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Clock Class

Maintains run-time timing state for a Timeline.

Namespace:  System.Windows.Media.Animation
Assembly:  PresentationCore (in PresentationCore.dll)

public class Clock : DispatcherObject

The Clock type exposes the following members.

  NameDescription
Protected methodClockInitializes a new instance of the Clock class, using the specified Timeline as a template. The new Clock object has no children.
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  NameDescription
Public propertyControllerGets a ClockController that can be used to start, pause, resume, seek, skip, stop, or remove this Clock.
Public propertyCurrentGlobalSpeedGets the rate at which the clock's time is currently progressing, compared to real-world time.
Protected propertyCurrentGlobalTimeGets the current global time, as established by the WPF timing system. 
Public propertyCurrentIterationGet the current iteration of this clock.
Public propertyCurrentProgressGets the current progress of this Clock within its current iteration.
Public propertyCurrentStateGets a value indicating whether the clock is currently Active, Filling, or Stopped.
Public propertyCurrentTimeGets this clock's current time within its current iteration.
Public propertyDispatcherGets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject.)
Public propertyHasControllableRootGets a value that indicates whether this Clock is part of a controllable clock tree.
Public propertyIsPausedGets a value that indicates whether this Clock, or any of its parents, is paused.
Public propertyNaturalDurationGets the natural duration of this clock's Timeline.
Public propertyParentGets the clock that is the parent of this clock.
Public propertyTimelineGets the Timeline from which this Clock was created.
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  NameDescription
Public methodCheckAccessDetermines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
Protected methodDiscontinuousTimeMovementWhen implemented in a derived class, will be invoked whenever a clock repeats, skips, or seeks.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Protected methodGetCanSlipReturns whether the Clock has its own external time source, which may require synchronization with the timing system.
Protected methodGetCurrentTimeCoreGets this clock's current time within its current iteration.
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodSpeedChangedWhen implemented in a derived class, will be invoked whenever a clock begins, skips, pauses, resumes, or when the clock's SpeedRatio is modified.
Protected methodStoppedWhen implemented in a derived class, will be invoked whenever a clock is stopped using the Stop method.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodVerifyAccessEnforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
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  NameDescription
Public eventCompletedOccurs when this clock has completely finished playing.
Public eventCurrentGlobalSpeedInvalidatedOccurs when the clock's speed is updated.
Public eventCurrentStateInvalidatedOccurs when the clock's CurrentState property is updated.
Public eventCurrentTimeInvalidatedOccurs when this clock's CurrentTime becomes invalid.
Public eventRemoveRequestedOccurs when the Remove method is called on this Clock or one of its parent clocks.
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A Timeline, by itself, doesn't actually do anything other than describe a segment of time. It's the timeline's Clock object that does the real work: it maintains timing-related run-time state for the timeline.

In most cases, a clock is created automatically for your timeline. When you animate by using a Storyboard or the BeginAnimation method, clocks are automatically created for your timelines and animations and applied to their targeted properties. For examples, see How to: Animate a Property by Using a Storyboard and How to: Animate a Property Without Using a Storyboard.

You can also create a Clock explicitly by using the CreateClock method. In performance-intensive scenarios, such as animating large numbers of similar objects, managing your own Clock use can provide performance benefits.

Clocks are arranged in trees that match the structure of the Timeline objects tree from which they are created. The root clock of such a timing tree can be interactively manipulated (paused, resumed, stopped, and so on) by retrieving its Controller. Non-root clocks cannot be directly controlled.

Once created, a clock cannot be modified (but it can be manipulated).

Using a Timeline as a Timer

A timeline's clock will only progress when there's an event handler associated with it or (in the case of an AnimationClock object) it is associated with a property. For this reason (and others), it's not recommended that you use a Timeline as a timer.

Notes to Inheritors

Derived classes should implement GetCurrentTimeCore if they want to modify how time flows for this clock. Derived classes can be made to do additional work when the clock repeats, skips, seeks, begins, pauses, resumes, or stops by overriding the DiscontinuousTimeMovement, SpeedChanged, and Stopped methods.

This example shows how to use Clock objects to animate a property.

There are three ways to animate a dependency property:

Storyboard objects and the BeginAnimation method enable you to animate properties without directly creating and distributing clocks (for examples, see How to: Animate a Property by Using a Storyboard and How to: Animate a Property Without Using a Storyboard); clocks are created and distributed for you automatically.

The following example shows how to create an AnimationClock and apply it to two similar properties.

/*
    This example shows how to create and apply
    an AnimationClock.
*/ 

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


namespace Microsoft.Samples.Animation.TimingBehaviors
{
    public class AnimationClockExample : Page
    {

        ScaleTransform myScaleTransform;

        public AnimationClockExample()
        {

            this.WindowTitle = "Opacity Animation Example";
            this.Background = Brushes.White;
            StackPanel myStackPanel = new StackPanel();
            myStackPanel.Margin = new Thickness(20);

            // Create a button that with a ScaleTransform. 
            // The ScaleTransform will animate when the 
            // button is clicked.
            Button myButton = new Button();
            myButton.Margin = new Thickness(50);
            myButton.HorizontalAlignment = HorizontalAlignment.Left;
            myButton.Content = "Click Me";           
            myScaleTransform = new ScaleTransform(1,1);
            myButton.RenderTransform = myScaleTransform;


            // Associate an event handler with the 
            // button's Click event.
            myButton.Click += new RoutedEventHandler(myButton_Clicked);

            myStackPanel.Children.Add(myButton);
            this.Content = myStackPanel;
        }

        // Create and apply and animation when the button is clicked. 
        private void myButton_Clicked(object sender, RoutedEventArgs e)
        {

            // Create a DoubleAnimation to animate the 
            // ScaleTransform.
            DoubleAnimation myAnimation = 
                new DoubleAnimation(
                    1, // "From" value
                    5, // "To" value  
                    new Duration(TimeSpan.FromSeconds(5))
                );
            myAnimation.AutoReverse = true;

            // Create a clock the for the animation.
            AnimationClock myClock = myAnimation.CreateClock();            

            // Associate the clock the ScaleX and 
            // ScaleY properties of the button's 
            // ScaleTransform.
            myScaleTransform.ApplyAnimationClock(
                ScaleTransform.ScaleXProperty, myClock);
            myScaleTransform.ApplyAnimationClock(
                ScaleTransform.ScaleYProperty, myClock);
        }
    }
}

For an example showing how to interactively control a Clock after it starts, see How to: Interactively Control a Clock.

.NET Framework

Supported in: 4.5.3, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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