Today I found another issue concerning Silverlight 2.0 animations: If you reference the same object in one storyboard multiple times you receive a "Catastrophic Failure" error:

You can use the following code to reproduce the error. This code snippet should fade in an image and fade it out again immediately after the first animation has finished:

<UserControl x:Class="SilverlightApplication2.Page"
    xmlns="http://schemas.microsoft.com/client/2007"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300">
    <Canvas x:Name="LayoutRoot" Background="White">
  <Image x:Name="Image2" Source="/6_Schuss_2_klein.png" Opacity="0" Width="54" Canvas.ZIndex="1" />
  <Image x:Name="Image1" Source="/6_Schuss_1_klein.png" Opacity="0" Canvas.ZIndex="0" />
 </Canvas>
</UserControl>

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Animation;

namespace SilverlightApplication2
{
 public partial class Page : UserControl
 {
  Storyboard storyboard;

  public Page()
  {
   InitializeComponent();
   Loaded+=new RoutedEventHandler(Page_Loaded);
  }

  void Page_Loaded(object sender, RoutedEventArgs e)
  {
   try
   {
    storyboard = new Storyboard();

    var animation = new DoubleAnimation();
    Storyboard.SetTargetName(animation, "Image1");
    Storyboard.SetTargetProperty(animation, "Opacity");
    animation.To = 1;
    animation.Duration = TimeSpan.FromSeconds(2);
    storyboard.Children.Add(animation);
    Resources.Add(storyboard);

Note that this second animation starts after the first animation (because of BeginTime). It references the same image as the first animation!

    animation = new DoubleAnimation();
    Storyboard.SetTargetName(animation, "Image1");
    Storyboard.SetTargetProperty(animation, "Opacity");
    animation.To = 0;
    animation.Duration = TimeSpan.FromSeconds(2);
    animation.BeginTime = TimeSpan.FromSeconds(2);
    storyboard.Children.Add(animation);

    storyboard.Begin();
   }
   catch (Exception ex)
   {
   }
  }
 }
}

storyboard.Begin throws the exception shown above.

However, if you try the same code with two different images everything runs fine:

using [...];

namespace SilverlightApplication2
{
 public partial class Page : UserControl
 {
  [...]
  void Page_Loaded(object sender, RoutedEventArgs e)
  {
   try
   {
    storyboard = new Storyboard();

    var animation = new DoubleAnimation();
    Storyboard.SetTargetName(animation, "Image1");
    Storyboard.SetTargetProperty(animation, "Opacity");
    animation.To = 1;
    animation.Duration = TimeSpan.FromSeconds(2);
    storyboard.Children.Add(animation);
    Resources.Add(storyboard);

Note that this time the second animation refrences a different image object than the first one!

    animation = new DoubleAnimation();
    Storyboard.SetTargetName(animation, "Image2");
    Storyboard.SetTargetProperty(animation, "Opacity");
    animation.To = 1;
    animation.Duration = TimeSpan.FromSeconds(2);
    animation.BeginTime = TimeSpan.FromSeconds(2);
    storyboard.Children.Add(animation);

    storyboard.Begin();
   }
   catch (Exception ex)
   {
   }
  }
 }
}

If you try the first sample which throws the exception in Silverlight in WPF you will see that it works fine there. Therefore I think the behavior described above is a bug in Silverlight 2.0 Beta 1.

Just for the sake of completeness here is the WPF code that demonstrates two animations on a single object. In contrast to Silverlight it works:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Animation;

namespace WpfApplication2
{
 public partial class Window1 : Window
 {
  Storyboard storyboard;

  public Window1()
  {
   InitializeComponent();
   Loaded += new RoutedEventHandler(Page_Loaded);
  }

  void Page_Loaded(object sender, RoutedEventArgs e)
  {
   try
   {
    storyboard = new Storyboard();

    var animation = new DoubleAnimation();
    Storyboard.SetTargetName(animation, "Image1");
    Storyboard.SetTargetProperty(animation, new PropertyPath(Image.OpacityProperty));
    animation.To = 1;
    animation.Duration = TimeSpan.FromSeconds(1);
    storyboard.Children.Add(animation);
    Resources.Add("sb", storyboard);

    animation = new DoubleAnimation();
    Storyboard.SetTargetName(animation, "Image1");
    Storyboard.SetTargetProperty(animation, new PropertyPath(Image.OpacityProperty));
    animation.To = 0;
    animation.Duration = TimeSpan.FromSeconds(1);
    animation.BeginTime = TimeSpan.FromSeconds(1);
    storyboard.Children.Add(animation);

    storyboard.Begin(this);
   }
   catch (Exception ex)
   {
   }
  }
 }
}