title: DataTrigger on WPF Animation
body: <p>My application has a few background worker, each doing different work. When I click the 'Start' button, all backgroundworker will start simultaneously.</p>
  
  <p>in my xaml, I had defined my animation of a rotate image:</p>
  
  <pre><code>&lt;window.Resources&gt;
      &lt;Storyboard x:Key="imageRotate"&gt;
          &lt;DoubleAnimation Storyboard.TargetName="transRotate"
                  Storyboard.TargetProperty="(Image.RenderTransform).(RotateTransform.Angle)"
                  From="0" To="360"
                  Duration="0:0:0.5"
                  AutoReverse="False"
                  RepeatBehavior="Forever"/&gt;
       &lt;/Storyboard&gt;
  &lt;/window.Resources&gt;
  </code></pre>
  
  <p>I want the animation to begin when all the backgroundworker started, and stop ONLY after ALL background worker stopped.</p>
  
  <p>I have a property call AreWorkersBusy:</p>
  
  <pre><code>private bool _areWorkerBusy;
  public bool AreWorkerBusy
  {
      get
      {
          return _areWorkerBusy;
      }
      set
      {
          bool isBusy = false;
          foreach(BackgroundWorker worker in BackgroundWorkerList)
          {
              if(worker.IsBusy)
                   isBusy = true;
          }
          _areWorkerBusy = isBusy;
      }
  }
  </code></pre>
  
  <p>but it's not dependencyProperty, so I can't bind to my animation's DataTrigger.</p>
  
  <p>Any workaround???</p>
  
  <p>Help!</p>