Conditionally Required Graphics Driver Functions

Besides the functions that are always required, certain other functions may be required, depending on how a driver is implemented. The conditionally-required functions are listed in the following table. If the driver manages its own primary surface (using the EngCreateDeviceSurface function to get a handle to the surface), or its own offscreen bitmaps, the driver must also support several drawing functions. Drivers writing to standard format DIBs usually allow GDI to manage most or all of these operations. Displays that support settable palettes must also support the DrvSetPalette function.

It is more common for a printer driver than a display driver to define or draw fonts. A display driver is not required to handle fonts. If the hardware has a resident font, the driver must supply information to GDI about this font. This information includes font metrics, mappings from Unicode to individual glyph identities, individual glyph attributes, and kerning tables.