IDirectDrawSurface7::PageUnlock method (ddraw.h)
Unlocks a system-memory surface, which then allows it to be paged out.
HRESULT PageUnlock( [in] DWORD unnamedParam1 );
Currently not used and must be set to 0.
If the method succeeds, the return value is DD_OK.
If it fails, the method can return one of the following error values:
A lock count is maintained for each surface and is incremented each time that IDirectDrawSurface7::PageLock is called for that surface. The count is decremented when PageUnlock is called. When the count reaches 0, the memory is unlocked, and can then be paged by the operating system.
PageUnlock works only on system-memory surfaces; it does not page-unlock a display-memory surface or an emulated primary surface. If an application calls PageUnlock on a display memory surface, the method does nothing except return DD_OK.
IDirectDrawSurface7::PageUnlock was not implemented in the IDirectDraw interface version.