Creating the Primary Surface

The primary surface is the surface currently visible on the monitor and is identified by the DDSCAPS_PRIMARYSURFACE flag. You can only have one primary surface for each DirectDraw object.

When you create a primary surface, remember that the dimensions and pixel format implicitly match the current display mode. Therefore, this is the one time you don't need to declare a surface's dimensions or pixel format. Frankly, if you do specify them, the call will fail and return DDERR_INVALIDPARAMS–even if the information you used matches the current display mode.

The following example shows how to prepare the DDSURFACEDESC structure members relevant for creating the primary surface.

DDSURFACEDESC ddsd; 
ddsd.dwSize = sizeof(ddsd); 
 
// Tell DirectDraw which members are valid. 
ddsd.dwFlags = DDSD_CAPS; 
 
// Request a primary surface. 
ddsd.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE;

After creating the primary surface, you can retrieve information about its dimensions and pixel format by calling it IDirectDrawSurface3::GetSurfaceDesc method.