pub unsafe extern "C" fn lv_draw_letter(
draw_ctx: *mut _lv_draw_ctx_t,
dsc: *const lv_draw_label_dsc_t,
pos_p: *const lv_point_t,
letter: u32,
)pub unsafe extern "C" fn lv_draw_letter(
draw_ctx: *mut _lv_draw_ctx_t,
dsc: *const lv_draw_label_dsc_t,
pos_p: *const lv_point_t,
letter: u32,
)