qz.appendImage() Hard crash on Mac

[tresf]

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

* Image used with written permission from bug submitter.

[tresf]

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-]

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.