[RESOLVED] WPF Application (.NET Core) DPI Issues

[squatman]

Hi,

I create a new VB WPF Application in .NET not .NET Framework.

In the Application Properties set:

• Target framework - .NET 9.0
• Target OS Version - 10.0.17763.0
• High DPI mode - Per monitor V2

• Add a Grid, Button and Label.

I have:

• Main display = 100% scaling
• Second display = 150% scaling

When I run the app it looks fine and crisp on my main display. If I drag to second display the title bar text, minimise, maximise and close buttons are all crisp still, but the Button and Label are blurry.

If I set my main display to 150% and run the app everything looks crisp.

I've seen online about adding lines to an app.manifest but it looks like this is intended for WinForms and/or .NET Framework projects.

Can anyone advise please.

Thank you.

[squatman]

For anyone who comes across this problem I managed to solve it with a bit of back and forth with ChatGPT!

My App didn't like the app.manifest method so ignore that.

Adding the following code to App.xaml.cs didn't work either:

        [DllImport("user32.dll")]
        private static extern bool SetProcessDpiAwarenessContext(IntPtr dpiContext);

        private static readonly IntPtr DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 = new IntPtr(-4);

        [STAThread]
        public static void Main()
        {
            SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);

            var app = new App();
            app.InitializeComponent();
            app.Run();
        }

I had to create a Class at the root of my project in solution explorer. Called it Program.cs, with the following content:

using System.Runtime.InteropServices;

namespace Layout_Test  // ? Make sure this matches your actual project namespace
{
    public class Program
    {
        [DllImport("user32.dll")]
        private static extern bool SetProcessDpiAwarenessContext(IntPtr dpiContext);

        private static readonly IntPtr DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 = new IntPtr(-4);

        [STAThread]
        public static void Main()
        {
            SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);

            var app = new App();
            app.InitializeComponent();
            app.Run();
        }
    }
}

Then in my project's .csproj file add <StartupObject>Layout_Test.Program</StartupObject> to the "PropertyGroup" so my full .csproj file was as follows:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net9.0-windows</TargetFramework>
    <RootNamespace>Layout_Test</RootNamespace>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UseWPF>true</UseWPF>
    <StartupObject>Layout_Test.Program</StartupObject>
  </PropertyGroup>

</Project>

ChatGPT's summary was as follows:

Method	Works?
SetProcessDpiAwarenessContext() in App.xaml.cs	? Not early enough
Manifest with dpiAwareness	?? Hit-or-miss on .NET SDK style
Main() in Program.cs + DPI set before WPF starts	? Correct and reliable

Hope this helps someone.