pub fn one_bit(def: &FontAtlasDef, image: &Image) -> Result<Vec<u8>, String>Expand description
The one-bit atlas (ONE_BIT_FILE) of the atlas
picture image laid out as def: each glyph in
cell index order, one byte per pixel row, the highest bit the left
pixel, set where the picture isn’t see-through; a wide glyph’s two
halves are two cells like any other. Fails for cells wider than 8
pixels.