使用vc++实现的一个简单的画图程序，其中主要是由CMyCADView类中的函数完成了画线的功能，主要是：OnDraw、OnLButtonDown和OnMouseMove这三个函数-Using vc++ implementation of a simple drawing program, which is mainly a function of the class by the CMyCADView completed the painting line, and mainly: OnDra