Judging from answers like this it looks like xaml inheritance works for WPF and UWP.

Does it work for WinUI 3?

Using code like this:

    <local:YourBaseClass x:Class="MyApp.ChildClass"
        ...
        xmlns:local="clr-namespace:MyApp">
    </local:YourBaseClass>

I get the error:

Error WMC0001 Unknown type 'YourBaseClass' in XML namespace 'clr-namespace:MyApp'

CodePudding user response：

Does it work for WinUI 3?

Yes. It almost exactly the same.

1. Create the base class that inherits from Microsoft.UI.Xaml.Window:

    public class YourBaseClass : Microsoft.UI.Xaml.Window
    {
        public YourBaseClass() : base()
        {
            Title = "Title...";
        }
    }
   

2. Modify MainWindow.xaml.cs to inherit from the new base class:

    public sealed partial class MainWindow : YourBaseClass
    {
        public MainWindow()
        {
            this.InitializeComponent();
        }
   
        private void myButton_Click(object sender, RoutedEventArgs e)
        {
            myButton.Content = "Clicked";
        }
    }
   

3. Modify the root element in MainWindow.xaml:

    <local:YourBaseClass
        x:Class="WinUI3App.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:WinUI3App"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
   
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
            <Button x:Name="myButton" Click="myButton_Click">Click Me</Button>
        </StackPanel>
    </local:YourBaseClass>