WPF Path Stroke Animation

Window1.xaml

<Window x:Class="PathDemo.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="PathDemo" Height="400" Width="800" Name="UI">
    <Grid DataContext="{Binding ElementName=UI}">
        <Path x:Name="lo" Data="M 50,100 S 100,132 150,86 200,173 250,76 300,81 350,136 400,87 450,166 500,87 550,96" 
              Stroke="White" StrokeThickness="13" StrokeDashArray="{Binding StrokeArray}" />
        <Path Name="core" Data="M 50,100 S 100,132 150,86 200,173 250,76 300,81 350,136 400,87 450,166 500,87 550,96" 
              Stroke="Blue" StrokeThickness="2">
            <Path.OpacityMask>
                <VisualBrush Visual="{Binding ElementName=lo}" />
            </Path.OpacityMask>
        </Path>
        <Button Content="Start" Height="49" Width="150" Click="Button_Click_1" 
                Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="97,167,0,0" />
    </Grid>
</Window>

Window1.xaml.cs

using System;
using System.Collections.Generic;
using System.Text;
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.Animation;

namespace PathDemo
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();  
        }
        
        public double StrokeValue
        {
            get { return (double)GetValue(StrokeValueProperty); }
            set { SetValue(StrokeValueProperty, value); }
        }

        public static readonly DependencyProperty StrokeValueProperty =
            DependencyProperty.Register("StrokeValue", typeof(double), typeof(Window1)
            , new PropertyMetadata(0.0, new PropertyChangedCallback(OnStrokeValueChanged)));

        private static void OnStrokeValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            (d as Window1).StrokeArray = new DoubleCollection { (double)e.NewValue, 100 };
        }

        public DoubleCollection StrokeArray
        {
            get { return (DoubleCollection)GetValue(StrokeArrayProperty); }
            set { SetValue(StrokeArrayProperty, value); }
        }

        public static readonly DependencyProperty StrokeArrayProperty =
            DependencyProperty.Register("StrokeArray", typeof(DoubleCollection), typeof(Window1)
            , new PropertyMetadata(new DoubleCollection { 0, 100 }));


        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            var storyboard = new Storyboard();
            var animation = new DoubleAnimation(0,50,new Duration(TimeSpan.FromSeconds(5)));
            storyboard.Children.Add(animation);
            Storyboard.SetTarget(animation, this);
            Storyboard.SetTargetProperty(animation,new PropertyPath( Window1.StrokeValueProperty));
            storyboard.Begin();
        }
    }
}