Licensed under the GPLv3+.
See FBInk ;).
See the basic example, it's basically LuaJIT + ffi + FBInk ;). There's absolutely zero higher-level wrapping, so you can pretty much follow FBInk's C API.
For a slightly more fleshed out real world use case, see NanoClock.
With the idea being to help people avoid having to set up a cross-compilation toolchain, I've prepared LuaJIT builds for Kindle & Kobo ;).
On Kobo, it should automatically pickup my own FBInk builds, either from the standalone package or from KoboStuff; while on Kindle, it'll pick up the one from the Python package (but you can also get a shared lib from the standalone package and put it in the right place, f.g., in a lib folder next to the luajit binary).