使用WMI改变显示器亮度

本文主要是介绍使用WMI改变显示器亮度，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

前言

最近遇到了新的需求，需要通过代码去改变显示器的亮度。通过调研发现，改变显示器亮度的方式有三种
1.调节伽马值
2.使用WMI
3.使用DDC/CI协议
然而这三个方法都各有缺点：
第一个方式：调节伽马值，效果会收到显示器的影响，有的显示器，或者驱动，会去校准显示器亮度。如果你改变了伽马值，在你的鼠标脱离程序的时候，屏幕亮度就会被校准回去。
第二个方式：使用WMI。使用WMI是不支持台式电脑的，只能在笔记本上面生效。这个也是我在调试的时候发现的，总是被拒绝访问，去查了才知道台式不支持。然后在笔记本下做了校验，发现确实是可以实现的。
第三个方式：使用DDC/CI协议。DDC/CI，全称为 Display Data Channel / Command Interface，是一种用于计算机显示设备（如显示器、投影仪等）之间通信的协议。它允许计算机与显示器共享信息，使得计算机能够读取显示器的状态和特性，例如分辨率、色彩特性等。

DDC/CI 的构成
DDC/CI 协议主要构建在两个较早的标准之上：

DDC (Display Data Channel):

DDC 是一种用于监视器和计算机之间通信的协议，允许计算机访问显示器的 EDID（Extended Display Identification Data）信息，EDID 是描述显示器特性的标准化数据结构。
CI (Command Interface):

Command Interface 允许计算机向显示器发送命令，包括但不限于调节明亮度、对比度、开启或关闭显示器等功能。

DDC/CI 的工作原理
I²C 通信: DDC/CI 的底层协议使用 I²C（Inter-Integrated Circuit）总线，使其可以支持主设备和从设备的双向通信。通常情况下，计算机作为主设备，显示器作为从设备。

EDID 读取: 计算机在启动时通过 DDC 读取显示器的 EDID，以确定最佳的分辨率和刷新率等设置。

命令发送: 计算机可以通过 DDC/CI 向显示器发送各种控制命令，比如：

调整亮度和对比度
切换输入信号源（如 HDMI、DisplayPort 等）
查询显示器当前的状态和设置

DDC/CI 的应用
显示器控制: DDC/CI 允许用户通过软件来控制显示器的许多设置，例如调节亮度、对比度和色温。许多监视器和显示器厂商都提供支持 DDC/CI 的软件工具来实现这些功能。

自动化脚本: 一些高级用户和系统管理员可以利用 DDC/CI 编写自动化脚本，以便远程管理和控制多个显示器的设置。

多显示器支持: 在多显示器环境中，DDC/CI 使得通过计算机系统统一管理多个显示器的设置成为可能。

如何使用 DDC/CI
软件工具
有几种工具可以帮助用户利用 DDC/CI 控制显示器：

DDC/CI 控制工具: 许多开源和商业软件，如 Monitorian （Windows 上的应用程序），可以通过 DDC/CI 来调整监视器的亮度和其他设置。

命令行工具: 例如 ddcutil 在 Linux 平台上，可以用来通过命令行与 DDC/CI 兼容的显示器进行交互。

注意事项
显示器支持: 并非所有显示器都支持 DDC/CI，因此确保你的显示器具有此功能。

驱动问题: 某些情况下，操作系统或显卡驱动程序可能需要支持 DDC/CI，以确保正常工作。

使用WMI调节显示器亮度

直接上代码吧，代码其实都是差不多的，主要在于你执行怎样的WQL操作，做什么样的操作。其余步骤都是差不多的。
头文件

#pragma once#include <QtWidgets/QMainWindow>
#include "ui_QtTestPro.h"class QtTestPro : public QMainWindow
{Q_OBJECTpublic:QtTestPro(QWidget *parent = Q_NULLPTR);int Init();int GetBrightness();void PrintError(HRESULT hres);int SetBrightness(int brightness);void Cleanup();~QtTestPro();private slots:void on_btnUp_clicked();void on_btnDown_clicked();private:Ui::QtTestProClass ui;
};

cpp文件

#include "QtTestPro.h"#include <QPushButton>
#include <iostream>
#include <string>
#include <windows.h>
#include <objbase.h>
#include <wbemidl.h>
#include <comdef.h>
#include <mutex>
#include<QDebug>#pragma comment(lib, "wbemuuid.lib")
#pragma comment(lib, "comsuppw.lib")using namespace std;// wmi namespace
IWbemLocator* wmiLocator = NULL;
IWbemServices* wmiNamespace = 0;
BSTR wmiPath = SysAllocString(L"root\\wmi");
HRESULT hr = S_OK;// brightnessAdjustmentClass
IWbemClassObject* brightnessAdjustmentClass = NULL;
IWbemClassObject* brightnessAdjustmentClassInstant = NULL;
IWbemClassObject* brightnessAdjustmentClassObject = NULL;
IWbemClassObject* brightnessAdjustmentMethodInstant = NULL;
IEnumWbemClassObject* brightnessAdjustmentClassEnum = NULL;BSTR brightnessAdjustmentClassPath = SysAllocString(L"WmiMonitorBrightnessMethods");
BSTR brightnessAdjustmentMethodName = SysAllocString(L"WmiSetBrightness");
BSTR brightnessAdjustmentMethodArgName1 = SysAllocString(L"Timeout");
BSTR brightnessAdjustmentMethodArgName2 = SysAllocString(L"Brightness");
BSTR brightnessAdjustmentClassQuery = SysAllocString(L"Select * from WmiMonitorBrightnessMethods");// brightnessClass
IEnumWbemClassObject* brightnessClassEnum = NULL;
//IWbemClassObject *brightnessClass = NULL;
IWbemClassObject* brightnessClassObject = NULL;BSTR brightnessClassPath = SysAllocString(L"WmiMonitorBrightness");
BSTR brightnessVariableName = SysAllocString(L"CurrentBrightness");
BSTR brightnessQuery = SysAllocString(L"Select * from WmiMonitorBrightness");QtTestPro::QtTestPro(QWidget* parent): QMainWindow(parent)
{ui.setupUi(this);connect(ui.btnUp, &QPushButton::clicked, this, &QtTestPro::on_btnUp_clicked);connect(ui.btnDown, &QPushButton::clicked, this, &QtTestPro::on_btnDown_clicked);// 全局唯一//auto m = CreateMutexA(NULL, TRUE, "{CAF16FA1-1E0C-419B-9D45-99B5719ED318}");//if (ERROR_ALREADY_EXISTS == GetLastError())//	return;int r = Init();if (r != 0)return;}QtTestPro::~QtTestPro() {// 清理//UnregisterHotKey(hwnd, hotKeyId1);//UnregisterHotKey(hwnd, hotKeyId2);//GlobalDeleteAtom(hotKeyId1);//GlobalDeleteAtom(hotKeyId2);//Cleanup();
}//
int QtTestPro::Init()
{// Initialize COM and connect up to CIMOM  hr = CoInitialize(0);if (FAILED(hr))return -1;hr = CoInitializeSecurity(NULL, -1, NULL, NULL, RPC_C_AUTHN_LEVEL_DEFAULT, RPC_C_IMP_LEVEL_IMPERSONATE, NULL, EOAC_NONE, NULL);if (FAILED(hr))return -1;hr = CoCreateInstance(CLSID_WbemLocator, 0, CLSCTX_INPROC_SERVER, IID_IWbemLocator, (LPVOID*)&wmiLocator);if (FAILED(hr))return -1;hr = wmiLocator->ConnectServer(_bstr_t(L"ROOT\\WMI"), NULL, NULL, NULL, 0, NULL, NULL, &wmiNamespace);if (hr != WBEM_S_NO_ERROR)return -1;hr = CoSetProxyBlanket(wmiNamespace, RPC_C_AUTHN_WINNT, RPC_C_AUTHZ_NONE, NULL, RPC_C_AUTHN_LEVEL_CALL, RPC_C_IMP_LEVEL_IMPERSONATE, NULL, EOAC_NONE);if (hr != WBEM_S_NO_ERROR)return -1;//_bstr_t(L"ROOT\\CIMV2");// query variable enumhr = wmiNamespace->ExecQuery(_bstr_t(L"WQL"), _bstr_t(L"Select * from WmiMonitorBrightnessMethods"), WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &brightnessAdjustmentClassEnum);if (hr != WBEM_S_NO_ERROR)return -1;/*hr = wmiNamespace->ExecQuery(_bstr_t(L"WQL"), brightnessQuery, WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &brightnessClassEnum);if (hr != WBEM_S_NO_ERROR)return -1;*/// get class objULONG ret;hr = brightnessAdjustmentClassEnum->Next(WBEM_INFINITE, 1, &brightnessAdjustmentClassObject, &ret);if (hr != WBEM_S_NO_ERROR){qDebug() << "Failed to retrieve the next object. Error code = 0x"<< hex << hr << dec << endl;return -1;}hr = wmiNamespace->GetObject(brightnessAdjustmentClassPath, 0, NULL, &brightnessAdjustmentClass, NULL);if (hr != WBEM_S_NO_ERROR)return -1;// get brightness adjust method instanthr = brightnessAdjustmentClass->GetMethod(brightnessAdjustmentMethodName, 0, &brightnessAdjustmentClassInstant, NULL);if (hr != WBEM_S_NO_ERROR)return -1;hr = brightnessAdjustmentClassInstant->SpawnInstance(0, &brightnessAdjustmentMethodInstant);if (hr != WBEM_S_NO_ERROR)return -1;return 0;//HRESULT hres; Step 1: -------------------------------------------------- Initialize COM. ------------------------------------------hres = CoInitializeEx(0, COINIT_MULTITHREADED);//hres = CoInitialize(0);//if (FAILED(hres))//{//	PrintError(hres);//	qDebug() << "Failed to initialize COM library. Error code = 0x"//		<< hex << hres << endl;//	return 1;                  // Program has failed.//} Step 2: -------------------------------------------------- Set general COM security levels --------------------------//hres = CoInitializeSecurity(//	NULL,//	-1,                          // COM authentication//	NULL,                        // Authentication services//	NULL,                        // Reserved//	RPC_C_AUTHN_LEVEL_DEFAULT,   // Default authentication//	RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation//	NULL,                        // Authentication info//	EOAC_NONE,                   // Additional capabilities//	NULL                         // Reserved//	);//if (FAILED(hres))//{//	cout << "Failed to initialize security. Error code = 0x"//		<< hex << hres << endl;//	CoUninitialize();//	return 1;                    // Program has failed.//} Step 3: --------------------------------------------------- Obtain the initial locator to WMI -------------------------//IWbemLocator *pLoc = NULL;//hres = CoCreateInstance(//	CLSID_WbemLocator,//	0,//	CLSCTX_INPROC_SERVER,//	IID_IWbemLocator, (LPVOID *)&pLoc);//if (FAILED(hres))//{//	cout << "Failed to create IWbemLocator object."//		<< " Err code = 0x"//		<< hex << hres << endl;//	CoUninitialize();//	return 1;                 // Program has failed.//} Step 4: ----------------------------------------------------- Connect to WMI through the IWbemLocator::ConnectServer method//IWbemServices *pSvc = NULL; Connect to the root\cimv2 namespace with the current user and obtain pointer pSvc to make IWbemServices calls.//hres = pLoc->ConnectServer(//	_bstr_t(L"ROOT\\CIMV2"), // Object path of WMI namespace//	NULL,                    // User name. NULL = current user//	NULL,                    // User password. NULL = current//	0,                       // Locale. NULL indicates current//	NULL,                    // Security flags.//	0,                       // Authority (for example, Kerberos)//	0,                       // Context object//	&pSvc                    // pointer to IWbemServices proxy//	);//if (FAILED(hres))//{//	cout << "Could not connect. Error code = 0x"//		<< hex << hres << endl;//	pLoc->Release();//	CoUninitialize();//	return 1;                // Program has failed.//}//cout << "Connected to ROOT\\CIMV2 WMI namespace" << endl; Step 5: -------------------------------------------------- Set security levels on the proxy -------------------------//hres = CoSetProxyBlanket(//	pSvc,                        // Indicates the proxy to set//	RPC_C_AUTHN_WINNT,           // RPC_C_AUTHN_xxx//	RPC_C_AUTHZ_NONE,            // RPC_C_AUTHZ_xxx//	NULL,                        // Server principal name//	RPC_C_AUTHN_LEVEL_CALL,      // RPC_C_AUTHN_LEVEL_xxx//	RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx//	NULL,                        // client identity//	EOAC_NONE                    // proxy capabilities//	);//if (FAILED(hres))//{//	cout << "Could not set proxy blanket. Error code = 0x"//		<< hex << hres << endl;//	pSvc->Release();//	pLoc->Release();//	CoUninitialize();//	return 1;               // Program has failed.//} Step 6: -------------------------------------------------- Use the IWbemServices pointer to make requests of WMI ---- For example, get the name of the operating system//IEnumWbemClassObject* pEnumerator = NULL;//hres = pSvc->ExecQuery(//	bstr_t("WQL"),//	bstr_t("SELECT * FROM Win32_DesktopMonitor"),//L"Select * from WmiMonitorBrightnessMethods  "SELECT * FROM Win32_OperatingSystem" "SELECT * FROM Win32_DesktopMonitor"//	WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,//	NULL,//	&pEnumerator);//if (FAILED(hres))//{//	cout << "Query for operating system name failed."//		<< " Error code = 0x"//		<< hex << hres << endl;//	pSvc->Release();//	pLoc->Release();//	CoUninitialize();//	return 1;               // Program has failed.//} Step 7: ------------------------------------------------- Get the data from the query in step 6 -------------------//IWbemClassObject *pclsObj = NULL;//ULONG uReturn = 0;//while (pEnumerator)//{//	HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1,//		&pclsObj, &uReturn);//	if (0 == uReturn)//	{//		break;//	}//	VARIANT vtProp;//	VariantInit(&vtProp);//	// Get the value of the Name property//	hr = pclsObj->Get(L"Name", 0, &vtProp, 0, 0);//	qDebug() << " OS Name : " << vtProp.bstrVal << endl;//	VariantClear(&vtProp);//	pclsObj->Release();//} Cleanup ========//pSvc->Release();//pLoc->Release();//pEnumerator->Release();//CoUninitialize();//return 0;   // Program successfully completed.}void QtTestPro::PrintError(HRESULT hres)
{LPVOID lpMsgBuf;FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,NULL,hres,MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),(LPWSTR)&lpMsgBuf,0, NULL);qDebug()<< L"Error: " << (LPWSTR)lpMsgBuf << endl;LocalFree(lpMsgBuf);
}int QtTestPro::GetBrightness()
{// 每次都需要查询if (brightnessClassEnum) brightnessClassEnum->Release();if (brightnessClassObject) brightnessClassObject->Release();HRESULT hr = wmiNamespace->ExecQuery(_bstr_t(L"WQL"), brightnessQuery, WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &brightnessClassEnum);if (hr != WBEM_S_NO_ERROR)return -1;DWORD ret;hr = brightnessClassEnum->Next(WBEM_INFINITE, 1, &brightnessClassObject, &ret);if (hr != WBEM_S_NO_ERROR)return -1;// 获得亮度值VARIANT brightnessValue;VariantInit(&brightnessValue);hr = brightnessClassObject->Get(brightnessVariableName, 0, &brightnessValue, 0, 0);if (hr != WBEM_S_NO_ERROR)return -1;ui.label->setText(QString::number(brightnessValue.uintVal));return brightnessValue.uintVal;
}int QtTestPro::SetBrightness(int brightness)
{// 亮度范围是 [0, 100]brightness = min(max(brightness, 0), 100);// write brightness adjust paramsVARIANT var;VariantInit(&var);V_VT(&var) = VT_BSTR;// write timeout paramV_BSTR(&var) = SysAllocString(L"0");hr = brightnessAdjustmentMethodInstant->Put(brightnessAdjustmentMethodArgName1, 0, &var, CIM_UINT32);if (hr != WBEM_S_NO_ERROR)return -1;// write brightness paramV_BSTR(&var) = SysAllocString(to_wstring(brightness).c_str());hr = brightnessAdjustmentMethodInstant->Put(brightnessAdjustmentMethodArgName2, 0, &var, CIM_UINT8);VariantClear(&var);if (hr != WBEM_S_NO_ERROR)return -1;// 获取 method instant path 和 executeVARIANT pathVariable;VariantInit(&pathVariable);hr = brightnessAdjustmentClassObject->Get(_bstr_t(L"__PATH"), 0, &pathVariable, NULL, NULL);if (hr != WBEM_S_NO_ERROR)return -1;hr = wmiNamespace->ExecMethod(pathVariable.bstrVal, brightnessAdjustmentMethodName, 0, NULL, brightnessAdjustmentMethodInstant, NULL, NULL);VariantClear(&pathVariable);if (hr != WBEM_S_NO_ERROR)return -1;return 0;
}void QtTestPro::Cleanup()
{// 清理SysFreeString(wmiPath);SysFreeString(brightnessAdjustmentClassPath);SysFreeString(brightnessAdjustmentMethodName);SysFreeString(brightnessAdjustmentMethodArgName1);SysFreeString(brightnessAdjustmentMethodArgName2);SysFreeString(brightnessAdjustmentClassQuery);SysFreeString(brightnessClassPath);SysFreeString(brightnessVariableName);SysFreeString(brightnessQuery);brightnessAdjustmentClass->Release();brightnessAdjustmentMethodInstant->Release();brightnessAdjustmentClassInstant->Release();brightnessAdjustmentClassObject->Release();brightnessAdjustmentClassEnum->Release();//if (brightnessClass) brightnessClass->Release();brightnessClassObject->Release();brightnessClassEnum->Release();wmiNamespace->Release();wmiLocator->Release();CoUninitialize();
}// 亮度进阶值
void QtTestPro::on_btnUp_clicked() {GetBrightness();SetBrightness(ui.lineEdit->text().toInt());
}void QtTestPro::on_btnDown_clicked() {GetBrightness();SetBrightness(ui.lineEdit->text().toInt());
}

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