Cómo: Cambiar la velocidad de un reloj sin cambiar la velocidad de su escala de tiempo

La propiedad SpeedRatio de un objeto ClockController permite cambiar la velocidad de un objeto Clock sin modificar la propiedad SpeedRatio de la escala de tiempo (Timeline) del reloj. En el ejemplo siguiente, se utiliza un controlador ClockController para modificar interactivamente la propiedad SpeedRatio de un reloj. El evento CurrentGlobalSpeedInvalidated y la propiedad CurrentGlobalSpeed del reloj se utilizan para mostrar la velocidad global actual del reloj cada vez que se cambia su SpeedRatio interactiva.

Ejemplo

'
'  This example shows how to interactively control 
'  the speed of a clock
'

Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Shapes
Imports System.Windows.Media.Animation

Namespace Microsoft.Samples.Animation.TimingBehaviors
    Public Class ClockControllerSpeedRatioExample
        Inherits Page

        Private myControllableClock As AnimationClock
        Private speedRatioButton As Button
        Private speedRatioSettingTextBox As TextBox
        Private doubleParseResult As Double = 1
        Private currentGlobalSpeedTextBlock As TextBlock

        Public Sub New()
            Dim mainPanel As New StackPanel()

            ' Create a rectangle to animate.
            Dim animatedRectangle As New Rectangle()
            animatedRectangle.Width = 100
            animatedRectangle.Height = 100
            animatedRectangle.Fill = Brushes.Orange
            mainPanel.Children.Add(animatedRectangle)
            ' Create a DoubleAnimation to
            ' animate its width.
            Dim widthAnimation As New DoubleAnimation(100, 500, New Duration(TimeSpan.FromSeconds(5)))
            'widthAnimation.RepeatBehavior = RepeatBehavior.Forever
            widthAnimation.AutoReverse = True
            widthAnimation.SpeedRatio = 0.5

            ' Create a clock from the animation.
            myControllableClock = widthAnimation.CreateClock()

            ' Apply the clock to the rectangle's Width property.
            animatedRectangle.ApplyAnimationClock(Rectangle.WidthProperty, myControllableClock)

            '
            ' Create some controls the enable the user to
            ' interactively control the SpeedRatio of the clock. 
            '            
            Dim speedRatioDetailsPanel As New StackPanel()
            speedRatioDetailsPanel.Margin = New Thickness(0,20,0,20)
            speedRatioDetailsPanel.Orientation = Orientation.Horizontal
            Dim speedRatioLabel As New Label()
            speedRatioLabel.Content = "Speed Ratio:"
            speedRatioDetailsPanel.Children.Add(speedRatioLabel)

            ' Create a text box so that the user can
            ' specify the amount by which to seek.
            speedRatioSettingTextBox = New TextBox()
            speedRatioSettingTextBox.Text = myControllableClock.Controller.SpeedRatio.ToString()
            speedRatioSettingTextBox.VerticalAlignment = VerticalAlignment.Top
            AddHandler speedRatioSettingTextBox.TextChanged, AddressOf seekAmountTextBox_TextChanged
            speedRatioDetailsPanel.Children.Add(speedRatioSettingTextBox)

            ' Create a button to apply SpeedRatio changes.
            speedRatioButton = New Button()
            speedRatioButton.Content = "Apply Speed Ratio"
            AddHandler speedRatioButton.Click, AddressOf speedRatioButton_Clicked
            speedRatioDetailsPanel.Children.Add(speedRatioButton)

            mainPanel.Children.Add(speedRatioDetailsPanel)

            ' Display the clock's global speed information.
            Dim myLabel As New Label()
            myLabel.Content = "CurrentGlobalSpeed "
            mainPanel.Children.Add(myLabel)
            currentGlobalSpeedTextBlock = New TextBlock()
            currentGlobalSpeedTextBlock.Text = myControllableClock.CurrentGlobalSpeed.ToString()
            mainPanel.Children.Add(currentGlobalSpeedTextBlock)

            ' List for speed changes.
            AddHandler myControllableClock.CurrentGlobalSpeedInvalidated, AddressOf myControllableClock_currentGlobalSpeedInvalidated

            Me.Content = mainPanel
        End Sub


        ' Updates the clock's SpeedRatio.
        Private Sub speedRatioButton_Clicked(ByVal sender As Object, ByVal e As RoutedEventArgs)

            ' This statement triggers a CurrentGlobalSpeedInvalidated
            ' event.
            myControllableClock.Controller.SpeedRatio = doubleParseResult

        End Sub

        ' Displays the current global speed.
        Private Sub myControllableClock_currentGlobalSpeedInvalidated(ByVal sender As Object, ByVal e As EventArgs)

            currentGlobalSpeedTextBlock.Text = myControllableClock.CurrentGlobalSpeed.ToString() & " Event triggered at: " & Date.Now.ToString()

        End Sub

        ' Verifies that speedRatioSettingTextBox has valid text content.
        ' If it doesn't, the speedRatioButton is disabled.
        Private Sub seekAmountTextBox_TextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)

            Dim theTextBox As TextBox = CType(e.Source, TextBox)
            If theTextBox.Text Is Nothing OrElse theTextBox.Text.Length < 1 OrElse Double.TryParse(theTextBox.Text, System.Globalization.NumberStyles.Any, Nothing, doubleParseResult) = False Then
                speedRatioButton.IsEnabled = False
            Else
                speedRatioButton.IsEnabled = True
            End If

        End Sub

    End Class
End Namespace

/*
  This example shows how to interactively control 
  the speed of a clock
*/
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Media.Animation;

namespace Microsoft.Samples.Animation.TimingBehaviors
{
    public class ClockControllerSpeedRatioExample : Page
    {

        private AnimationClock myControllableClock;
        private Button speedRatioButton;
        private TextBox speedRatioSettingTextBox;
        private double doubleParseResult = 1;
        private TextBlock currentGlobalSpeedTextBlock;

        public ClockControllerSpeedRatioExample()
        {
            StackPanel mainPanel = new StackPanel();

            // Create a rectangle to animate.
            Rectangle animatedRectangle = new Rectangle();
            animatedRectangle.Width = 100;
            animatedRectangle.Height = 100;
            animatedRectangle.Fill = Brushes.Orange;
            mainPanel.Children.Add(animatedRectangle);
            // Create a DoubleAnimation to
            // animate its width.
            DoubleAnimation widthAnimation = 
                new DoubleAnimation(
                    100,
                    500, 
                    new Duration(TimeSpan.FromSeconds(5)));
            //widthAnimation.RepeatBehavior = RepeatBehavior.Forever;
            widthAnimation.AutoReverse = true;
            widthAnimation.SpeedRatio = 0.5;

            // Create a clock from the animation.
            myControllableClock = widthAnimation.CreateClock();

            // Apply the clock to the rectangle's Width property.
            animatedRectangle.ApplyAnimationClock(
                Rectangle.WidthProperty, myControllableClock);    

            //
            // Create some controls the enable the user to
            // interactively control the SpeedRatio of the clock. 
            //            
            StackPanel speedRatioDetailsPanel = new StackPanel();
            speedRatioDetailsPanel.Margin = new Thickness(0,20,0,20);
            speedRatioDetailsPanel.Orientation = Orientation.Horizontal;
            Label speedRatioLabel = new Label();
            speedRatioLabel.Content = "Speed Ratio:";
            speedRatioDetailsPanel.Children.Add(speedRatioLabel);

            // Create a text box so that the user can
            // specify the amount by which to seek.
            speedRatioSettingTextBox = new TextBox();
            speedRatioSettingTextBox.Text = 
                myControllableClock.Controller.SpeedRatio.ToString();
            speedRatioSettingTextBox.VerticalAlignment = VerticalAlignment.Top;
            speedRatioSettingTextBox.TextChanged += 
                new TextChangedEventHandler(seekAmountTextBox_TextChanged);
            speedRatioDetailsPanel.Children.Add(speedRatioSettingTextBox);          

            // Create a button to apply SpeedRatio changes.
            speedRatioButton = new Button();
            speedRatioButton.Content = "Apply Speed Ratio";
            speedRatioButton.Click += new RoutedEventHandler(speedRatioButton_Clicked);  
            speedRatioDetailsPanel.Children.Add(speedRatioButton);

            mainPanel.Children.Add(speedRatioDetailsPanel);

            // Display the clock's global speed information.
            Label myLabel = new Label();
            myLabel.Content = "CurrentGlobalSpeed ";
            mainPanel.Children.Add(myLabel);
            currentGlobalSpeedTextBlock = new TextBlock();
            currentGlobalSpeedTextBlock.Text = 
                myControllableClock.CurrentGlobalSpeed.ToString();
            mainPanel.Children.Add(currentGlobalSpeedTextBlock);

            // List for speed changes.
            myControllableClock.CurrentGlobalSpeedInvalidated += 
                new EventHandler(myControllableClock_currentGlobalSpeedInvalidated);

            this.Content = mainPanel;
        }


        // Updates the clock's SpeedRatio.
        private void speedRatioButton_Clicked(object sender, RoutedEventArgs e)
        {

            // This statement triggers a CurrentGlobalSpeedInvalidated
            // event.
            myControllableClock.Controller.SpeedRatio = doubleParseResult; 

        }

        // Displays the current global speed.
        private void myControllableClock_currentGlobalSpeedInvalidated(object sender, EventArgs e)
        {

            currentGlobalSpeedTextBlock.Text = 
                myControllableClock.CurrentGlobalSpeed.ToString()
                + " Event triggered at: " 
                + DateTime.Now.ToString();   

        }        

        // Verifies that speedRatioSettingTextBox has valid text content.
        // If it doesn't, the speedRatioButton is disabled.
        private void seekAmountTextBox_TextChanged(object sender, TextChangedEventArgs e)
        {

            TextBox theTextBox = (TextBox)e.Source;
            if (theTextBox.Text == null || theTextBox.Text.Length < 1
                || Double.TryParse(theTextBox.Text, 
                    System.Globalization.NumberStyles.Any, 
                    null, out doubleParseResult) == false)
                speedRatioButton.IsEnabled = false;
            else 
                speedRatioButton.IsEnabled = true;

        }

    }
}