Blitting Basics
Images can be copied to a DirectDraw surface using the IDirectDrawSurface::Blt method. This method is called on the destination surface and receive the source surface as a parameter.
The destination and source surfaces can be one and the same, and you do not have to worry about overlap — DirectDraw takes care to preserve all source pixels before overwriting them.
The video hardware might also contain a hardware blitter. You can determine the blitting capabilities of the hardware from the DDCAPS structure obtained in the lpDDDriverCaps parameter of the IDirectDraw::GetCaps method. If the dwCaps member contains DDCAPS_BLT, the hardware has at least minimal blitting capabilities.
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