CODEWITHSUNDEEP
c#wpfcustom-controls
David
David

Reputation: 537

WPF – Custom Control – Inherited DependencyProperty and PropertyChangedCallback

In the case of the Custom Control like the following, how to add PropertyChangedCallback for inherited DependencyProperty IsEnabledProperty?

public class MyCustomControl : ContentControl
{
      // Custom Dependency Properties

      static MyCustomControl ()
      {
           DefaultStyleKeyProperty.OverrideMetadata(typeof(MyCustomControl), new FrameworkPropertyMetadata(typeof(MyCustomControl)));
           // TODO (?) IsEnabledProperty.OverrideMetadata(typeof(MyCustomControl), new PropertyMetadata(true, CustomEnabledHandler));
      }

      public CustomEnabledHandler(DependencyObject d, DependencyPropertyChangedEventArgs e)
      {
           // Implementation
      }
}

Yes, there is another option like listen to the IsEnabledChangeEvent

public class MyCustomControl : ContentControl
{
      public MyCustomControl()
      {
           IsEnabledChanged += …
      }
}

But I don't like the approach register event handler in every instance. So I prefer the metadata overriding.

Upvotes: 1

Views: 1349

Answers (1)

Clemens
Clemens

Reputation: 128098

This works:

static MyCustomControl()
{
    DefaultStyleKeyProperty.OverrideMetadata(typeof(MyCustomControl),
        new FrameworkPropertyMetadata(typeof(MyCustomControl)));

    IsEnabledProperty.OverrideMetadata(typeof(MyCustomControl),
        new FrameworkPropertyMetadata(IsEnabledPropertyChanged));
}

private static void IsEnabledPropertyChanged(
    DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
    Debug.WriteLine("{0}.IsEnabled = {1}", obj, e.NewValue);
}

Upvotes: 3

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