本方法参考 https://www.cnblogs.com/zhaotianff/p/17296406.html实现

#include <windows.h>   // 包含 Windows API 函数和数据结构
#include <iostream>    // 用于 std::cout

qreal cx;
qreal scale;

float GetMonitorScalingRatio(HMONITOR monitor)
{
    MONITORINFOEX info ={ };
    info.cbSize = sizeof(info);
    GetMonitorInfo(monitor, &info);
    DEVMODE devmode = {};
    devmode.dmSize = sizeof(DEVMODE);
    EnumDisplaySettings(info.szDevice, ENUM_CURRENT_SETTINGS, &devmode);
    return static_cast<float>(devmode.dmPelsWidth) / (info.rcMonitor.right - info.rcMonitor.left);
}

void PrintMonitorInfo(HMONITOR monitor) {
    MONITORINFOEX info = {};
    info.cbSize = sizeof(info);
    if (GetMonitorInfo(monitor, &info)) {
        std::cout << "Monitor Name: " << info.szDevice << '\n';
        std::cout << "Resolution: "
                  << (info.rcMonitor.right - info.rcMonitor.left) << "x"
                  << (info.rcMonitor.bottom - info.rcMonitor.top) << '\n';
        // 获取原始分辨率
        DEVMODE originalMode = {};
        originalMode.dmSize = sizeof(DEVMODE);
        if (EnumDisplaySettings(info.szDevice, ENUM_REGISTRY_SETTINGS, &originalMode)) {
            std::cout << "Original Resolution: "
                      << originalMode.dmPelsWidth << "x"
                      << originalMode.dmPelsHeight << '\n';
        } else {
            std::cerr << "Failed to get original display settings for " << info.szDevice << ".\n";
        }
    } else {
        std::cerr << "Failed to get monitor info.\n";
    }
}

void getScreenInfo() {
    ::EnumDisplayMonitors(
        nullptr,
        nullptr,
        [](HMONITOR hMonitor,
           HDC Arg2,
           LPRECT Arg3,
           LPARAM Arg4)
        {
            PrintMonitorInfo(hMonitor);
            float s = GetMonitorScalingRatio(hMonitor);
            std::cout << s << std::endl;
            return TRUE;
        },
        0);
}

运行结果

Monitor Name: 0x83f938
Resolution: 3072x1728
Original Resolution: 3840x2160
1.25
Monitor Name: 0x83f938
Resolution: 2560x1440
Original Resolution: 3840x2160
1.5