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DiscreteDoubleKeyFrame Class

Animates from the Double value of the previous key frame to its own Value using discrete interpolation.

Namespace:  System.Windows.Media.Animation
Assembly:  PresentationCore (in PresentationCore.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
public class DiscreteDoubleKeyFrame : DoubleKeyFrame
<DiscreteDoubleKeyFrame .../>

The DiscreteDoubleKeyFrame type exposes the following members.

  NameDescription
Public methodDiscreteDoubleKeyFrame()Initializes a new instance of the DiscreteDoubleKeyFrame class.
Public methodDiscreteDoubleKeyFrame(Double)Initializes a new instance of the DiscreteDoubleKeyFrame class with the specified ending value.
Public methodDiscreteDoubleKeyFrame(Double, KeyTime)Initializes a new instance of the DiscreteDoubleKeyFrame class with the specified ending value and key time.
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  NameDescription
Public propertyCanFreezeGets a value that indicates whether the object can be made unmodifiable. (Inherited from Freezable.)
Public propertyDependencyObjectTypeGets the DependencyObjectType that wraps the CLR type of this instance.  (Inherited from DependencyObject.)
Public propertyDispatcherGets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject.)
Public propertyIsFrozenGets a value that indicates whether the object is currently modifiable. (Inherited from Freezable.)
Public propertyIsSealedGets a value that indicates whether this instance is currently sealed (read-only). (Inherited from DependencyObject.)
Public propertyKeyTime Gets or sets the time at which the key frame's target Value should be reached. (Inherited from DoubleKeyFrame.)
Public propertyValue Gets or sets the key frame's target value. (Inherited from DoubleKeyFrame.)
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  NameDescription
Public methodCheckAccessDetermines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
Public methodClearValue(DependencyProperty)Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier. (Inherited from DependencyObject.)
Public methodClearValue(DependencyPropertyKey)Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey. (Inherited from DependencyObject.)
Public methodCloneCreates a modifiable clone of the Freezable, making deep copies of the object's values. When copying the object's dependency properties, this method copies expressions (which might no longer resolve) but not animations or their current values. (Inherited from Freezable.)
Protected methodCloneCoreMakes the instance a clone (deep copy) of the specified Freezable using base (non-animated) property values. (Inherited from Freezable.)
Public methodCloneCurrentValueCreates a modifiable clone (deep copy) of the Freezable using its current values. (Inherited from Freezable.)
Protected methodCloneCurrentValueCoreMakes the instance a modifiable clone (deep copy) of the specified Freezable using current property values. (Inherited from Freezable.)
Public methodCoerceValueCoerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject. (Inherited from DependencyObject.)
Protected methodCreateInstanceInitializes a new instance of the Freezable class. (Inherited from Freezable.)
Protected methodCreateInstanceCoreCreates a new instance of DiscreteDoubleKeyFrame. (Overrides Freezable.CreateInstanceCore().)
Public methodEqualsDetermines whether a provided DependencyObject is equivalent to the current DependencyObject. (Inherited from DependencyObject.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodFreeze()Makes the current object unmodifiable and sets its IsFrozen property to true. (Inherited from Freezable.)
Protected methodFreezeCoreMakes the Freezable object unmodifiable or tests whether it can be made unmodifiable. (Inherited from Freezable.)
Public methodGetAsFrozenCreates a frozen copy of the Freezable, using base (non-animated) property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable.)
Protected methodGetAsFrozenCoreMakes the instance a frozen clone of the specified Freezable using base (non-animated) property values. (Inherited from Freezable.)
Public methodGetCurrentValueAsFrozenCreates a frozen copy of the Freezable using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable.)
Protected methodGetCurrentValueAsFrozenCoreMakes the current instance a frozen clone of the specified Freezable. If the object has animated dependency properties, their current animated values are copied. (Inherited from Freezable.)
Public methodGetHashCodeGets a hash code for this DependencyObject. (Inherited from DependencyObject.)
Public methodGetLocalValueEnumeratorCreates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (Inherited from DependencyObject.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodGetValueReturns the current effective value of a dependency property on this instance of a DependencyObject. (Inherited from DependencyObject.)
Public methodInterpolateValueReturns the interpolated value of a specific key frame at the progress increment provided. (Inherited from DoubleKeyFrame.)
Protected methodInterpolateValueCoreInterpolates between the previous key frame value and the value of the current key frame using discrete interpolation. (Overrides DoubleKeyFrame.InterpolateValueCore(Double, Double).)
Public methodInvalidatePropertyRe-evaluates the effective value for the specified dependency property (Inherited from DependencyObject.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnChangedCalled when the current Freezable object is modified. (Inherited from Freezable.)
Protected methodOnFreezablePropertyChanged(DependencyObject, DependencyObject)Ensures that appropriate context pointers are established for a DependencyObjectType data member that has just been set. (Inherited from Freezable.)
Protected methodOnFreezablePropertyChanged(DependencyObject, DependencyObject, DependencyProperty)This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code. (Inherited from Freezable.)
Protected methodOnPropertyChangedOverrides the DependencyObject implementation of OnPropertyChanged to also invoke any Changed handlers in response to a changing dependency property of type Freezable. (Inherited from Freezable.)
Public methodReadLocalValueReturns the local value of a dependency property, if it exists. (Inherited from DependencyObject.)
Protected methodReadPreambleEnsures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties. (Inherited from Freezable.)
Public methodSetCurrentValueSets the value of a dependency property without changing its value source. (Inherited from DependencyObject.)
Public methodSetValue(DependencyProperty, Object)Sets the local value of a dependency property, specified by its dependency property identifier. (Inherited from DependencyObject.)
Public methodSetValue(DependencyPropertyKey, Object)Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property. (Inherited from DependencyObject.)
Protected methodShouldSerializePropertyReturns a value that indicates whether serialization processes should serialize the value for the provided dependency property. (Inherited from DependencyObject.)
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.)
Protected methodWritePostscriptRaises the Changed event for the Freezable and invokes its OnChanged method. Classes that derive from Freezable should call this method at the end of any API that modifies class members that are not stored as dependency properties. (Inherited from Freezable.)
Protected methodWritePreambleVerifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties. (Inherited from Freezable.)
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  NameDescription
Public eventChangedOccurs when the Freezable or an object it contains is modified. (Inherited from Freezable.)
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  NameDescription
Explicit interface implemetationPrivate propertyIKeyFrame.ValueGets or sets the value associated with a KeyTime instance. (Inherited from DoubleKeyFrame.)
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This class is used as part of a DoubleKeyFrameCollection in conjunction with a DoubleAnimationUsingKeyFrames to animate a Double property value along a set of key frames.

A key frame defines a segment of the DoubleAnimationUsingKeyFrames to which it belongs. Each key frame has a target Value and a KeyTime. The KeyTime specifies the time at which the key frame's Value should be reached. A key frame animates from the target value of the previous key frame to its own target value. It starts when the previous key frame ends and ends when its own key time is reached.

Discrete key frames like DiscreteDoubleKeyFrame create sudden "jumps" between values (no Interpolation). In other words, the animated property does not change until the key frame's key time is reached at which point the animated property goes suddenly to the target value.

This example shows how to animate the value of a property that takes a Double by using key frames.

The following example moves a rectangle across a screen. The example uses the DoubleAnimationUsingKeyFrames class to animate the X property of a TranslateTransform applied to a Rectangle. This animation, which repeats indefinitely, uses three key frames in the following manner:

  1. During the first three seconds, uses an instance of the LinearDoubleKeyFrame class to move the rectangle along a path at a steady rate from its starting position to the 500 position. Linear key frames like LinearDoubleKeyFrame create a smooth linear transition between values.

  2. At the end of the fourth second, uses an instance of the DiscreteDoubleKeyFrame class to suddenly move the rectangle to the next position. Discrete key frames like DiscreteDoubleKeyFrame create sudden jumps between values. In this example, the rectangle is at the starting position and then suddenly appears at the 500 position.

  3. In the final two seconds, uses an instance of the SplineDoubleKeyFrame class to move the rectangle back to its starting position. Spline key frames like SplineDoubleKeyFrame create a variable transition between values according to the value of the KeySpline property. In this example, the rectangle begins by moving slowly and then speeds up exponentially toward the end of the time segment.


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

namespace Microsoft.Samples.KeyFrameExamples
{
    /// <summary>
    /// This example shows how to use the DoubleAnimationUsingKeyFrames class to
    /// animate the position of an object.
    /// Key frame animations enable you to create complex animations 
    /// by specifying multiple destination values
    /// and controlling the animation's interpolation method.
    /// </summary>
    public class AltDoubleAnimationUsingKeyFramesExample : Page
    {
        public AltDoubleAnimationUsingKeyFramesExample()
        {
            Title = "DoubleAnimationUsingKeyFrames Example";
            Background = Brushes.White;
            Margin = new Thickness(20);

            // Create a NameScope for this page so that
            // Storyboards can be used.
            NameScope.SetNameScope(this, new NameScope());

            // Create a rectangle.
            Rectangle aRectangle = new Rectangle();
            aRectangle.Width = 100;
            aRectangle.Height = 100;
            aRectangle.Stroke = Brushes.Black;
            aRectangle.StrokeThickness = 5;

            // Create a Canvas to contain and
            // position the rectangle.
            Canvas containerCanvas = new Canvas();
            containerCanvas.Width = 610;
            containerCanvas.Height = 300;
            containerCanvas.Children.Add(aRectangle);
            Canvas.SetTop(aRectangle, 100);
            Canvas.SetLeft(aRectangle, 10);         

            // Create a TranslateTransform to 
            // move the rectangle.
            TranslateTransform animatedTranslateTransform = 
                new TranslateTransform();
            aRectangle.RenderTransform = animatedTranslateTransform;  

            // Assign the TranslateTransform a name so that
            // it can be targeted by a Storyboard.
            this.RegisterName(
                "AnimatedTranslateTransform", animatedTranslateTransform);

            // Create a DoubleAnimationUsingKeyFrames to
            // animate the TranslateTransform.
            DoubleAnimationUsingKeyFrames translationAnimation 
                = new DoubleAnimationUsingKeyFrames();
            translationAnimation.Duration = TimeSpan.FromSeconds(6);

            // Animate from the starting position to 500
            // over the first second using linear
            // interpolation.
            translationAnimation.KeyFrames.Add(
                new LinearDoubleKeyFrame(
                    500, // Target value (KeyValue)
                    KeyTime.FromTimeSpan(TimeSpan.FromSeconds(3))) // KeyTime
                );

            // Animate from 500 (the value of the previous key frame) 
            // to 400 at 4 seconds using discrete interpolation.
            // Because the interpolation is discrete, the rectangle will appear
            // to "jump" from 500 to 400.
            translationAnimation.KeyFrames.Add(
                new DiscreteDoubleKeyFrame(
                    400, // Target value (KeyValue)
                    KeyTime.FromTimeSpan(TimeSpan.FromSeconds(4))) // KeyTime
                );

            // Animate from 400 (the value of the previous key frame) to 0
            // over two seconds, starting at 4 seconds (the key time of the
            // last key frame) and ending at 6 seconds.
            translationAnimation.KeyFrames.Add(
                new SplineDoubleKeyFrame(
                    0, // Target value (KeyValue)
                    KeyTime.FromTimeSpan(TimeSpan.FromSeconds(6)), // KeyTime
                    new KeySpline(0.6,0.0,0.9,0.0) // KeySpline
                    )
                );

            // Set the animation to repeat forever. 
            translationAnimation.RepeatBehavior = RepeatBehavior.Forever;

            // Set the animation to target the X property
            // of the object named "AnimatedTranslateTransform."
            Storyboard.SetTargetName(translationAnimation, "AnimatedTranslateTransform");
            Storyboard.SetTargetProperty(
                translationAnimation, new PropertyPath(TranslateTransform.XProperty));

            // Create a storyboard to apply the animation.
            Storyboard translationStoryboard = new Storyboard();
            translationStoryboard.Children.Add(translationAnimation);

            // Start the storyboard after the rectangle loads.
            aRectangle.Loaded += delegate(object sender, RoutedEventArgs e)
            {
                translationStoryboard.Begin(this);
            };

            Content = containerCanvas;
        }

    }
}



<!-- This example shows how to use the DoubleAnimationUsingKeyFrames to 
     animate the position of an object. 
     Key frame animations enable you to create complex animations 
     by specifying multiple destination values
     and controlling the animation's interpolation method.
-->
<Page 
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Title="DoubleAnimationUsingKeyFrames Example"
  Background="White" Margin="20">       
  <Canvas Width="610" Height="300">

    <!-- The position of this rectangle is animated using 
         a key frame animation. -->
    <Rectangle 
      Canvas.Top="100"
      Canvas.Left="10"
      Height="100"
      Width="100"
      Stroke="Black"
      StrokeThickness="5">
      <Rectangle.RenderTransform>
        <TranslateTransform x:Name="AnimatedTranslateTransform" />
      </Rectangle.RenderTransform>

      <Rectangle.Triggers>
        <EventTrigger RoutedEvent="Rectangle.Loaded">
          <BeginStoryboard>
            <Storyboard>

              <!-- Animate the TranslateTransform.X property using 3 KeyFrames
                   which animates the rectangle along a straight line. 
                   This animation repeats indefinitely. -->
              <DoubleAnimationUsingKeyFrames
                Storyboard.TargetName="AnimatedTranslateTransform"
                Storyboard.TargetProperty="X"
                Duration="0:0:6"
                RepeatBehavior="Forever">

                <!-- Using a LinearDoubleKeyFrame, the rectangle moves 
                     steadily from its starting position to 500 over 
                     the first 3 seconds.  -->
                <LinearDoubleKeyFrame Value="500" KeyTime="0:0:3" />

                <!-- Using a DiscreteDoubleKeyFrame, the rectangle suddenly 
                     appears at 400 after the fourth second of the animation. -->
                <DiscreteDoubleKeyFrame Value="400" KeyTime="0:0:4" />

                <!-- Using a SplineDoubleKeyFrame, the rectangle moves 
                     back to its starting point. The
                     animation starts out slowly at first and then speeds up. 
                     This KeyFrame ends after the 6th
                     second. -->
                <SplineDoubleKeyFrame KeySpline="0.6,0.0 0.9,0.00" Value="0" KeyTime="0:0:6" />
              </DoubleAnimationUsingKeyFrames>
            </Storyboard>
          </BeginStoryboard>
        </EventTrigger>
      </Rectangle.Triggers>
    </Rectangle>
  </Canvas>
</Page>


For the complete sample, see KeyFrame Animation Sample.

For consistency with other animation examples, the code versions of this example use a Storyboard object to apply the DoubleAnimationUsingKeyFrames. Alternatively, when applying a single animation in code, it is simpler to use the BeginAnimation method instead of using a Storyboard. For an example, see How to: Animate a Property Without Using a Storyboard.

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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.
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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