UWP Xaml tiling image brush

imagetilebrush.cs

public sealed class ImageTileBrush : XamlCompositionBrushBase
{
  private CompositionSurfaceBrush _surfaceBrush;
    
  public ImageTileBrush() { }

  public static readonly DependencyProperty ImageSourceUriProperty = DependencyProperty.Register(
    "ImageSourceUri",
    typeof(Uri),
    typeof(ImageTileBrush),
    new PropertyMetadata(null, OnImageSourceUriChanged)
  );

  public Uri ImageSourceUri
  {
    get { return (Uri)GetValue(ImageSourceUriProperty); }
    set { SetValue(ImageSourceUriProperty, value); }
  }

  private static void OnImageSourceUriChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
  {      
    var brush = (ImageTileBrush)o;      
    if (brush.CompositionBrush != null)
    {
      var surface = LoadedImageSurface.StartLoadFromUri(new Uri(e.NewValue.ToString()));        
      brush._surfaceBrush.Surface = surface;
    }
  }

  protected override void OnConnected()
  {
    // Delay creating composition resources until they're required.
    if (CompositionBrush == null)
    {
      var surface = LoadedImageSurface.StartLoadFromUri(ImageSourceUri);
      _surfaceBrush = Window.Current.Compositor.CreateSurfaceBrush(surface);
      _surfaceBrush.Stretch = CompositionStretch.None;

      var borderEffect = new BorderEffect()
      {
        Source = new CompositionEffectSourceParameter("source"),
        ExtendX = Microsoft.Graphics.Canvas.CanvasEdgeBehavior.Wrap,
        ExtendY = Microsoft.Graphics.Canvas.CanvasEdgeBehavior.Wrap
      };

      var borderEffectFactory = Window.Current.Compositor.CreateEffectFactory(borderEffect);
      var borderEffectBrush = borderEffectFactory.CreateBrush();
      borderEffectBrush.SetSourceParameter("source", _surfaceBrush);
      CompositionBrush = borderEffectBrush;
    }
  }

  protected override void OnDisconnected()
  {
    // Dispose of composition resources when no longer in use.
    if (CompositionBrush != null)
    {
      CompositionBrush.Dispose();
      CompositionBrush = null;
    }
  }
}