C# - Zoombares WPF Fenster

/// <summary>
/// Stellt ein Windows Anwendungsfnester dar, welches die Basisimplementation eine Zoomfunktion besitzt.
/// </summary>
[ContentProperty("ZoomableContent")]
public class ZoomableWindow : Window
{
    public ZoomableWindow()
    {
        this.border = new Border();
        this.border.PreviewMouseWheel += this_PreviewMouseWheel;
        this.border.LayoutTransform = this.zoom = new ScaleTransform();

        base.Content = scrollViewer = new ScrollViewer()
        {
            HorizontalScrollBarVisibility = ScrollBarVisibility.Auto,
            VerticalScrollBarVisibility = ScrollBarVisibility.Auto,
            Content = border,
            Background = Brushes.Transparent,
        };
    }

    protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
    {
        base.OnPropertyChanged(e);
        if (e.Property == Control.BackgroundProperty)
        {
            //Hintergrund des Borders auf die Farbe des Fensters setzen
            border.Background = (Brush)e.NewValue;
        }
    }

    public UIElement ZoomableContent
    {
        get
        {
            return this.border.Child;
        }
        set
        {
            this.border.Child = value;
        }
    }

    private new object Content
    {
        get { throw new NotSupportedException(); }
        set { throw new NotSupportedException(); }
    }

    Border border;
    ScaleTransform zoom;
    ScrollViewer scrollViewer;

    void SetZoomFactorInternal(double d)
    {
        if (d <= 0)
            throw new NotSupportedException();

        zoom.ScaleX = d;
        zoom.ScaleY = d;
    }

    void this_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
    {
        if (this.AllowZoom)
        {
            if (Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl))
            {
                var p = Math.Abs(e.Delta) / 100D + 1D;//Prozent ermitteln, mit den die aktuelle Zoomtiefe verändert wird
                if (e.Delta > 0)
                    this.ZoomFactor *= p;
                else if (e.Delta < 0)
                    this.ZoomFactor *= 1 / p;

                SetZoomFactorInternal(this.ZoomFactor);
            }
            e.Handled = true;
        }
    }

    private static void OnZoomFactorChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        (d as ZoomableWindow).SetZoomFactorInternal((double)e.NewValue);
    }

    /// <summary>
    /// Ruft einen Wert ab, der angibt ob de Benutzer zoomen kann oder legt diesen Wert fest.
    /// </summary>
    public bool AllowZoom
    {
        get { return (bool)GetValue(AllowZoomProperty); }
        set { SetValue(AllowZoomProperty, value); }
    }
    /// <summary>
    /// Ruft den Prozentsatz ab, auf den das Fenster gezoomt wurde oder legt den Prozentsatz fest.
    /// </summary>
    public double ZoomFactor
    {
        get { return (double)GetValue(ZoomFactorProperty); }
        set { SetValue(ZoomFactorProperty, value); }
    }

    /// <summary>
    /// Bezeichnet die <see cref="AllowZoom"/>-Abhängigkeitseigenschaft.
    /// </summary>
    public static readonly DependencyProperty AllowZoomProperty = DependencyProperty.Register("AllowZoom", typeof(bool), typeof(ZoomableWindow), new PropertyMetadata(true));
    /// <summary>
    /// Bezeichnet die <see cref="ZoomFactor"/>-Abhängigkeitseigenschaft.
    /// </summary>
    public static readonly DependencyProperty ZoomFactorProperty = DependencyProperty.Register("ZoomFactor", typeof(double), typeof(ZoomableWindow), new PropertyMetadata(1D, OnZoomFactorChanged));
}