WPF Canvas不会渲染绑定到ItemsControl的Shapes

Question

I create Polygons in code that get added to an generic ObservableList. That is my ViewModel.

class CanvasViewModel : ModelBase
{
    private WpfObservableRangeCollection<Shape> CanvasShapes { get; set; }
//...
}

The Shape are proper WPF shapes. No container or anything. Furthermore I set the Style of these shapes also programmatically, as an example:

public void ApplyStyle(Style style)
    {
        style.Setters.Add(new Setter(Shape.FillProperty, Brushes.DodgerBlue));
    }

As you can see, I am definitely setting a color to these shapes. My issue is that in my program, when I start it, the canvas gets rendered (I can see it when I set the background of the canvas to any color) but none of the shapes I add to the ObservableRangeCollection (they are definitely in the collection.)

Here's the Page code for the CanvasPage:

<ItemsControl ItemsSource="{Binding CanvasShapes}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas/>
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
</ItemsControl>

I figure since these are proper WPF shapes that I don't need to add any DataTemplates to them or anything, however I think this is where I'm mistaken.

And here's the CodeBehind of the Window that currently initializes these functions (I know this is bad practice, it's just to get the programm running for testing purposes):

public MainWindow()
    {
        InitializeComponent();
        CanvasPage canvasPage = new CanvasPage()
        //boilerplate...
        var canvasViewModel = new CanvasViewModel(...);
        canvasPage.DataContext = canvasViewModel;
        this._NavigationFrame?.Navigate(canvasPage);
    }

Here's a MCV version of this issue:

Viewmodel.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Media;
using System.Windows.Shapes;

namespace MVCE
{
    class ViewModel
    {
        public ObservableCollection<Shape> CanvasShapes;

        public ViewModel()
        {
            CanvasShapes = new ObservableCollection<Shape>();
            var polygon = new Polygon();
            var pointCollection = new PointCollection
            {
                new Point(100, 100),
                new Point(100, -100),
                new Point(-100, -100),
                new Point(-100, 100)
            };
            polygon.Points = pointCollection;
            Style style = new Style();
            style.Setters.Add( new Setter(Shape.FillProperty, Brushes.Aquamarine));

            polygon.Style = style;
            CanvasShapes.Add(polygon);
        }
    }
}

MainWindow.cs

<Window x:Class="MVCE.MainWindow"
        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:MVCE"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">

    <DockPanel>
        <Frame x:Name="_NavigationFrame" NavigationUIVisibility="Hidden" />
    </DockPanel>

</Window>

MainWindow.xaml.cs

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;

namespace MVCE
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            ViewModel viewModel = new ViewModel();
            var page = new Page1();
            page.DataContext = viewModel;
            _NavigationFrame.Navigate(page);
        }
    }
}

CanvasPage.xaml (.cs file is default)

<Page x:Class="MVCE.Page1"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:MVCE"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="800"
      Title="Page1">

    <ItemsControl ItemsSource="{Binding CanvasShapes}" Background="Brown">
        <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
                <Canvas/>
            </ItemsPanelTemplate>
        </ItemsControl.ItemsPanel>
    </ItemsControl>
</Page>

Answer 1

I figured it out.

The issue was that my ObservableCollection in my ViewModel was set to private. Due to this, the DataBinding seemed to have issues. I thought it would work due to reflection, but I was mistaken. Setting the collection to public fixed it right away.