hb_draw_funcs_t

Glyph draw callbacks.

#hb_draw_move_to_func_t, #hb_draw_line_to_func_t and #hb_draw_cubic_to_func_t calls are necessary to be defined but we translate #hb_draw_quadratic_to_func_t calls to #hb_draw_cubic_to_func_t if the callback isn't defined.