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Cómo: Animar un objeto Boolean mediante fotogramas clave

  • Artículo

En este ejemplo se muestra cómo animar el valor de propiedad booleano de un control Button mediante fotogramas clave.

Ejemplo

En el ejemplo siguiente se usa la clase BooleanAnimationUsingKeyFrames para animar la propiedad IsEnabled de un control Button. Todos los fotogramas clave de este ejemplo usan una instancia de clase DiscreteBooleanKeyFrame. Los fotogramas clave discretos como DiscreteBooleanKeyFrame crean saltos repentinos entre valores, es decir, el movimiento de la animación se entrecorta.

// 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.

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. -->
<Page 
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://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>

Para consultar el ejemplo completo, vea Ejemplo de animación mediante fotogramas clave.

Vea también