bug: pngimage.c: Disable the check on interlace_method if WRITE_INTERLACE is not supported. #623
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…LACE is not supported. Inside libpng if interlacing a PNG is disabled libpng silently removes it. This updates pngimage.c to not check the interlace in the resultant image, other behavior is still checked. Signed-off-by: John Bowler <[email protected]>
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This is behaviour that dates back to the dawn of libpng. It's happening in Nevertheless that seems to have been a bug-fix; The danger of removing it now is that it is entirely possible quite a lot of code depends on it; pngimage uses pretty much the original design for png_info handling. |
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Approved, typos notwithstanding. (But I got them.)
Just so you know, I'd like to avoid using the label "bug" for something that isn't core libpng. This is a conditional compilation issue in a contributed test program, so I'll label it as test. For somebody who has a cursory look in the git history (e.g. "with git log --oneline), mentioning a bug fix in a test program (not in the core libpng) looks unnecessarily scary. And the name pngimage.c doesn't help alleviating such a concern, either.
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Integrated both in libpng16 and libpng18. |
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Technically it is a "PNG stream", not a "PNG file" because a file is always a stream (in ISO-C) but the inverse does not apply. Hum, in fact in the NT file system, Reiser4 and, arguably, traditional MACOS a "file" is a structured object however libpng can only write a PNG as a stream. |
Inside libpng if interlacing a PNG is disabled libpng silently removes
it. This updates pngimage.c to not check the interlace in the resultant
image, other behavior is still checked.
Signed-off-by: John Bowler [email protected]