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Clock.CurrentStateInvalidated Event

Occurs when the clock's CurrentState property is updated.

Namespace: System.Windows.Media.Animation
Assembly: PresentationCore (in presentationcore.dll)
XML Namespace:  http://schemas.microsoft.com/winfx/2006/xaml/presentation

public event EventHandler CurrentStateInvalidated
/** @event */
public void add_CurrentStateInvalidated (EventHandler value)

/** @event */
public void remove_CurrentStateInvalidated (EventHandler value)

In JScript, you can handle the events defined by a class, but you cannot define your own.
You cannot use this event in XAML.

Use the CurrentStateInvalidated event when you want to be notified if when the clock starts, stops, or fills. The Object parameter of the EventHandler event handler is the Clock whose state was invalidated.

Pausing a Clock does not change its CurrentState. To be notified when a clock becomes paused, use the CurrentGlobalSpeedInvalidated event.

Although this event occurs when the ClockState becomes invalid, that doesn't necessarily mean the ClockState changed: a Clock that switches from Active to Filling and then back to Active in the same tick will cause this event to fire, but its CurrentState property won't actually change.

A clock's CurrentStateInvalidated event occurs when its CurrentState becomes invalid, such as when the clock starts or stops. You can register for this event with directly using a Clock, or you can register using a Timeline.

In the following example, a Storyboard and two DoubleAnimation objects are used to animate the width of two rectangles. The CurrentStateInvalidated event is used to listen for clock state changes.

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
  x:Class="Microsoft.Samples.Animation.TimingBehaviors.StateExample"
  Background="LightGray">
  <StackPanel Margin="20">
  
    <TextBlock 
      Name="ParentTimelineStateTextBlock"></TextBlock>
    <TextBlock 
      Name="Animation1StateTextBlock"></TextBlock>
    <Rectangle 
      Name="Rectangle01"
      Width="100" Height="50" Fill="Orange" />    
    <TextBlock Name="Animation2StateTextBlock"></TextBlock>
    <Rectangle 
      Name="Rectangle02"
      Width="100" Height="50" Fill="Gray" />  
      
    <Button Content="Start Animations" Margin="20">
      <Button.Triggers>
        <EventTrigger RoutedEvent="Button.Click">
          <BeginStoryboard>
            <Storyboard RepeatBehavior="2x" AutoReverse="True"
              CurrentStateInvalidated="parentTimelineStateInvalidated" >
              <DoubleAnimation
                Storyboard.TargetName="Rectangle01"
                Storyboard.TargetProperty="Width"
                From="10" To="200" Duration="0:0:9"
                BeginTime="0:0:1" 
                CurrentStateInvalidated="animation1StateInvalidated"/>
              <DoubleAnimation
                Storyboard.TargetName="Rectangle02"
                Storyboard.TargetProperty="Width"
                From="10" To="200" Duration="0:0:8"
                BeginTime="0:0:1" 
                CurrentStateInvalidated="animation2StateInvalidated" />            
            </Storyboard>
          </BeginStoryboard>
        </EventTrigger>
      </Button.Triggers>
    </Button>
  
  
  </StackPanel>
</Page>

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;

namespace Microsoft.Samples.Animation.TimingBehaviors
{

    public partial class StateExample : Page
    {        
        
        private void parentTimelineStateInvalidated(object sender, EventArgs args)
        {
            Clock myClock = (Clock)sender;
            ParentTimelineStateTextBlock.Text += 
                myClock.CurrentTime.ToString() + ":" 
                + myClock.CurrentState.ToString() + " ";        
        }
        
        private void animation1StateInvalidated(object sender, EventArgs args)
        {
        
            Clock myClock = (Clock)sender;
            
            Animation1StateTextBlock.Text += 
                myClock.Parent.CurrentTime.ToString() + ":" 
                + myClock.CurrentState.ToString() + " ";     
        }
        
        private void animation2StateInvalidated(object sender, EventArgs args)
        {

            Clock myClock = (Clock)sender;
            Animation2StateTextBlock.Text += 
                myClock.Parent.CurrentTime.ToString() + ":" 
                + myClock.CurrentState.ToString() + " ";                 
        }
    }
}

The following illustration shows the different states the animations enter as the parent timeline (Storyboard) progresses.

Clock states for a Storyboard with two animations

The following table shows the times at which Animation1's CurrentStateInvalidated event fires:

Time (Seconds)

1

10

19

21

30

39

State

Active

Active

Stopped

Active

Active

Stopped

The following table shows the times at which Animation2's CurrentStateInvalidated event fires:

Time (Seconds)

1

9

11

19

21

29

31

39

State

Active

Filling

Active

Stopped

Active

Filling

Active

Stopped

Notice that Animation1's CurrentStateInvalidated event fires at 10 seconds, even though its state remains Active. That's because its state changed at 10 seconds, but it changed from Active to Filling and then back to Active in the same tick.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0
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