Pooja PoojariandAndy De George
692293bda8
* Updated H2 and column headers. * Metadata update. * Minor edits. * Apply suggestions from code review Co-authored-by: Andy (Steve) De George <[email protected]>
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title, description, ms.date, ms.custom, dev_langs, helpviewer_keywords, ms.assetid
| title | description | ms.date | ms.custom | dev_langs | helpviewer_keywords | ms.assetid | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| How to: Receive Notification When a Clock's State Changes | Learn how to receive notification when a Clock's state changes. | 03/30/2017 | devdivchpfy22 |
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How to: Receive Notification When a Clock's State Changes
A clock's xref:System.Windows.Media.Animation.Clock.CurrentStateInvalidated event occurs when its xref:System.Windows.Media.Animation.Clock.CurrentState%2A becomes invalid, such as when the clock starts or stops. You can register for this event with directly using a xref:System.Windows.Media.Animation.Clock, or you can register using a xref:System.Windows.Media.Animation.Timeline.
In the following example, a xref:System.Windows.Media.Animation.Storyboard and two xref:System.Windows.Media.Animation.DoubleAnimation objects are used to animate the width of two rectangles. The xref:System.Windows.Media.Animation.Timeline.CurrentStateInvalidated event is used to listen for clock state changes.
Example
[!code-xamltimingbehaviors_snip#_graphicsmm_StateExampleMarkupWholePage]
[!code-csharptimingbehaviors_snip#_graphicsmm_StateEventHandlers] [!code-vbtimingbehaviors_snip#_graphicsmm_StateEventHandlers]
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 xref:System.Windows.Media.Animation.Timeline.CurrentStateInvalidated event fires:
| Time (Seconds) | State |
|---|---|
| 1 | Active |
| 10 | Active |
| 19 | Stopped |
| 21 | Active |
| 30 | Active |
| 39 | Stopped |
The following table shows the times at which Animation2's xref:System.Windows.Media.Animation.Timeline.CurrentStateInvalidated event fires:
| Time (Seconds) | State |
|---|---|
| 1 | Active |
| 9 | Filling |
| 11 | Active |
| 19 | Stopped |
| 21 | Active |
| 29 | Filling |
| 31 | Active |
| 39 | Stopped |
Notice that Animation1's xref:System.Windows.Media.Animation.Timeline.CurrentStateInvalidated event fires at 10 seconds, even though its state remains xref:System.Windows.Media.Animation.ClockState.Active. That's because its state changed at 10 seconds, but it changed from xref:System.Windows.Media.Animation.ClockState.Active to xref:System.Windows.Media.Animation.ClockState.Filling and then back to xref:System.Windows.Media.Animation.ClockState.Active in the same tick.