gammaramp.cpp

一个可以通过串口读取传感器的亮度信息,然后发送数据到主机中,根据这个值可以来设置我们显示屏的亮度

// GammaRamp.cpp: implementation of the CGammaRamp class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "windows.h"
#include "GammaRamp.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

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_SetDeviceGammaRamp)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.
	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;
}