出处：http://www.nirsoft.net/vc/change_screen_brightness.html
SetDeviceGammaRamp API函数位于Gdi32.ll中，接收一个256*3 RGB值的数组。
增加这个数组中的值会使屏幕更亮，而减少这些值会使屏幕变暗。
可以通过增加或减少的红/绿/蓝成分的值来显示影响。例如：在所有RGB值中增加蓝色分量将增加整个显示的蓝色。
下面的类封装调用GetDeviceGammaRamp和SetDeviceGammaRamp，并设置屏幕的亮度，提供setbrightness功能。
C++ GammaRamp.h
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 |
#ifndef GAMMARAMP_H_ #define GAMMARAMP_H_ /* CGammaRamp class Encapsulates the Gamma Ramp API and changes the brightness of the entire screen. Written by Nir Sofer. http://www.nirsoft.net */ class CGammaRamp { protected: HMODULE hGDI32; HDC hScreenDC; typedef BOOL (WINAPI *Type_GetDeviceGammaRamp)(HDC hDC, LPVOID lpRamp); typedef BOOL (WINAPI *Type_SetDeviceGammaRamp)(HDC hDC, LPVOID lpRamp); Type_GetDeviceGammaRamp pGetDeviceGammaRamp; Type_SetDeviceGammaRamp pSetDeviceGammaRamp; public: CGammaRamp(); ~CGammaRamp(); BOOL LoadLibrary(); void FreeLibrary(); BOOL LoadLibraryIfNeeded(); BOOL SetDeviceGammaRamp(HDC hDC, LPVOID lpRamp); BOOL GetDeviceGammaRamp(HDC hDC, LPVOID lpRamp); BOOL SetBrightness(HDC hDC, WORD wBrightness); }; #endif//#ifndef GAMMARAMP_H_ |
C++ GammaRamp.cpp
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 |
#include <windows.h> #include "gammaramp.h" /* CGammaRamp class Encapsulates the Gamma Ramp API and changes the brightness of the entire screen. Written by Nir Sofer. http://www.nirsoft.net */ CGammaRamp::CGammaRamp() { //Initialize all variables. hGDI32 = NULL; hScreenDC = NULL; pGetDeviceGammaRamp = NULL; pSetDeviceGammaRamp = NULL; } CGammaRamp::~CGammaRamp() { FreeLibrary(); } BOOL CGammaRamp::LoadLibrary() { BOOL bReturn = FALSE; FreeLibrary(); //Load the GDI library. hGDI32 = ::LoadLibrary("gdi32.dll"); if (hGDI32 != NULL) { //Get the addresses of GetDeviceGammaRamp and SetDeviceGammaRamp API functions. pGetDeviceGammaRamp = (Type_GetDeviceGammaRamp)GetProcAddress(hGDI32, "GetDeviceGammaRamp"); pSetDeviceGammaRamp = (Type_SetDeviceGammaRamp)GetProcAddress(hGDI32, "SetDeviceGammaRamp"); //Return TRUE only if these functions exist. if (pGetDeviceGammaRamp == NULL || pSetDeviceGammaRamp == NULL) { FreeLibrary(); } else { bReturn = TRUE; } } return bReturn; } void CGammaRamp::FreeLibrary() { //Free the GDI library. if (hGDI32 != NULL) { ::FreeLibrary(hGDI32); hGDI32 = NULL; } } BOOL CGammaRamp::LoadLibraryIfNeeded() { BOOL bReturn = FALSE; if (hGDI32 == NULL) { LoadLibrary(); } if (pGetDeviceGammaRamp != NULL && pSetDeviceGammaRamp != NULL) { bReturn = TRUE; } return bReturn; } BOOL CGammaRamp::SetDeviceGammaRamp(HDC hDC, LPVOID lpRamp) { //Call to SetDeviceGammaRamp only if this function is successfully loaded. if (LoadLibraryIfNeeded()) { return pSetDeviceGammaRamp(hDC, lpRamp); } else { return FALSE; } } BOOL CGammaRamp::GetDeviceGammaRamp(HDC hDC, LPVOID lpRamp) { //Call to GetDeviceGammaRamp only if this function is successfully loaded. if (LoadLibraryIfNeeded()) { return pGetDeviceGammaRamp(hDC, lpRamp); } else { return FALSE; } } BOOL CGammaRamp::SetBrightness(HDC hDC, WORD wBrightness) { /* Changes the brightness of the entire screen. This function may not work properly in some video cards. The wBrightness value should be a number between 0 and 255. 128 = Regular brightness above 128 = brighter below 128 = darker If hDC is NULL, SetBrightness automatically load and release the display device context for you. */ BOOL bReturn = FALSE; HDC hGammaDC = hDC; //Load the display device context of the entire screen if hDC is NULL. if (hDC == NULL) hGammaDC = GetDC(NULL); if (hGammaDC != NULL) { //Generate the 256-colors array for the specified wBrightness value. WORD GammaArray[3][256]; for (int iIndex = 0; iIndex < 256; iIndex++) { int iArrayValue = iIndex * (wBrightness + 128); if (iArrayValue > 65535) { iArrayValue = 65535; } GammaArray[0][iIndex] = GammaArray[1][iIndex] = GammaArray[2][iIndex] = (WORD)iArrayValue; } //Set the GammaArray values into the display device context. bReturn = SetDeviceGammaRamp(hGammaDC, GammaArray); } if (hDC == NULL) { ReleaseDC(NULL, hGammaDC); } return bReturn; } |
C++ Main.cpp
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 |
#include <Windows.h> #include "gammaramp.h" int WINAPI WinMain( HINSTANCE hInstance, // handle to current instance HINSTANCE hPrevInstance, // handle to previous instance LPSTR lpCmdLine, // command line int nCmdShow // show state ) { //Example for changing the brightness with CGammaRamp class: //Be aware that this exmaple may not work properly in all Video cards. CGammaRamp GammaRamp; //Make the screen darker: GammaRamp.SetBrightness(NULL, 64); //Wait 3 seconds: Sleep(3000); //Return back to normal: GammaRamp.SetBrightness(NULL, 128); return 0; } |