This page and the things it links to are somewhat out-of-date. Check LXR for more up-to-date APIs in mozilla/gfx/thebes
I've been giving some thought to what kind of wrappers we want for cairo. They should be pretty thin, but allow us flexibility to add new features and helper functions. This code is being called "Thebes".
These are pretty rough and need more thought, but here are some of the classes I've been thinking of.
All these classes use gfxFloat as their floating point type (currently typedefed to 'double'). This will probably stay 'double' but might be typedefed to 'float' on small devices.