How can I change Windows 10 Display Scaling Programmatically using C#

Question

I\'m trying to find a way to change the Display Scaling in Windows 10 Programmatically using C#.

Let me also say that, I\'m not trying to create a application that a

Answer 1

Here is my code based on @Sahil Singh's:

Dll project to wrap the C++ API:

stdafx.h:

#pragma once

#include "targetver.h"

#define WIN32_LEAN_AND_MEAN             // Exclude rarely-used stuff from Windows headers
// Windows Header Files
#include 

// reference additional headers your program requires here
#ifdef __cplusplus
extern "C" {
#endif
    extern __declspec(dllexport) void PrintDpiInfo();
    extern __declspec(dllexport) void SetDPIScaling(INT32 adapterIDHigh, UINT32 adapterIDlow, UINT32 sourceID, UINT32 dpiPercentToSet);
    extern __declspec(dllexport) void RestoreDPIScaling();
#ifdef __cplusplus
}
#endif

DpiHelper.cpp:

// DpiHelper.cpp : Defines the exported functions for the DLL application.
//

#include "stdafx.h"
#include "DpiHelper.h"
#include 
#include 
#include 
#include 

DpiHelper.h is the same as the referenced answer. Create an C++ Dll project in Visual studio and add/put in the above code and use the dll in the bellow C# application.

A C# console application that set DPI according to command line parameters and restore them when press any key:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace DispSetEx
{
    class Program
    {



        [DllImport("DpiHelper.dll")]
        static public extern void PrintDpiInfo();

        [DllImport("DpiHelper.dll")]
        static public extern int SetDPIScaling(Int32 adapterIDHigh, UInt32 adapterIDlow, UInt32 sourceID, UInt32 dpiPercentToSet);
        [DllImport("DpiHelper.dll")]
        static public extern void RestoreDPIScaling();

        static void Main(string[] args)
        {
            if ((args.Length % 3) != 0)
            {
                Console.WriteLine("wrong parameters");
                return;
            }

//print the DPI info, you need to set the command line parameters
//according to this
            PrintDpiInfo();

    //commandline parameters should be of groups of three
    //each groups's tree paramters control a desktop's setting
    //in each group:
    //GPUIdhigh.GPUIdlow DesktopIndexInGPU DPIScalingValue
    //for example:
    //    0.1234 0 100 //set the DPI scaling to 100 for desktop 0 on GPU 0.1234
    //    0.4567 0 125 //set the DPI scaling to 125 for desktop 0 on GPU 0.5678
    //    0.4567 1 150 //set the DPI scaling to 150 for desktop 1 on GPU 0.5678
    //in most cases GPUIdhigh is 0.
    //you can use the monitor name to identify which is which easily
    //you need to set the command line parameters according to the result of PrintDpiInfo
    //e.g. you should only set the DPI scaling to a value that is supported by 
    //that desktop. 


            for (int i = 0; i < args.Length / 3; i++)
            {
                string[] sa = args[i * 3].Split(new char[] { '.' });

                Int32 adapterHigh = Int32.Parse(sa[0]);
                UInt32 adapterLow = UInt32.Parse(sa[1]);
                UInt32 source = UInt32.Parse(args[i * 3 + 1]);
                UInt32 dpiscale = UInt32.Parse(args[i * 3 + 2]);

                SetDPIScaling(adapterHigh, adapterLow, source,dpiscale);
            }

            Console.WriteLine("Press any key to resotre the settings...");
            Console.ReadKey();

            RestoreDPIScaling();  
        }
    }
}