Drawing a compressed PNG image

Subject: Drawing a compressed PNG image

From: "John Kerr" <email@hidden>

Date: Fri, 30 Sep 2005 14:43:17 -0400

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Thread-index: AcXF4fJz37EuVkRnS5mg/Q/jBzEmtQADKhCw

I have some monochrome PNG’s that are not drawing in Quartz with the correct foreground / background color orientation. i.e. the black pixels are coming out white and the white pixels are coming out black.

This is only happening with PNG’s that have a clutID == 0 in the ImageDescription structure I am getting from Quicktime. When this field is 0, it seems that the ImageDescription idSize is 24 bytes larger to accommodate a ColorTable at the end.

I am creating my PNG data provider with a pointer to the image data portion of the atom, which is separate from the ImageDescription that has the color table. It seems to draw ok except for the color inversion. I thought that the ImageDescription part of a Quicktime atom was just a redundant extraction of information from the image data.

Is this possibly a bug in Quartz handling of PNG’s, or am I not supplying the right information to Quartz?

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