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IDirectDrawSurface5::PageLock

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This method prevents a system-memory surface from being paged out while a blit operation using direct memory access (DMA) transfers to or from system memory is in progress.

HRESULT PageLock(
  DWORD dwFlags
);

Parameters

  • dwFlags
    This parameter is currently not used and must be set to zero.

Return Values

If the method succeeds, the return value is DD_OK.

If the method fails, the return value may be one of the following error values:

DDERR_CANTPAGELOCK
DDERR_INVALIDOBJECT
DDERR_INVALIDPARAMS
DDERR_SURFACELOST

Remarks

You must call this method to make use of DMA support. If you do not, the blit occurs using software emulation.

The performance of the operating system could be negatively affected if too much memory is locked.

A lock count is maintained for each surface and is incremented each time IDirectDrawSurface5::PageLock is called for that surface. The count is decremented when IDirectDrawSurface5::PageUnlock is called. When the count reaches zero, the memory is unlocked and can then be paged by the operating system.

This method works only on system-memory surfaces; it will not page lock a display-memory surface or an emulated primary surface. If an application calls this method on a display memory surface, the method will do nothing and return DD_OK.

This method was not implemented in the IDirectDraw interface; it has no effect in Windows CE.

Requirements

OS Versions: Windows CE 2.12 and later. Version 2.12 requires DXPAK 1.0 or later.
Header: Ddraw.h.
Link Library: Ddraw.lib.

See Also

IDirectDrawSurface5::PageUnlock

 Last updated on Thursday, April 08, 2004

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