通过指定一种颜色把一幅位图变透明,这个从Cbitmap派生的位图类使你可以通过指定一种颜色把一幅位图变透明，而它的使用差不多同Cbitamp一样简单。-through a designated colors of a bitmap transparent change, this Cbitmap derived from the bitmap type so you can designate an colors of a bitmap transparent change, while its