Q75005: Handling NULL lpDrawMode in a Display Driver

Article: Q75005
Product(s): Microsoft Windows Device Driver Kit
Version(s): 3.0,3.1; WINDOWS:3.11
Operating System(s): 
Keyword(s): 
Last Modified: 03-NOV-1999

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The information in this article applies to:

- Microsoft Windows Device Development Kit (DDK) for Windows, versions 3.0, 3.1 
- Microsoft Windows for Workgroups version 3.11 
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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 query words: 3.00 3.10 3.11 DDKDISPLAY

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Keywords          :  
Technology        : kbAudDeveloper kbWin3xSearch kbWinDDKSearch kbWFWSearch kbWinDDK300 kbWinDDK310 kbWFW311
Version           : :3.0,3.1; WINDOWS:3.11

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