熟练使用Visual C++ 6.0里面的MFC，实现直线的扫描转换的三种常用算法：数值微分法（DDA算法），中点画线法，Bresenham算法。-Skilled use of Visual C++ 6 inside the MFC, the realization of linear scan conversion of the three commonly used algorithms: numerical differentiation (DDA algorithm), the midpoint line drawing method, Bresenham algorithm.