Windows Shell Programming
Contents
1. 12 Whatis the Windows Shell The Windows shell is nothing like the UNIX or the DOS shells With UNIX shells and their command line interfaces CLI users have to know that a feature exists before they can use it Compare this to the Windows shell which can advertise new features to the user For example let us look at how a user would go about opening a JPEG file To view the picture with a com mand line interface users have to know that they need a graphics viewer to 2 If you have no UNIX experience think back to the days of MS DOS Now imagine a lot more expressiveness and power on the command line o chol 5 10 00 1 15 PM Page 4 Chapter 1 p Windows Shell Programming look at the file and how to start a viewer Windows provides hooks that allow the viewer application to advertise its association with the JPEG files When users select a file with the right mouse button Windows will reveal a menu allowing them to view move or possibly even translate the file to another graphics format They discover these capabilities simply by knowing that a right mouse click will tell them what they can do with the file This circum vents the need to tell the users about all the different programs available for file manipulation The Windows shell provides the means to interact with the computer The shell is composed of the following elements The Desktop When Windows starts up this is the first thing a user sees2. Shlwapi dll on a system does not guarantee that Shell32 dll has the same version number All W indows 98 systems have version 4 72 of Shell32 dll Version 5 80 of Comct32 dll and version 5 0 of Shlwapi dll are distributed with Internet Explorer 5 They will be found on all systems on which Internet Explorer 5 is installed ex cept W indows 2000 Internet Explorer 5 does not update the shell so version 5 0 of Shell3 2 dIl will not be found on W indows NT W indows 95 or W indows 98 systems Version 5 0 of Shell32 dll will be distributed with W indows 2000 along with version 5 0 of Shlwapi dll and version 5 81 of Comct32 dll 15 Summary Chapter 1 outlines what the book is about and where to find information on the various extensions I have tried to make each chapter independent of the others and I have cross referenced other sections as needed Chapters 9 through 11 break this rule because namespace extensions make for bigger projects than things like context menu extensions Section 1 4 outlined the versions of the shell and how to get them to your users This book covers a lot of the shell but you may discover that pieces are missing Before you send me an e mail flaming me for incompetence poor upbringing or anything else check out the Prentice Hall Web site at www phptrcom or visit my site at wwwsscoottseely com These sites are up dated regularly so if neither contains the new information you have uncov ered e mail me to let me
3. The Taskbar The taskbar provides a clock a way to start applica tions and a place for applications to notify the user about program activity With Active Desktop installed the taskbar can contain tool bars beyond the standard task list The Control Panel The Control Panel provides a single location to configure devices and programs on the computer Besides the abil ity to add applets to the Control Panel some of the packaged Con trol Panel applets allow third parties to add extra property pages Internet Explorer Like it or not Microsoft has made the browser part of the shell For some time now we have been able to view drives across the network as if they were on the local machine It is easy to see the benefits of viewing FIP sites the same way The only stretch happens when looking at hyperlinks Hyperlinks and HTML documents allow us to navigate to new directories and files by clicking on links in files This navigational model seems as valid as the hierarchical file systems we use on a daily basis Because of the spider web that HTML documents produce browsers present the best known way to navigate these documents Integrating the browser allows Internet Explorer to be the ultimate in common file type navigation Windows Explorer Windows Explorer allows us to navigate what ever information is presented on our machines It provides the abil ity to move files around drop files on other files and display infor mation regardi
4. to under stand the shell There is a need to explain these things more clearly than the Microsoft Developer Network does 2 Show how to use MFC and ATL to enhance the shell The book targets a specific group of developers those who use Visual C as their development tool of choice Consequently I have a responsibility to show the readers how to develop solutions that leverage what they already know For example if something displays a window the reader wants to know how to use a CWnd to handle the message loop 3 Speed up development time This book targets programmers who have projects to complete as fast as possible Many of them will not even read an entire chapter unless they have problems that they can not figure out For some readers the most valuable part of the book will probably be the included CD To them the book is nothing more than a user manual for that CD Because I went the extra step to see how to create generic solutions I forced myself to understand the technology outside the scope of my current sample project Many of the libraries and wizards presented in the book take the unfamiliar Windows shell and mold it to the world of the MFC ATL devel oper C is an extremely pliant language and will let you do almost any thing Together MFC ATL and C allow you to do amazing things Using them along with the libraries and wizards in this book the reader will realize the benefits of learning the ins and outs of MFC
5. 8 Chapter 9 Namespace Extensions Starting with this chapter and continuing through Chapter 11 I departed from the rule of one topic per chapter Developing a namespace extension can be as complex as developing a full scale application As a result I chose to sepa rate the subject matter into distinct chapters When a namespace extension is activated it assumes a lot of control over Explorers menus toolbars and right hand pane You have to make a lot of design decisions and understand user expectations This chapter goes into detail explaining the interaction be tween Explorer and an extension It then explains what a user will expect from a full featured namespace 7 I would really appreciate a cleanup handler from the Visual Studio team that would delete all the PCH SBR OBJ APS PLG and OPT files from the hard drive o chol 5 10 00 1 15 PM Page 9 g 1 3 Chapter Summaries 9 1 3 9 Chapter 10 Tools to Build a Namespace Extension Once the interaction and design of a namespace extension has been ex plained Chapter 9 we need to make the whole experience of building a namespace something easier to do For example I have no desire to build menus the way I would for context menu handlers I would rather handle these by building them using the Visual Studio menu editor This chapter ex plains a library and wizard that allow quick creation of a namespace exten sion Along the way I explain why I chose one design over an
6. ard Building an applet using the wizard 1 3 4 Chapter 5 Screen Savers Screen savers do so much more than entertain and delight bored work ers They also help extend the life of a monitor lock up a computer when the user is away and hide what one was working on when called away from the machine This chapter presents a library that is feature compatible with 5 This is the little window on the taskbar that the clock lives in 6 MMC Snap ins are not part of the shell Thankfully wizards and libraries are pro vided for them in Visual C o chol 5 10 00 1 15 PM Page 7 p 1 3 Chapter Summaries 7 SCRNSAVE LIB with an added benefit you can use MFC to do all your work Chapter 5 covers the following topics Screen saver responsibilities Screen saver internals Benefits of SCRNSAVE LIB over writing your own An MFC Screen Saver App wizard Writing a screen saver using the wizard 1 3 5 Chapter 6 File Viewers A file viewer presents a read only view of the file You can look at and some times even print the file but you cannot do anything else to the file Viewers exist for most Microsoft documents including Word Excel and PowerPoint You can also find them for viewing other file types including bitmaps text files and executables DLLs and EXEs Chapter 6 covers these topics File viewer basics when to create a viewer how to invoke one etc File viewer internals A File Viewer library wi
7. ch01 5 10 00 1 15 PM Page 1 Windows Shell Programming ith each operating system release service pack and Internet Explorer upgrade Microsoft adds more possibilities for vendors to extend and enhance the Windows user interface This has been the case with earlier versions of Windows through its latest release Windows 2000 The first version of Windows many of us did any serious development for was Windows 3 x With the 3 x versions you could add limited modifications to the shell Control Panel applets Screen savers File manager extensions The early file manager extensions allowed developers to only add menu items and toolbar buttons On any given Windows installation a computer could have up to five extensions installed A lot of time has passed since then and the developers at Microsoft have continued to enhance the extensi bility of the shell With Windows 2000 the shell still allows you to write your own Control Panel applets and screen savers but you can also do more much more For example you can Customize the Windows taskbar Add extra menu options when right clicking on a file Add advanced handling of folders drives and printers Handle new data formats when a file is copied and pasted Allow specialized actions when a file gets dropped on a file type Monitor copying of folders drives and printers Add your own views of data in Windows Explorer 1 o chol 5 10 00 1 15 PM Page 2 F Chapter 1 Window
8. he operation 7 7 Drag and Drop Handler A context menu handler that the shell calls when the user drops an object after dragging it to a new posi tion 7 8 1 3 7 Chapter 8 Disk Cleanup Handlers Today s large hard drives allow us to install many programs and store thou sands of files Because of all this space most of us do not actively clean up anymore If an application leaves temp files strewn about our machines we will not notice the decline in space for months Other programs such as web browsers cache web pages to speed up perceived download times As a re sult the task of maintaining one s hard drive has become very difficult To address the problem Microsoft introduced disk cleanup handlers with Win dows 98 As a developer you have a responsibility to provide a handler for any application you create that leaves behind temporary or unnecessary files A handler also comes in handy when an application that you think is well be haved uses temporary files Many applications will leave these behind if the computer loses power A handler can clean up part of the resulting mess Most sizable applications need a cleanup handler On any non trivial project make sure you include development time for one of these Chapter 8 covers the following topics The Disk Cleanup Utility and its relationship to disk cleanup han dlers The various interfaces employed by disk cleanup handlers and how they work An example program 1 3
9. know what I ve missed The first person to name any missing feature will be named on the Web site and in the acknowledge ments section of the next revision of this book I will list your name unless you ask me not to and the item you caught to acknowledge your contribu tion I apologize for not covering everything in the shell this first go around Microsoft has updated the shell seven times in five years I had to decide to leave out some minor features Now go extend the shell
10. livers these clarifying notes Note 1 The 4 00 versions of Shell32 dll and Comct32 dll are found on the original versions of W indows 95 and W indows NT 4 N ew versions of Commct dll were shipped with all Internet Explorer releases Shlwapi dll first shipped with Internet Explorer 4 0 so its first version number is 4 71 The shell was not updated with the Internet Explorer 3 0 release so Shell3 2 dll does not have a version 4 70 W hile Shell32 dll versions 4 71 and 4 72 were shipped with the corresponding Internet Explorer releases they were not necessarily installed see N ote 2 For subsequent releases the version numbers for the three DLs are not identical In general you should assume that all three DLs may have different version numbers and test each one separately 10 From MSDN Article Title Shell and Common Controls Versions o ch01 5 10 00 1 15 PM Page 11 F Note 2 Note 3 1 5 Summary 11 All systems with Internet Explorer 4 0 or 4 01 will have the associated version of C om ct32 dll and Shlwapi dll 4 71 or 4 72 respectively However for systems prior to W in dows 98 Internet Explorer 4 0 and 4 01 can be installed with or without the integrated shell If they are installed with the integrated shell the associated version of Shell32 dll will be installed If they are installed without the integrated shell Shell32 dll is not up dated In other words the presence of version 4 71 or 4 72 of Comct32 dll or
11. n icon in the tray 1 3 2 Chapter 3 Application Desktop Toolbars The best known application desktop toolbar or appbar is the taskbar The first runner up in popularity is the Microsoft Office Shortcut Bar Appbars pro vide a nice way to present information without getting in the users way They usually dock to one of the edges of the desktop and sit there The user can even make them automatically hide themselves so that they take up al most no space on the screen Chapter 3 covers the following topics Guidelines for creating appbars Explanation of how appbars work Explanation of AppBarlib and the MFC Application Desktop Tool bar AppWizard How to use the tools presented to build an appbar of your own 1 3 3 Chapter 4 Control Panel Applets The Control Panel provides a place to put any utilities for configuring hard ware or software For example you would place applets to configure a ser vice or fax machine there People expect to find the configuration utility for background processes and hardware in the Control Panel Microsoft also has a new utility out the Microsoft Management Console If your configuration user interface works best in a dialog write an applet Otherwise write an MMC snap in Chapter 4 covers the following items How to decide if the Control Panel is an appropriate place to put your applet Ways of packaging Control Panel applets Control Panel basics Motivation and design of a Control Panel applet wiz
12. ng files among other things If you want to add something that is not file related you can do so by extending Ex plorer s capabilities File Viewers The people at Microsoft will cringe when they see this because the feature has been removed from the operating sys 3 Specifically these are the display keyboard and mouse applets 4 See Chapter 9 for how to customize Explorer o chol 5 10 00 1 15 PM Page 5 g 1 3 Chapter Summaries 5 tem as of Windows 98 SE Still Windows 95 98 and Windows NT 4 0 all provide hooks that allow vendors to distribute DLLs which present a read only view of a file Typically users can distribute the viewer without risk of copyright or licensing violations Disk Cleanup Starting with Windows 98 the shell provides a jani tor named CLEANMGR EXE Applications can provide the janitor with instructions on how to free up space on the local hard drives This way when users need more space they do not have to start by deciding which files they should get rid of Instead the janitor gets rid of all the truly useless stuff first The Registry The entire registry is not a part of the shell although two parts of the registry do a significant job of customizing the user s interaction with Windows HKEY CURRENT USER HKCU and HKEY LOCAL MACHINE HKLM Because of this the shell team has created a number of functions that make it easier for pro grams to interact with those two hives 13 Chapte
13. nology it should also make it easier to use that technology For ex ample I have a few fairly popular C books Effective C by Scott Meyers More Effective C by Scott Meyers Large Scale C Software Design by John Lakos C FAQs by Marshall Cline and Greg Lomow The C Programming Language by Bjarne Stroustrup I have learned more from the first four books than from the fifth which was written by the inventor of the language Do not get me wrong Stroustrup s text has helped me around syntactical errors but the others have given me tools to write better code faster I will try to show how to write good code that uses and enhances the Windows shell In order to accomplish this I pro vide a lot of fully functional examples as well as what I hope are production quality libraries and wizards to make your life easier 1 Stroustrup has written many articles and USENET posts that will help you use the language better However The C Programming Language is just a language refer ence not a how to do it better kind of book o chol 5 10 00 1 15 PM Page 3 g 1 2 What is the Windows Shell 3 In the following pages I want to accomplish a number of things 1 Explain how the shell works and what opportunities for en hancement are available The first thing the reader expects from this book is that it will explain the shell in detail This means going over many of the interfaces functions and other items needed
14. om the SDK version 9 The desktop update did not ship with Internet Explorer 5 0 as an installable com ponent o ch01 5 10 00 1 15 PM Page 10 10 Chapter 1 Windows Shell Programming Radio Bars You can add extra toolbars to the top of Intemet Ex plorer and Windows Explorer to do whatever you want them to do HTML Based Bands Microsoft implemented an HTML capable band object This band object allows you to display HTML by sim ply writing a REG script and some HTML 14 Versions of the Shell In order to use the content in chapters 6 through 12 and the appendices ef fectively you must be cognizant of the shell version your application works with Your user will be able to use pretty much anything you write as long as they are running version 4 72 of the shell distributed with Internet Explorer 4 01 and Internet Explorer 4 0 SP1 In the past Microsoft has bundled interim shell updates with Internet Explorer not as a separate package The grid below shows the various versions of the shell and gives you an idea of how to upgrade your users to the correct version Version DLL Distribution Platform 4 00 All Windows 95 NT 4 0 4 70 All Internet Explorer 3 x 4 71 All Internet Explorer 4 0 4 72 All Internet Explorer 4 01 and Windows 98 5 00 Shlwapi dll Internet Explorer 5 5 00 Shell32 dll Windows 2000 5 80 Comctl32 dll Internet Explorer 5 5 81 Comctl32 dll Windows 2000 Along with the preceding table Microsoft de
15. other so that you have more insight as you debug your own namespaces 1 3 10 Chapter 11 Namespace Extension Example The Registry This chapter covers the design and construction of a namespace extension that contains many of the capabilities found in REGEDIT It also covers all the decisions I had to make What should I put into the Explorer menu What buttons should show up in the toolbars What should the context menus look like What data should I display 1 3 11 Chapter 12 Explorer Bars and Desktop Bands Way back in Chapter 2 I explained how to manipulate the taskbar but avoided the topic of adding extra band objects The topic really deserves sep arate treatment because of the breadth of things you can do Using band ob jects you can add the following types of toolbars Desk bands These augment the toolbars available in the taskbar They are only available when Active Desktop has been installed This feature is included with Windows 98 2000 and courtesy of In ternet Explorer version 4 x and Active Desktop Comm Bands These display information at the bottom of Internet Explorer and Windows Explorer Only one comm band can display at any given time Explorer Bands These display on the left hand side of Internet Explorer and Windows Explorer Only one explorer band can dis play at any given time 8 This example has a few more capabilities than the SDK registry namespace exten sion example and takes nothing fr
16. r Summaries My aim was to present each topic so that it stands on its own You should be able to go to any one chapter and find all the information you need to get your job done The only required reading in this book is this chapter and the chapter that covers your topic unless your topic is namespace extensions A namespace extension can be a fairly complex beast As a result that topic is split into three chapters one to explain namespace extensions one to docu ment the library and wizard I wrote and one to design and create an exten sion Furthermore in each chapter I reference the related material found in the appendices and other chapters as needed For example many of the shell customizations require you to implement the COM interface IcontextMenu so whenever IContextMenu enters the discussion I reference section 7 2 Each of the following sections describes a chapter in the book and what extending the shell in that area can do 1 3 1 Chapter 2 The Taskbar This chapter explains how to manipulate the taskbar It teaches how to do the following Get information about the taskbar location size auto hide always on top Add and remove taskbar buttons which can either increase or de crease the number of applications that appear to be running Add and remove links on the Start menu o ch01 5 10 00 1 15 PM Page 6 p 6 Chapter 1 Windows Shell Programming Add icons to the system tray It also shows how to animate a
17. s Shell Programming Add various types of toolbars to Windows and Internet Explorer Allow the shell to do work for you in your own applications such as filename auto completion Looking at the list it should be clear that the shell is no longer a simple windowing environment We can customize Windows as we see fit and Mi crosoft gives us this ability at a price they increase the chance of Windows instability This level of customization makes it such that no two installations of Windows ever remain the same for very long As the user installs more ap plications on their machine the shell gains new capabilities and features A few applications will add items to the system tray clock area on the taskbar Another may add items to a context menu in Explorer If the machine sud denly or worse slowly becomes unstable the user will not blame the peo ple at Foobar Inc for a bad shell extension To the user all of the right click functionality drag and drop capabilities and Explorer enhancements are part of the operating system so Microsoft will be blamed for shoddy workman ship This means that we have a responsibility to create stable additions so that people continue to trust Microsoft operating systems with their corporate and personal data Failing to do so may lead Microsoft to remove our ability to customize the shell 11 Goals of this Book It is my belief that a book on a specific technology should not just explain the tech
18. zard A sample file viewer 1 3 6 Chapter 7 Shell Extensions If you want to find out how to set what users will see and what they can do within Windows Explorer check out this chapter You can also do some in teresting things to the folders printers and drives attached to the machine Chapter 7 explains the following items Extensions registered by file type a k a class Context Menu Handler Adds items to the context menu a k a right click menu for a file object You may add verbs and other ac tions for a file type 7 2 Icon Handler Typically used to add icons specific to the file ob ject You can also use this to add icons for all files belonging to the same class 7 3 Data Handler Provides an DataObject interface for a specific class type The shell passes this interface to the OLE DoDragDrop func tion 7 4 Drop Handler Provides drop behavior for files that can accept drag and drop objects 7 5 Property Sheet Handler Adds pages to the property sheet that the shell displays for a given file type You can also extend items such as the Display Properties dialog using a property sheet handler 7 6 Extensions associated with file operations and directories move copy rename etc o ch01 5 10 00 1 15 PM Page 8 p 8 Chapter 1 Windows Shell Programming Copy Hook Handler These get called whenever a folder object is about to be copied moved deleted or renamed The handler can allow or prevent t
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