DWORD (APIENTRY *PDD_MAPMEMORY)(
PDD_MAPMEMORYDATA lpMapMemory
);
MapMemory is the DirectDraw object callback that maps or unmaps application-modifiable portions of the frame buffer into or from the user-mode address space of the specified process.
MapMemory returns a callback status code indicating how it handled the memory operation.
MapMemory is called to perform memory mapping before the first call to Lock. It is called to unmap memory after the last UnLock call is made.