Display Driver Escape Codes (Windows CE .NET Driver Development)

Display Driver Escape Codes

Windows CE .NET

Applications may need to communicate directly with a display driver. An escape code mechanism makes this possible. Applications can invoke the ExtEscape function to pass an escape code and optional data to a display driver. ExtEscape, in turn, passes those parameters to the display driver's DrvEscape function. DrvEscape processes the escape code, returns a value to ExtEscape, which then returns the value to the application. DrvEscape should take no action and return zero for unsupported escape codes.

The following table shows the escape codes for display drivers. You can define additional driver-specific escape codes, starting at the decimal value 100,000. Microsoft reserves all escape code values up to 99,999. Not all sample display drivers implement these escape codes.

Escape code Value Description
QUERYESCSUPPORT 8 Determines whether a display driver supports a particular escape code.
GETVFRAMEPHYSICAL 6144 Returns the physical memory location of the video frame buffer.
GETVFRAMELEN 6145 Returns the length of the video frame buffer.
DBGDRIVERSTAT 6146 Returns display driver statistics.
SETPOWERMANAGEMENT 6147 Requests a particular power management state.
GETPOWERMANAGEMENT 6148 Queries the current power management state.
CONTRASTCOMMAND 6149 Applies a display contrast setting.
DRVESC_GETGAMMAVALUE 6202 Retrieves the gamma value by calling GetGammaValue. GetGammaValue is part of Ctlblt.lib and should not be called by the application. Applications also should not use the ExtEscape function to invoke this driver. Set the gamma value through the SystemParametersInfo function with the SPI_GETFONTSMOOTHINGCONTRAST flag.
DRVESC_SETGAMMAVALUE 6201 Sets the gamma value by calling SetGammaValue. Applications should not use the ExtEscape function to invoke this driver. Set the gamma value through the SystemParametersInfo function with the SPI_SETFONTSMOOTHINGCONTRAST flag.
DRVESC_SETSCREENROTATION 6301 Sets the screen rotation value.
DRVESC_GETSCREENROTATION 6302 Retrieves the screen rotation value.
DRVESC_SAVEVIDEOMEM 6501 Saves the video RAM that must persist across a suspend or resume operation.

If HKEY_LOCAL_MACHINE\SYSTEM\GWE\PORepaint is 3, DRVESC_SAVEVIDEOMEM is invoked at suspend time.

DRVESC_RESTOREVIDEOMEM 6502 Restores the contents of the video RAM after resuming operation.
DRVESC_QUERYVIDEOMEMUSED 6503 Returns the amount of video memory in use. This is used to determine how much nonvolatile memory needs to be allocated before the save operation.
Reserved 6150 through 99,999 Reserved for future use.

See Also

Node2D | Advanced Display Driver Power Management | Contrast Control | Display Driver Architecture | Display Driver Extensions | Display Driver Samples

 Last updated on Tuesday, May 18, 2004

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