def fillRect(self, x, y, w, h, color=None, aa=False):
md.fill_rect(self.set, x, y, w, h, color, aa)<EOL>
Draw a solid rectangle with top-left corner at (x, y), width w and
height h.

:param aa: if True, use Bresenham's algorithm for line drawing;
    otherwise use Xiaolin Wu's algorithm