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Multimedia software requires high-performance graphics. Through DirectDraw, Microsoft enables a much higher level of efficiency and speed in graphics-intensive applications for Windows than is possible with GDI, while maintaining device independence. DirectDraw provides tools to perform such key tasks as:
- Manipulating multiple display surfaces
- Accessing the video memory directly
- Page flipping
- Back buffering
- Managing the palette
- Clipping
Additionally, DirectDraw enables you to query the display hardware's capabilities at run time, then provide the best performance possible given the host computer's hardware capabilities.
As with other DirectX components, DirectDraw uses the hardware to its greatest possible advantage, and provides software emulation for most features when hardware support is unavailable. Device independence is possible through use of the hardware abstraction layer, or HAL. For more information about the HAL, see the hardware abstraction layer.
The DirectDraw component provides services through COM-based interfaces. In the most recent iteration, these interfaces are IDirectDraw4, IDirectDrawSurface5, IDirectDrawPalette, IDirectDrawClipper, and IDirectDrawVideoPort. Note that, in addition to these interfaces, DirectDraw continues to support all previous versions. The DirectDraw component doesn't expose an IDirectDraw3interface, the interface versions skipped from IDirectDraw2to IDirectDraw4.
For more information about COM concepts that you should understand to create applications with the DirectX APIs, see DirectX and the Component Object Model.
The DirectDraw object represents the display adapter and exposes its methods through the IDirectDraw, IDirectDraw2, and IDirectDraw4interfaces. The DirectDrawCreatefunction is used to create a DirectDraw object.
After creating a DirectDraw object, you can create surfaces for it by calling the IDirectDraw4::CreateSurfacemethod. Surfaces represent the memory on the display hardware, but can exist on either video memory or system memory. DirectDraw extends support for palettes, clipping (useful for windowed applications), and video ports through its other interfaces.
Last updated on Tuesday, May 18, 2004