A Microsoft® Windows NT® display driver must support several DDI functions. In addition, the driver should support any operation it can do more efficiently than GDI; although the driver will be smaller and easier to write if it makes maximum use of existing GDI capabilities.
At a minimum, every display driver must do the following:
1.Enable and disable the graphics hardware.
2.Supply GDI with information about hardware capabilities.
3.Enable the drawing surface.
4.If the surface is device-managed, carry out graphics operations. At a minimum, this includes transferring bitmaps, and drawing text.
Driver calls are serialized for any given surface.
Some functions are required, depending on the type of display driver, while others are optional and their inclusion in the driver depends on what functionality the driver is to optimize. The topics that follow list the required, conditionally required, and optional DDI functions for display drivers.