Software Engineering and Computer Games

25.5. A memory-based device context

In order to keep our rapidly animated Windows displays from flickering, we use the cMemoryDC objects as virtual windows, or memory bitmaps. It is not a standard MFC class like CPoint, nor is it a well-known kind of user-written class like cVector. cMemoryDC is a special memory device context class that the author implemented here in order to make Windows programming easier.

The cMemoryDC class is a child of the standard CDC class. This means that we can write to a cMemoryDC with the same graphics methods that the CDC class uses to put graphics into an onscreen window or onto a printer page. And because cMemoryDC is a kind of CDC, we can use the powerful CDC::BitBlt method to do extremely fast copying from ...