#/* a custom shape, that could be wrapped in a function */
x0	   = 0.1   #/*< parameters like cairo_rectangle */
y0	   = 0.1
rect_width  = 0.8
rect_height = 0.8
radius = 0.4   #/*< and an approximate curvature radius */

snippet_normalize (cr, width, height)

x1=x0+rect_width
y1=y0+rect_height
#if (!rect_width || !rect_height)
#    return
if rect_width/2<radius:
    if rect_height/2<radius:
        cr.move_to  (x0, (y0 + y1)/2)
        cr.curve_to (x0 ,y0, x0, y0, (x0 + x1)/2, y0)
        cr.curve_to (x1, y0, x1, y0, x1, (y0 + y1)/2)
        cr.curve_to (x1, y1, x1, y1, (x1 + x0)/2, y1)
        cr.curve_to (x0, y1, x0, y1, x0, (y0 + y1)/2)
    else:
        cr.move_to  (x0, y0 + radius)
        cr.curve_to (x0 ,y0, x0, y0, (x0 + x1)/2, y0)
        cr.curve_to (x1, y0, x1, y0, x1, y0 + radius)
        cr.line_to (x1 , y1 - radius)
        cr.curve_to (x1, y1, x1, y1, (x1 + x0)/2, y1)
        cr.curve_to (x0, y1, x0, y1, x0, y1- radius)

else:
    if rect_height/2<radius:
        cr.move_to  (x0, (y0 + y1)/2)
        cr.curve_to (x0 , y0, x0 , y0, x0 + radius, y0)
        cr.line_to (x1 - radius, y0)
        cr.curve_to (x1, y0, x1, y0, x1, (y0 + y1)/2)
        cr.curve_to (x1, y1, x1, y1, x1 - radius, y1)
        cr.line_to (x0 + radius, y1)
        cr.curve_to (x0, y1, x0, y1, x0, (y0 + y1)/2)
    else:
        cr.move_to  (x0, y0 + radius)
        cr.curve_to (x0 , y0, x0 , y0, x0 + radius, y0)
        cr.line_to (x1 - radius, y0)
        cr.curve_to (x1, y0, x1, y0, x1, y0 + radius)
        cr.line_to (x1 , y1 - radius)
        cr.curve_to (x1, y1, x1, y1, x1 - radius, y1)
        cr.line_to (x0 + radius, y1)
        cr.curve_to (x0, y1, x0, y1, x0, y1- radius)

cr.close_path ()

cr.set_source_rgb (0.5,0.5,1)
cr.fill_preserve ()
cr.set_source_rgba (0.5,0,0,0.5)
cr.stroke ()