How to set PerMonitor DpiAwareness for .NET 6 Windows desktop application?

Question

Hi,

I am having problem setting WPF window based desktop .NET 6 application to work as PerMonitor DpiAware.

System default automatic scaling schema...

• When user changes Windows 10 display setting scale, WPF-Window is being scaled accordingly.
• Also, when window is dragged to another display, that has different scale, window is being scaled.

I want to prevent these automatic scaling because I'm using my own scaling schema.

Before .NET 6, when application was using WPF 4.8, following two items together were preventing such automatic behavior:

A) @ app.manifest

...
<application xmlns="urn:schemas-microsoft-com:asm.v3">
    <windowsSettings>
        <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>
        <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitor</dpiAwareness>
    </windowsSettings>
</application>
...

B) @ app.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.8"/>
    </startup>
  <runtime>
    <AppContextSwitchOverrides value="Switch.System.Windows.DoNotScaleForDpiChanges=true"/>
  </runtime>
</configuration>

Now, @ .NET 6, that is not working anymore!

How to tell Windows to stop automatic windows scaling for an desktop Net 6 application?

Thanks in advance!
Vladimir

Answer 1

Hi!

I have found solution... trick was ... app.config file is not NET6 compatible.

So, AppContextSwitchOverrides … Switches like...

Switch.System.Windows.DoNotScaleForDpiChanges  

are transferred from

"appname".config => "appname".runtimeconfig.json

In order to control these switches ... I had to put new item group into *.csproj

   <Project>  
   ...  
   <ItemGroup>  
      <RuntimeHostConfigurationOption Include="Switch.System.Windows.DoNotScaleForDpiChanges" Value="true" />  
      <RuntimeHostConfigurationOption Include="Switch.System.IO.UseLegacyPathHandling" Value="false" />  
   </ItemGroup>  
   ...  
   </Project>  

So, RuntimeHostConfigurationOption has done the job!

Thanks for your time!
V.

P.S. app.manifest still stands as like it was before.