WPF Programming, How to move an event to another class (outside)

Question

I have the problem that I want to add an event from XAML directly to another class. The standard class, which is used, is the MainWindow.

In my situation I want to define, which class should be used for the event.

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }
    private void Window_Closing_Event(object sender, System.ComponentModel.CancelEventArgs e)
    {
    }
}

public class differentClass
{
    public differentClass()
    {
    }
    private void Window_Closing_Event(object sender, System.ComponentModel.CancelEventArgs e)
    {
    }
}

Maybe someone can help me, how I can use the event from the second class without any code in the MainWindow.

Answer 1

There is a Behavior class for this purpose. You will need to add the reference to the System.Windows.Interactivity in the project: How to add System.Windows.Interactivity to project?

using System.Windows;
using System.Windows.Controls;
using System.Windows.Interactivity;

public class CustomWindowHandlerBehavior: Behavior<Window>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.Closing+= Window_Closing_Event;
    }

    protected override void OnDetaching()
    {
        AssociatedObject.Closing-= Window_Closing_Event;
        base.OnDetaching();
    }

    private void Window_Closing_Event(object sender, System.ComponentModel.CancelEventArgs e)
    {
        //...
    }
}

using this behavior in XAML:

<Window
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity">
    <i:Interaction.Behaviors>
        <local:CustomWindowHandlerBehaviour />
    </i:Interaction.Behaviors>
<Window/>