一个演示vc环境下图形映射模式的例子，对初学者来说，掌握不同映射模式的关系是进行图形程序开发的基础，代码简洁，值得参考。-A demo the vc environment the graphical mapping mode example, for beginners to grasp the relationship of the different mapping mode graphics program developed on the basis of the code is si