Libpencil is a library for exporting images in the RISC OS Drawfile format. Drawfile is a vector (object orientated) graphics format. Libpencil is written in C. It is currently in development for use with NetSurf and is intended to be suitable for use in other projects too.
You can browse the source code via the online interface.
If you would like to help develop Libpencil, or have questions about the library, please join the NetSurf developer mailing list.