I got it to work. Here’s a working patch. It’s not fully feature-complete, (but then again, neither is the PNG loader,) but it’s a good starting point.
I hereby give my permission to include this code in the SDL_Image library, under whatever licenses it’s released under.
-------------- next part --------------
A non-text attachment was scrubbed…
Name: png.diff
Type: application/octet-stream
Size: 11398 bytes
Desc: not available
URL: http://lists.libsdl.org/pipermail/sdl-libsdl.org/attachments/20090405/3a4967cd/attachment.obj