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MatrixAnimationUsingPath.IsAngleCumulative Property

  • Reference

Definition

Namespace:
System.Windows.Media.Animation
Assembly:
PresentationCore.dll

Gets or sets a value that specifies whether the rotation angle of the animated matrix should accumulate over repetitions.

public:
 property bool IsAngleCumulative { bool get(); void set(bool value); };
public bool IsAngleCumulative { get; set; }
member this.IsAngleCumulative : bool with get, set
Public Property IsAngleCumulative As Boolean

Property Value

Boolean

true if the animation's rotation angle should accumulate over repetitions; otherwise, false. The default is false.

Examples

The following example uses two similar MatrixAnimationUsingPath animations to animate the same rectangle. Both animations have the same PathGeometry setting, which causes the rectangle to rotate as it moves along the screen to the right, and both animations are set to repeat four times. The first animation's IsAngleCumulative property is set to false, so the rectangle jumps back to its original angle when the animation repeats. The second animation's IsAngleCumulative property is set to true; as a result, the rectangle angle appears to increase when the animation repeats, rather than jumping back to its original value.

<Page 
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
  <StackPanel Margin="50">
      
    <!-- The Rectangle that is animated across the screen by animating
         the MatrixTransform applied to the button. -->
    <Rectangle 
      Width="75" Height="25"
      HorizontalAlignment="Left"
      VerticalAlignment="Top"
      Stroke="Black" StrokeThickness="1">
      <Rectangle.RenderTransform>
        <MatrixTransform x:Name="myMatrixTransform">
          <MatrixTransform.Matrix >
            <Matrix OffsetX="10" OffsetY="100"/>
          </MatrixTransform.Matrix>
        </MatrixTransform>
      </Rectangle.RenderTransform>
      <Rectangle.Fill>
        <LinearGradientBrush>
          <GradientStop Color="Lime" Offset="0.0" />
          <GradientStop Color="Gray" Offset="1.0" />
        </LinearGradientBrush>
      </Rectangle.Fill>
    </Rectangle>

    <!-- Shows the animation path. -->
    <Path
      Stroke="Black" StrokeThickness="5"
      Data="M 0,0 A 50,50 0 1 0 100,0" />
    
    <StackPanel Margin="0,200,0,0" Orientation="Horizontal">
    <Button Content="Animate with IsAngleCumulative set to False"
      HorizontalAlignment="Left" Padding="5">
      <Button.Triggers>
        <EventTrigger RoutedEvent="Button.Click">
          <BeginStoryboard>
            <Storyboard>

              <!-- The angle generated by this animation does not
                   accumulate over repetitions. As a result, 
                   the rectangle appears to jump back to its 
                   starting angle when the animation repeats.  -->
              <MatrixAnimationUsingPath
                Storyboard.TargetName="myMatrixTransform"
                Storyboard.TargetProperty="Matrix"
                Duration="0:0:2" 
                RepeatBehavior="4x" 
                IsOffsetCumulative="True" 
                IsAngleCumulative="False"
                DoesRotateWithTangent="True">
                <MatrixAnimationUsingPath.PathGeometry>
                  <PathGeometry Figures="M 0,0 A 50,50 0 1 0 100,0" />
                </MatrixAnimationUsingPath.PathGeometry>
              </MatrixAnimationUsingPath>
            </Storyboard>
          </BeginStoryboard>
        </EventTrigger>
      </Button.Triggers>   
    </Button>
    
     <Button Content="Animate with IsAngleCumulative set to True"
      HorizontalAlignment="Left" 
      Padding="5">
      <Button.Triggers>
        <EventTrigger RoutedEvent="Button.Click">
          <BeginStoryboard>
            <Storyboard>
            
              <!-- The angle generated by this animation accumulates
                   over repetitions. As a result, the rectangle's
                   rotation appears seamless.  -->
              <MatrixAnimationUsingPath
                Storyboard.TargetName="myMatrixTransform"
                Storyboard.TargetProperty="Matrix"
                Duration="0:0:2" 
                RepeatBehavior="4x" 
                IsOffsetCumulative="True" 
                IsAngleCumulative="True"
                DoesRotateWithTangent="True">
                <MatrixAnimationUsingPath.PathGeometry>
                  <PathGeometry Figures="M 0,0 A 50,50 0 1 0 100,0" />
                </MatrixAnimationUsingPath.PathGeometry>
              </MatrixAnimationUsingPath>
            </Storyboard>
          </BeginStoryboard>
        </EventTrigger>
      </Button.Triggers>   
    </Button>   
    </StackPanel>
    
    
  </StackPanel>
</Page>

Remarks

If this property is set to true, the rotation angle of the animated matrix will accumulate as the animation repeats. If your path is a small arc, a cumulative angle will cause your object to continuously rotate with each repeat instead of restarting the rotation. When combined with an IsOffsetCumulative of true, your object might appear to tumble while it bounces (depending on the path you specify). For related information, see IsOffsetCumulative.

Setting this property has no effect if DoesRotateWithTangent is false.

This property determines whether the animation matrix's angle accumulates when the animation repeats because of its RepeatBehavior setting; it does not cause the offset to accumulate when the animation is restarted. For information on how to make an animation build off a previous animation's values, see IsAdditive.

Dependency Property Information

Item Value
Identifier field IsAngleCumulativeProperty
Metadata properties set to true None

Applies to

See also