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En este ejemplo se muestra cómo animar las propiedades Color y Offset de los objetos GradientStop.
Ejemplo
En el ejemplo siguiente se animan tres puntos de degradado dentro de LinearGradientBrush. En el ejemplo se utilizan tres animaciones, cada una de las cuales anima un punto de degradado diferente:
La primera animación, un objeto DoubleAnimation, anima la propiedad Offset del primer punto de degradado desde 0.0 hasta 1.0 y de nuevo hasta 0.0. Como resultado, el primer color del degradado cambia del lado izquierdo al derecho del rectángulo y vuelve al izquierdo.
La segunda animación, ColorAnimation, anima la propiedad Color del segundo punto de degradado desde Purple hasta Yellow y de nuevo hasta Purple. Como resultado, el color central del degradado cambia del púrpura al amarillo y vuelve al púrpura.
La tercera animación, ColorAnimation, anima la opacidad de la propiedad Color del tercer punto de degradado en -1 y vuelve al punto inicial. Como resultado, el tercer color del degradado se desvanece y, a continuación, se vuelve de nuevo opaco.
Imports Microsoft.VisualBasic
Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Animation
Imports System.Windows.Shapes
Namespace BrushesIntroduction
Public Class GradientStopAnimationExample
Inherits Page
Public Sub New()
Title = "GradientStop Animation Example"
Background = Brushes.White
' Create a NameScope for the page so that
' Storyboards can be used.
NameScope.SetNameScope(Me, New NameScope())
' Create a rectangle. This rectangle will
' be painted with a gradient.
Dim aRectangle As New Rectangle()
aRectangle.Width = 200
aRectangle.Height = 100
aRectangle.Stroke = Brushes.Black
aRectangle.StrokeThickness = 1
' Create a LinearGradientBrush to paint
' the rectangle's fill.
Dim gradientBrush As New LinearGradientBrush()
' Create gradient stops for the brush.
Dim stop1 As New GradientStop(Colors.MediumBlue, 0.0)
Dim stop2 As New GradientStop(Colors.Purple, 0.5)
Dim stop3 As New GradientStop(Colors.Red, 1.0)
' Register a name for each gradient stop with the
' page so that they can be animated by a storyboard.
Me.RegisterName("GradientStop1", stop1)
Me.RegisterName("GradientStop2", stop2)
Me.RegisterName("GradientStop3", stop3)
' Add the stops to the brush.
gradientBrush.GradientStops.Add(stop1)
gradientBrush.GradientStops.Add(stop2)
gradientBrush.GradientStops.Add(stop3)
' Apply the brush to the rectangle.
aRectangle.Fill = gradientBrush
'
' Animate the first gradient stop's offset from
' 0.0 to 1.0 and then back to 0.0.
'
Dim offsetAnimation As New DoubleAnimation()
offsetAnimation.From = 0.0
offsetAnimation.To = 1.0
offsetAnimation.Duration = TimeSpan.FromSeconds(1.5)
offsetAnimation.AutoReverse = True
Storyboard.SetTargetName(offsetAnimation, "GradientStop1")
Storyboard.SetTargetProperty(offsetAnimation, New PropertyPath(GradientStop.OffsetProperty))
'
' Animate the second gradient stop's color from
' Purple to Yellow and then back to Purple.
'
Dim gradientStopColorAnimation As New ColorAnimation()
gradientStopColorAnimation.From = Colors.Purple
gradientStopColorAnimation.To = Colors.Yellow
gradientStopColorAnimation.Duration = TimeSpan.FromSeconds(1.5)
gradientStopColorAnimation.AutoReverse = True
Storyboard.SetTargetName(gradientStopColorAnimation, "GradientStop2")
Storyboard.SetTargetProperty(gradientStopColorAnimation, New PropertyPath(GradientStop.ColorProperty))
' Set the animation to begin after the first animation
' ends.
gradientStopColorAnimation.BeginTime = TimeSpan.FromSeconds(3)
'
' Animate the third gradient stop's color so
' that it becomes transparent.
'
Dim opacityAnimation As New ColorAnimation()
' Reduces the target color's alpha value by 1,
' making the color transparent.
opacityAnimation.By = Color.FromScRgb(-1.0F, 0F, 0F, 0F)
opacityAnimation.Duration = TimeSpan.FromSeconds(1.5)
opacityAnimation.AutoReverse = True
Storyboard.SetTargetName(opacityAnimation, "GradientStop3")
Storyboard.SetTargetProperty(opacityAnimation, New PropertyPath(GradientStop.ColorProperty))
' Set the animation to begin after the first two
' animations have ended.
opacityAnimation.BeginTime = TimeSpan.FromSeconds(6)
' Create a Storyboard to apply the animations.
Dim gradientStopAnimationStoryboard As New Storyboard()
gradientStopAnimationStoryboard.Children.Add(offsetAnimation)
gradientStopAnimationStoryboard.Children.Add(gradientStopColorAnimation)
gradientStopAnimationStoryboard.Children.Add(opacityAnimation)
' Begin the storyboard when the left mouse button is
' pressed over the rectangle.
AddHandler aRectangle.MouseLeftButtonDown, Sub(sender As Object, e As MouseButtonEventArgs) gradientStopAnimationStoryboard.Begin(Me)
Dim mainPanel As New StackPanel()
mainPanel.Margin = New Thickness(10)
mainPanel.Children.Add(aRectangle)
Content = mainPanel
End Sub
End Class
End Namespace
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
namespace BrushesIntroduction
{
public class GradientStopAnimationExample : Page
{
public GradientStopAnimationExample()
{
Title = "GradientStop Animation Example";
Background = Brushes.White;
// Create a NameScope for the page so that
// Storyboards can be used.
NameScope.SetNameScope(this, new NameScope());
// Create a rectangle. This rectangle will
// be painted with a gradient.
Rectangle aRectangle = new Rectangle();
aRectangle.Width = 200;
aRectangle.Height = 100;
aRectangle.Stroke = Brushes.Black;
aRectangle.StrokeThickness = 1;
// Create a LinearGradientBrush to paint
// the rectangle's fill.
LinearGradientBrush gradientBrush = new LinearGradientBrush();
// Create gradient stops for the brush.
GradientStop stop1 = new GradientStop(Colors.MediumBlue, 0.0);
GradientStop stop2 = new GradientStop(Colors.Purple, 0.5);
GradientStop stop3 = new GradientStop(Colors.Red, 1.0);
// Register a name for each gradient stop with the
// page so that they can be animated by a storyboard.
this.RegisterName("GradientStop1", stop1);
this.RegisterName("GradientStop2", stop2);
this.RegisterName("GradientStop3", stop3);
// Add the stops to the brush.
gradientBrush.GradientStops.Add(stop1);
gradientBrush.GradientStops.Add(stop2);
gradientBrush.GradientStops.Add(stop3);
// Apply the brush to the rectangle.
aRectangle.Fill = gradientBrush;
//
// Animate the first gradient stop's offset from
// 0.0 to 1.0 and then back to 0.0.
//
DoubleAnimation offsetAnimation = new DoubleAnimation();
offsetAnimation.From = 0.0;
offsetAnimation.To = 1.0;
offsetAnimation.Duration = TimeSpan.FromSeconds(1.5);
offsetAnimation.AutoReverse = true;
Storyboard.SetTargetName(offsetAnimation, "GradientStop1");
Storyboard.SetTargetProperty(offsetAnimation,
new PropertyPath(GradientStop.OffsetProperty));
//
// Animate the second gradient stop's color from
// Purple to Yellow and then back to Purple.
//
ColorAnimation gradientStopColorAnimation = new ColorAnimation();
gradientStopColorAnimation.From = Colors.Purple;
gradientStopColorAnimation.To = Colors.Yellow;
gradientStopColorAnimation.Duration = TimeSpan.FromSeconds(1.5);
gradientStopColorAnimation.AutoReverse = true;
Storyboard.SetTargetName(gradientStopColorAnimation, "GradientStop2");
Storyboard.SetTargetProperty(gradientStopColorAnimation,
new PropertyPath(GradientStop.ColorProperty));
// Set the animation to begin after the first animation
// ends.
gradientStopColorAnimation.BeginTime = TimeSpan.FromSeconds(3);
//
// Animate the third gradient stop's color so
// that it becomes transparent.
//
ColorAnimation opacityAnimation = new ColorAnimation();
// Reduces the target color's alpha value by 1,
// making the color transparent.
opacityAnimation.By = Color.FromScRgb(-1.0F, 0F, 0F, 0F);
opacityAnimation.Duration = TimeSpan.FromSeconds(1.5);
opacityAnimation.AutoReverse = true;
Storyboard.SetTargetName(opacityAnimation, "GradientStop3");
Storyboard.SetTargetProperty(opacityAnimation,
new PropertyPath(GradientStop.ColorProperty));
// Set the animation to begin after the first two
// animations have ended.
opacityAnimation.BeginTime = TimeSpan.FromSeconds(6);
// Create a Storyboard to apply the animations.
Storyboard gradientStopAnimationStoryboard = new Storyboard();
gradientStopAnimationStoryboard.Children.Add(offsetAnimation);
gradientStopAnimationStoryboard.Children.Add(gradientStopColorAnimation);
gradientStopAnimationStoryboard.Children.Add(opacityAnimation);
// Begin the storyboard when the left mouse button is
// pressed over the rectangle.
aRectangle.MouseLeftButtonDown += delegate(object sender, MouseButtonEventArgs e)
{
gradientStopAnimationStoryboard.Begin(this);
};
StackPanel mainPanel = new StackPanel();
mainPanel.Margin = new Thickness(10);
mainPanel.Children.Add(aRectangle);
Content = mainPanel;
}
}
}
<Page
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
Title="GradientStop Animation Example"
Background="White">
<StackPanel Margin="10">
<Rectangle
Width="200"
Height="100"
Stroke="Black" StrokeThickness="1">
<Rectangle.Fill>
<LinearGradientBrush>
<GradientStop x:Name="GradientStop1" Color="MediumBlue" Offset="0.0" />
<GradientStop x:Name="GradientStop2" Color="Purple" Offset="0.5" />
<GradientStop x:Name="GradientStop3" Color="Red" Offset="1.0" />
</LinearGradientBrush>
</Rectangle.Fill>
<Rectangle.Triggers>
<EventTrigger RoutedEvent="Rectangle.MouseLeftButtonDown">
<BeginStoryboard>
<Storyboard>
<DoubleAnimation
Storyboard.TargetName="GradientStop1"
Storyboard.TargetProperty="Offset"
From="0.0" To="1.0" Duration="0:0:1.5"
AutoReverse="True" />
<ColorAnimation
Storyboard.TargetName="GradientStop2"
Storyboard.TargetProperty="Color"
From="Purple" To="Yellow"
Duration="0:0:1.5"
AutoReverse="True"
BeginTime="0:0:3" />
<ColorAnimation
Storyboard.TargetName="GradientStop3"
Storyboard.TargetProperty="Color"
Duration="0:0:1.5"
AutoReverse="True"
BeginTime="0:0:6">
<ColorAnimation.By>
<Color ScA="-1" ScR="0" ScB="0" ScG="0" />
</ColorAnimation.By>
</ColorAnimation>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Rectangle.Triggers>
</Rectangle>
</StackPanel>
</Page>
Aunque en este ejemplo se utiliza un objeto LinearGradientBrush, el proceso es el mismo para animar objetos GradientStop dentro de RadialGradientBrush.
Para obtener más ejemplos, vea Brushes Sample.