col = (gint)(sqrt((gdouble)l / grid_size) * width / height + 0.999);
col = CLAMP(col, 1, l / grid_size + 1);
row = (gint)((gdouble)l / grid_size / col);
col = (gint)(sqrt((gdouble)l / grid_size) * width / height + 0.999);
col = CLAMP(col, 1, l / grid_size + 1);
row = (gint)((gdouble)l / grid_size / col);