CD - Canvas Draw

CD_DBUFFER - Double Buffer Driver (cddbuf.h)

Implements the concept of offscreen drawing.


The canvas is created by means of a call to function cdCreateCanvas(CD_DBUFFER, Data), after which other functions in the CD library can be called as usual. This function creates a CD canvas based on an existing window canvas (Native Windows or IUP). The parameter Data is a pointer to the already created canvas.

Any amount of such canvases may exist simultaneously. It is important to note that a call to function cdKillCanvas is required to properly end the driver. Call function cdKillCanvas in this driver before calling cdKillCanvas in the window driver.

The drawing functions will function normally, as if they were drawing in the server image driver. When function cdFlush is executed, the image is drawn in the window canvas passed as parameter in the canvas creation.

When the window's size changes, the server image is automatically recreated in the same size as the canvas. This is done in the function cdActivate.

Behavior of Functions

This driver is greatly platform-dependent. For further detail, see the Behavior of Functions in each platform: Microsoft Windows (GDI), Windows Using GDI+, X-Windows (XLIB). However, it should be noted that some functions behave differently from the basic functions of each platform.