graphics on the Bresenham line drawing algorithm, the midpoint of the algorithm...

代码说明：

关于图形学中的Bresenham画线算法，中点画圆算法的实现，以及五边形，六边形，七边形填充。-graphics on the Bresenham line drawing algorithm, the midpoint of the algorithm to achieve Circle, and pentagons, hexagons, heptagon filled.