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I see in different painting examples you consistantly create a CExtMemoryDC. but I don’t see where it is flipped or drawn the the display. Can you provide more information about this class?

Thanks,
Seth

The CExtMemoryDC::__Flush() is an internal method that draws the content of in-memory surface into the original device context. This method is invoked from the CExtMemoryDC::~CExtMemoryDC() destructor. But you can also invoke it explicitly. In most cases, you should simply declare an in-stack local CExtMemoryDC variable and specify a pointer to the original device context in the constructor parameter. Sometimes you may also need to specify the rectangular area of the original device context. This may be needed if you want to use only some part of the surface. The CExtMemoryDC::__MDC_OPT_*** flags are typically not required. They are designed for the very specific painting tasks described in the code comments next to each constant.