Figure 9.1 shows where the printer driver exists in the Windows NT printing architecture.
Figure 9.1 The Printer Driver in Windows NT
It is only through GDI that a Windows NT printer driver communicates with the application and, by way of the spooler, sends printer instructions to the device. That is, a printer driver is driven by requests from GDI. If the driver determines that a print-related request can be adequately processed by GDI services, it can pass the call back for the graphics engine to handle. This is referred to as punting the call. This method of deferring function calls to GDI, when no special processing is required for the particular printer device, allows the driver to be smaller and can significantly shorten its development time.
Since the graphics engine can perform much of the rendering and printing functionality, and always works in conjunction with a printer driver, it is recommended that you refer to the GDI Support for Graphics Drivers and its subsequent topics before proceeding with the printer driver topics that follow. The GDI overview topics provide information on topics such as: