如何让CDC上输出的文字、图形具有保持功能，集合类CPtrArray的使用，CPaintDC与CClientDC的区别与应用，OnPaint与OnDraw在CView中的关系及实现内幕，滚动窗口的实现，坐标空间，映射方式，设备坐标与逻辑坐标的转换。元文件设备描述表的使用，如何利用兼容DC实现图形的保存和再现。-CDC on how to output text, graphics with a hold function, the use of collection classes CPtrArray, CPaintDC and CClientDC and application of the distinction, OnPaint and OnDraw in the relationship and achieve CView inside, rolling window implementation, coordinate space mapping, device coordinates and logical coordinates conversion. Metafile device context to use, how to use the compatible DC to achieve the preservation and reproduction of graphics.