在 WPF 中为自定义框架元素实现 Stretch=“Fill”

我有一个自定义框架元素，它是对折线的对偶。此元素旨在在折线中点的位置绘制标记，并将充当叠加层。

我已经成功地绘制了点，但不知道如何实现折线等法线形状所具有的 Stretch="Fill" 功能。我的课程代码如下。

如果有人能启发我如何为此添加拉伸功能，我将不胜感激。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using ReactiveUI;
namespace Weingartner.WPF
{
    public class PolyMarkers : FrameworkElement
    {
        static PolyMarkers()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(PolyMarkers), new FrameworkPropertyMetadata(typeof(PolyMarkers)));
        }
        public PointCollection Points
        {
            get { return (PointCollection)GetValue(PointsProperty); }
            set { SetValue(PointsProperty, value); }
        }
        // Using a DependencyProperty as the backing store for Points.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty PointsProperty =
            DependencyProperty.Register(
                "Points", 
                typeof(PointCollection), 
                typeof(PolyMarkers), 
                new PropertyMetadata(new PointCollection()));
        private VisualCollection Children;
        public PolyMarkers()
        {
            this.WhenAny(t => t.Points, x =>
            {
                return x.Value.Select(p =>
                {
                    return CreateDrawingVisualEllipses(p, 10, 10);
                });
            }).Subscribe(x =>
            {
                foreach (var shape in x)
                {
                    AddVisualChild(shape);
                }
                InvalidateMeasure();
                InvalidateArrange();
                InvalidateVisual();
            });

        }
        private DrawingVisual CreateDrawingVisualEllipses(Point location, int dx, int dy)
        {
            DrawingVisual drawingVisual = new DrawingVisual();
            DrawingContext drawingContext = drawingVisual.RenderOpen();
            drawingContext.DrawEllipse(Brushes.Maroon, null, location, dx, dy);
            drawingContext.Close();
            return drawingVisual;
        }

        // Provide a required override for the VisualChildrenCount property.
        protected override int VisualChildrenCount
        {
            get { return Children.Count; }
        }
        // Provide a required override for the GetVisualChild method.
        protected override Visual GetVisualChild(int index)
        {
            if (index < 0 || index >= Children.Count)
            {
                throw new ArgumentOutOfRangeException();
            }
            return Children[index];
        }
    }
}