Article ID: 322724 - Last Review: July 22, 2004 - Revision: 1.1

PRB: Poor Video Performance on Compatible Bitmaps After a Video Mode Change

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This article was previously published under Q322724

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SYMPTOMS

You may experience severe video performance degradation after you perform a video mode change when compatible bitmaps are involved.

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The BitBlt operations from the screen to a compatible bitmap in the application take a lot longer to complete after you perform a video mode change. This is because all compatible bitmaps are converted to system device-independent bitmaps (DIBs). The system DIBs are no longer in the video memory; therefore, you experience the delay in the completion of the BitBlt operations in the application.

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RESOLUTION

To resolve this issue, restart the application after the video mode change takes effect. When the application is restarted, it re-creates the compatible bitmaps, which then reside in the video memory. A better way to handle this situation is to watch for WM_DISPLAYCHANGE messages, and then re-create any compatible bitmaps that the application needs.

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