How do I get the outline of a UI element?

Question

Basically WPF elements are rectangular in shape.
And it is very easy to get their outline through their Width and Height.
But in the general case, the contour of an element can be any line, including consisting of several contours that do not intersect with each other.
I expected that the VisualTreeHelper.GetClip () method would return the geometry of the contour. But in my attempts, it always returns null.
Perhaps I am using it incorrectly, or it is not suitable for this purpose at all.

My attempt at getting the outlines:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;

namespace CopyGeometryElements
{
    public partial class CopyGeometryElementsWindow : Window
    {
        public CopyGeometryElementsWindow()
        {
            InitializeComponent();
        }

        private void OnCopy(object sender, RoutedEventArgs e)
        {
            foreach (UIElement uie
                in source.Children)
            {
                // Always returns null
                var geometry = VisualTreeHelper.GetClip(uie);

                var offset = uie.TranslatePoint(new Point(), source);
                var copy = new Path()
                {
                    Data=geometry,
                    Stroke = Brushes.Red,
                    StrokeThickness=2
                };
                Canvas.SetLeft(copy, offset.X);
                Canvas.SetTop(copy, offset.Y);
                target.Children.Add(copy);
            }
        }
    }
}

<Window x:Class="CopyGeometryElements.CopyGeometryElementsWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:CopyGeometryElements"
        mc:Ignorable="d"
        Title="CopyGeometryElementsWindow" Height="450" Width="800">
    <Grid Background="AliceBlue">
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <Grid x:Name="source"
              Margin="10" Background="White">
            <Border BorderBrush="Green" BorderThickness="2"
                    CornerRadius="15"
                    Width="40" Height="60" Margin="10"
                    HorizontalAlignment="Left" VerticalAlignment="Top"/>
            
            <Ellipse Stroke="Green" StrokeThickness="2"
                     Width="40" Height="60"
                     HorizontalAlignment="Left" VerticalAlignment="Top"
                     Margin="200,100,0,0"/>

            <Polygon Stroke="Green" StrokeThickness="2"
                      HorizontalAlignment="Left" VerticalAlignment="Top"
                      Margin="100,150,0,0" 
                      Points="0,0 100,100 0,200 50,100">
            </Polygon>
        </Grid>
        <Button Grid.Column="1" Padding="15 5"
                HorizontalAlignment="Center" VerticalAlignment="Center"
                Click="OnCopy">
            <TextBlock Text="Copy the geometry of all shapes from the left panel to the right"
                       Width="80"
                       TextWrapping="Wrap"
                       TextAlignment="Center"/>
        </Button>
        <Canvas x:Name="target" Grid.Column="2" Background="White"
                Margin="10"/>
    </Grid>
</Window>

Answer 1

As im sure this code just getting ur Clip. For Example:

<Button Height="35" Width="75">
    <Button.Clip>
        <GeometryGroup>
            <RectangleGeometry Rect="0, 0, 100, 100"/>
        </GeometryGroup>
    </Button.Clip>
</Button>

In this case you can get this Clip.

    var figure = VisualTreeHelper.GetClip(uie);

But your Clip is Empty, consequently your result will be null