pango_layout_set_text(f->layout, str, -1);
pango_layout_set_width(f->layout, -1);
pango_layout_get_pixel_extents(f->layout, NULL, &rect);
pango_layout_set_text(f->layout, str, -1);
pango_layout_set_width(f->layout, -1);
pango_layout_get_pixel_extents(f->layout, NULL, &rect);