Activate Zoombox only when a ModifierKey is pressed

[sa-he]

In my current scenario the Zoombox control contains other custom user-controls that support drag&drop and other mouse-related features.

Therefore, I'd appreciate if the Zoombox activates it’s functionality only if e.g. the Control-key is pressed. The following code-snippet demonstrates my idea. OnMouseWheel also would need to respect ActivateOn accordingly..

What do you think of this idea?

  public ModifierKeys ActivateOn
   {
       get { return (ModifierKeys)GetValue(ActivateOnProperty); }
       set { SetValue(ActivateOnProperty, value); }
   }

   public static readonly DependencyProperty ActivateOnProperty = DependencyProperty.Register(nameof(ActivateOn), typeof(ModifierKeys), typeof(Zoombox), new PropertyMetadata(ModifierKeys.None));

   /// <inheritdoc />
   protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
   {
       if (e is null)
       {
           throw new ArgumentNullException(nameof(e));
       }

       this.position = e.GetPosition(this);
       if (ActivateOn == ModifierKeys.None || Keyboard.Modifiers.HasFlag(ActivateOn))
       {
           _ = this.CaptureMouse();
       }

       base.OnMouseLeftButtonDown(e);
   }

[JohanLarsson]

I get the use case, wonder if there is a simpler way.
https://github.com/GuOrg/Gu.Wpf.Geometry/blob/master/Gu.Wpf.Geometry/Zoombox.cs#L424
Not an ideal implementation for flexibility, should perhaps have been implemented using gestures.
While not awesome there is always the option to subclass ZoomBox and override and add the check.

About the idea I agree it is a solution but it does not feel very idiomatic and discoverable. Feels more like an ad-hoc solution that would be a better fit in application code.

[sa-he]

Subclassing is not my prefered solution but it seems to work.

Subclassing looks like this:

protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        if (ActivateOn == ModifierKeys.None || Keyboard.Modifiers.HasFlag(ActivateOn))
        {
            base.OnMouseLeftButtonDown(e);
        }
    }

Up to now, I used this Zoombox (https://github.com/xceedsoftware/wpftoolkit/wiki/Zoombox) which has several 'Modifier' properties for dragging and zooming.

Are there any other/better solutions than subclassing or modifier-keys?
Maybe events Zooming and Dragging where you can set e.Enabled = ...my condition... ? It provides more flexibility, but it is better idiomatic/discoverable?