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PICT, QuickTime-Compressed Testing

If the picture contains any QuickTime-compressed images, the images will need to pass through the StdPix bottleneck. This is a new graphics routine introduced by QuickTime. Unlike standard QuickDraw images, which only call StdBits, QuickTime-compressed images need to be decompressed first in the StdPix routine. QuickDraw uses StdBits to render the decompressed image. Swap out the QuickDraw bottlenecks and place code in the StdPix routine. If this code is called when you call DrawPicture, you know you have a compressed picture. To determine the type of compression, you can access the image description using GetCompressedPixMapInfo. The cType field of the ImageDescription record will give you the codec type. See the CollectPictColors snippet and "Inside QuickTime and Component-Based Managers" in develop Issue 13, specifically pages 46 and 47, for more information on swapping out the bottlenecks.

[May 01 1995]

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