Imported from David-Li0406/meta-skill-evloving (skill-flow/data/skills-refined-skillclaw-36k/skillsmp/creating-wpf-animations/SKILL.md). Install upstream with npx skills add David-Li0406/meta-skill-evloving --skill creating-wpf-animations. Copyright stays with the author.

WPF Animation Patterns

WPF animations create visual effects by changing property values over time.

1. Animation Components

Storyboard (container)
├── Timeline (time control)
│   ├── Animation (value change)
│   │   ├── DoubleAnimation
│   │   ├── ColorAnimation
│   │   └── ...
│   └── AnimationUsingKeyFrames (keyframes)
│       ├── DoubleAnimationUsingKeyFrames
│       └── ...
└── EasingFunction (acceleration/deceleration)

2. Basic Animation (XAML)

2.1 DoubleAnimation

<Button Content="Hover Me" Width="100">
    <Button.Style>
        <Style TargetType="Button">
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Trigger.EnterActions>
                        <BeginStoryboard>
                            <Storyboard>
                                <!-- Width animation -->
                                <DoubleAnimation
                                    Storyboard.TargetProperty="Width"
                                    To="150"
                                    Duration="0:0:0.3"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </Trigger.EnterActions>
                    <Trigger.ExitActions>
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation
                                    Storyboard.TargetProperty="Width"
                                    To="100"
                                    Duration="0:0:0.3"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </Trigger.ExitActions>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Button.Style>
</Button>

2.2 ColorAnimation

<Border x:Name="AnimatedBorder" Background="Blue" Width="100" Height="100">
    <Border.Triggers>
        <EventTrigger RoutedEvent="MouseEnter">
            <BeginStoryboard>
                <Storyboard>
                    <!-- Background color animation -->
                    <ColorAnimation
                        Storyboard.TargetProperty="(Border.Background).(SolidColorBrush.Color)"
                        To="Red"
                        Duration="0:0:0.5"/>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
        <EventTrigger RoutedEvent="MouseLeave">
            <BeginStoryboard>
                <Storyboard>
                    <ColorAnimation
                        Storyboard.TargetProperty="(Border.Background).(SolidColorBrush.Color)"
                        To="Blue"
                        Duration="0:0:0.5"/>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Border.Triggers>
</Border>

2.3 ThicknessAnimation (Margin, Padding)

<Border x:Name="SlidingBorder" Margin="0,0,0,0">
    <Border.Triggers>
        <EventTrigger RoutedEvent="Loaded">
            <BeginStoryboard>
                <Storyboard>
                    <!-- Slide-in effect -->
                    <ThicknessAnimation
                        Storyboard.TargetProperty="Margin"
                        From="-100,0,0,0"
                        To="0,0,0,0"
                        Duration="0:0:0.5"/>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Border.Triggers>
</Border>

3. EasingFunction

3.1 Main Easing Types

<Storyboard>
    <DoubleAnimation Storyboard.TargetProperty="Width" To="200" Duration="0:0:0.5">
        <DoubleAnimation.EasingFunction>
            <!-- Various easing functions -->

            <!-- Smooth deceleration -->
            <QuadraticEase EasingMode="EaseOut"/>

            <!-- Elastic effect -->
            <!--<ElasticEase Oscillations="3" Springiness="5"/>-->

            <!-- Bounce effect -->
            <!--<BounceEase Bounces="3" Bounciness="2"/>-->

            <!-- Back effect (overshoot) -->
            <!--<BackEase Amplitude="0.3"/>-->

            <!-- Circular easing -->
            <!--<CircleEase EasingMode="EaseInOut"/>-->
        </DoubleAnimation.EasingFunction>
    </DoubleAnimation>
</Storyboard>

3.2 EasingMode

4. KeyFrame Animation

4.1 DoubleAnimationUsingKeyFrames

<Storyboard>
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity">
        <!-- Sequential keyframes -->
        <LinearDoubleKeyFrame Value="0.3" KeyTime="0:0:0.2"/>
        <LinearDoubleKeyFrame Value="1.0" KeyTime="0:0:0.4"/>
        <SplineDoubleKeyFrame Value="0.5" KeyTime="0:0:0.8">
            <SplineDoubleKeyFrame.KeySpline>
                <KeySpline ControlPoint1="0.5,0" ControlPoint2="0.5,1"/>
            </SplineDoubleKeyFrame.KeySpline>
        </SplineDoubleKeyFrame>
        <EasingDoubleKeyFrame Value="1.0" KeyTime="0:0:1">
            <EasingDoubleKeyFrame.EasingFunction>
                <BounceEase/>
            </EasingDoubleKeyFrame.EasingFunction>
        </EasingDoubleKeyFrame>
    </DoubleAnimationUsingKeyFrames>
</Storyboard>

4.2 ObjectAnimationUsingKeyFrames (Discrete Values)

<Storyboard>
    <!-- Visibility toggle (non-continuous values) -->
    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
        <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}"/>
        <DiscreteObjectKeyFrame KeyTime="0:0:1" Value="{x:Static Visibility.Hidden}"/>
        <DiscreteObjectKeyFrame KeyTime="0:0:2" Value="{x:Static Visibility.Visible}"/>
    </ObjectAnimationUsingKeyFrames>
</Storyboard>

5. Transform Animation

5.1 RenderTransform Animation

<Button Content="Rotate" RenderTransformOrigin="0.5,0.5">
    <Button.RenderTransform>
        <RotateTransform x:Name="RotateTransform" Angle="0"/>
    </Button.RenderTransform>
    <Button.Triggers>
        <EventTrigger RoutedEvent="Click">
            <BeginStoryboard>
                <Storyboard>
                    <!-- Rotation animation -->
                    <DoubleAnimation
                        Storyboard.TargetName="RotateTransform"
                        Storyboard.TargetProperty="Angle"
                        By="360"
                        Duration="0:0:0.5"/>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Button.Triggers>
</Button>

5.2 Composite Transform Animation

<Border Width="100" Height="100" Background="Blue" RenderTransformOrigin="0.5,0.5">
    <Border.RenderTransform>
        <TransformGroup>
            <ScaleTransform x:Name="Scale" ScaleX="1" ScaleY="1"/>
            <RotateTransform x:Name="Rotate" Angle="0"/>
            <TranslateTransform x:Name="Translate" X="0" Y="0"/>
        </TransformGroup>
    </Border.RenderTransform>
    <Border.Triggers>
        <EventTrigger RoutedEvent="MouseEnter">
            <BeginStoryboard>
                <Storyboard>
                    <!-- Simultaneous animations -->
                    <DoubleAnimation Storyboard.TargetName="Scale"
                                     Storyboard.TargetProperty="ScaleX"
                                     To="1.2" Duration="0:0:0.2"/>
                    <DoubleAnimation Storyboard.TargetName="Scale"
                                     Storyboard.TargetProperty="ScaleY"
                                     To="1.2" Duration="0:0:0.2"/>
                    <DoubleAnimation Storyboard.TargetName="Rotate"
                                     Storyboard.TargetProperty="Angle"
                                     To="10" Duration="0:0:0.2"/>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Border.Triggers>
</Border>

6. Animation in Code

6.1 Basic Animation

namespace MyApp.Animations;

using System;
using System.Windows;
using System.Windows.Media.Animation;

public static class AnimationHelper
{
    /// <summary>
    /// Opacity fade animation
    /// </summary>
    public static void FadeIn(UIElement element, double durationSeconds = 0.3)
    {
        var animation = new DoubleAnimation
        {
            From = 0,
            To = 1,
            Duration = TimeSpan.FromSeconds(durationSeconds),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseOut }
        };

        element.BeginAnimation(UIElement.OpacityProperty, animation);
    }

    public static void FadeOut(UIElement element, double durationSeconds = 0.3, Action? onCompleted = null)
    {
        var animation = new DoubleAnimation
        {
            From = 1,
            To = 0,
            Duration = TimeSpan.FromSeconds(durationSeconds),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseIn }
        };

        if (onCompleted is not null)
        {
            animation.Completed += (s, e) => onCompleted();
        }

        element.BeginAnimation(UIElement.OpacityProperty, animation);
    }
}

6.2 Composite Animation with Storyboard

namespace MyApp.Animations;

using System;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Animation;

public static class StoryboardHelper
{
    /// <summary>
    /// Scale up + fade in animation
    /// </summary>
    public static void ScaleFadeIn(FrameworkElement element, double durationSeconds = 0.3)
    {
        // Setup transform
        var scaleTransform = new ScaleTransform(0.8, 0.8);
        element.RenderTransform = scaleTransform;
        element.RenderTransformOrigin = new Point(0.5, 0.5);
        element.Opacity = 0;

        var storyboard = new Storyboard();

        // Opacity animation
        var opacityAnimation = new DoubleAnimation
        {
            To = 1,
            Duration = TimeSpan.FromSeconds(durationSeconds),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseOut }
        };
        Storyboard.SetTarget(opacityAnimation, element);
        Storyboard.SetTargetProperty(opacityAnimation, new PropertyPath(UIElement.OpacityProperty));
        storyboard.Children.Add(opacityAnimation);

        // ScaleX animation
        var scaleXAnimation = new DoubleAnimation
        {
            To = 1,
            Duration = TimeSpan.FromSeconds(durationSeconds),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseOut }
        };
        Storyboard.SetTarget(scaleXAnimation, element);
        Storyboard.SetTargetProperty(scaleXAnimation,
            new PropertyPath("RenderTransform.ScaleX"));
        storyboard.Children.Add(scaleXAnimation);

        // ScaleY animation
        var scaleYAnimation = new DoubleAnimation
        {
            To = 1,
            Duration = TimeSpan.FromSeconds(durationSeconds),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseOut }
        };
        Storyboard.SetTarget(scaleYAnimation, element);
        Storyboard.SetTargetProperty(scaleYAnimation,
            new PropertyPath("RenderTransform.ScaleY"));
        storyboard.Children.Add(scaleYAnimation);

        storyboard.Begin();
    }
}

6.3 Stop/Resume Animation

namespace MyApp.Animations;

using System.Windows;
using System.Windows.Media.Animation;

public sealed class AnimationController
{
    private readonly Storyboard _storyboard;
    private readonly FrameworkElement _target;

    public AnimationController(Storyboard storyboard, FrameworkElement target)
    {
        _storyboard = storyboard;
        _target = target;
    }

    public void Start()
    {
        _storyboard.Begin(_target, isControllable: true);
    }

    public void Pause()
    {
        _storyboard.Pause(_target);
    }

    public void Resume()
    {
        _storyboard.Resume(_target);
    }

    public void Stop()
    {
        _storyboard.Stop(_target);
    }

    public void Seek(TimeSpan offset)
    {
        _storyboard.Seek(_target, offset, TimeSeekOrigin.BeginTime);
    }
}

7. VisualStateManager Integration

7.1 State-Based Animation

<Style TargetType="{x:Type Button}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Button}">
                <Border x:Name="Border" Background="{TemplateBinding Background}">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal">
                                <Storyboard>
                                    <ColorAnimation
                                        Storyboard.TargetName="Border"
                                        Storyboard.TargetProperty="(Border.Background).(SolidColorBrush.Color)"
                                        To="#2196F3" Duration="0:0:0.2"/>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="MouseOver">
                                <Storyboard>
                                    <ColorAnimation
                                        Storyboard.TargetName="Border"
                                        Storyboard.TargetProperty="(Border.Background).(SolidColorBrush.Color)"
                                        To="#1976D2" Duration="0:0:0.2"/>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Pressed">
                                <Storyboard>
                                    <ColorAnimation
                                        Storyboard.TargetName="Border"
                                        Storyboard.TargetProperty="(Border.Background).(SolidColorBrush.Color)"
                                        To="#0D47A1" Duration="0:0:0.1"/>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <ContentPresenter/>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

8. Performance Considerations

// Performance optimization hints
RenderOptions.SetBitmapScalingMode(element, BitmapScalingMode.LowQuality);
Timeline.SetDesiredFrameRate(storyboard, 30); // Default 60fps → 30fps

9. References

• Animation Overview - Microsoft Docs
• Storyboards Overview - Microsoft Docs