Wpf Adorner not responding to interactions

Question

I'm trying to create an overlay in wpf (with darkening background), similar to the ones you can find on the web to popup images. I would like it to be reusable in more than 1 part of the application, with diffent types of content.

this is the temporary code of the constructor of the adorner class (just to try)

private readonly Grid _grid = new Grid();

public DarkOverlayAdorner(UIElement adornedElement, Object content) :
        base(adornedElement)
{
     _grid.Background = new SolidColorBrush(Color.FromArgb(99, 0, 0, 0));
     IsHitTestVisible = true;
     var visual = content as UIElement;
     if (visual != null)
        _grid.Children.Add(visual);
}

In addition in the class (of course), I have the ovverrides of MeasureOverride and ArrangeOverride to give the adorner the correct size of the adorned element, GetVisualChild, and VisualChildCount...

The problem here is that the adorner is correctly shown, but no events or behaviour are applied on the adorned element. For example:

AdornerLayer layer = AdornerLayer.GetAdornerLayer(textBoxProva);
layer.Add(new DarkOverlayAdorner(textBoxProva, new Button{Content = "prova"}));

The button here is shown, but I can-t click the button and no effects on button mouseover are applied. I still can't figure out the problem.

Answer 1

Ok, I've lost a lot of time trying to figure out what was the problem. In the end I found the solution:

If you want the element added to react to events, I think that the element must be bound to the visual tree of the adorner. The way to do it is to use a VisualCollection, intitialized to the adorner itself:

    VisualCollection visualChildren;
    FrameworkElement @object;

    public DarkOverlayAdorner(UIElement adornedElement) :
        base(adornedElement)
    {
        visualChildren = new VisualCollection(this);
        @object = new Button {Content = "prova"};
        visualChildren.Add(@object);
    }
    protected override Visual GetVisualChild(int index)
    {
        return visualChildren[index];
    }

This way the events are correctly routed.

Answer 2

You might want to take a look at the ChildWindow control in the Extended WPF Toolkit. It is a control that pops up a Window with a modal background effect, and you can specify the content to put inside the Window.