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qzind / qz-print

Archive for legacy qz-print versions (1.8, 1.9). See https://github.com/qzind/tray for modern versions.
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qz.appendImage() Hard crash on Mac #75

Closed tresf closed 9 years ago

tresf commented 9 years ago

The attached image crashes QZ Tray out completely with a Mac stacktrace when printed using qz.appendImage().

image_sample_orig_broken

* Image used with written permission from bug submitter.

tresf commented 9 years ago

The bugs seems to be specific to Java, Mac and the image format, which is a 1-bit Grayscale PNG image.

A work-around is to use ImageMagic to perform image conversion and forcing the PNG color-type property to zero, which bumps the 1-bit to 8-bit and prevents the crash from occurring via -define png:color-type=0. This has the benefit of maintaining the grayscale palette, but a downside of doubling the image size (e.g. 13KB to 26KB)

convert original-1-bit.png -define png:color-type=0 fixed-8-bit.png
Vzor- commented 9 years ago

This issue was with OS X 10.10 but not 10.9.5. It only happens with images that had a palette smaller than 16 colors, or a 4 bit pixel data size.

The fix was to take the palette out and putting it in a 256 color buffered image we can pad out the palette to 8 bits without introducing dithering. Note: If any dithering DOES happen it is due to the strangeness of Java and not the palette.

After the fix we had a similar issue with a full ARBG image that had a BufferedImage.getType() of TYPE_CUSTOM, crash. If any more images crash, log their type, look up the enum in the constant-values section of JavaDocs, then add it to the badTypes array.