In WPF, how can I do animation until background worker finishes its work?

Question

I have an application that do some hard stuff when user clicks a start button and takes a long time. During this I would like to do some animation over a label, for example, changing opacity from 0 to 1 and vice versa and change foreground color between several colors at the same time changing opacity. I want it stops doing animation when background worker finishes its work. How can I do this? and how can I start animation and stop it from c#?

Answer 1

Your animations will be hosted in a Storyboard.

• To make the animations run indefinitely, set the Storyboard's RepeatBehavior to Forever.
• To start the animations when you kick off the BackgroundWorker, call the Storyboard.Begin method.
• To stop the animations when the BackgroundWorker finishes, in your RunWorkerCompleted event handler, call the Storyboard.Stop method.

Here's an example:

<Window.Resources>
  <Storyboard x:Key="sb" Duration="0:0:2" RepeatBehavior="Forever">
    <DoubleAnimation Storyboard.TargetName="l"
                     Storyboard.TargetProperty="Opacity"
                     From="1" To="0" AutoReverse="True" />
    <ColorAnimation Storyboard.TargetName="l"
                    Storyboard.TargetProperty="Foreground.Color"
                    From="HotPink" To="Lime" AutoReverse="True" />
  </Storyboard>
</Window.Resources>

<StackPanel>
  <Label Name="l" FontSize="72">Oh noes!</Label>
  <Button Click="Button_Click">Animate me!</Button>
</StackPanel>

And the Button_Click handler:

private void Button_Click(object sender, RoutedEventArgs e)
{
  ((Storyboard)(FindResource("sb"))).Begin();
  // and kick off your BackgroundWorker
}