INF: Handling NULL lpDrawMode in a Display Driver

ID Number: Q75005

3.00 3.10

WINDOWS

Summary:

In the Microsoft Windows graphical environment, the graphics device

interface (GDI) should never pass a NULL lpDrawMode to a display

driver. However, when a printer driver uses the brute interface to

call the BitBlt routine in the display driver, the calling printer

driver provides the parameters, including lpDrawMode, to the display

driver. In this case, GDI cannot prevent the driver from sending

incorrect parameters.

For this reason, a display driver must be robust and must not crash

when it receives incorrect arguments.

The source code for the 8514/A display driver, included with the

Microsoft Windows Device Development Kit (DDK), provides a good

example of how to handle operations with a NULL lpDrawMode parameter.

Additional reference words: 3.00 3.10 DDKDISPLAY