Q How can I tell whether or not a picture is QuickTime-compressed?
A The key to your question is "sit in the bottlenecks." 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 with QuickTime.
Unlike standard QuickDraw images, which only call StdBits, QuickTime-compressed
images need to be decompressed first in the StdPix routine. Then QuickDraw uses
StdBits to render the decompressed image. So, swap out the QuickDraw
bottlenecks, and put some code in the StdPix routine. If it's 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 Snippets: Imaging: Graphics: CollectPictColors
snippet and page 46-47 of develop Issue 13 for further reference on swapping
out the bottlenecks.
[May 01 1995]
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