GetDeviceGammaRamp function (wingdi.h)

Article
09/23/2022

The GetDeviceGammaRamp function gets the gamma ramp on direct color display boards having drivers that support downloadable gamma ramps in hardware.

Important

We strongly recommend that you don't use this API. Use of this API is subject to major limitations. See SetDeviceGammaRamp for more information.

Syntax

BOOL GetDeviceGammaRamp(
  HDC    hdc,
  LPVOID lpRamp
);

Parameters

hdc

Specifies the device context of the direct color display board in question.

lpRamp

Points to a buffer where the function can place the current gamma ramp of the color display board. The gamma ramp is specified in three arrays of 256 WORD elements each, which contain the mapping between RGB values in the frame buffer and digital-analog-converter (DAC) values. The sequence of the arrays is red, green, blue.

Return value

If this function succeeds, the return value is TRUE.

If this function fails, the return value is FALSE.

Example

WORD gArray[3][256];
GetDeviceGammaRamp(handle, gArray);  
// `handle` is the device context. See GetDC for more details.
// `gArray` will hold the gamma array values in a 2-D array

Remarks

Direct color display modes do not use color lookup tables and are usually 16, 24, or 32 bit. Not all direct color video boards support loadable gamma ramps. GetDeviceGammaRamp succeeds only for devices with drivers that support downloadable gamma ramps in hardware.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	wingdi.h
Library	Gdi32.lib
DLL	Gdi32.dll

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