Cairo should build without PNG only in the same way that GTK+ does: - The user has to explicitly turn it off on the configure line - The user gets warned that building without PNG will not give you a fully functional cairo library. It's really silly for apps to have to test for Cairo having PNG support before using it. Original bug was reported here: http://bugzilla.gnome.org/show_bug.cgi?id=319632
This happens when you configure cairo without PNG: configure: WARNING: Could not find libpng in the pkg-config search path configure: WARNING: *** To run the tests, cairo must be built with png support *** ... the following features: PNG functions: no ... But when building with jhbuild it is very easy to miss those lines. Took me lots of time to spot the problem. I suggest that the configure script should fail unless invoked with --disable-png when it can't find libpng.
This has bitten *lots* of Gnome testers; I really like Owen's comments on the matter: http://bugzilla.gnome.org/show_bug.cgi?id=319632#c9.
This will be fixed pretty soon when my --enable-<backend> patch is integrated. But independently, note that Pango HEAD doesn't suffer from this bug anymore (or at least it's not supposed to.)
This is fixed in latest snapshots.
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