中点分割裁减算法的实现，ＶＣ＋＋，左键画出任意条直线，右键画出矩形进行裁减-midpoint of the segmentation algorithm to achieve reductions, VC + +, painted arbitrary menu of straight lines, right-painted rectangle for the reduction

一个简单的中点分割直线裁减算法，实现直线在屏幕中的裁剪算法-A simple linear reduction of the mid-point division algorithm in a straight line on the screen clipping algorithm