问如何使用C#以编程方式更改Windows 10显示

EN

DpiHelper::DPIScalingInfo DpiHelper::GetDPIScalingInfo(LUID adapterID, UINT32 sourceID)

bool DpiHelper::SetDPIScaling(LUID adapterID, UINT32 sourceID, UINT32 dpiPercentToSet)

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using Microsoft.Win32;

namespace SetDpiScale
{
    public partial class Form1 : Form
    {
        public enum DMDO
        {
            DEFAULT = 0,
            D90 = 1,
            D180 = 2,
            D270 = 3
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
        struct DEVMODE
        {
            public const int DM_PELSWIDTH = 0x80000;
            public const int DM_PELSHEIGHT = 0x100000;
            private const int CCHDEVICENAME = 32;
            private const int CCHFORMNAME = 32;

            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCHDEVICENAME)]
            public string dmDeviceName;
            public short dmSpecVersion;
            public short dmDriverVersion;
            public short dmSize;
            public short dmDriverExtra;
            public int dmFields;

            public int dmPositionX;
            public int dmPositionY;
            public DMDO dmDisplayOrientation;
            public int dmDisplayFixedOutput;

            public short dmColor;
            public short dmDuplex;
            public short dmYResolution;
            public short dmTTOption;
            public short dmCollate;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCHFORMNAME)]
            public string dmFormName;
            public short dmLogPixels;
            public int dmBitsPerPel;
            public int dmPelsWidth;
            public int dmPelsHeight;
            public int dmDisplayFlags;
            public int dmDisplayFrequency;
            public int dmICMMethod;
            public int dmICMIntent;
            public int dmMediaType;
            public int dmDitherType;
            public int dmReserved1;
            public int dmReserved2;
            public int dmPanningWidth;
            public int dmPanningHeight;
        }

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static extern int ChangeDisplaySettings([In] ref DEVMODE lpDevMode, int dwFlags);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            ChangeDPI(0); // 100%
        }
        private void button2_Click(object sender, EventArgs e)
        {
            ChangeDPI(1); // 125%
        }

        void ChangeDPI(int dpi)
        {
            RegistryKey key = Registry.CurrentUser.OpenSubKey("Control Panel", true);

            key = key.OpenSubKey("Desktop", true);
            key = key.OpenSubKey("PerMonitorSettings", true);
            key = key.OpenSubKey("*monitor id where to change the dpi*", true); // my second monitor here

            key.SetValue("DpiValue", dpi);

            SetResolution(1920, 1080); // this sets the resolution on primary screen
            SetResolution(2560, 1440); // returning back to my primary screens default resolution
        }

        private static void SetResolution(int w, int h)
        {
            long RetVal = 0;

            DEVMODE dm = new DEVMODE();

            dm.dmSize = (short)Marshal.SizeOf(typeof(DEVMODE));

            dm.dmPelsWidth = w;
            dm.dmPelsHeight = h;

            dm.dmFields = DEVMODE.DM_PELSWIDTH | DEVMODE.DM_PELSHEIGHT;


            RetVal = ChangeDisplaySettings(ref dm, 0);
        }
    }
}

SPI_SETLOGICALDPIOVERRIDE   Do not use. 
0x009F

SystemParametersInfo(SPI_SETLOGICALDPIOVERRIDE, relativeIndex, (LPVOID)0, 1);

100,125,150,175,200,225,250,300,350, 400, 450, 500

SystemParametersInfo(SPI_GETLOGICALDPIOVERRIDE, 0, (LPVOID)&dpi, 1);

#include <iostream>
#include <Windows.h>

using namespace std;


static const UINT32 DpiVals[] = { 100,125,150,175,200,225,250,300,350, 400, 450, 500 };

/*Get default DPI scaling percentage.
The OS recommented value.
*/
int GetRecommendedDPIScaling()
{
    int dpi = 0;
    auto retval = SystemParametersInfo(SPI_GETLOGICALDPIOVERRIDE, 0, (LPVOID)&dpi, 1);

    if (retval != 0)
    {
        int currDPI = DpiVals[dpi * -1];
        return currDPI;
    }

    return -1;
}

void SetDpiScaling(int percentScaleToSet)
{
    int recommendedDpiScale = GetRecommendedDPIScaling();

    if (recommendedDpiScale > 0)
    {
        int index = 0, recIndex = 0, setIndex = 0 ;
        for (const auto& scale : DpiVals)
        {
            if (recommendedDpiScale == scale)
            {
                recIndex = index;
            }
            if (percentScaleToSet == scale)
            {
                setIndex = index;
            }
            index++;
        }
        
        int relativeIndex = setIndex - recIndex;
        SystemParametersInfo(SPI_SETLOGICALDPIOVERRIDE, relativeIndex, (LPVOID)0, 1);
    }
}

int main()
{
    for (;;)
    {
        int n = 0, dpiToSet = 0;
        cout << R"(
            1. Show Recommended DPI
            2. Set DPI
            Anything else to exit
)";
        cin >> n;
        switch (n)
        {
        case 1:
            cout << "recommened scaling: " << GetRecommendedDPIScaling() << "%" << endl;
            break;
        case 2:
            cout << "enter scaling to set in percentage" << endl;
            cin >> dpiToSet;
            SetDpiScaling(dpiToSet);
            break;
        default:
            exit(0);
            break;
        }
    }
    return 0;
}