code: def drawRoundRect(self, x, y, w, h, r, color=None, aa=False):
          
          md.draw_round_rect(self.set, x, y, w, h, r, color, aa)
docs: Draw a rounded rectangle with top-left corner at (x, y), width w,
          height h, and corner radius r
  
          :param aa: if True, use Bresenham's algorithm for line drawing;
              otherwise use Xiaolin Wu's algorithm