Coding style conformance
I noticed that the source code of the gdk-pixbuf project does not seem to conform to the coding style of other GNOME project (eg indentation of 8 chars). I also found several files with a totally different coding style (probably coming from a legacy source code).
It would be better, imho, to reformat the whole code once with tool such as clang-format
or others just to be sure to have a better conformance to coding style policy of the GNOME project. See this clang-format
configuration file written by Philip Withnall to catch GNOME coding style.