Visual C++语言提供了虚屏功能，利用它及Windows GDI图形函数，可编制出功能强大的图形处理程序。虚拟屏幕的原理是，首先定义一个虚拟设备描述表及一块位图象数据区，将本应在实际窗口的绘画处理转移到此图象数据区（这块图象数据区功能相当于视频存储区），绘画操作完成后可通过图象传递，将结果弹出到可视窗口。许多Windows环境的图形处理或CAD系统都采用了这种技术。如GIS软件Mapinfo、AutoCAD for Windows等，它们的图形操作功能如开窗、漫游等的基础都是建立在虚屏基础上，并且将操作界面都作成工具窗（一种特殊的窗口，客户区内规则地排列着图象按钮响应操作代码）的形式，直观、灵活且便于用户选择操作。VC++的CDC类、CBitmap类封装了对虚屏的操作，利用类的继承性，也可很容易的实现工具窗。-Visual C++ provides a virtual screen function, use it, and Windows GDI graphics functions, can be prepared in a powerful graphics program. The principle of the virtual screen, first define a virtual device descr iption table and a bit image data area, the present should be transferred in the actual window painting processing of this image data area (this image data area function equivalent to the video memory area ), after the completion of the painting operation can be passed through the image, the results of the pop-up to the visible window. Graphics or CAD system for many Windows environment using this technology. GIS software Mapinfo, AutoCAD for Windows and other graphics operations functions such as windows, roaming the foundation are built on the basis of the virtual screen, and the operator interface made ​ ​ tool window (a special window, the client area regularly arranged in the form of image button in response to the operation code), intuitive, flexible and user-fri