Windows CE provides several methods for obtaining a device context handle, depending on whether the device is a display, printer, or memory device. You use a display device context to draw in the client area of a screen. You use a memory device context to store bitmapped images in memory rather than sending it to an output device. A memory device context enables Windows CE to treat a portion of memory as a virtual device. You use a printer device context to send output to a printer.
It is important when using a device context that you release or delete it when it is no longer in use. Releasing a device context frees the device for use by other applications.
Note Failure to delete objects no longer in use can significantly affect performance.