它主要完成的功能有画直线、曲线、圆、椭圆、矩形、多边形；支持剪贴板的操作；支持撤销、重复；保存成位图文件；打开位图文件。-It is mainly the function of the completion of painting a straight line, curve, round, oval, rectangular, polygonal support clipboard operations to support the revocation, repeat preserv