What is wrong with the custom attached property?

Question

Hi,

In visual studio I get "XAML parsing error" when a story board is run. The application launches but when I mouseover a button which has been templated, the error is shown.

My buttons template (using visual states etc) has a circle that scales which is passed in via a custom attached property.

The code that raises the error at runtime is the value property below:

<DoubleAnimationUsingKeyFrames BeginTime="00:00:00"
    Storyboard.TargetName="Document"
    Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)">
  <EasingDoubleKeyFrame KeyTime="00:00:00.7000000"
     Value="{Binding Path=(local:MyAttachedProperties.Scaling), RelativeSource={RelativeSource TemplatedParent}}" />
</DoubleAnimationUsingKeyFrames>;

The code for the attached property is:

public class MyAttachedProperties
{
  public static readonly DependencyProperty ScalingProperty =
    DependencyProperty.RegisterAttached("Scaling",
      typeof(double), typeof(MyAttachedProperties), null);

  // Scaling
  public static double GetScaling(DependencyObject obj) 
  { 
    return (double)obj.GetValue(ScalingProperty); 
  }
  public static void SetScaling(DependencyObject obj, double value) 
  { 
    obj.SetValue(ScalingProperty, value); 
  }
}

and for my button I have:

 <Button Height="76"
         Content="Gallery"
         Style="{StaticResource MyRotatingButtonStyle}" 
         Padding="10"
         local:MyAttachedProperties.Scaling="2" />

Answer 1

In Silverlight you can't bind on an Animation object they don't derive from FrameworkElement which is required in Silverlight 3 for binding to work.

To achieve your goal you will need to write some code to find the EasingDoubleKeyFrame and adjust the value directly.