[gentoo-dev] FYI: libpng16 won't be able to show some broken icons libpng15 was still able to

[Samuli Suominen]

Short version:

If you see "PNG IDAT errors" like:

program: IDAT: invalid distance too far back `test1.png' @

WARNING **: Icon test1 missing: (0) Fatal error reading PNG image file: 
Decompression error in IDAT

Then you should use >=media-gfx/pngcrush-1.7.57 built with 
USE="-system-libs" to it's using libpng 1.5.15 to correct the IDAT in 
the .png files using command:

$ pngcrush -fix -force old.png new.png

These bogus images were visible with libpng15 and earlier but now that 
improved code was committed these bogus files stopped showing as a 
side-effect. If I understood correct this is not going to be fixed in 
the library itself. Caused by slightly bad combination of libpng and 
zlib and some tool.

Long version:

http://bugs.gentoo.org/466190
http://bugzilla.gnome.org/show_bug.cgi?id=698286
+ the ML links mentioned in the bugs

Figured this is useful for every maintainer to know.