说明：  用TurboC实现的画图小程序。图形界面，包括多边形、折线的画图，移动，放大缩小，旋转，以及多边形的截取功能。另外附带凸包算法的演示效果。
(TurboC achieved by drawing applet. Graphical interface, including polygon, polyline drawing, move, zoom, rotate, and the interception of polygon features. Also attached to the convex hull algorithm for demonstration effect.)