实现一个画图程序。很好的画直线，圆弧，椭圆弧，多边形，能够自定义颜色。对多边形、椭圆和圆能够进行填充。要求结果可以存盘，但不必存成图片文件。-Implement a drawing program. A very good painting straight lines, arcs, elliptical arcs, polygons, can be custom color. On the polygon, ellipse and circle can be filled. Save results can be requested, but not necessarily stored as image files.