLayout or when using one of its subclasses you will normally use the basic methods described in the following sections Instantiating a Subclass of IlvGraphLayout Attaching a Grapher ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 17 BASIC OPERATIONS WITH ILVGRAPHLAYOUT Performing a Layout Detaching a Grapher Instantiating a Subclass
506. ut short link mode 203 move method IlvGraphModel class 301 moveLabel method IlvLabelingModel class 386 389 moveNode method IlvGraphModel class 301 Multiple Layout accessing sublayouts 287 allowed time parameter 285 application domain 282 attaching graph and labeling models 287 code sample 282 combining multiple and recursive layout 288 connected components parameter 285 features 285 for experts 287 288 generic parameters 285 percentage completion parameter 285 recursive layout 283 save to named properties 286 simple layout 283 specific parameters 286 stop immediately parameter 286 the reference labeling model 288 N nested graph 306 Layout Provider 311 nested subgraphs 349 nesting for each graph in nested graph 315 node box interface feature Link Layout 207 nodes relative position constraints 169 nodes placement algorithm Topological Mesh Layout 62 nodes placement allowed time Topological Mesh Layout 62 438 ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL nodes placement iterations parameter Topological Mesh Layout 62 node side filter feature Link Layout 206 number of iterations parameter Uniform Length Edges Layout 87 number of optimization iterations Link Layout short link mode 209 obstacle and nonzoomable labels 379 default labeling model 346 definition 340 example obstacles 341 examples of related obstacles 361 ignoring 347 offset parameter 370 positioning at 360 positioning at polylin
507. ut bus Sample Here is a sample drawing produced with the Bus Layout Figure 4 105 Bus Topology Produced with the Bus Layout What Types of Graphs Bus network topologies a set of nodes connected to a bus object Application Domains Application domains of the Bus Layout include Telecom and networking LAN diagrams Electrical engineering circuit block diagrams Industrial engineering equipment resource control charts 222 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL Bus LAYOUT Features Displays bus topologies Takes into account the size of the nodes so that no overlapping occurs Provides several ordering alignment and flow direction options Allows easy customization of the dimensional parameters Brief Description of the Algorithm Bus topology is well known in network management and telecommunications fields The Bus Layout class can display these topologies nicely It represents the bus as a serpent polyline The width of the serpent is user defined via the width of the layout region parameter and the height is computed so that enough space is available for all the nodes Code Sample Below is a code sample using the 11vBusLayout class import ilog views import ilog views graphic import ilog views graphlayout import ilog views graphlayout bus IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher
508. ut method IlvGraphLayout class 23 SetB setBottomMargin method IlvGridLayout class 263 setBranchOffset method IlvTreeLayout class 116 123 setBus method IlvBusLayout class 228 setBusWidthAdjustingEnabled method IlvBusLayout class 231 setC setClusterId method IlvCircularLayout class 246 setConnectorStyle method IlvHierarchicalLayout class 147 IlvTreeLayout class 112 setCoordinatesMode method IlvDefaultLabelingModel class 380 IlvGrapherAdapter class 327 setCrossingReductionEnabled method IlvLongLinkLayout class 215 setD setDestinationPointMode method UsER S MANUAL setDisconnectedGraphOffset method IlvHierarchicalLayout class 149 IlvLinkLayout class 197 IlvCircularLayout class 251 setE setEastWestNeighboring method IlvTreeLayout class 130 setExteriorCycleId method IlvTopologicalMeshLayout class 64 setF se se se se se tFallbackRouteEnabled method IlvLongLinkLayout class 215 tFilter method tFirstGraphLayout method IlvMultipleLayout class 287 tFixed method IlvGraphLayout class 32 33 tFlowDirection method IlvBusLayout class 230 260 IlvHierarchicalLayout class 143 IlvTreeLayout class 105 setForceFitToLayoutRegion method setFromPortIndex method IlvHierarchicalLayout class 156 setFromPortSide method se se se tGlobalAlignment method IlvTreeLayout class 106 108 IlvHierarchicalLay
509. ut parameters is applied to all subgraphs of the nested graph IlvRecursiveLayout INTERNAL PROVIDER MODE The layout is applied using an internal recursive layout provider The layout styles of individual subgraphs can be specified by using the method set Layout IlvRecursiveLayout SPECIFIED PROVIDER MODE The layout is applied using an explicitely specified layout provider ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL RECURSIVE LAYOUT Reference Layout Mode This mode should be used if you want to apply the same layout style with the same global layout parameters to the entire nested graph You first need to allocate the reference layout that is a new instance of any graph layout algorithm except IlvRecursiveLayout that should be applied to all subgraphs of the nested graph Then you allocate the Recursive Layout using the constructor with the reference layout as argument IlvRecursiveLayout IlvGraphLayout referenceLayout The reference layout is internally actually only used for the top level graph of the nested graph Clones of the reference layout are used for the subgraphs Hence all subgraphs are laid out with the same global layout parameters In order to change the global layout parameters you can access the reference layout by IlvGraphLayout getReferenceLayout Global layout parameters are those parameters that are independent from specific nodes or links Other la
510. ut with a new outer cycle requires very little CPU time Using the Layout Region Parameter Often overlapping nodes can be avoided by simply increasing the size of the layout region Figure 4 12 shows a graph drawing where several nodes overlap because the layout region is too small for the graph Figure 4 13 shows the same graph after increasing the size of the layout region As you can see now there are no overlapping nodes Figure 4 12 Graph Layout Small Layout Region and Overlapping Nodes 68 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TOPOLOGICAL MESH LAYOUT TML Figure 4 13 Graph Layout Larger Layout Region and No Overlapping Nodes Using a Link Clipping Interface By default TML does not place the connection points of links It relies on the link connectors of the nodes to determine the connection points If no link connectors are installed at the nodes the default behavior is to connect to a point at the border of the bounding box of the nodes If the node has a nonrectangular shape such as a triangle rhombus or circle you may want the connection points to be placed exactly on the border of the shape This can be achieved by specifying a link clip interface The link clip interface allows you to correct the calculated connection point so that it lies on the border of the shape An example is shown in Figure 4 14 gt lt S gt EM e 3 o without clipping with clipping Figure 4 14 E
511. ut without any additional tip over options Then it tries to tip over the root node and the leaves simultaneously then the root and its children and the leaves and its parent then additionally the children of these children and the parents of these parents and so on As result the nodes in the middle of the tree use normal alignment and the nodes closest to the root or leaves use the tip over alignment This is the slowest strategy because it includes all trials of the strategy leaves over as well as all tries of the strategy tip roots over Tip Over Fast The fast tip over provides a compromise among all other strategies The heuristic tries a small selection of the other strategies not all possibilities Therefore it is the fastest strategy for large graphs To use this strategy set the layout mode as follows layout setLayoutMode IlvTreeLayout TIP OVER It is possible that all four strategies yield the same result because the strategies are not disjoint that is certain trials are performed in all four strategies In addition the tip over modes do not necessarily produce the optimal layout that gives the best possible fit to the aspect ratio The reason is that some unusual configurations of tip over alignment are never tried because doing so would cause the running time to be too high 128 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT For Experts Additional Tips and Tricks Specifying East We
512. vTreeLayout class They apply to all layout modes Root Node The final layout is influenced mainly by the choice of the root node The root node is placed in a prominent position For instance in a top down drawing with free layout mode it is placed at the top of the tree With the radial layout mode it is placed at the center of the tree The spanning tree is calculated starting from the root node If the graph is disconnected the layout algorithm needs one root node for each connected component r lt gt gt 3 The layout algorithm automatically selects a root node when needed It uses a heuristic that calculates preferences for all nodes to become a root It chooses the node with the highest preference The heuristic gives nodes without incoming links the highest preference and leaf nodes without outgoing links the lowest preference Hence in a directed tree the canonical root is always chosen automatically Itis possible to influence the choice of the root node To select a node explicitly as the root use the method ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 101 TREE LAYOUT void setRoot Object node This gives the node the maximal preference to become the root during layout If only one node is specified this way the algorithm selects this node If several nodes of the same connected component are specified this way the layout algorithm chooses one of them as the
513. value use the Link Layout algorithm to lay out the links representing routes of a network of graphical objects towns geo positioned on a cartographical map When several links connect to the same side of a node they overlap while expect them to respect the link offset or the grid size parameter of the Link Layout Why Some dimensional parameters of the layout algorithms need to be chosen with respect to the size of the nodes This is the case of the link offset and the bypass distance parameters for the Short Link Layout and the grid size for the Long Link Layout Indeed their default values are not appropriate when the nodes are very large Often nodes placed on a map for instance a world map have a very large size Compared to this size the default values of the parameters are so small that they appear to be zero The solution is to increase the values of the dimensional parameters taking into account the size of the nodes If different nodes have different sizes either the medium or the largest size of the nodes can be used to compute the parameters as a fraction of this size ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 337 soJnjeoaJj e o 5 gt 2 lt o 5 o QUESTIONS AND ANSWERS ABOUT USING THE LAYOUT ALGORITHMS 338 ILOG JVIEWS GRAPH LAYOUT 5 5 USER S MANUAL o gt mp 3 r Automa
514. vePerIteration float maxMove float getMaxAllowedMovePerIteration Link Length Weight The layout algorithm is based on the computation of attraction and repulsion forces for each of the nodes and the iterative search of an equilibrum configuration One of these forces is related to the objective of obtaining a link length close to the specified preferred length The weight of this force representing the total amount of forces is controlled by a parameter that can be set and retrieved with the following methods void setLinkLengthWeight float weight float getLinkLengthWeight The default value is 1 Increasing this parameter can help obtain link lengths closer to the specified length but increasing too much can increase the number of link crossings Additional Node Repulsion Weight An additional repulsion force can be computed between nodes that are not connected by a link The weight of this force representing the total amount of forces is controlled by a parameter that can be set and retrieved using the following methods void setAdditionalNodeRepulsionWeight float weight float getAdditionalNodeRepulsionWeight The default value of this parameter is 0 that is by default this force is not computed Setting this weight to some small values for instance 0 2 that is one fifth of the default link length weight can help avoid overlaps between nodes that are not connected by links The following pictures allow
515. vel It determines the order of the nodes within each level by analyzing where the node touches the reference line For instance if the flow direction is towards the bottom it determines from the x coordinate of the nodes how they are ordered within the levels If long links span several levels the algorithm can preserve the shape of a long link It determines the point where a link crosses the level reference line It creates a bend point for the long link inside the level It tries to preserve the order of the bend points in each level For instance if in a flow direction towards the bottom a long link bypasses another node on the right side then the incremental layout tries to find a similar shape of the link that bypasses the node on the right side as illustrated in Figure 4 78 Finally the layout tries to calculate the absolute positions of the nodes that respect the levels and the ordering within the levels It tries to balance the node positions However it also tries to place each node close to its previous position Both criteria often compete with each other because in order to get a perfect balance nodes must sometimes move far from their original position The Hierarchical Layout contains a parametrized heuristic to satisfy both criteria ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 163 r lt gt gt 3 HIERARCHICAL LAYOUT 164 Figure 4 78 Incremental Layout Phases
516. verlapping nodes cannot always be avoided Nevertheless the layout algorithm often produces a drawing with no overlapping nodes Brief Description of the Algorithm This algorithm implements a relatively simple version of the Spring Embedder which is a well known force directed layout algorithm based on an analogy between graphs and mechanical systems Nodes correspond to point masses and links correspond to springs Attractive and repulsive forces between each pair of nodes are defined depending on the distance between the nodes and on the connectivity of the graph The algorithm searches for a sort of minimal energy configuration of the graph iteratively computing the positions of the nodes Code Sample Below is a code sample using the IlvSpringEmbedderLayout class import ilog views import ilog views graphlayout import ilog views graphlayout springembedder IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher Fill in the grapher with nodes and links here IlvSpringEmbedderLayout layout new IlvSpringEmbedderLayout layout attach grapher try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code 74 ILOG JVIEwS GRAPH LAYOUT 5 5 USER S MANUAL SPRING EMBEDDER LAYOUT catch IlvGraphLayoutException e System err println e
517. void setLinkStyle int style The valid values for style are IlvUniformLengthEdgesLayout NO RESHAPE STYLE None of the links is reshaped in any manner IlvUniformLengthEdgesLayout STRAIGHT LINE STYLE All the intermediate points of the links if any are removed This is the default value Note If STRAIGHT LINE STYLE is selected the layout algorithm may raise an IlvInappropriateLinkException when the layout is performed on an 11vGrapher and links that cannot be given a straight line shape are used Such links are IlvOneLinkImage IlvDoubleLinkImage IlvOneSplineLinkImage and IlvDoubleSplineLinkImage You can use the method EnsureAppropriateLinkTypes orEnsureAppropriateLinks defined in IlvGraphLayoutUtil fo automatically replace inappropriate links This can be done before layout or when the 11vInappropriateLinkException is caught For details on these methods see the ILOG JViews Graph Layout Reference Manual For details on the graph model see Using the Graph Model on page 297 To obtain the current choice use the following method int getLinkStyle Number of Iterations The iterative computation of the layout algorithm is stopped if the time exceeds the allowed time see Allowed Time on page 22 or if the number of iterations exceeds the allowed number of iterations To specify this number use the method void setAllowedNumberOfIterations int it
518. w in a uniform direction Q E 5 gt m lt S o 2 e ilog views graphlayout link layout algorithm that reshapes the links of a graph without moving the nodes ilog views graphlayout link longlink For long orthogonal links ilog views graphlayout link shortlink For short links e ilog views graphlayout multiple A facility that combines multiple layout algorithms into one graphic object e ilog views graphlayout random layout algorithm that moves the nodes of the graph at randomly computed positions inside an user defined region e ilog views graphlayout recursive layout algorithm that can be used to control the layout of nested graphs containing subgraphs and intergraph links e ilog views graphlayout springembedder A layout algorithm that can be used to lay out any type of graph e ilog views graphlayout topologicalmesh layout algorithm that can be used to lay out cyclic graphs e ilog views graphlayout tree layout algorithm that arranges the nodes of a tree horizontally or vertically starting from the root of the tree A radial layout mode allows you to arrange the nodes of a tree on concentric circles around the root of the tree e ilog views graphlayout uniformlengthedges A layout algorithm that can be used to lay out any type of graph and allows you to specify the length of the links ilog views graphlayout labellayout A layout algorithm for automatic
519. w route is searched for the links that are no longer on the grid or that overlap with nodes The shape and the connection side of the rerouted links can change completely However links that are already on the grid and do not overlap nodes or other links are not rerouted in incremental mode It is also possible to specify which link must be rerouted by the next incremental layout even though the layout has not changed To select an individual link to be used for incremental rerouting use the following method G JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL LINK LAYOUT void markForIncremental Object link Intergraph Link Routing A nested graph is a graph with nodes that are subgraphs In a nested graph normal links and intergraph links can occur see Nested Managers and Nested Graphers in the ILOG JViews Graphics Framework User s Manual Normally both end nodes of a link belong to the same subgraph Intergraph links are those links whose end nodes belong to different subgraphs Intergraph links belong to the lowest common grapher in the nesting structure that contains both end nodes Figure 4 93 shows a nested graph with blue normal links and red intergraph links Figure 4 93 Nested Graph With Normal Links blue and Intergraph Links red By default the Link Layout routes only the normal links of a graph But it can route intergraph links as well To enable intergraph link routing call layout setInterGraphLinksMode true If the int
520. ween the corresponding clusters The Circular Layout algorithm is designed for the case where the graph obtained in this manner is a tree that is a graph with no cycles If cycles exist the layout is performed using a spanning tree of the graph Starting from a root cluster either a ring or a star the clusters that are connected to the root cluster are drawn on a circle that is concentric to the root cluster The radius of the circle is computed to avoid overlapping clusters Next the algorithm lays out the clusters connected to these last clusters on a larger circle and so on Each circle is called a level For networks that are not connected that is disconnected groups of clusters exist in the graph more than one spanning tree exists Each spanning tree is laid out separately and placed near the others You can see this in the sample drawings in Samples on page 238 In the clustering mode SUBGRAPHS each subgraph cluster keeps its initial position The subgraphs can be placed either by a different layout algorithm or interactively Code Sample Below is a code sample using the 11vCircularLayout class import ilog views import ilog views graphlayout import ilog views graphlayout circular IlvGrapher grapher new IlvGrapher IlvManagerView view new IlvManagerView grapher 242 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL CIRCULAR LAYOUT IlvCircularLayout layout new IlvCircularLayout la
521. wing method is provided boolean supportsLayoutOfConnectedComponents Layout Region Some layout algorithms can control the size of the graph drawing and can take into account a user defined layout region For example for some layout algorithms you can specify that the layout should fit a given rectangle within a manager view or that it should fit the entire manager view ILOG JViews allows you to specify a layout region in three different ways As the visible area of a given manager view the argument view usually the view that is used for displaying the grapher void setLayoutRegion IlvManagerView view Asarectangle the argument rect with the dimensions being given in manager view coordinates the argument view usually the view that is used for displaying the grapher void setLayoutRegion IlvManagerView view IlvRect rect Asarectangle the argument rect with the dimensions being given in manager view coordinates void setLayoutRegion IlvRect rect You can use the last method if you want to perform the layout with no manager view attached to the grapher or if you want to define the layout region in manager coordinates You can obtain the current layout region setting using the following method ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 25 m 07 v O 5 a LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT IlvRect getSpecLayoutRegion This method returns a co
522. with siblings directly neighbored to each other Tip over alignment means a sequential arrangement of the children instead Normal Alignment Tip Over Alignment Figure 4 34 Normal Alignment and Tip over Alignment Tip over alignment is useful when the tree has many leaves With normal alignment a tree with many leaves would result in the layout being very wide If the global alignment style is set to tip over the drawing is very tall rather than wide To balance the width and height of the drawing you can set the global alignment to mixed layout setGlobalAlignment IlvTreeLayout MIXED 108 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL TREE LAYOUT Also you can set the individual alignment to tip over for some parents with a high number of children as follows layout setAlignment parent IlvTreeLayout TIP OVER Tip over alignment can be specified explicitly for some or all of the nodes Furthermore the Tree Layout offers layout modes that automatically determine when to tip over yielding a drawing that fits into a given aspect ratio These layout modes are described in Tip Over Layout Modes on page 126 Besides the normal tip over alignment there is also a variant that distributes the subtrees on both sides of the center line that starts at the parent You can specify this variant at a parent node with a high number of children as follows layout setAlignment parent IlvTreeLayout TIP OVER BOTH SIDES T
523. withDefaults return new MyOwnLayoutNodeProperty name this node withDefaults protected IlvGraphLayoutLinkProperty createLayoutLinkProperty String name IlvGraphic link boolean withDefaults return new MyOwnLayoutLinkProperty name this link withDefaults Further Applications of Layout Properties The layout properties can be serialized If you prefer to use the standard serialization mechanism of Java instead of iv1 files it is recommended to use the layout properties as well because it guarantees that only the parameters are serialized and not any temporary data that may exist in the layout instance The following code shows an easy way to copy the parameter setting from 1ayout1 to layout2 IlvGrapherAdapter adapterl IlvGrapherAdapter layoutl getGraphModel IlvGrapherAdapter adapter2 IlvGrapherAdapter layout2 getGraphModel adapterl saveParametersToNamedProperties layoutl true adapter2 loadParametersFromNamedProperties layout2 The following code shows an easy way to undo temporary changes of layout parameters IlvGrapherAdapter adapter IlvGrapherAdapter layout getGraphModel adapter saveParametersToNamedProperties layout true change layout parameters work with changed parameters restore the layout parameters as they were before adapter loadParametersFromNamedProperties layout Using the Filtering Features to Lay Out a Part of an llvGrapher Note To understand this section be
524. y be the desired result In other situations the user may want to produce different layouts in order to select the best one This can be achieved by performing the layout several times using different seed values Here is an example of how this parameter can be used in combination with the java util Random class in your implementation of the method IlvGraphLayout layout Random random isUseSeedValueForRandomGenerator new Random getSeedValueForRandomGenerator new Random To specify the seed value use the method void setSeedValueForRandomGenerator long seed and to obtain the current value long getSeedValueForRandomGenerator The default value is 0 Note The user defined seed value is used only if you call the method void setUseSeedValueForRandomGenerator boolean option withatrue argument You can read the current option using the method boolean isUseSeedValueForRandomGenerator To indicate whether a subclass of I1vGraphLayout supports this parameter the following method is provided boolean supportsRandomGenerator The default implementation returns alse A subclass can override this method in order to return true to indicate that this parameter is supported Save Parameters to Named Properties The base class 11vGraphLayout provides support for saving the layout parameters such as isAnimate or isMemorySavings to 1 files or to transfer the parameters to named properties This
525. y potential positions for one label the automatic label placement algorithm should find the best position for the label so that itis close to its graphic object not too close to unrelated objects and not overlapped by any obstacle Labels occur in many application areas diagrams geographic maps charts and so on ILOG JViews labeling can be applied to all these areas that is it is not restricted to placing labels in a graph For instance if you want to place labels at the cities in a geographic map you can use the Annealing Label Layout algorithm with appropriate point label descriptors For simplicity we focus in this Getting Started section on placing labels at links in a graph In ILOG JViews graphic objects subclasses of 11vGraphic are contained in a manager 1ilvManager and graphs are managed by graphers 11vGrapher which is a subclass of IlvManager Because the ILOG JViews Label Layout algorithms can be applied not only to graphs but also to any graphic objects the algorithms work on 11vManager Consequently a label layout algorithm is not a subclass of 11vGraphLayout and does not use an I1vGraphModel JViews provides a label layout framework that is despite many similarities completely independent from the graph layout framework The label layout framework distinguishes simply between graphic objects called labels that must be placed and graphic objects called obstacles that must not move but occupy space th
526. you are using the class I1vTopologicalMeshLayout Subclasses of IlvGraphLayoutReport are used to store layout algorithm dependent information ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 19 LAYOUT PARAMETERS AND FEATURES IN ILVGRAPHLAYOUT You must call the method performLayout inside a try block because it can throw an exception The exception can be of the type 11vGraphLayoutException or one of its subclasses IlvInappropriateGraphException and IlvInappropriateLinkException The first indicates internal problems in the layout algorithm or an unexpected situation The second exception indicates that a particular grapher cannot be laid out with the layout algorithm For example the Topological Mesh Layout cannot be used on an acyclic graph that is a pure tree The third exception indicates that a particular type of link or link connector cannot be used for this layout The recommended type of linkis IlvPolylineLinkImage Or IlvSplineLinkImage or subclasses For layouts that do not reshape the links by adding intermediate points the class IlvLinkImage can also be used Detaching a Grapher You call the detach method when you no longer need the layout instance of an attached grapher If the det ach method is not called some objects may not be garbage collected This method also performs cleaning operations on the grapher properties that may have been added by the layout algorithm on the grapher s objects are removed vo
527. yout Time This field contains the total duration of the layout algorithm at the end of the layout To read the time in milliseconds use the method long getLayoutTime Percentage of Completion This field contains an estimate of the percentage of the layout that has been completed To access the percentage use the method int getPercentageComplete Layout Events and Listeners The label layout framework provides the same event mechanism as the graph layout framework The following events may occur LabelLayoutEvent corresponds to GraphLayoutEvent see Layout Event Listeners on page 294 You can install a listener to these events at the layout instance by labelLayout addLabelLayoutEventListener listener The listener must implement the LabelLayoutEventListener interface and receives events while the layout is running A typical example is to check how much of the layout has already completed class MyLabelLayoutListener implements LabelLayoutEventListener public void layoutStepPerformed LabelLayoutEvent event IlvLabelLayoutReport layoutReport event getLayoutReport System out println percentage of completion layoutReport getPercentageComplete ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL THE BASE CLASSES ILVLABELINGMODEL AND ILVLABELLAYOUT LabelLayoutParameterEvent corresponds to GraphLayoutParameterEvent see Parameter Event Listeners on page 295 Yo
528. yout attach grapher Fill in the grapher with nodes and links here create identifier for cluster 0 IlvClusterNumber clusterId new IlvClusterNumber 0 specify the cluster identifier for cluster 0 Assume there are three nodes nodel node2 node3 the ordering of the nodes nodel node2 node3 layout setClusterId nodel clusterId 0 index 0 layout setClusterId node2 clusterId 1 index 1 layout setClusterId node3 clusterId 2 index 2 create identifier for cluster 1 clusterId new IlvClusterNumber 1 specify the cluster identifier for cluster 1 Assume there are three nodes node4 node5 node6 the ordering of the nodes node4 node5 node6 layout setClusterId node4 clusterId 1 index 1 layout setClusterId node5 clusterId 2 index 2 layout setClusterId node6 clusterId 0 index 0 try IlvGraphLayoutReport layoutReport layout performLayout int code layoutReport getCode System out println Layout completed layoutReport codeToString code catch IlvGraphLayoutException e System err println e getMessage Generic Features and Parameters The 11vCircularLayout class supports the following generic parameters as defined in the IlvGraphLayout class r lt c gt e gt 3 Layout of Connected Components Layout Region Link Clipping Link Connection Box Preserve Fixed Lin
529. yout class 214 setT setTerminationPointFilter method IlvLongLinkLayout class 214 setting a maximal children angle Tree Layout 125 setting even spacing for the first circle Tree Layout 124 setting invisible root node parameter Tree Layout 124 setTipOverBranchOffset method IlvTreeLayout class 117 setTopMargin method IlvGridLayout class 263 setToPortIndex method IlvHierarchicalLayout class 156 setToPortSide method IlvHierarchicalLayout class 154 156 setTowardsPreferredPosition method IlvAnnealingLabelDescriptor class 375 setU setUseDefaultParameters method IlvGraphLayout class 36 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL 445 INDEX setV setVerticalAlignment method IlvBusLayout class 233 IlvGridLayout class 260 rticalGridBase method ongLinkLayout class 205 rticalGridOffset method GridLayout class 262 ongLinkLayout class 205 rticalLinkOffset method HierarchicalLayout class 160 rticalMinOffset method LongLinkLayout class 205 rticalNodeLinkOffset method HierarchicalLayout class 160 rticalNodeOffset method HierarchicalLayout class 160 r B Yi se se se se se se ticaloffsetToLevel method usLayout class 235 ticalOffsetToPreviousLevel method BusLayout class 235 se se tH GR A A AT FA CV rA Pt setW setWestEastNeighboring method IlvTreeLayout class 130 S continued short link mode Link Layout
530. yout is saved without its parameters Therefore after loading the iv1 file the preferred layout will have in this case the default values for all its parameters e withDefaults the flag has the same meaning as for the method saveParametersToNamedProperties e traverse if the flag is true the method applies recursively to the subgraphs Otherwise the method saves only the preferred layout of the grapher adapter on which the method is called The following code example shows how to save the preferred layouts to iv1 files IlvGrapher grapherA new IlvGrapher IlvGrapher grapherB new IlvGrapher fill the graphers with nodes and links grapherB is added as a subgraph of grapherA grapherA addNode grapherB false Create the grapher adapter for the topmost graph IlvGrapherAdapter adapterA new IlvGrapherAdapter grapherA Get a grapher adapter for the subgraph IlvGraphModel adapterB adapterA getGraphModel grapherB create the layout provider IlvDefaultLayoutProvider provider new IlvDefaultLayoutProvider specify the preferred layouts for each grapher this automatically attaches the layouts provider setPreferredLayout adapterA new IlvTreeLayout soJnjeoaJj e o 5 gt 2 lt 5 o ILOG JViEWS GRAPH LAYOUT 5 5 UsER s MANUAL 317 SAVING LAYOUT PARAMETERS AND PREFERRED LAYOUTS 318 provider setPreferredLayout adapterB new IlvGridLayout
531. yout parameters are local to specific nodes or links For instance in IlvHierarchicalLayout the method setGlobalLinkStyle style is a global layout parameter while the method set LinkStyle link style is local layout parameter If you need to set layout parameters that are local to an individual node or link you need to access the particular clone of the reference layout that is responsible for the subgraph that owns the node or link After attaching the Recursive Layout to the top level grapher or graph model you can retrieve the layout instance of a specific subgraph by IlvGraphLayout getLayout Object subgraph However in reference layout mode it makes no sense to modify any global layout parameter on the returned instance The global layout parameters are always taken from the reference layout only If you pass nu11 as subgraph you get the layout instance of the top level graph This is actually the same layout instance as the reference layout The reference layout and its clones used during recursive layout remain attached to the subgraphs or the graph models of the subgraphs respectively as long as the Reference Layout itself is attached When detaching the Reference Layout all layouts of subgraphs are automatically detached as well Internal Provider Mode r lt gt gt 3 This mode should be used if you want to perform graph layout on a nested graph but either you need in
532. youts on page 315 Stop Immediately The layout algorithm stops after cleanup if the method stopImmediately is called For a description of this method in the 11vGraphLayout class see Stop Immediately on page 35 If the layout stops early because the allowed time has elapsed the nodes and links are not moved from their positions before the layout call and the result code in the layout report is I1vGraphLayoutReport STOPPED AND INVALID Specific Parameters The following parameters are specific to the IlvHierarchicalLayout class Flow Direction The flow direction parameter specifies the direction in which the majority of the links should point If the flow direction is to the top or to the bottom the node levels are oriented horizontally and the links mostly vertically If the flow direction is to the left or to the right the node levels are oriented vertically and the links mostly horizontally If the flow direction is to the bottom the nodes of the level with index 0 are placed at the top border of the drawing The nodes with level index 0 are usually the root nodes of the drawing that is the nodes without incoming links If the flow direction is to the top the nodes with level index 0 are placed at the bottom border of the drawing If the flow direction is to the right the nodes are placed at the left border of the drawing 142 ILOG JViEWS GRAPH LAYOUT 5 5 USER S MANUAL HIERARCHICAL LAYOUT Flow to Right

ILOG JViews 5.5 Graph Layout User's Manual

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