In response to device-independent application calls routed through GDI, a graphics driver must ensure that its graphics device produces the required output. A graphics driver controls graphics output by implementing as much of the Device Driver Interface (DDI) as is necessary.
DDI function names have the form DrvXxx. GDI calls these DrvXxx functions to pass data to the driver. In response to a request from an application, if GDI determines that a function is supported by the driver, GDI calls that function. It is the responsibility of the driver to support the function and return to GDI upon its completion.
This chapter describes the DDI functions of which all graphics driver writers must be aware. DDI function declarations, structure definitions, and constants can be found in winddi.h. This include file is shipped with the Windows NT DDK. See the Graphics Driver Reference for detailed information on each of the DDI entry point functions, GDI service functions, and DDI structures and types.
Note When a device driver returns an error, it can call EngSetLastError to log an extended error code. The application program can then retrieve the error code.