Microsoft KB Archive/77934

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Determining That Display Driver Supports Transparent Mode

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Q77934

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The information in this article applies to:


 * Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1

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SUMMARY
In some display drivers compatible with Microsoft Windows, the BitBlt and StretchBlt functions support transparent mode. Before using this feature, an application must determine whether the display driver supports this mode by calling the GetDeviceCaps function.

MORE INFORMATION
Two of the multimedia display drivers, MMV7VGA.DRV and MMWD480.DRV, support transparent mode. When using GetDeviceCaps to determine the capabilities of these drivers, it is common to use the RASTERCAPS index. However, to determine if transparent mode is supported, an application must use the CAPS1 index.

Use the bitwise AND operator with C1_TRANSPARENT mask to determine if the appropriate bit is set; if it is, the driver supports transparent mode. The following code fragment demonstrates this test:

  bTransSupport = (GetDeviceCaps(hDC, CAPS1) & C1_TRANSPARENT) ? TRUE : FALSE; Additional query words: 3.00 3.10 no32bit

Keywords : kb16bitonly

Issue type :

Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310