(GL) Manual - BiPOM Electronics
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1. draw rectangle and flush memory buffer to hardware DrawRectangle sx sy ex ey RenderBuffer delayMs 200 calculate coordinates of the next rectangle sx 10 sy 5 ex Sx 20 ey sy 10 draw the same sequence of rectangles but from the top right corner to down left corner calculate coordinates of the first rectangle ex width 1 ey 10 SX ex 20 sy ey 10 draw 11 rectangles for num 0 num lt 11 num draw rectangle and flush memory buffer to hardware DrawRectangle sx sy ex ey RenderBuffer delayMs 200 calculate coordinates of next rectangle sx 10 sy 5 ex SX 20 ey sy 10 First the function draws rectangles from the top left to the bottom right corners of the screen It calculates the starting point and the ending point coordinates of the first rectangle Then the function draws 11 rectangles in a loop Each new rectangle is moved 10 pixels to the left and 5 pixels to the bottom Rectangles are drawn with a little delay Each new rectangle is drawn on the display immediately because directly after DrawRectangle the function calls RenderBuffer 4 CirclesDemo This demo function draws several circles with different foreground colors and line width set to 2 pixels on the first screen Let s look at the code set line width to 2 pixels SetLineWidth 2 num 0 radius 5 while num lt 6 change color mak2. Flush to real hardware RenderBuffer Restore old background color SetBkColor oldBkColor SetColor Sets the foreground color in current graphics context int SetColor COLORREF color new background color Parameters color in New foreground color Return values GL_OK on success GL_ERROR on error Examples Initialize graphics context oe Get current foreground color COLORREF oldColor GetColor Set new foreground color SetColor OLED_4BIT_GRAYSCALE_15 Draw circle DrawCircle 10 10 5 Flush to real hardware RenderBuffer Restore old foreground color SetColor oldColor GetColor Gets the foreground color of the current graphics context COLORREF GetColor void Parameters Nothing Return values Foreground color value of the current graphics context or GL_ERROR if some error occurs Examples See SetColor example SetTextSize Sets the new text size in the current graphics context int SetTextSize int Size new text size Parameters Size in New text size This is one of predefined constants TEXT_SMALL TEXT_MEDIUM TEXT_LARGE Return values GL_OK on success GL_ERROR on error Remarks This version of library has only three text sizes You cannot change font or set any other size Please refer to BIPOM Professional Graphics Library GPL for more sophisticated font support Examples char Msg 32 Hello int text_width
3. 20 RenderBuffer destroy created contexts ShutdownGL hContext1 RenderBuffer Forces driver to copy all the drawn primitives from video RAM buffer to real hardware int RenderBuffer void Parameters Nothing Return values GL_OK on success GL_ERROR on error Notes When you call draw functions like DrawLine DrawCircle etc the driver draws all primitives in driver RAM memory buffer Only when you call RenderBuffer function the memory buffer will copied to the hardware You don t see any changes on the physical display until you call RenderBuffer Examples See InitializeGL example SetPixelWidth Draws pixel with specified width int SetPixelWidth iB int x X coordinate of pixel int y Y coordinate of pixel char width Width of pixel COLORREF color Color of pixel Parameters x y width color in X coordinate of pixel in Y coordinate of pixel in Width of pixel in Color of pixel Return values GL_OK on success GL_ERROR on error Examples Initialize graphics context MET Draw light pixel in point 10 10 SetPixelWidth 10 10 1 OLED_4BIT_GRAYSCALE_15 Draw light pixel in point 20 20 SetPixelWidth 20 20 2 OLED_4BIT_GRAYSCALE_15 Draw light pixel in point 30 30 SetPixelWidth 30 30 3 OLED_4BIT_GRAYSCALE_15 Flush to real hardware RenderBuffer The pictures below illustrate how the pixels will be drawn SetPixe
4. yp GreetingsMsg1 draw 2nd line of text calculate coordinates of start point of text to center the text on screen text_width GetTextWidth GreetingsMsg2 xp width 2 text_width 2 yp height 3 DrawText xp yp GreetingsMsg2 draw 3rd line of text calculate coordinates of start point of text to center the text on screen text_width GetTextWidth GreetingsMsg3 xp width 2 text_width 2 yp height 3 2 DrawText xp yp GreetingsMsg3 flush memory buffer to hardware RenderBuffer delayMs 2000 First this function determines the width and the height of the screen It calls two functions GetWidth and GetHeight The screen resolutions are saved into two variables width and height The function use these to place text on the screen Next step is to set foreground and background colors This is done with SetColor and SetBkColor functions Then the function clears the screen by calling ClearDisplay function Also it changes the size of font to TEXT_LARGE The function SetTextSize does this Then the function calculates position of the top left point of text text_width GetTextWidth GreetingsMsg1 xp width 2 text_width 2 yp 0 GetTextWidth function returns a width of the string parameter in pixels The current text size used to determine a width of each symbol Then the function calls DrawText and draws text on the screen at the specified position First line is drawn
5. 0 int xp 0 int yp 0 Get current text size int oldTextSize GetTextSize Get screen sizes int width GetWidth int height GetHeight Set new text size SetTextSize TEXT_LARGE calculate coordinates of start point of text to center the text on screen text_width GetTextWidth Msg xp width 2 text_width 2 yp 0 draw Msg string on the screen DrawText xp yp Msg Flush to real hardware RenderBuffer Restore old text size SetTextSize oldTextSize GetTextSize Gets a text size in the current graphics context int GetTextSize void Parameters Nothing Return values The text size in the current graphics context or GL_ERROR if some error occurs Examples See SetTextSize example GetTextWidth Gets a text string width in pixels depending on the current text size int GetTextWidth const char pText Parameters pText in Pointer to null terminated string Return values The text width in the pixels or GL_LERROR if some error occurs Examples See SetTextSize example SetLineWidth Sets new width of lines in the current graphics context int SetLineWidth int Width new line width Parameters Width in New line width in pixels Return values GL_OK on success GL_ERROR on error Examples Get current line width int oldLineWidth GetLineWidth Set new line width SetLineWidth 3 Draw line from point 5 5 to p
6. 2 points set foreground color ClearDisplay SetLineWidth 2 SetColor OLED_4BIT_GRAYSCALE_15 draw horizontal lines with different color and width ystep y coordinate step between lines xwidth width of each line ystep height 4 xwidth width for num 0 num lt 5 num make color of each next series of line is more dark SetColor OLED_4BIT_GRAYSCALE_15 num 2 ypos 3 num start draw next lines on 3 pixel lower then previous xpos 0 left x start coordinate xwidth width start width while ypos lt height draw line and flush memory buffer to hardware DrawLine xpos ypos xpos xwidth ypos RenderBuffer delayMs 400 calculate start point coordinate and width of next line ypos ystep xpos 10 xwidth 20 delayMs 2000 First the function clears the display and sets the foreground The function SetLineWidth sets the line width to 2 pixels Then the function calculates the distance between lines ystep and width of the first line xwidth Then the function starts two loops First loop will draw four series of lines Lines of each series have its own color The second loop draws lines of one series Before starting the second loop the program sets the new start Y coordinate and restores the width of the line and starting X coordinate In the second loop the program calls DrawLine to draw the next line After DrawLine the program calls RenderB
7. line from point 5 5 to point 10 10 DrawLine 5 5 10 10 Flush to real hardware RenderBuffer Restore old line width SetLineWidth oldLineWidth DrawRectangle Draws a rectangle on 2 points int DrawRectangle int LeftX X coordinate of the first point int TopY Y coordinate of the first point int RightX X coordinate of the second point int BottomY Y coordinate of the second point Parameters LeftX in Left X coordinate of rectangle TopY in Top Y coordinate of rectangle RightX in Right X coordinate of rectangle BottomY in Bottom Y coordinate of rectangle Return values GL_OK on success GL_ERROR on error Remarks LeftX TopY x RightX BottomY Examples Get current line width int oldLineWidth GetLineWidth Set new line width SetLineWidth 3 Draw rectangle with left top point 5 5 and right bottom point 10 10 Drawrectangle 5 5 50 50 Flush to real hardware RenderBuffer Restore old line width SetLineWidth oldLineWidth DrawPolyline Draws a polyline int DrawPolyline int numPoints Number of points in array POINT points Array of points char Closed Should be drawn the line between the first and last the points Parameters numPoints in Number of points in array points in Array of points Closed in Should be drawn line between first and last points Return values GL_OK on success GL_E
8. the same value as a background color then draws the same arc as previous This clears the arc Then the function increments the radius of the arc and line width Also it moves X coordinate of the center point 7 TextDemo This function shows how to draw text on the screen This function shows three screens Each of the screens shows one of available fonts small medium large On the first screen you see text Small font drawn with the small font Let s look at the code pass 1 test small font clear display SetColor OLED_4BIT_GRAYSCALE_ 15 SetBkColor OLED_4BIT_GRAYSCALE_0 ClearDisplay set small font as current SetTextSize TEXT_SMALL calculate coordinates of start point of text to center the text on screen text_width GetTextWidth Small font xp width 2 text_width 2 yp height 3 draw text and flush memory buffer to hardware DrawText xp yp Small font RenderBuffer First the function sets the foreground and background colors and clears the display Then it sets small font as current font Then it calculates coordinates of the start point of the text to center the text on the screen and calls DrawText function This function draws text to the memory buffer Then the function calls RenderBuffer to draw text on the display The next screen shows medium font size text The function follows the same steps as small font The only difference is in SetTextSize functio
9. 5 height 2 3 OLED_4BIT_GRAYSCALE_15 SetPixelWidth width 3 2 5 height 2 3 OLED_4BIT_GRAYSCALE_15 flush memory buffer to hardware RenderBuffer delayMs 500 clear pupils pixels in old position SetPixelWidth width 3 5 height 2 3 OLED_4BIT_GRAYSCALE_0 SetPixelWidth width 3 2 5 height 2 3 OLED_4BIT_GRAYSCALE_0 draw new pupils pixels in new position SetPixelWidth width 3 5 height 2 3 OLED_4BIT_GRAYSCALE_15 SetPixelWidth width 3 2 5 height 2 3 OLED_4BIT_GRAYSCALE_15 flush memory buffer to hardware RenderBuffer delayMs 500 clear pupils pixels in old position SetPixelWidth width 3 5 height 2 3 OLED_4BIT_GRAYSCALE_0 SetPixelWidth width 3 2 5 height 2 3 OLED_4BIT_GRAYSCALE_0 draw new pupils pixels in new position SetPixelWidth width 3 height 2 3 OLED_4BIT_GRAYSCALE_15 SetPixelWidth width 3 2 height 2 3 OLED_4BIT_GRAYSCALE_15 flush memory buffer to hardware RenderBuffer The function makes several calls to DrawEllipse to draw eyes and SetPixelWidth to draw pupils of eyes To determine the position and the sizes of ellipses the function uses width and height of the screen When the function draws eyes it waits 0 5 seconds and animates the pupils First it sets the foreground color to the same value as background and draws pupils at the old place This clears pixels at the old position Then the function moves pupils
10. BiPOM Graphics Library User Manual Date 14 May 2007 Document Revision 1 01 BiPOM Electronics 16301 Blue Ridge Road Missouri City Texas 77489 Telephone 1 713 283 9970 Fax Fax 1 281 416 2806 E mail info bipom com Web www bipom com 1996 2007 by BiPOM Electronics All rights reserved BiPOM Graphics Library User Manual No part of this work may be reproduced in any manner without written permission of BIPOM Electronics All trademarked names in this manual are the property of respective owners TABLE OF CONTENTS 1 OVERVIEW 2 SCREEN STRUCTURE 3 CONSTANTS 4 TYPES 5 COLOR SCHEME 6 ERROR HANDLING 7 FUNCTIONS 8 OLED DEMO 1 OVERVIEW BiPOM Graphics Library GL is an open source graphics library written in GNUARM C Compiler for ARM microcontroller This library allows drawing simple graphics primitives on a display which is connected to an ARM microcontroller board GL features e Driver interface that allows adding support for new displays without recompiling GL e Support up to 4 different displays simultaneously e Support follows primitives Pixels Lines Polylines Rectangles Circles Ellipses Arcs 3 bitmap fonts 0000000 0 e Set line width e Clear full screen or part of screen e Set foreground and background colors 2 SCREEN STRUCTURE GL screen has the following structure Width X l 0 0 Height Y coordinate Width 1 Height 1 GL supports 2 function
11. BkColor OLED_4BIT_GRAYSCALE_0 SetColor OLED_4BIT_GRAYSCALE_15 ClearDisplay set large font SetTextSize TEXT_LARGE calculate coordinates of start point of text to center the text on screen text_width GetTextWidth GoodbyeDemoMsg1 xp width 2 text_width 2 yp height 3 draw text DrawText xp yp GoodbyeDemoMsg1 set small font SetTextSize TEXT_SMALL calculate coordinates of start point of text to center the text on screen text_width GetTextWidth GoodbyeDemoMsg2 xp width 2 text_width 2 yp height 3 2 draw text DrawText xp yp GoodbyeDemoMsg2 flush memory buffer to hardware RenderBuffer delayMs 5000
12. RROR on error Remarks If the third function argument Closed is zero then DrawPolyline draws numPoints 1 lines The first point and the last point are the beginning and the end of polyline If third function argument is not zero then DrawPolyline draws a polygon The picture below shows how the third argument affects the result Closed 0 Closed 0 Examples Array of points for polyline POINT pArray 4 pArray 0 x 0 pArray 0 y 0 pArray 1 x 10 pArray 1 y 0 pArray 2 x 10 pArray 1 y 10 pArray 3 x 0 pArray 3 y 10 Draw polyline with 3 segments DrawPolyline 4 pArray 0 Draw polyline with connected first and last point DrawPolyline 4 pArray 1 Flush to real hardware RenderBuffer DrawCircle Draws a circle with the center in point x y and specified radius int DrawCircle int x X coordinate of the center point int y Y coordinate of the center point int radius Radius of the circle Parameters x in X coordinate of the center point in Y coordinate of the center point radius in Radius of the circle Return values GL_OK on success GL_ERROR on error Note radius Examples Center x y Draw circle with the center in the point 20 20 and radius 10 pixels DrawCircle 20 20 10 Flush to real hardware RenderBuffer DrawEllipse Draws an ellipse with the center in the point x y width xRadius
13. and height yRadius int DrawCircle int x X coordinate of the center point int y Y coordinate of the center point int xRadius width of the ellipse int yRadius height of the ellipse Parameters x in X coordinate of the center point in Y coordinate of the center point XRadius in Width of the ellipse yRadius in Height of the ellipse Return values GL_OK on success GL_ERROR on error Notes Height Examples Draw ellipse with the center in the point 20 20 width is 20 pixels height is 10 pixels DrawEllipse 20 20 20 10 Flush to real hardware RenderBuffer DrawArc Draws an arc of circle int DrawArc int xCenter X coordinate of the center point int yCenter Y coordinate of the center point int Radius Radius float StartAngle Start angle of the arc float ArcAngle Arc angle Parameters xCenter in X coordinate of the center point yCenter in Y coordinate of the center point Radius in Radius of the arc StartAngle in Start angle of the arc in radians ArcAngle in Arc angle in radians Return values GL_OK on success GL_ERROR on error Note Arc is always drawn in counterclockwise direction Center point Radius Examples Draw arc DrawArc 50 50 0 PI Flush to real hardware RenderBuffer StartAngle DrawText Draws a text string int DrawText int x X coordinate of the top left point int y Y coordinat
14. at the top of the screen yp set to zero The second and the third lines are drawn in the same manner At first the function calculates the text width Then depending on text width it calculates the X coordinate Also it sets the Y coordinate to draw next line below the previous and calls DrawText function At the end of the function GreetingsDemo the function RenderBuffer is called This function copies memory buffer to the real hardware OLED display At this point you can see the changes on the display Finally delayMs function is called This is a standard function from BiPOM library It forces microcontroller to wait the specified number of milliseconds before it continues with the execution of the program 2 LinesDemo LinesDemo shows different types of lines First it shows the name of the demo Let s look at the code get width and height of screen in pixels width GetWidth height GetHeight set back color to black and clear display SetBkColor OLED_4BIT_GRAYSCALE_0 ClearDisplay calculate coordinates of start point of text to center the text on screen text_width GetTextWidth LinesDemoMsg xp width 2 text_width 2 yp height 3 draw text and flush memory buffer to hardware DrawText xp yp LinesDemoMsg RenderBuffer delayMs 2000 As you can see this code is very similar to the previous function GreetingsDemo LinesDemo sets the background color clears the dis
15. coordinates and sets new foreground color Then SetPixelWidth is called to draw new pupils in the new position and RenderBuffer is called to draw all the changes on the display There is a delay of 0 5 seconds before the next animation step This is a very simple technique of animation On the next screen this function draws several horizontal and vertical ellipses Let s look at the code ClearDisplay SetLineWidth 1 step width 5 draw 5 vertical ellipses for num 0 num lt 5 num draw ellipse and flush memory buffer to hardware each next ellipse moved to the right on step pixels DrawEllipse step num 14 height 2 10 height 2 2 RenderBuffer delayMs 200 SetLineWidth 2 for num 0 num lt 3 num draw ellipse and flush memory buffer to hardware each next ellipse has smaller X and Y radiuses on 10 pixels DrawEllipse width 2 1 height 2 1 width 2 10 num 2 height 2 10 num 2 RenderBuffer delayMs 200 There are 2 loops First loop draws five vertical ellipses this is the ellipse which has height greater then width All ellipses have the same width and height but each next ellipse is drawn to the left of the previous position The function calls DrawEllipse function to draw an ellipse with the specified center point and width and height Then it calls RenderBuffer to draw the changes immediately on the display The second loop draws three horizontal ellipses width gr
16. d On the next screen this function draws Olympic circles Let s look at the code ClearDisplay SetLineWidth 2 SetColor OLED_4BIT_GRAYSCALE_15 radius 20 DrawCircle width 2 radius 1 5 height 3 radius DrawCircle width 2 height 3 radius DrawCircle width 2 radius 1 5 height 3 radius DrawCircle width 2 radius height 3 2 radius DrawCircle width 2 radius height 3 2 radius flush memory buffer to hardware RenderBuffer As you can see all the circles have a radius of 20 pixels The function calls DrawCircle function five times to draw five circles on the screen 5 EllipsesDemo This function shows different ellipses On the first screen this function draws animated eyes with ellipses Let s look at the code draw 2 eye DrawEllipse width 3 height 2 width 6 height 6 DrawEllipse width 3 2 height 2 width 6 height 6 RenderBuffer delayMs 200 draw 2 draw pupils DrawEllipse width 3 height 2 height 8 height 6 DrawEllipse width 3 2 height 2 height 8 height 6 SetPixelWidth width 3 height 2 3 OLED_4BIT_GRAYSCALE_15 SetPixelWidth width 3 2 height 2 3 OLED_4BIT_GRAYSCALE_15 RenderBuffer delayMs 500 clear pupils pixels in old position SetPixelWidth width 3 height 2 3 OLED_4BIT_GRAYSCALE_0 SetPixelWidth width 3 2 height 2 3 OLED_4BIT_GRAYSCALE_0 draw new pupils pixels in new position SetPixelWidth width 3
17. e next circle darker then previous SetColor OLED_4BIT_GRAYSCALE_15 num 2 draw circle and flush memory buffer to hardware DrawCircle width 2 height 2 1 radius RenderBuffer delayMs 200 add 5 pixels to radius to draw larger circle radius 5 num The code is very simple First the function sets the starting radius to 5 pixels Then it draws five circles ina loop Before calling DrawCircle the function sets new foreground color makes each new circle darker Then it calls DrawCircle to draw a circle in the video buffer and RenderBuffer to show the circle on the display immediately After this the function increases radius by 5 pixels and continues loop On the next screen the function draws several circles from the left side of the screen to the right side of the screen The center point of all the circles lies on the same horizontal axis in the middle of the screen Let s look at the code all circles has radius 20 pixels radius 20 draw 10 circles for num 0 num lt 10 num draw circle and flush memory buffer to hardware DrawCircle num 9 22 height 2 radius RenderBuffer delayMs 200 Each circle has a radius of 20 pixels Y coordinate of the center point of the circle is half of the height of the screen X coordinate is moved from left to right The function calls DrawCircle in a loop to draw nine circles In the loop only the X coordinate of the center point is change
18. e of the top left point const char pText Null terminated string Parameters x in X coordinate of the top left point in Y coordinate of the top left point pText in Null terminated string Return values GL_OK on success GL_ERROR on error Remarks Point x y specifies the top left point from wich the text is being drawn You can set the text size by calling SetTextSize function NOTE Text is drawn in foreground color Backgound of font rectangle is drawn in background color x y So Examples Draw arc DrawText 1 1 Hello World Flush to real hardware RenderBuffer 8 OLED DEMO BiPOM Graphics Library provides a DEMO program which demonstrates all the features of the library for an OLED display 128x64 4 bit grayscale color DEMO is a C program written in GNUARM C compiler using BiPOM s Micro IDE Integrated Development Environment You can find this DEMO program under Examples in BiPOM ARM7 Development System release This program uses Graphics Library and OLED_124x64x4 display driver Demo program contains two functions int main void the entry point of program void OLED_GL_Demo void the function which makes graphics output Let s look at these functions int main void Initialize the system Initialize delayMs 2000 uart0Puts n rBIPOM MINI MAX ARM uart0Puts n rOLED 1 DEMO Initialize_SPI DATAFLASH_SPI SPI_7MHZ_BUS I
19. eater than height Also these ellipses are drawn with line width of 2 pixels 6 ArcsDemo This function shows how different arcs can be drawn On the first screen you see six arcs Let s look at the code calculate center point of first arc step width 6 xc step yc height 3 2 all arcs has radius in 15 pixels radius 15 s_angle 0 0f start angel 0 a_angle 3 1415f length of arc is Pl draw 6 arcs for num 0 num lt 3 num DrawArc xc yc radius s_angle a_angle DrawArc xc height 3 radius a_angle a_angle RenderBuffer delayMs 200 calculate x coordinate of center of next arc xc step 2 In order to draw an arc we should have the following values center point coordinates radius start angle and arc angle See DrawArc function description for more information All the arcs on the first screen have a radius of 15 pixels Also all the arcs have an arc angle equal to PI 3 1415 radians half of the circle The function draws two arcs in the loop the first from the start angle of 0 radians the second from the start angle of PI 3 1415 radians As soon as the arcs are drawn the function calls RenderBuffer to copy video buffer to real hardware Then it moves the X coordinate by 1 6 of the width and continues the loop On the second screen this function draws an animated wave Let s look at the code set start angle and angle of arc s_angle
20. float 3 1415 1 5 1 5 Pl a_angle 3 1415f length of arc is PI repeat 3 times for i 0 i lt 3 i set initial line width color center point coordinates and radius step width 12 line_width 1 xc 0 yc height 2 radius 5 draw 7 waves for num 0 num lt 7 num change line width and color make next wave more dark and more thick SetLineWidth line_width SetColor OLED_4BIT_GRAYSCALE_15 num 2 draw arc and flush memory buffer to hardware DrawArc xc yc radius s_angle a_angle RenderBuffer delayMs 200 clear previous drawn arc to make animation effect SetColor OLED_4BIT_GRAYSCALE_0 DrawArc xc yc radius s_angle a_angle calculate coordinates of center point of next arc xc step num 1 increase line width and radius of next arc line_width radius 5 This function draws the same animation three times Each time the function draws several arcs from the left side of the screen to the right side of the screen Each next arc is bigger has bigger radius thicker and darker Each time the function draws seven waves Before drawing the next arc the function sets new foreground color and line width Then it calls DrawArc to draw next arc After this it calls RenderBuffer to the draw arc on the physical display After small delay this function clears this arc from the memory buffer in the following way At first it sets foreground color to
21. lWidth 1 1 1 OLED_4BIT_GRAYSCALE_0 0 1 2 3 4 5 6 Wl NN AeIwIN o SetPixelWidth 1 1 2 OLED_4BIT_GRAYSCALE_0 0 1 213 415 6 DW Nn BR W NM o SetPixelWidth 2 2 3 OLED_4BIT_GRAYSCALE_0 0 1 213 41 5 6 DW Nn AIIN o ClearDisplay Fills the screen with background color int ClearDisplay void Parameters Nothing Return values GL_OK on success GL_ERROR on error Examples Initialize graphics context ME cise Set background color SetBkColor OLED_4BIT_GRAYSCALE_0 Clear the screen with color OLED_4BIT_GRAYSCALE_0 ClearDisplay Flush to real hardware RenderBuffer Set background color SetBkColor OLED_4BIT_GRAYSCALE_15 Clear the screen with color OLED_4BIT GRAYSCALE_15 ClearDisplay Flush to real hardware RenderBuffer ClearRectangle Fills the specified rectangle with background color int ClearDisplay int x1 X coordinate of the left top point int y1 Y coordinate of the left top point int x2 X coordinate of the right bottom point int y2 Y coordinate of the right bottom point Parameters x1 in X coordinate of the left top point yl in Y coordinate of the left top point x2 in X coordinate of the right bottom point y2 in Y c
22. lor The OLED_4BIT_GRAYSCALE_15 is the lightest color Driver header file also provides constants for allowed display interfaces Constant OLED_128_64 4 INTERFACE_1 Driver should use 1 physical interface to OLED display OLED_128_64 4 INTERFACE_2 Driver should use 2 physical interface to OLED display Microcontroller board can have 2 OLED displays at the same time When you want to use the display you should initialize one of these two interfaces Please see InitializeGL function 4 TYPES GL library provides the following types POINT This is the structure that represents X and Y coordinate of point P_POINT This is the C pointer to POINT COLORREF Color of pixel POINT has 2 fields POINT x X coordinate of the point POINT y Y coordinate of the point COLORREF is an unsigned long value that represents the color value Indexed color or RGB value depending on the display driver 6 ERROR HANDLING Each function in BIPOM Graphics Library returns GL_ERROR constant if an error occurs in this function BiPOM Graphics Library defines the following constants GL_OK This value is returned from the function if no error occurs GL_ERROR This value is returned from the function if an error occurs Example try to set new color int err SetColor OLED_COLOR_15 if err GL_ERROR function failed Read extended error code int ext_err GetLastE
23. lue is GL_LERROR you should not call any drawing function Drawing functions always return GL_ERROR if a graphics context has not been created After initialization of graphics context program OLED _GL_Demo function is called This function draws display output lines rectangles circles and others When this function is finished the program frees the graphics context It calls ShutdownGL with handle to the graphics context as argument This function frees all internal resources You should call ShutdownGL when the graphics context is no more needed Let s look at the OLED_GL_Demo function void OLED_GL_Demo run demo GreetingsDemo LinesDemo RectanglesDemo CirclesDemo EllipsesDemo ArcsDemo FontsDemo GoodbyeDemo This function calls several functions Each of them shows one part of demo 1 GreetingsDemo This function shows the greeting text See the picture below Let s look at this function Most codes in this function are also used in other ones void GreetingsDemo int xp yp int width height int text_width width GetWidth height GetHeight SetBkColor OLED_4BIT_GRAYSCALE_0 SetColor OLED_4BIT_GRAYSCALE_ 15 ClearDisplay draw 1st line of text SetTextSize TEXT_LARGE calculate coordinates of start point of text to center the text on screen text_width GetTextWidth GreetingsMsg1 xp width 2 text_width 2 yp 0 DrawText xp
24. n Now it has TEXT_MEDIUM as its parameter Let s look the code pass 1 test small font clear display SetColor OLED_4BIT_GRAYSCALE_15 SetBkColor OLED_4BIT_GRAYSCALE_0 ClearDisplay set small font as current SetTextSize TEXT_MEDIUM calculate coordinates of start point of text to center the text on screen text_width GetTextWidth Medium font xp width 2 text_width 2 yp height 3 draw text and flush memory buffer to hardware DrawText xp yp Medium font RenderBuffer The third screen shows the large font size text The function follows the same steps as small font and medium font The only difference is in SetTextSize function Now it has TEXT_LARGE as its parameter Let s look at the code pass 1 test small font clear display SetColor OLED_4BIT_GRAYSCALE_15 SetBkColor OLED_4BIT_GRAYSCALE_0 ClearDisplay set small font as current SetTextSize TEXT_LARGE calculate coordinates of start point of text to center the text on screen text_width GetTextWidth Large font xp width 2 text_width 2 yp height 3 draw text and flush memory buffer to hardware DrawText xp yp Large font RenderBuffer 8 GoodbyeDemo This function is very similar to GreetingsDemo It shows two lines of text Let s look at the code get width and height of screen in pixels width GetWidth height GetHeight clear screen Set
25. nitialize Graphics Library int hContext1 InitializeGL OLED_128_ 64 4 OLED_128 64 4 INTERFACE_1 if hContext1 GL_ERROR uart0Puts n rlnvalid handle to context uartOPuts n rlnitializedGL failed return 1 uartOPuts n rGraphics Library initialized OLED_GL_Demo ShutdownGL hContext1 uart0Puts n rGraphics Library closed return 0 As first step the program initializes hardware of ARM7 board controller UARTO SPI interface Next step is to call InitializeGL function in order to obtain graphics context for specified display In our case we use OLED display with a resolution of 128x64 pixels and 4 bit grayscale This display is connected to the board through the first interface We specified this using the argument to InitializeGL function First parameter is a constant OLED_128 64 4 which identifies the type of display the second parameter is a constant OLED_128 64 4 INTERFACE_1 which identifies the number of hardware interface In order to use these constants you need to include the header file of the driver for your display Also you need to include the header file of the library include lt GL Drivers oled_128x64x4 oled_128x64x4 h gt include lt GL InterfaceGL 1 01 GL h gt After calling InitializeGL we should check if the function returns a valid handle to the graphics context If InitializeGL fails it returns GL_ERROR Any other value is a handle to the graphics context If the return va
26. ns current foreground color SetTextSize Sets one of predefined fonts as current font GetTextSize Gets current font constant GetTextWidth Returns width of text string in pixels SetLineWidth Sets width of line GetLineWidth Gets current width of line Draw graphics primitives functions DrawLine Draws line DrawRectangle Draws rectangle DrawPolyline Draws polyline closed or not closed DrawCircle Draws circle DrawEllipse Draws ellipse DrawArc Draws arc of circle DrawText Draws text string InitializeGL Initializes internal variables of GL Also initializes driver and specified physical interface of display int InitializeGL unsigned long Driver Predefined Driver constant from driver header file unsigned char Interface Predefined display interface constant Parameters Driver in Predefined Driver constant from the driver header file Interface in Predefined display interface constant Return values If the function succeeds the return value is the handle to graphics context If the function fails the return value is GL_ERROR Notes You should save the returned handle to graphics context You should pass this handle to ShutdownGL function when you are finished using the GL You can initialize 4 graphics contexts at the same time These can be different displays connected to different physical interfaces as shown belo
27. oint 10 10 DrawLine 5 5 10 10 Flush to real hardware RenderBuffer Restore old line width SetLineWidth oldLineWidth The pictures below illustrate how the lines appear when drawn with line width greater then 1 SetLineWidth 2 DrawLine 1 1 5 5 0 1 2 3 4 5 1647 8 9 O CO NI DY TU BY WwW NH SetLineWidth 3 DrawLine 1 1 5 5 GetLineWidth Gets a width of lines in the current graphics context int GetLineWidth void Parameters Nothing Return values A width of lines in the current graphics context or GL_ERROR if some error occurs Examples See SetLineWidth example DrawLine Draws a straight line between 2 points int DrawLine int StartX X coordinate of first point int StartY Y coordinate of first point int EndXx X coordinate of second point int Endy Y coordinate of second point Parameters StartX in X coordinate of the first point StartY in Y coordinate of the first point EndX in X coordinate of the second point EndY in Y coordinate of the second point Return values GL_OK on success GL_ERROR on error Notes StartX StartY EndX EndY Examples Get current line width int oldLineWidth GetLineWidth Set new line width SetLineWidth 3 Draw
28. om InitializeGL Parameters hContext in Handle to graphics context returned from InitializeGL function Return values GL_OK on success GL_ERROR on error Note You should call this function to all initialized contexts Examples Please see InitializeGL example SwitchToContext Switches the current graphics context to specified graphics context int SwitchToContext int hContext handle to context returned from InitializeGL Parameters hContext in Handle to graphics context returned from InitializeGL function Return values GL_OK on success GL_ERROR on error Remarks You should call this function if you use several displays at the same time Examples Please see InitializeGL example GetWidth Returns the width of the screen in pixels int GetWidth void Return values The width of the screen in pixels or GL_LERROR on error Examples initialize OLED displays int hContext1 InitializeGL OLED_128_64_4 OLED_128_64_4 INTERFACE_1 int width GetWidth int height GetHeight draw line from top left corner to bottom right corner of the screen DrawlLine 0 0 width 1 height 1 RenderBuffer destroy created contexts ShutdownGL hContext1 GetHeight Returns the height of the screen in pixels int GetHeight void Return values The height of the screen in pixels or GL_ERROR on error Examples See GetWidth example SetPixel Sets the specified pixel
29. on the screen to the specified color int SetPixel int x X coordinate of pixel int y Y coordinate of pixel unsigned long Color color of pixel Parameters x in X coordinate of pixel in Y coordinate of pixel Color in Color of pixel Should be one of the indexed colors or RGB value if display supports RGB Return values GL_OK on success GL_ERROR on error Examples initialize OLED displays int hContext1 InitializeGL OLED_128 64 4 OLED 128 64 4 INTERFACE_1 Set pixel in position 10 20 to the lightest state SetPixel 10 20 OLED_4BIT_GRAYSCALE_15 RenderBuffer destroy created contexts ShutdownGL hContext1 GetPixel Gets color of the specified pixel COLORREF GetPixel int x X coordinate of pixel int y Y coordinate of pixel Parameters X in X coordinate of pixel y in Y coordinate of pixel Return values The color of the specified pixel in current color scheme If the display supports indexed color then the function returns the index value If display supports RGB then function returns RGB value If some error occurs the function returns GL_ERROR Examples initialize OLED displays int hContext1 InitializeGL OLED_128_64_4 OLED_128_64_4 INTERFACE_1 Set pixel in position 10 20 to the lightest state SetPixel 10 20 OLED_4BIT_GRAYSCALE_15 Variable color will have value OLED_4BIT_GRAYSCALE_15 COLORREF color GetPixel 10
30. oordinate of the right bottom point Return values GL_OK on success GL_ERROR on error Examples Initialize graphics context isos Set background color SetBkColor OLED_4BIT_GRAYSCALE_0 Clear the rectangle with top left corner in point 20 10 and bottom right corner in point 40 50 with color OLED_4BIT_GRAYSCALE_0 ClearRectangle 20 10 40 50 Flush to real hardware RenderBuffer Set background color SetBkColor OLED_4BIT_GRAYSCALE_15 Clear the rectangle with top left corner in point 0 0 and bottom right corner in point 10 20 with color OLED_4BIT_GRAYSCALE_15 ClearRectangle 0 0 10 20 Flush to real hardware RenderBuffer SetBkColor Sets the background color in current graphics context int SetBkColor COLORREF color new background color Parameters color in New background color Return values GL_OK on success GL_ERROR on error Examples See ClearDisplay example GetBkColor Gets the background color of the current graphics context COLORREF GetBkColor void Parameters Nothing Return values Background color value of the current graphics context or GL_ERROR if some error occurs Examples Initialize graphics context HH cia Get current background color COLORREF oldBkColor GetBkColor Set new background color SetBkColor OLED_4BIT_GRAYSCALE_15 Clear the screen with color OLED_4BIT_GRAYSCALE_15 ClearDisplay
31. play calculates the width of text and starting point of text and draws the text on the screen Then LinesDemo waits 2 seconds and continues with the execution of the program As next step LinesDemo draws two fans from the top left and the top right corners of the screen as shown below Let s look at the code ClearDisplay color OLED 4BIT_GRAYSCALE_15 xpos1 0 xpos2 width 1 step width 15 num 0 while num lt 14 set new color of line SetColor color draw 2nd lines DrawLine 0 0 xpos1 height DrawLine width 1 0 xpos2 height flush memory buffer to hardware RenderBuffer delayMs 200 move positions of second point xpos1 step xpos2 step make color of line more dark color num delayMs 2000 First the function clears the display Then it sets the initial values of variables color of line X coordinate of the bottom point and step between the lines Then the program goes into a loop and draws 14 lines from the top left and right corners to the bottom side of the screen On each step the function sets a new value for the foreground color and moves the X coordinate for the bottom point Next line is drawn after a small delay 200 milliseconds When all lines are drawn the function waits 2 seconds before continuing execution After the delay this function draws next portion of lines Let s look at the code clear display set line width to
32. program draws rectangles of different sizes from large to small Each next rectangle is drawn with thicker line Let s look at the code calculate 2 points of the largest rectangle sx sy 0 ex width 1 ey height 1 line_width 1 draw 5 rectangles for num 0 num lt 5 num Change line width and color SetLineWidth line_width SetColor OLED_4BIT_GRAYSCALE_15 num 2 draw rectangle and flush memory buffer to hardware DrawRectangle sx sy ex ey RenderBuffer delayMs 200 calculate cordinates of next rectangle sx 10 sy 5 ex 10 ey 5 change line width line_width First the function calculates the coordinates of the largest rectangle Then it draws four rectangles in the loop Before drawing a rectangle the function sets the new foreground color darker and line width thicker Then the function calls RenderBuffer to draw rectangles on the screen After this the function calculates new coordinates of the next smaller rectangle On the next screen the function draws two sequences of rectangles from the top left and the top right corners to the bottom right and the bottom left corners of the screen Let s look at the code ClearDisplay SetLineWidth 1 SetColor OLED_4BIT_GRAYSCALE_15 calculate coordinates of first rectangle in the top left corner sx sy 0 ex Sx 20 ey sy 10 draw 11 rectangles for num 0 num lt 11 num
33. rror now ext_err content error code List of extended error codes Constant i Description GL_NO_ERROR No error occurred The operation completed successfully 7 FUNCTIONS GL has the following functions Function Description Initializing functions Initializes internal variables of GL Also initializes driver and specified iitalieeo physical interface of display Destroys current selected graphics context Also destroys all resources SOWOL allocated in driver for this graphics context SwitchToContext Switches current graphics context to specified driver interface Functions that work with video RAM buffer GetWidth Returns width of the screen in pixels GetHeight Returns height of the screen in pixels RenderBuffer Forces copy of all drawn primitives from video buffer to real hardware SetPixel Sets specified pixel to specified color GetPixel Gets color of specified pixel Functions to draw pixels SetPixelWidth Sets pixel with specified width and color to specified pixel Functions to clear display or rectangle ClearDisplay Clears screen with background color ClearRectangle Clears specified rectangle with background color Function to set get settings of graphics context SetBkColor Sets background color GetBkColor Returns current background color SetColor Sets foreground color GetColor Retur
34. s to determine the size of the screen int GetWidth Returns width of current display in pixels int GetHeight Returns height of current display in pixels NOTE Depending on selected driver the size of the screen may be different 3 CONSTANTS GL and driver header file provide several constants to simplify using the library GL text constants TEXT_SMALL This constant is used to set small bitmap font as the current font TEXT_MEDIUM This constant is used to set medium bitmap font as the current font TEXT_LARGE This constant is used to set large bitmap font as the current font These constants are used to select the current font to draw the text See functions SetTextSize and GetTextSize GL provides several color constants for 4 bit grayscale OLED display This display has only 16 indexed colors GL color constants 4 bit grayscale OLED OLED_4BIT_GRAYSCALE_0 0x0 OLED_4BIT_GRAYSCALE_1 Ox1 OLED_4BIT_GRAYSCALE_2 0x2 OLED_4BIT_GRAYSCALE_3 0x3 OLED_4BIT_GRAYSCALE_4 0x4 OLED_4BIT_GRAYSCALE_5 0x5 OLED_4BIT_GRAYSCALE_6 0x6 OLED_4BIT_GRAYSCALE_7 0x7 OLED_4BIT_GRAYSCALE_8 0x8 OLED_4BIT_GRAYSCALE_9 0x9 OLED_4BIT_GRAYSCALE_10 OxA OLED_4BIT_GRAYSCALE_11 OxB OLED_4BIT_GRAYSCALE_12 OxC OLED_4BIT_GRAYSCALE_13 OxD OLED_4BIT_GRAYSCALE_14 OxE OLED_4BIT_GRAYSCALE_15 OxF The OLED_4BIT_GRAYSCALE_0 is the darkest co
35. uffer in order to apply all changes immediately Lines are drawn with a little delay 200 milliseconds Then the function calculates X and Y coordinates of the next line and its width After this the function waits again 2 seconds and draws the last demo screen This is a very simple code The program makes several calls to DrawLine function to draw this shape Lines are drawn with a little delay Let s look at the code pass 3 ClearDisplay SetColor OLED_4BIT_GRAYSCALE_15 SetLineWidth 1 draw borders along all four sides DrawLine 0 0 width 1 0 DrawLine 0 0 0 height 1 DrawLine width 1 0 width 1 height 1 DrawLine 0 height 1 width 1 height 1 RenderBuffer delayMs 1000 draw cross in the center of display SetColor OLED_4BIT_GRAYSCALE_10 SetLineWidth 2 DrawLine width 2 0 width 2 height 1 DrawLine 0 height 2 width height 2 RenderBuffer delayMs 1000 draw diagonal cross in the center of display SetColor OLED_4BIT_GRAYSCALE_ 15 SetLineWidth 1 DrawLine width 2 height 2 0 0 DrawLine width 2 height 2 0 height DrawLine width 2 height 2 width 0 DrawLine width 2 height 2 width height RenderBuffer delayMs 2000 As you can see this function uses width and height variables to determine coordinates of points 3 RectanglesDemo This demo function draws rectangles The first screen shows rectangles drawn with different line width The
36. w First display 5 g Interface 1 D J T a 2 D Interface 2 4 5 Second Display In this example the user program uses 2 OLED displays Each of these displays is connected to its own IO ports GL Driver knows which ports are used for interface 1 and 2 So when you pass one of predefined interface constants to InitializeGL function the driver initializes the specified interface Graphics library remembers the first initialized context as active so if you start drawing all the graphics output will point to this graphics context Example initialize 2 OLED displays int hContext1 InitializeGL OLED_128 64 4 OLED_128 64 4 INTERFACE_1 int hContext2 InitializeGL OLED_128 64 4 OLED_128 64 4 INTERFACE _2 check if context initialized successfully if hContext GL_ERROR hContext2 GL_ERROR return set foreground color SetColor OLED_4BIT_GRAYSCALE_15 by default now active is hContext1 so circle will be drawn on 1 display DrawCircle 10 10 10 RenderBuffer switch context to second display SwitchT oContext hContext2 draw this circle on second display DrawCircle 20 20 10 RenderBuffer destroy created contexts ShutdownGL hContext1 ShutdownGL hContext2 ShutdownGL Destroys current selected graphics context Also destroys all resources allocated in the driver for this graphics context int ShutdownGL int hContext handle to context returned fr
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