@staticmethod
def draw_path(ctx, center_x, center_y, width, height=None):
    """Draws an upright triangle on the Cairo context without stroking or
        filling it.
        
        @see: ShapeDrawer.draw_path"""
    height = height or width
    ctx.move_to(center_x - width / 2, center_y + height / 2)
    ctx.line_to(center_x, center_y - height / 2)
    ctx.line_to(center_x + width / 2, center_y + height / 2)
    ctx.close_path()
