## Printer Device Driver

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### Shadow DC

Because the driver cannot handle bit maps, the driver must use the graphics engine and display device. The driver creates a shadow memory DC in display for each DC enabled for the printer (done in prde_EnableDC). If the driver is enabling a memory DC, the shadow memory DC will be used for all calls. Otherwise, the shadow memory DC will be used mainly for handling the bit maps.

In some functions, usually main entry points, the DC type is checked against memory. If the DC is memory, the call is routed to hdcMemory using an InnerGRE entry point.