The function jgraphics_image_surface_draw_fast() is not exported from the kernel, although its prototype appears in jgraphics.h. It would be great to have it working for the next revision of the SDK as it’s quite useful to draw surfaces efficiently.
I get the same problem – good to know not just me – frustrating however. I was able to create some PNG’s (mysteriously) while debugging but can’t seem to get back to them (I compiled over my code cause I thought it didn’t work-the PNG’s showed up but the file names were weird like "K*". What I was doing was:
(first fill the surface with your drawing…)
jgraphics_write_image_surface_to_filedata(my_surface, JGRAPHICS_FILEFORMAT_PNG, &data, &size);