Timeline.CurrentStateInvalidated Event
Occurs when the CurrentState property of the timeline's Clock is updated.
Assembly: PresentationCore (in PresentationCore.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
Use the CurrentStateInvalidated event when you want to be notified when a timeline's Clock starts, stops, or fills.
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.
The Object parameter of the EventHandler event handler is the Clock that was created for this timeline.
Although this event handler appears to be associated with a timeline, it actually registers with the Clock created for this timeline. For more information, see the Timing Events Overview.
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.
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 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
