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DoubleAnimationUsingKeyFrames Object

Animates the value of a Double property along a set of KeyFrames.

XAML
<DoubleAnimationUsingKeyFrames ...>
  oneOrMoreDoubleKeyFrames
</DoubleAnimationUsingKeyFrames>
Scripting
To create an object using scripting, see CreateFromXAML.

XAML Values

oneOrMoreDoubleKeyFrames One or more DoubleKeyFrame object elements that define the key frames for the animation. These can be any mixture of <LinearDoubleKeyFrame .../>, <DiscreteDoubleKeyFrame .../>, and <SplineDoubleKeyFrame .../>. Object elements defined here become members of the collection held by the KeyFrames property, when accessed by scripting at runtime.

Remarks

A key frame animation's target values are defined by its KeyFrames property, which contains a collection of DoubleKeyFrame objects. Each DoubleKeyFrame defines a segment of the animation with its own target Value and KeyTime. When the animation runs, it progresses from one key value to the next at the specified key times.

There are three types of DoubleKeyFrame classes, one for each supported interpolation method: LinearDoubleKeyFrame, DiscreteDoubleKeyFrame, and SplineDoubleKeyFrame.

When declaring a DoubleAnimationUsingKeyFrames in XAML, the order of the DoubleKeyFrame object elements is not significant, because the KeyTime controls the timing and therefore the order in which the key frames are executed. However, it is good markup style to keep the element order the same as the KeyTime sequence order.

Examples

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.
XAML
<Canvas
  xmlns="http://schemas.microsoft.com/client/2007"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Width="400" Height="300">
  <Rectangle Fill="Blue" 
    Width="50" Height="50">
    <Rectangle.RenderTransform>
      <TranslateTransform 
        x:Name="MyAnimatedTranslateTransform" 
        X="0" Y="0" />
    </Rectangle.RenderTransform>
    <Rectangle.Triggers>
      <EventTrigger RoutedEvent="Rectangle.Loaded">
        <BeginStoryboard>
          <Storyboard>

            <!-- Animate the TranslateTransform's X property
                 from 0 to 350, then 50,
                 then 200 over 10 seconds. -->
            <DoubleAnimationUsingKeyFrames
              Storyboard.TargetName="MyAnimatedTranslateTransform"
              Storyboard.TargetProperty="X"
              Duration="0:0:10">

                <!-- 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>

See Also

Key-Frame Animations Overview
Animation Overview
Interactive Animations Overview

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