Microsoft KB Archive/141486

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DOCERR: No DDI ReEnable Docs for Windows 95 Display Minidriver

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Q141486

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The information in this article applies to:


 * Microsoft Win32 Device Driver Kit (DDK) Windows 95

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SUMMARY
The Windows 95 Device Driver Kit did not include any formal documentation for the display mini-driver ReEnable function. This article supplements the DDK samples with further corrected information.

MORE INFORMATION
Pseudo Function Prototype:

BOOL ReEnable ( LPPDEVICE, LPSTR );

Parameters:

lpPDevice - Long pointer to the display drivers PDEVICE structure stored by the GDI. lpGDIInfo - Long pointer to the current GDIINFO structure stored by           the GDI.

Return Value:

The return value is FALSE if the function failed, otherwise it is TRUE.

Comments:

ReEnable is called by GDI to change the display resolution dynamically.

If the display driver supports ReEnable, it should set C1_REINIT_ABLE in the GDIInfo structure's dpCaps1 field. The GDI won't call this DDI unless the new resolution is one that satisfied the ValidateMode call the GDI did earlier.

This function should retrieve the new resolution value from the registry (via a call to VDD's VDD_GET_DISPLAY_CONFIG service), and map it into a resolution ID (0 = 320x200, 1=640x480, 2=800x600, 3=1024x768). This resolution should be set in a global variable, which is the wResolution variable in the DDK's samples, for use elsewhere in the driver. ReEnable should then call the display drivers Enable twice to set up the GDIInfo block and the PDevice block appropriately.