WPF TransitionControl Events

The RadTransitionControl raises the following specific events:

• TriggeringTransion: This event is fired before a transition is started. The event handler receives two arguments:

  • The sender argument contains the RadTransitionControl. This argument is of type object but can be cast to the RadTransitionControl type.

  • A TriggeringTransitionEventArgs object. It exposes only the Cancel property, which allows you to cancel the transition, as demonstrated in Example 1. Note, that even if the transition is cancelled, the Content will still be changed.

  Example 1: Canceling the TriggeringTransion event

  • C#
  • VB.NET

      private void RadTransitionControl_TriggeringTransition(object sender, TriggeringTransitionEventArgs e) 
      { 
          // you can specify a condition for cancelling here 
          e.Cancel = true; 
      } 

      Private Sub RadTransitionControl_TriggeringTransition(ByVal sender As Object, ByVal e As TriggeringTransitionEventArgs) 
          ' you can specify a condition for cancelling here 
          e.Cancel = True 
      End Sub 

• TransitionStatusChanged: This event is fired anytime there is a change in the content and the transition animation. The event handler receives two arguments:

  • The sender argument contains the RadTransitionControl. This argument is of type object, but can be cast to the RadTransitionControl type.

  • A TransitionStatusChangedEventArgs object. It exposes a Status property which is of type TransitionStatus.

  Example 2: Handling the TransitionStatusChanged event

  • C#
  • VB.NET

      private void RadTransitionControl_TransitionStatusChanged(object sender, TransitionStatusChangedEventArgs e) 
      { 
          switch (e.Status) 
          { 
              case TransitionStatus.Started: 
                  // The transition has been idle and a new transition is triggered. 
                  break; 
              case TransitionStatus.Interrupted: 
                  // A new transition has started before the old one has completed. 
                  break; 
              case TransitionStatus.Completed: 
                  // The transition has completed and the RadTransitionControl is now idle. 
                  break; 
              default: 
                  break; 
          } 
      } 

      Private Sub RadTransitionControl_TransitionStatusChanged(ByVal sender As Object, ByVal e As TransitionStatusChangedEventArgs) 
          Select Case e.Status 
              Case TransitionStatus.Started 
                  ' The transition has been idle and a new transition is triggered. 
              Case TransitionStatus.Interrupted 
                  ' A new transition has started before the old one has completed. 
              Case TransitionStatus.Completed 
                  ' The transition has completed and the RadTransitionControl is now idle. 
              Case Else 
          End Select 
      End Sub 

When Does a Transition Start?

To check if new content is available or whether a transition has started, you should take care to handle both cases: Started and Interrupted. They both indicate that a new transition has started/new content is available, with the difference being whether the RadTransitionControl has been playing another transition or not.

Is There a Transition Currently Playing?

If you want to do some UI related logic, like disabling buttons, while a transition is in progress, you could use the Started and Interrupted states to set the buttons to disabled and the Completed state to reset them back to enabled.

You can also use the IsTransitionIdle property. It allows you to bind the IsEnabled of a UIElement to the IsTransitionIdle property, as demonstrated in Example 3.

Example 3: Using the IsTransitionIdle property

• XAML

<Button Content="Sample button" IsEnabled="{Binding IsTransitionIdle, ElementName=RadTransitionControl}"/> 
 
<telerik:RadTransitionControl x:Name="RadTransitionControl"> 
    <telerik:RadTransitionControl.Transition> 
        <telerik:SlideAndZoomTransition /> 
    </telerik:RadTransitionControl.Transition> 
</telerik:RadTransitionControl>