As posted in another post, many apps have problems with windows scaling.

See these screen-dumps from Windows lengthy guide that was found here

UPDATE 2020. After Windows “Creators update”, they made things slightly more complicated, sorry…

Here is a reasonably minimalistic approach. You will often just need code like this:

    public partial class Form1 : Form {
         public Form1() {
             InitializeComponent();
             DPI_Per_Monitor.TryEnableDPIAware(this, SetUserFonts);
         }
         void SetUserFonts(float scaleFactorX, float scaleFactorY) {
            var OldFont = Font;
            Font = new Font(OldFont.FontFamily, 11f * scaleFactorX, OldFont.Style, GraphicsUnit.Pixel); 
            OldFont.Dispose();
         }
         protected override void DefWndProc(ref Message m) {
             DPI_Per_Monitor.Check_WM_DPICHANGED(SetUserFonts,m, this.Handle);
             base.DefWndProc(ref m);
         }
     }

You will need to obey a few rules, but often it can be implemented in existing code in minutes!

Continue reading “The EASY way to make a C# Windows.forms app really per monitor DPI aware” →

Some claim that you need a third party tool to have a TreeView vith multi-line text (outside WPS).

But it is actually rather easy to do with a few additional steps with the standard TreeView.

Continue reading “Windows TreeView with e.g. multi-line tree content” →

If you run a command like this it works fine to any remote machine

    schtasks.exe /query /s SomePC /U MyAccount /P XXXXX

If you try to let it point back to your own machine you get an error-message

    ERROR: User credentials are not allowed on the local machine.

BUT this is actually FALSE!!!

Continue reading “Windows, Oddity with Schtasks.exe, and falsely reported error.” →

It took me quite some digging to find a clean way to set the standard default volume without external libs. So here the result.

If you do not want the console output, remove the writeline, and change the project from Console to Windows App.

I suggest using it as a Scheduled Task triggered by connect to user session and/or similar.

It is composed of a couple of bits and pieces combined/reduced primarily from these three.

https://stackoverflow.com/questions/31928429

https://stackoverflow.com/questions/36625576

https://social.msdn.microsoft.com/Forums/expression/en-US/90c6405d-44f6-48ce-82aa-c48a9b09dfb4

using System;
using System.Runtime.InteropServices;

namespace SetAudioLevel {
    class Program {

        [ComImport]
        [Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        private interface IMMDeviceEnumerator {
            void _VtblGap1_1();
            int GetDefaultAudioEndpoint(int dataFlow, int role, out IMMDevice ppDevice);
        }
        private static class MMDeviceEnumeratorFactory {
            public static IMMDeviceEnumerator CreateInstance() {
                return (IMMDeviceEnumerator)Activator.CreateInstance(Type.GetTypeFromCLSID(new Guid("BCDE0395-E52F-467C-8E3D-C4579291692E"))); // a MMDeviceEnumerator
            }
        }
        [Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        private interface IMMDevice {
            int Activate([MarshalAs(UnmanagedType.LPStruct)] Guid iid, int dwClsCtx, IntPtr pActivationParams, [MarshalAs(UnmanagedType.IUnknown)] out object ppInterface);
        }

        [Guid("5CDF2C82-841E-4546-9722-0CF74078229A"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        public interface IAudioEndpointVolume
        {
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE RegisterControlChangeNotify(/* [in] */__in IAudioEndpointVolumeCallback *pNotify) = 0;
            int RegisterControlChangeNotify(IntPtr pNotify);
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE UnregisterControlChangeNotify(/* [in] */ __in IAudioEndpointVolumeCallback *pNotify) = 0;
            int UnregisterControlChangeNotify(IntPtr pNotify);
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE GetChannelCount(/* [out] */ __out UINT *pnChannelCount) = 0;
            int GetChannelCount(ref uint pnChannelCount);
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE SetMasterVolumeLevel( /* [in] */ __in float fLevelDB,/* [unique][in] */ LPCGUID pguidEventContext) = 0;
            int SetMasterVolumeLevel(float fLevelDB, Guid pguidEventContext);
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE SetMasterVolumeLevelScalar( /* [in] */ __in float fLevel,/* [unique][in] */ LPCGUID pguidEventContext) = 0;
            int SetMasterVolumeLevelScalar(float fLevel, Guid pguidEventContext);
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE GetMasterVolumeLevel(/* [out] */ __out float *pfLevelDB) = 0;
            int GetMasterVolumeLevel(ref float pfLevelDB);
            //virtual /* [helpstring] */ HRESULT STDMETHODCALLTYPE GetMasterVolumeLevelScalar( /* [out] */ __out float *pfLevel) = 0;
            int GetMasterVolumeLevelScalar(ref float pfLevel);
        }

        static void Main(string[] args) {
            int Level = 20;
            if (args.Length == 1) { int.TryParse(args[0], out Level); }

            try {
                IMMDeviceEnumerator deviceEnumerator = MMDeviceEnumeratorFactory.CreateInstance();
                IMMDevice speakers;
                const int eRender = 0;
                const int eMultimedia = 1;
                deviceEnumerator.GetDefaultAudioEndpoint(eRender, eMultimedia, out speakers);

                object aepv_obj;
                speakers.Activate(typeof(IAudioEndpointVolume).GUID, 0, IntPtr.Zero, out aepv_obj);
                IAudioEndpointVolume aepv = (IAudioEndpointVolume)aepv_obj;
                Guid ZeroGuid = new Guid();
                int res = aepv.SetMasterVolumeLevelScalar(Level / 100f, ZeroGuid);

                Console.WriteLine($"Audio set for {Level}%");
                //Console.Beep();
            } catch (Exception ex) { Console.WriteLine($"**Could not set audio level** {ex.Message}"); }
        }
    }
}

.