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Given the basic goals and premises discussed in the previous section, the definition of DDHAL for Windows CE has been designed as a modified version of the DDHAL for desktop Windows.
The key differences are as follows:
- The 32-bit and 16-bit desktop Windows DDHAL implementations have been combined into a single 32-bit implementation that is part of a Windows CE display driver instead of a separate DLL or part of a display minidriver.
- Desktop-specific portions, related to VDD and kernel services, are omitted.
- A new entry point has been added to allow DirectDraw to
initialize the DirectDraw HAL for the current display driver.
Other functional or terminological differences between the Windows for desktop implementation and the Windows CE implementation include:
- There is no support for palletized primary surfaces. Primary surfaces have a 16-bit minimum pixel width.
- The special features of AGP (such as sharing system RAM as video memory) are not supported.
- Implementations of Windows CE for TV platforms that rely heavily on emulated software alpha blending composition may want to differentiate between GDIsurfaces and active, screen, or primarysurfaces. These are all the same in a desktop implementation.
- The driver is responsible for video management. DirectDraw does
not offer a VIDMEM-style heap management service. GPE-based heap
management services can be used to satisfy this requirement.
Last updated on Tuesday, July 13, 2004