How to get the position of an element in a StackPanel?

Question

Say I have a StackPanel that gets dynamically filled with copy, changing the Y position of elements inside it. I have a specific element within that StackPanel that I want to find the Y position of (relative to the StackPanel or otherwise) after the StackPanel is done repositioning all of it's children.

StackPanel sp = new StackPanel();
sp.Children.Add(someTextBlock);
sp.Children.Add(element1);
sp.Children.Add(element2);
...
someTextBlock.Text = "Lorem ipsum dolor..." // some text that pushes children of > index down
// element1 got pushed down to some unknown position based on text length
// now want to find the Y position of element1

I noticed that methods like this: http://forums.silverlight.net/forums/p/16787/55881.aspx#55881 don't work since the position returned is the position of the StackPanel and not the child element I'm targeting.

score 15 · Accepted Answer · answered Oct 02 '09 at 17:15

15

The methods in the link you posted should work fine, provided you call them correctly.

You need to call them with the correct UIElement - in this case, using element1 to the RootVisual will give you the full position of element1:

var transform = element1.TransformToVisual(Application.Current.RootVisual as FrameworkElement);        
Point absolutePosition = transform.Transform(new Point(0, 0));

answered Oct 02 '09 at 17:15

Reed Copsey

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+1. I was looking for ages for that, serves me right for not actually following the link in the question (why do I hate doing that?) – AnthonyWJones Oct 02 '09 at 20:36
any idea how to get the position in a WPF application as well ? – eran otzap Mar 29 '13 at 22:12
@eranotzap This works in a WPF application, as well. http://msdn.microsoft.com/en-us/library/system.windows.media.visual.transformtovisual.aspx – Reed Copsey Mar 29 '13 at 22:46

score 1 · Answer 2 · answered Jan 06 '22 at 23:08

A small note to Reed's answer.

My UserControl has a StackPanel. It didn't work for me when I called it in

private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
    sp.Children.Add(someTextBlock);
    sp.Children.Add(element1);
    sp.Children.Add(element2);

    var transform = element1.TransformToVisual(Application.Current.RootVisual as FrameworkElement);        
    Point absolutePosition = transform.Transform(new Point(0, 0));
}

It work when I call it in

 private void UserControl_LayoutUpdated(object sender, EventArgs e)
        {
         ...
        }

I hope it helps to someone.

How to get the position of an element in a StackPanel?

2 Answers2

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