Simple Draw

This is an example of a simple drawing program using a IUP canvas:

cdCanvas* canvas = cdCreateCanvas(CD_NATIVEWINDOW, IupGetAttribute(IupCanvas,"WID")); 
cdCanvasLineStyle(canvas, CD_DASHED);
cdCanvasLine(canvas, 0, 0, 100, 100);

If you want to use World Coordinates:

cdCanvas* canvas = cdCreateCanvas(CD_NATIVEWINDOW, IupGetAttribute(IupCanvas,"WID")); 
wdCanvasViewport(canvas, 0, 100, 0, 100);
wdCanvasWindow(canvas, -1.5, 1.5, -3000, 3000);
cdCanvasLineStyle(canvas, CD_DASHED);
wdCanvasLine(canvas, -0.5, -500, 1.0, 1000);

Off Screen Drawing (Double Buffering)

To draw in the background and later on transfer the drawing to the screen, use:

cdCanvas* canvas = cdCreateCanvas(CD_NATIVEWINDOW, IupGetAttribute(IupCanvas,"WID")); 
cdCanvas* db_canvas = cdCreateCanvas(CD_DBUFFER, canvas); cdCanvasActivate(db_canvas); // update canvas size, window could be resized
cdCanvasLineStyle(db_canvas, CD_DASHED);
cdCanvasLine(db_canvas, 10, 10, 50, 50);
cdCanvasFlush(db_canvas); // swap to the window canvas

To draw in a RGB image, use:

cdCanvas* canvas = cdCreateCanvasf(CD_IMAGERGB, "%dx%d", width, height);
cdCanvasLineStyle(canvas, CD_DASHED); 
cdCanvasLine(canvas, 10, 10, 50, 50); 

To save the contents of the CD_IMAGERGB canvas in a file using IM, after drawing and before destroying the canvas do:

unsigned char* data = cdCanvasGetAttribute(canvas, "REDIMAGE"); // Also a pointer to the full buffer
imImage* image = imImageInit(width, height, IM_RGB, IM_BYTE, data, NULL, 0); 
// Can use also IM_RGB|IM_ALPHA is canvas has support for alpha
imFileImageSave(file_name, "PNG", image);
image->data[0] = NULL; // to avoid duplicate memory release

Or using another approach:

imImage* image = imImageCreate(width, height, IM_RGB, IM_BYTE);
// Can also call imImageAddAlpha if alpha support is wanted

cdCanvas* canvas = cdCreateCanvasf(CD_IMAGERGB, "%dx%d %p %p %p", width, height, 
                                   image->data[0], image->data[1], image->data[2]);
cdCanvasLineStyle(canvas, CD_DASHED); 
cdCanvasLine(canvas, 10, 10, 50, 50); 

imFileImageSave(file_name, "PNG", image);

Lua Samples

To draw in a RGB image in CDLua for Lua 5:

bitmap = cd.CreateBitmap(200,200,cd.RGB)
canvas = cd.CreateCanvas(cd.IMAGERGB, bitmap)
canvas:Font("Times", cd.BOLD, 12)
canvas:Text(10, 10, "Test")

Check the file or samples_cdlua5.tar.gz for several samples in Lua. For some of them you will need also the IUP libraries. You can also browse the examples folder.

Screen Capture in Windows

Using a NULL parameter to the NATIVEWINDOW driver you can get access to the entire screen:

cdCanvas *canvas = cdCreateCanvas(CD_NATIVEWINDOW, NULL);
cdCanvasGetSize(canvas, &width, &height, NULL, NULL);
// allocate red, green and blue pointers
cdCanvasGetImageRGB(canvas, red, green, blue, 0, 0, width, height);

Generating an EMF file that contains an IM Image in Lua

image = im.FileImageLoadBitmap(image_filename)
canvas = cd.CreateCanvas(cd.EMF,emf_filename.." "..image:Width().."x"..image:Height())

Complete Example

We have created an application called Simple Draw that illustrates the use of all functions in the CD library (including WD). You can see the source code in the file

Example for Tests

The CDTEST example is actually one of the applications used to test virtually all functions of the CD library. Its interface uses the IUP library, and it can run in several platforms. You can take either the .EXE files or the source code. Extract the files creating subfolders, using parameter "-d". Warning: This application is not didactic.