PDD_FREEDRIVERMEMORY callback function (ddrawint.h)

Article
02/22/2024

The DdFreeDriverMemory callback function frees offscreen or nonlocal display memory to satisfy a new allocation request.

Syntax

PDD_FREEDRIVERMEMORY PddFreedrivermemory;

DWORD PddFreedrivermemory(
  PDD_FREEDRIVERMEMORYDATA unnamedParam1
)
{...}

Parameters

unnamedParam1

Points to a DD_FREEDRIVERMEMORYDATA structure that contains the details of the free request.

Return value

DdFreeDriverMemory returns one of the following callback codes:

Remarks

The driver should implement DdFreeDriverMemory when it has DirectDraw manage all offscreen display memory management, including allocations for DrvCreateDeviceBitmap. DirectDraw requests for allocations in offscreen memory should always take precedence over GDI device bitmap allocations.

DirectDraw calls DdFreeDriverMemory when it does not have enough offscreen or nonlocal display memory to allocate a surface requested by an application. The driver should move a GDI device bitmap from offscreen memory into system memory and then immediately return. Bitmap moves can be accomplished by calling EngModifySurface.

DirectDraw will continually call DdFreeDriverMemory until there is enough offscreen memory from which to allocate the requested surface or until the driver returns DDERR_OUTOFMEMORY.

Requirements

Requirement	Value
Target Platform	Desktop
Header	ddrawint.h (include Winddi.h)