DoubleAnimation - On start event? - wpf

Question

I have a storyboard defined:
<Grid.Resources>
<Storyboard x:Key="MasterAnim" x:Name="MasterAnim" Duration="0:0:10" >
<DoubleAnimation x:Name="ANIMATABLE_WidthExp"
Storyboard.TargetName="ANIMELEMENT_SboardRect1"
Storyboard.TargetProperty="Width"
From="100"
To="800"
Duration="0:0:5" />
<DoubleAnimation x:Name="ANIMATABLE_HeightExp"
Storyboard.TargetName="ANIMELEMENT_SboardRect1"
Storyboard.TargetProperty="Height"
From="100"
To="800"
BeginTime="0:0:5"
Duration="0:0:5" />
</Storyboard>
</Grid.Resources>
Is there any way of capturing when each of the double animations are about to start? I need to call a method on the element that it's targeting before the animation starts but im not sure what the best way to go about it is.

Answer 1

There's no Started event, but you can handle the CurrentTimeInvalidated, CurrentStateInvalidated and Completed events on the DoubleAnimation. CurrentStateInvalidated is probably all you need.
private void DoubleAnimationCurrentTimeInvalidated(object sender, EventArgs e)
{
var clock = (AnimationClock) sender;
Debug.WriteLine(string.Format("CurrentTime: state={0}, progress={1}, time={2}", clock.CurrentState, clock.CurrentProgress, clock.CurrentTime));
}
private void DoubleAnimationCurrentStateInvalidated(object sender, EventArgs e)
{
var clock = (AnimationClock)sender;
Debug.WriteLine(string.Format("CurrentState: state={0}", clock.CurrentState));
}
private void DoubleAnimationCompleted(object sender, EventArgs e)
{
var clock = (AnimationClock) sender;
Debug.WriteLine(string.Format("Completed: state={0}", clock.CurrentState));
}
Ignoring the current time we get
CurrentState: state=Active
CurrentState: state=Filling
Completed: state=Filling
when the animation runs.