Animations continue to run even when the control is detached from its parent

Is this intended behavior? If I have a Label animating across the screen and I remove it with canvas1.Children.Remove(label) it seems that the animation continues to run behind the scenes and even fires AnimationCompleted even though I have no references to the label or to the DoubleAnimation I used to animate it with. What if the animation was endless?

Do I really need to do my own bookkeeping and stop the animation myself when removing a control from its parent?

Solution

Do I really need to do my own bookkeeping

Yes, you can only Animate Dependency properties and Dependency properties are static so even if your Control is no longer referenced the Animation will continue.

Depending on the purpose of your Animation you may it may be as simple as setting the Animations FillBehavior to Stop

animation.FillBehavior = FillBehavior.Stop;

This will stop the animation TimeLine when it completes, but this is not always a great solution if you have repeating animations or animations that set certain values as when the animation stops the property animated will return to its original value immediately.

If FillBehavior.Stop does not work in your situation you call stop Animations and Storyboards in other ways.

If the Animation is a Storyboard you can call StopStoryboard

When you use BeginStoryboard you can supply a Name, which you can then use in StopStoryboard:

  <BeginStoryboard Name="myStoryboard" ......... />

  <StopStoryboard BeginStoryboardName="myStoryboard" />

Trigger Storyboard example:

<Trigger>
   <Trigger.EnterActions>
        <BeginStoryboard Name="myStoryboard">
          <Storyboard ..... />
       </BeginStoryboard>
   </Trigger.EnterActions>
   <Trigger.ExitActions>
      <StopStoryboard BeginStoryboardName="myStoryboard" />
   </Trigger.ExitActions>
</Trigger>

Or in code behind you can just call Stop on your storyboard:

myStoryboard.Stop();

If you are creating a simple Animation in code behind you can stop it by applying a null TimeLine to the DependencyProperty you animated.

Example:

// Start
myLabel.BeginAnimation(Canvas.LeftProperty, new DoubleAnimation(10.0, 100.0, new Duration(TimeSpan.FromSeconds(5)));

// Stop
myLabel.BeginAnimation(Canvas.LeftProperty, null);