LinearPointKeyFrame Class

Reference

Definition

Namespace:: Microsoft.UI.Xaml.Media.Animation

Important

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Edit

Animates from the Point value of the previous key frame to its own Value, using linear interpolation.

public ref class LinearPointKeyFrame sealed : PointKeyFrame

/// [Windows.Foundation.Metadata.Activatable(65536, "Microsoft.UI.Xaml.WinUIContract")]
/// [Windows.Foundation.Metadata.ContractVersion(Microsoft.UI.Xaml.WinUIContract, 65536)]
/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
/// [Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
class LinearPointKeyFrame final : PointKeyFrame

[Windows.Foundation.Metadata.Activatable(65536, "Microsoft.UI.Xaml.WinUIContract")]
[Windows.Foundation.Metadata.ContractVersion(typeof(Microsoft.UI.Xaml.WinUIContract), 65536)]
[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
[Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
public sealed class LinearPointKeyFrame : PointKeyFrame

Public NotInheritable Class LinearPointKeyFrame
Inherits PointKeyFrame

<LinearPointKeyFrame .../>

Inheritance: Object Platform::Object IInspectable DependencyObject PointKeyFrame LinearPointKeyFrame

Attributes: ActivatableAttribute ContractVersionAttribute MarshalingBehaviorAttribute ThreadingAttribute

Examples

This XAML example moves an ellipse along a triangular path. The example uses the PointAnimationUsingKeyFrames class to animate the Center property of an EllipseGeometry. This animation uses three key frames in the following manner:

During the first half second, it uses an instance of the LinearPointKeyFrame class to move the ellipse along a path at a steady rate from its starting position. Linear key frames such as LinearPointKeyFrame create a smooth linear interpolation between values.
During the end of the next half second, it uses an instance of the DiscretePointKeyFrame class to suddenly move the ellipse along the path to the next position. Discrete key frames like DiscretePointKeyFrame create sudden jumps between values.
During the final two seconds, it uses an instance of the SplinePointKeyFrame class to move the ellipse back to its starting position. Spline key frames like SplinePointKeyFrame create a variable transition between values according to the values of the KeySpline property. In this example, the animation begins slowly and speeds up exponentially toward the end of the time segment.

<Canvas Width="400" Height="300">
    <Canvas.Resources>
        <Storyboard x:Name="myStoryboard">

            <!-- Animating the Center property uses 3 KeyFrames, which animate
             the ellipse allong a triangular path. -->
            <PointAnimationUsingKeyFrames
          Storyboard.TargetProperty="Center"
          Storyboard.TargetName="MyAnimatedEllipseGeometry"
          Duration="0:0:5" RepeatBehavior="Forever" EnableDependentAnimation="True">

                <!-- Over the first half second, Using a LinearPointKeyFrame, the ellipse 
               moves steadily from its starting position along the first line of the 
               trianglar path.  -->
                <LinearPointKeyFrame KeyTime="0:0:0.5" Value="100,300" />

                <!-- Using a DiscretePointKeyFrame, the ellipse suddenly changes position
               after the first second of the animation. -->
                <DiscretePointKeyFrame KeyTime="0:0:1" Value="400,300" />

                <!-- Using a SplinePointKeyFrame, the ellipse moves back to its starting
               position. It moves slowly at first and then speeds up. This key frame 
               takes 2 seconds to complete. -->
                <SplinePointKeyFrame KeySpline="0.6,0.0 0.9,0.00" 
                 KeyTime="0:0:3" Value="200,100" />
            </PointAnimationUsingKeyFrames>
        </Storyboard>
    </Canvas.Resources>
    <Path Fill="Blue" Loaded="Start_Animation">
        <Path.Data>

            <!-- Describes an ellipse. -->
            <EllipseGeometry x:Name="MyAnimatedEllipseGeometry"
             Center="200,100" RadiusX="15" RadiusY="15" />
        </Path.Data>
    </Path>
</Canvas>

// Start the animation when the object loads
private void Start_Animation(object sender, RoutedEventArgs e)
{
    myStoryboard.Begin();
}

Remarks

Key-frame animations permit more than one target value that is reached at a point along the animation timeline. In other words each key frame can specify a different intermediate value, and the last key frame reached is the final animation value. By specifying multiple values to animate, you can make more complex animations. You'd typically have at least two keyframes in a PointAnimationUsingKeyFrames with LinearPointKeyFrame, otherwise a PointAnimation would have been simpler.

For more info on how to use key-frame animations, see Key-frame animations and easing function animations.

Constructors

LinearPointKeyFrame()

Initializes a new instance of the LinearPointKeyFrame class.

Properties

Dispatcher	Always returns `null` in a Windows App SDK app. Use DispatcherQueue instead. (Inherited from DependencyObject)
DispatcherQueue	Gets the `DispatcherQueue` that this object is associated with. The `DispatcherQueue` represents a facility that can access the `DependencyObject` on the UI thread even if the code is initiated by a non-UI thread. (Inherited from DependencyObject)
KeyTime	Gets or sets the time at which the key frame's target Value should be reached. (Inherited from PointKeyFrame)
Value	Gets or sets the key frame's target value. (Inherited from PointKeyFrame)

Methods

ClearValue(DependencyProperty)	Clears the local value of a dependency property. (Inherited from DependencyObject)
GetAnimationBaseValue(DependencyProperty)	Returns any base value established for a dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject)
GetValue(DependencyProperty)	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject)
ReadLocalValue(DependencyProperty)	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject)
RegisterPropertyChangedCallback(DependencyProperty, DependencyPropertyChangedCallback)	Registers a notification function for listening to changes to a specific DependencyProperty on this DependencyObject instance. (Inherited from DependencyObject)
SetValue(DependencyProperty, Object)	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject)
UnregisterPropertyChangedCallback(DependencyProperty, Int64)	Cancels a change notification that was previously registered by calling RegisterPropertyChangedCallback. (Inherited from DependencyObject)

Applies to

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