wpf - Why Storyboard value wouldn't get from a resource or binding?

Question

I have construction below and it works:

 <Storyboard x:Key="GrowOnStart">
   <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(Canvas.Left)" Storyboard.TargetName="window">
            <EasingDoubleKeyFrame KeyTime="0" Value="1024"/>

Why it doesn't work if I try something like this:

  <EasingDoubleKeyFrame KeyTime="0" Value="{DynamicResource StartingPositionLeft}"/>

And yes, I defined the resource before the storyboard. And the statement like the next one wouldn't work either:

 <EasingDoubleKeyFrame KeyTime="0" Value="{Binding StartingPositionLeft}"/>

And yes it's a public property on code behind and this.DataContext set to this.

Answer 1

This is because Animations are freezable objects. There is more information in the MSDN Documentation, but basically it means you can't use binding because properties in the frozen object (i.e. the animation) cannot change.

To get around this limitation, you will need to do some or all of the work in code-behind.