Object​Animation​Using​Key​Frames Object​Animation​Using​Key​Frames Object​Animation​Using​Key​Frames Class

Definition

Animates the value of an Object property along a set of KeyFrames over a specified Duration.

public sealed class ObjectAnimationUsingKeyFrames : Timeline, IObjectAnimationUsingKeyFramespublic sealed class ObjectAnimationUsingKeyFrames : Timeline, IObjectAnimationUsingKeyFramesPublic NotInheritable Class ObjectAnimationUsingKeyFrames Inherits Timeline Implements IObjectAnimationUsingKeyFrames
<ObjectAnimationUsingKeyFrames>oneOrMoreDiscreteObjectKeyFrames</ObjectAnimationUsingKeyFrames>
Inheritance
ObjectAnimationUsingKeyFramesObjectAnimationUsingKeyFramesObjectAnimationUsingKeyFrames
Attributes
Windows 10 requirements
Device family
Windows 10 (introduced v10.0.10240.0)
API contract
Windows.Foundation.UniversalApiContract (introduced v1)

Inherited Members

Inherited properties

Inherited methods

Inherited events

Remarks

Examples

The following example uses the ObjectAnimationUsingKeyFrames class to animate the Fill property of a Rectangle. This animation uses two key frames in the following manner:

  1. Using a DiscreteObjectKeyFrame, the Fill property of the Rectangle suddenly changes to a LinearGradientBrush after the first two seconds of the animation.
  2. After the third second of the animation, the Fill property is suddenly changed to a different LinearGradientBrush, which remains until the end of the animation (four seconds total).
<StackPanel>
    <StackPanel.Resources>
        <Storyboard x:Name="myStoryboard">

            <!-- ObjectAnimationUsingKeyFrames is used to animate properties that take
         an object as a value. This animation lasts for 4 seconds using 3 KeyFrames which
         swap different brush objects at regular intervals, making the background of the Page
         change. -->
            <ObjectAnimationUsingKeyFrames
         Storyboard.TargetName="animatedRectangle"
         Storyboard.TargetProperty="Fill"
         Duration="0:0:4" RepeatBehavior="Forever">
                <ObjectAnimationUsingKeyFrames.KeyFrames>

                    <!-- Note: Only discrete interpolation (DiscreteObjectKeyFrame) is available for 
                use with ObjectAnimationUsingKeyFrames which merely swaps objects according to
                a specified timeline. Other types of interpolation are too problematic to apply
                to objects.  -->
                    <!-- Using a DiscreteObjectKeyFrame, the Fill property of the Rectangle suddenly  
                changes to a LinearGradientBrush after the first two seconds of the animation. -->
                    <DiscreteObjectKeyFrame KeyTime="0:0:2">
                        <DiscreteObjectKeyFrame.Value>
                            <LinearGradientBrush>
                                <LinearGradientBrush.GradientStops>
                                    <GradientStop Color="Yellow" Offset="0.0" />
                                    <GradientStop Color="Orange" Offset="0.5" />
                                    <GradientStop Color="Red" Offset="1.0" />
                                </LinearGradientBrush.GradientStops>
                            </LinearGradientBrush>
                        </DiscreteObjectKeyFrame.Value>
                    </DiscreteObjectKeyFrame>

                    <!-- After the third second of the animation, the Fill property is suddenly changed 
                to a different LinearGradientBrush which remains until the end of the animation 
                (4 seconds total). -->
                    <DiscreteObjectKeyFrame KeyTime="0:0:3">
                        <DiscreteObjectKeyFrame.Value>
                            <LinearGradientBrush>
                                <LinearGradientBrush.GradientStops>
                                    <GradientStop Color="White" Offset="0.0" />
                                    <GradientStop Color="MediumBlue" Offset="0.5" />
                                    <GradientStop Color="Black" Offset="1.0" />
                                </LinearGradientBrush.GradientStops>
                            </LinearGradientBrush>
                        </DiscreteObjectKeyFrame.Value>
                    </DiscreteObjectKeyFrame>

                </ObjectAnimationUsingKeyFrames.KeyFrames>
            </ObjectAnimationUsingKeyFrames>
        </Storyboard>
    </StackPanel.Resources>

    <!-- The Fill property of this rectangle is animated. -->
    <Rectangle x:Name="animatedRectangle" Loaded="Rectangle_Loaded" Width="300" Height="300" />

</StackPanel>
// When the rectangle loads, begin the animation.
private void Rectangle_Loaded(object sender, RoutedEventArgs e)
{
    myStoryboard.Begin();
}
' When the rectangle loads, begin the animation.
Private Sub Rectangle_Loaded(ByVal sender As Object, ByVal e As EventArgs)
    myStoryboard.Begin()
End Sub

Constructors

ObjectAnimationUsingKeyFrames() ObjectAnimationUsingKeyFrames() ObjectAnimationUsingKeyFrames()

Initializes a new instance of the ObjectAnimationUsingKeyFrames class.

public ObjectAnimationUsingKeyFrames()public ObjectAnimationUsingKeyFrames()Public Sub New()
Attributes

Properties

EnableDependentAnimation EnableDependentAnimation EnableDependentAnimation

Gets or sets a value that declares whether animated properties that are considered dependent animations should be permitted to use this animation declaration.

public PlatForm::Boolean EnableDependentAnimation { get; set; }public bool EnableDependentAnimation { get; set; }Public ReadWrite Property EnableDependentAnimation As bool
<ObjectAnimationUsingKeyFrames EnableDependentAnimation="bool" />
Value
bool bool bool

true if the animation can be used for a dependent animation case. false if the animation cannot be used for a dependent animation case. The default is false.

Attributes

Remarks

What's considered a dependent animation?

Not all custom animations you create can run by default in a Windows Runtime app, if the animation system determines that the animation might cause bad performance in your UI. Animations where the system determines there could be a performance impact are called dependent animations. It's dependent because your animation is actively and frequently updating objects on the UI thread, which is also where current user input and other programmatic updates are making runtime changes to UI.

A dependent animation that's consuming extensive system resources on the UI thread can make the app appear unresponsive in certain situations. If your animation causes a layout change or otherwise has the potential to impact performance on the UI thread, you often need to explicitly enable the animation to see it run. That's what the EnableDependentAnimation property on specific animation classes is for. Use this property with caution, because setting it to true means you are deliberately acknowledging that the animation might slow down other operations on the UI thread when it runs.

For more info, see Storyboarded animations. That topic includes a list of the criteria for an independent animation. An animation is a dependent animation if it doesn't satisfy at least one of those criteria. For the specific property you intend to animate, and for the specifics of your animation, compare your intended animation to the criteria to see whether it would be considered dependent or independent by the system.

Another way to discover whether your animations are dependent is that you might receive a warning from your XAML design surface or tool after you compose that animation, and the warning indicates that you'll need to set EnableDependentAnimation to true to see your animation run.

As an app developer, you can also choose to apply an app-wide setting that always disables dependent animations, even those where EnableDependentAnimation is true. See Timeline.AllowDependentAnimations. This is useful to you as an app developer if you're consuming controls where the templates have dependent animations, and you've identified that as a performance problem, but you don't want to have to retemplate the whole control to turn those animations off.

See Also

EnableDependentAnimationProperty EnableDependentAnimationProperty EnableDependentAnimationProperty

Identifies the EnableDependentAnimation dependency property.

public static DependencyProperty EnableDependentAnimationProperty { get; }public static DependencyProperty EnableDependentAnimationProperty { get; }Public Static ReadOnly Property EnableDependentAnimationProperty As DependencyProperty
Value
DependencyProperty DependencyProperty DependencyProperty

The identifier for the EnableDependentAnimation dependency property.

Attributes

KeyFrames KeyFrames KeyFrames

Gets the collection of ObjectKeyFrame objects that define the animation.

public ObjectKeyFrameCollection KeyFrames { get; }public ObjectKeyFrameCollection KeyFrames { get; }Public ReadOnly Property KeyFrames As ObjectKeyFrameCollection
<ObjectAnimationUsingKeyFrames>oneOrMoreDiscreteObjectKeyFrames</ObjectAnimationUsingKeyFrames>
Value
ObjectKeyFrameCollection ObjectKeyFrameCollection ObjectKeyFrameCollection

The collection of ObjectKeyFrame objects that define the animation. The default is an empty collection.

Attributes

See Also