cairo_arc (cr, 128.0, 128.0, 76.8, 0, 2 * M_PI);
cairo_clip (cr);
cairo_new_path (cr); /* current path is not
consumed by cairo_clip() */
cairo_rectangle (cr, 0, 0, 256, 256);
cairo_fill (cr);
cairo_set_source_rgb (cr, 0, 1, 0);
cairo_move_to (cr, 0, 0);
cairo_line_to (cr, 256, 256);
cairo_move_to (cr, 256, 0);
cairo_line_to (cr, 0, 256);
cairo_set_line_width (cr, 10.0);
cairo_stroke (cr);