After a bit of work, I can now use the whole 320×240 screen of the M5Stack — unfortunately I had to change the C sources a bit, to use 16-bit variables for the coordinates. That was a lack of foresight on my side, but it's now fixed and the pull requests for the change are up.

I also optimized the sprite drawing routines a little bit, and fixed a bug that would sometimes make the library fail to refresh some sprites. You can now also use floating point values for the sprite positions, and they will be rounded during the rendering.