How can I get the parent Popup for a UIElement?

问题

I have two questions on markup below:

<Popup>
    <Button x:Name="button"/>
</Popup>

Why does VisualTreeHelper.GetParent(button) return null?
How can I get the parent Popup for UIElement?

回答1:

Because the Button is only added to the visual tree when the popup is being displayed.
Hmm... tricky ...

Edit

There is an assumption in the following that your popup is defined in the XAML of UserControl so whilst its child may not be in the visual tree the popup primitive control is.

Re-using some code I've posted before (I really must get me a blog).

public static class VisualTreeEnumeration
{
    public static IEnumerable<DependencyObject> Descendents(this DependencyObject root)
    {
        int count = VisualTreeHelper.GetChildrenCount(root);
        for (int i = 0; i < count; i++)
        {
            var child = VisualTreeHelper.GetChild(root, i);
            yield return child;
            foreach (var descendent in Descendents(child))
                yield return descendent;
        }
    }
}

This adds an extension method to the DependencyObject which uses the VisualTreeHelper to unify the search for objects added in the visual tree. So in the usercontrol code behind you can do this:-

var popup this.Descendents()
        .OfType<Popup>()
        .Where(p => p.Child == button)
        .FirstOrDefault();

This will find the Popup which is the parent of "button".

回答2:

Instead of going through the VisualTree, have you just tried a while loop to walk up the .Parents for the elements?

    private void TryClosePopupParent(object o)
    {
        while (o != null)
        {
            Popup p = (o as Popup);
            if(p == null)
            {
                o = (o as FrameworkElement).Parent;
            }
            else 
            {
                p.IsOpen = false;
                break;
            }
        }
    }

I haven't ever tested it on something that doesn't have a PopUp as a parent, but it worked for me.

回答3:

Popup control is very annoying sometimes. And I have no idea at the moment why VisualTreeHelper.GetParent(button) returns null. But for the second this may help.

回答4:

zihotki's solution looks promising (i haven't tested it).

Although VisualTreeHelper.GetParent(button) returns null, you can use button.Parent, which should give you the popup object.

回答5:

Make sure that the PopUp is attached to the VisualTree. Find more information on this in the Remarks section http://msdn.microsoft.com/en-us/library/system.windows.controls.primitives.popup(v=vs.95).aspx

来源：https://stackoverflow.com/questions/2007550/how-can-i-get-the-parent-popup-for-a-uielement

标签

silverlight

popup

uielement