【Qt】Qt调节Windows声音和亮度

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一、效果走一波

二、核心思路与实现

（1）对于Windows声音的调节，使用Windows系统API来控制，核心代码如下：

bool CustomSlider::SetVolumeLevel(int level)
{
    HRESULT hr;
    IMMDeviceEnumerator* pDeviceEnumerator = 0;
    IMMDevice* pDevice = 0;
    IAudioEndpointVolume* pAudioEndpointVolume = 0;
    IAudioClient* pAudioClient = 0;

    try {
        hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL, __uuidof(IMMDeviceEnumerator), (void**)&pDeviceEnumerator);
        if (FAILED(hr)) throw "CoCreateInstance";
        hr = pDeviceEnumerator->GetDefaultAudioEndpoint(eRender, eMultimedia, &pDevice);
        if (FAILED(hr)) throw "GetDefaultAudioEndpoint";
        hr = pDevice->Activate(__uuidof(IAudioEndpointVolume), CLSCTX_ALL, NULL, (void**)&pAudioEndpointVolume);
        if (FAILED(hr)) throw "pDevice->Active";
        hr = pDevice->Activate(__uuidof(IAudioClient), CLSCTX_ALL, NULL, (void**)&pAudioClient);
        if (FAILED(hr)) throw "pDevice->Active";

        if (level == -2) {
            hr = pAudioEndpointVolume->SetMute(FALSE, NULL);
            if (FAILED(hr)) throw "SetMute";
        }
        else if (level == -1) {
            hr = pAudioEndpointVolume->SetMute(TRUE, NULL);
            if (FAILED(hr)) throw "SetMute";
        }
        else {
            if (level<0 || level>100) {
                hr = E_INVALIDARG;
                throw "Invalid Arg";
            }

            float fVolume;
            fVolume = level / 100.0f;
            hr = pAudioEndpointVolume->SetMasterVolumeLevelScalar(fVolume, &GUID_NULL);
            if (FAILED(hr)) throw "SetMasterVolumeLevelScalar";

            pAudioClient->Release();
            pAudioEndpointVolume->Release();
            pDevice->Release();
            pDeviceEnumerator->Release();
            return true;
        }
    }
    catch (...) {
        if (pAudioClient) pAudioClient->Release();
        if (pAudioEndpointVolume) pAudioEndpointVolume->Release();
        if (pDevice) pDevice->Release();
        if (pDeviceEnumerator) pDeviceEnumerator->Release();
        throw;
    }
    return false;
}

（2）调节Windows屏幕亮度。使用一个开源接口库：GammaRamp来控制。核心代码如下：

#include "GammaRamp.h"
CGammaRamp::CGammaRamp()
{
	//Initialize all variables.
	hGDI32 = NULL;
	hScreenDC = NULL;
	pGetDeviceGammaRamp = NULL;
	pSetDeviceGammaRamp = NULL;
}

CGammaRamp::~CGammaRamp()
{
	FreeLibrary();
}


BOOL CGammaRamp::LoadLibrary()
{
	BOOL bReturn = FALSE;

    char* ldName = "gdi32.dll";
    WCHAR wldName[128];
    memset(wldName,0,sizeof (wldName));
    MultiByteToWideChar(CP_ACP,0,ldName,strlen(ldName)+1,wldName,sizeof(wldName)/sizeof(wldName[0]));

	FreeLibrary();
	//Load the GDI library.
    hGDI32 = ::LoadLibrary(wldName);
	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.
	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;
}

三、注意事项

当在双屏显示或者在虚拟机环境中运行时，亮度调节无效，暂时不解！

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本文标签： 亮度声音QTWindows