-void gfxpolywriter_init(polywriter_t*w);
-void gfxcompactpolywriter_init(polywriter_t*w);
-
-gfxcompactpoly_t* gfxcompactpoly_from_gfxline(gfxline_t*line, double gridsize);
-gfxcompactpoly_t* gfxcompactpoly_from_file(const char*filename, double gridsize);