How to: Animate a Boolean by Using Key Frames
This example shows how to animate the Boolean property value of a Button control by using key frames.
Example
The following example uses the BooleanAnimationUsingKeyFrames class to animate the IsEnabled property of a Button control. All the key frames in this example use an instance of the DiscreteBooleanKeyFrame class. Discrete key frames like DiscreteBooleanKeyFrame create sudden jumps between values, that is, the movement of the animation is jerky.
' Demonstrates a BooleanAnimationUsingKeyFrames. The animation is used to
' animate the IsEnabled property of a button.
Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Shapes
Imports System.Windows.Media.Animation
Imports System.Windows.Media
Namespace Microsoft.Samples.KeyFrameExamples
Public Class BooleanAnimationUsingKeyFramesExample
Inherits Page
Public Sub New()
Title = "BooleanAnimationUsingKeyFrames Example"
Background = Brushes.White
Margin = New Thickness(20)
' Create a NameScope for this page so that
' Storyboards can be used.
NameScope.SetNameScope(Me, New NameScope())
Dim myStackPanel As New StackPanel()
myStackPanel.Orientation = Orientation.Vertical
myStackPanel.Margin = New Thickness(20)
' Create a TextBlock to introduce the example.
Dim myTextBlock As New TextBlock()
myTextBlock.Text = "Click the button to animate its IsEnabled property" & " with aBooleanAnimationUsingKeyFrames animation."
myStackPanel.Children.Add(myTextBlock)
' Create the Button that is the target of the animation.
Dim myButton As New Button()
myButton.Margin = New Thickness(200)
myButton.Content = "Click Me"
myStackPanel.Children.Add(myButton)
' Assign the Button a name so that
' it can be targeted by a Storyboard.
Me.RegisterName("AnimatedButton", myButton)
' Create a BooleanAnimationUsingKeyFrames to
' animate the IsEnabled property of the Button.
Dim booleanAnimation As New BooleanAnimationUsingKeyFrames()
booleanAnimation.Duration = TimeSpan.FromSeconds(4)
' All the key frames defined below are DiscreteBooleanKeyFrames.
' Discrete key frames create sudden "jumps" between values
' (no interpolation). Only discrete key frames can be used
' for Boolean key frame animations.
' Value at the beginning is false
booleanAnimation.KeyFrames.Add(New DiscreteBooleanKeyFrame(False, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(0.0)))) ' KeyTime - Target value (KeyValue)
' Value becomes true after the first second.
booleanAnimation.KeyFrames.Add(New DiscreteBooleanKeyFrame(True, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1.0)))) ' KeyTime - Target value (KeyValue)
' Value becomes false after the 2nd second.
booleanAnimation.KeyFrames.Add(New DiscreteBooleanKeyFrame(False, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(2.0)))) ' KeyTime - Target value (KeyValue)
' Value becomes true after the third second.
booleanAnimation.KeyFrames.Add(New DiscreteBooleanKeyFrame(True, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(3.0)))) ' KeyTime - Target value (KeyValue)
' Value becomes false after 3 and half seconds.
booleanAnimation.KeyFrames.Add(New DiscreteBooleanKeyFrame(False, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(3.5)))) ' KeyTime - Target value (KeyValue)
' Value becomes true after the fourth second.
booleanAnimation.KeyFrames.Add(New DiscreteBooleanKeyFrame(True, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(4.0)))) ' KeyTime - Target value (KeyValue)
' Set the animation to target the IsEnabled property
' of the object named "AnimatedButton".
Storyboard.SetTargetName(booleanAnimation, "AnimatedButton")
Storyboard.SetTargetProperty(booleanAnimation, New PropertyPath(Button.IsEnabledProperty))
' Create a storyboard to apply the animation.
Dim myStoryboard As New Storyboard()
myStoryboard.Children.Add(booleanAnimation)
' Start the storyboard when the button is clicked.
AddHandler myButton.Click, Sub(sender As Object, e As RoutedEventArgs) myStoryboard.Begin(Me)
Content = myStackPanel
End Sub
End Class
End Namespace
// Demonstrates a BooleanAnimationUsingKeyFrames. The animation is used to
// animate the IsEnabled property of a button.
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
{
public class BooleanAnimationUsingKeyFramesExample : Page
{
public BooleanAnimationUsingKeyFramesExample()
{
Title = "BooleanAnimationUsingKeyFrames 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());
StackPanel myStackPanel = new StackPanel();
myStackPanel.Orientation = Orientation.Vertical;
myStackPanel.Margin = new Thickness(20);
// Create a TextBlock to introduce the example.
TextBlock myTextBlock = new TextBlock();
myTextBlock.Text = "Click the button to animate its IsEnabled property"
+ " with aBooleanAnimationUsingKeyFrames animation.";
myStackPanel.Children.Add(myTextBlock);
// Create the Button that is the target of the animation.
Button myButton = new Button();
myButton.Margin = new Thickness(200);
myButton.Content = "Click Me";
myStackPanel.Children.Add(myButton);
// Assign the Button a name so that
// it can be targeted by a Storyboard.
this.RegisterName(
"AnimatedButton", myButton);
// Create a BooleanAnimationUsingKeyFrames to
// animate the IsEnabled property of the Button.
BooleanAnimationUsingKeyFrames booleanAnimation
= new BooleanAnimationUsingKeyFrames();
booleanAnimation.Duration = TimeSpan.FromSeconds(4);
// All the key frames defined below are DiscreteBooleanKeyFrames.
// Discrete key frames create sudden "jumps" between values
// (no interpolation). Only discrete key frames can be used
// for Boolean key frame animations.
// Value at the beginning is false
booleanAnimation.KeyFrames.Add(
new DiscreteBooleanKeyFrame(
false, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(0.0))) // KeyTime
);
// Value becomes true after the first second.
booleanAnimation.KeyFrames.Add(
new DiscreteBooleanKeyFrame(
true, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1.0))) // KeyTime
);
// Value becomes false after the 2nd second.
booleanAnimation.KeyFrames.Add(
new DiscreteBooleanKeyFrame(
false, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(2.0))) // KeyTime
);
// Value becomes true after the third second.
booleanAnimation.KeyFrames.Add(
new DiscreteBooleanKeyFrame(
true, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(3.0))) // KeyTime
);
// Value becomes false after 3 and half seconds.
booleanAnimation.KeyFrames.Add(
new DiscreteBooleanKeyFrame(
false, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(3.5))) // KeyTime
);
// Value becomes true after the fourth second.
booleanAnimation.KeyFrames.Add(
new DiscreteBooleanKeyFrame(
true, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(4.0))) // KeyTime
);
// Set the animation to target the IsEnabled property
// of the object named "AnimatedButton".
Storyboard.SetTargetName(booleanAnimation, "AnimatedButton");
Storyboard.SetTargetProperty(
booleanAnimation, new PropertyPath(Button.IsEnabledProperty));
// Create a storyboard to apply the animation.
Storyboard myStoryboard = new Storyboard();
myStoryboard.Children.Add(booleanAnimation);
// Start the storyboard when the button is clicked.
myButton.Click += delegate(object sender, RoutedEventArgs e)
{
myStoryboard.Begin(this);
};
Content = myStackPanel;
}
}
}
<!-- Demonstrates a BooleanAnimationUsingKeyFrames. The animation is used to
animate the IsEnabled property of a button. -->
<Page
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
WindowTitle="KeyFrameBoolean Animation Example">
<StackPanel Orientation="Vertical" Margin="20">
<TextBlock>
Click the button to animate its IsEnabled property with a
BooleanAnimationUsingKeyFrames animation.
</TextBlock>
<Button Name="myAnimatedButton" Margin="200">Click Me
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<BooleanAnimationUsingKeyFrames
Storyboard.TargetName="myAnimatedButton"
Storyboard.TargetProperty="IsEnabled"
Duration="0:0:4" FillBehavior="HoldEnd">
<!-- All the key frames below are DiscreteBooleanKeyFrames. Discrete key frames create
sudden "jumps" between values (no interpolation). Only discrete key frames can be used
for Boolean key frame animations. -->
<DiscreteBooleanKeyFrame Value="False" KeyTime="0:0:0" />
<DiscreteBooleanKeyFrame Value="True" KeyTime="0:0:1" />
<DiscreteBooleanKeyFrame Value="False" KeyTime="0:0:2" />
<DiscreteBooleanKeyFrame Value="True" KeyTime="0:0:3" />
<DiscreteBooleanKeyFrame Value="False" KeyTime="0:0:3.5" />
<DiscreteBooleanKeyFrame Value="True" KeyTime="0:0:4" />
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
</StackPanel>
</Page>
For the complete sample, see KeyFrame Animation Sample.
See Also
Reference
BooleanAnimationUsingKeyFrames