获取DPI、设置进程DPI感知(C++源码)

1、概述

本文实现如下功能：
1、设置进程 DPI 感知(告诉系统，程序自己处理dpi变化，不要拉伸我的界面)
2、获取系统或窗口所在显示器的 DPI
3、查询其他进程的 DPI 感知状态

2、源码

2.1、调用示例

    // 调用示例// 获取dpidpiUtil::InitDpiAPIFunc();dpiUtil::SetProcessDpiAware();UINT dpi = dpiUtil::GetDpiFromSystem();std::cout << "dpi:" << dpi << std::endl;HWND hwWxWork = FindWindowW(L"WeWorkWindow", L"企业微信");dpi = dpiUtil::GetDpiFromWindow(hwWxWork);std::cout << "dpi:" << dpi << std::endl;

2.2、源码

#ifndef dpi_util_h_
#define dpi_util_h_#include <windows.h>
#include <shellscalingapi.h>class dpiUtil
{
public:// 初始化dpistatic void InitDpiAPIFunc();// 获取系统dpistatic UINT GetDpiFromSystem();// 获取窗口对应显示器的dpistatic UINT GetDpiFromWindow(HWND hWnd);// 设置进程DPI感知(告诉系统，程序自己处理dpi变化，不要拉伸我的界面)// 在程序的入口处调用, DPI感知设置必须在创建第一个窗口前完成static bool SetProcessDpiAware();// 获取进程是否DPI感知static bool GetProcessDpiAwareness(DWORD pid, PROCESS_DPI_AWARENESS& awareness);
};#endif

#include "dpiUtil.h"
#include <memory>
#include "WinVerUtil.h"using funGetDpiForSystem = UINT(WINAPI*)(VOID);
using funGetDpiForWindow = UINT(WINAPI*)(HWND hwnd);
using funGetDpiForMonitor = HRESULT(__stdcall *)(HMONITOR, MONITOR_DPI_TYPE, UINT*, UINT*);
using funSetProcessDpiAwarenessContext = BOOL(__stdcall *)(DPI_AWARENESS_CONTEXT);
using funSetProcessDpiAwareness = HRESULT(__stdcall *)(PROCESS_DPI_AWARENESS);
using funSetProcessDPIAware = BOOL(__stdcall *)();
using funGetProcessDpiAwareness = HRESULT(__stdcall*)(HANDLE, PROCESS_DPI_AWARENESS*);funGetDpiForSystem g_fnGetDpiForSystem = nullptr;
funGetDpiForWindow g_fnGetDpiForWindow = nullptr;
funGetDpiForMonitor g_fnGetDpiForMonitor = nullptr;
funSetProcessDpiAwarenessContext g_fnSetProcessDpiAwarenessContext = nullptr;
funSetProcessDpiAwareness g_fnSetProcessDpiAwareness = nullptr;
funSetProcessDPIAware g_fnSetProcessDPIAware = nullptr;
funGetProcessDpiAwareness g_fnGetProcessDpiAwareness = nullptr;template <typename T>
bool GetFuncPtr(HMODULE h, T& ptr, const char* funcName)
{auto funcPtr = reinterpret_cast<T>(::GetProcAddress(h, funcName));if (funcPtr){ptr = funcPtr;return true;}return false;
}void dpiUtil::InitDpiAPIFunc()
{if (WinVerUtil::IsWindows10OrGreater()){HMODULE hUser32 = ::GetModuleHandle(L"user32.dll");if (hUser32 != nullptr){GetFuncPtr(hUser32, g_fnGetDpiForSystem, "GetDpiForSystem");GetFuncPtr(hUser32, g_fnGetDpiForWindow, "GetDpiForWindow");GetFuncPtr(hUser32, g_fnSetProcessDpiAwarenessContext, "SetProcessDpiAwarenessContext");GetFuncPtr(hUser32, g_fnSetProcessDPIAware, "SetProcessDPIAware");}}HMODULE hShcore = ::GetModuleHandle(L"shcore.dll");if (hShcore == nullptr){hShcore = ::LoadLibrary(L"shcore.dll");}if (hShcore != nullptr){GetFuncPtr(hShcore, g_fnGetDpiForMonitor, "GetDpiForMonitor");GetFuncPtr(hShcore, g_fnSetProcessDpiAwareness, "SetProcessDpiAwareness");GetFuncPtr(hShcore, g_fnGetProcessDpiAwareness, "GetProcessDpiAwareness");}
}UINT dpiUtil::GetDpiFromSystem()
{// win10 version 1703支持的api，返回主显示器的dpi// GetDpiForSystem() 返回主显示器的逻辑 DPI，但其值受进程 DPI Awareness 模式影响// 若进程未声明高 DPI 感知（默认为 Unaware），Windows 会启用 DPI 虚拟化，// 强制所有 DPI API 返回 96（即使系统缩放设为 125%），并由系统拉伸界面（导致模糊）// 要获取真实 DPI，必须通过SetProcessDpiAwarenessContext 声明 DPI 感知if (g_fnGetDpiForSystem != nullptr){return g_fnGetDpiForSystem();}// 降级方案：用GDI的GetDeviceCapsUINT dpi = 96;// 返回整个屏幕(桌面窗口) 的DCHDC hdc = ::GetDC(nullptr);if (hdc != nullptr){dpi = ::GetDeviceCaps(hdc, LOGPIXELSX);::ReleaseDC(nullptr, hdc);}return dpi;
}UINT dpiUtil::GetDpiFromWindow(HWND hWnd)
{if (!::IsWindow(hWnd)){return GetDpiFromSystem();}// GetDpiForWindow() 返回主显示器的逻辑 DPI，但其值受进程 DPI Awareness 模式影响// 若进程未声明高 DPI 感知（默认为 Unaware），Windows 会启用 DPI 虚拟化，// 强制所有 DPI API 返回 96（即使系统缩放设为 125%），并由系统拉伸界面（导致模糊）// 要获取真实 DPI，必须通过SetProcessDpiAwarenessContext 声明 DPI 感知if (g_fnGetDpiForWindow != nullptr){auto dpi = g_fnGetDpiForWindow(hWnd);if (dpi > 0){return dpi;}}if (g_fnGetDpiForMonitor != nullptr){UINT dpiX = 0;UINT dpiY = 0;if (SUCCEEDED(g_fnGetDpiForMonitor(::MonitorFromWindow(hWnd, MONITOR_DEFAULTTONEAREST), MDT_EFFECTIVE_DPI, &dpiX, &dpiY)) && dpiX != 0 && dpiY != 0){return dpiX;}}return GetDpiFromSystem();
}bool dpiUtil::SetProcessDpiAware()
{// win10if (g_fnSetProcessDpiAwarenessContext != nullptr){if (g_fnSetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2)){return true;}if (g_fnSetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE)){return true;}}// win8.1if (g_fnSetProcessDpiAwareness != nullptr){if (SUCCEEDED(g_fnSetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE))){return true;}}// vista+if (g_fnSetProcessDPIAware != nullptr){if (g_fnSetProcessDPIAware()){return true;}}return false;
}bool dpiUtil::GetProcessDpiAwareness(DWORD pid, PROCESS_DPI_AWARENESS& awareness)
{if (g_fnGetProcessDpiAwareness == nullptr){return false;}HANDLE hProcess = ::OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid);if (!hProcess) {return false;}bool success = SUCCEEDED(g_fnGetProcessDpiAwareness(hProcess, &awareness));::CloseHandle(hProcess);return success;
}