MSDN Documentation

Advanced Animations in WinUI

This tutorial explores advanced animation techniques available in Windows UI (WinUI) to create dynamic and engaging user experiences. We'll cover concepts like keyframe animations, chained animations, and leveraging the built-in animation system for sophisticated visual effects.

Understanding WinUI Animation Basics

WinUI provides a robust animation framework that allows you to animate properties of UI elements over time. The core idea is to define a starting value, an ending value, and a duration, and let the system handle the interpolation.

Keyframe Animations

Keyframe animations offer finer control by allowing you to define multiple intermediate states (keyframes) along the animation timeline. This is useful for creating complex motion paths or staged effects.

The primary API for keyframe animations is related to composition target updates and storyboard manipulation.

Example: Scale and Fade Animation

Let's create a simple animation that scales up an element while fading it in.

You can achieve this using C# and XAML. For instance, you might define a Storyboard in XAML:

<!-- In your XAML resource dictionary or control template -->
<Storyboard x:Key="ScaleFadeAnimation">
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" BeginTime="0:0:0.5">
        <LinearDoubleKeyFrame Value="1.0" KeyTime="0:0:1.0"/>
    </DoubleAnimationUsingKeyFrames>
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleX)" BeginTime="0:0:0.5">
        <LinearDoubleKeyFrame Value="1.2" KeyTime="0:0:1.0"/>
    </DoubleAnimationUsingKeyFrames>
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" BeginTime="0:0:0.5">
        <LinearDoubleKeyFrame Value="1.2" KeyTime="0:0:1.0"/>
    </DoubleAnimationUsingKeyFrames>
</Storyboard>

And trigger it from code-behind:

// Assuming 'myElement' is the element you want to animate
var storyboard = (Storyboard)this.Resources["ScaleFadeAnimation"];
if (storyboard != null)
{
    Storyboard.SetTarget(storyboard, myElement);
    storyboard.Begin();
}

Chained Animations

Chaining animations involves sequencing multiple animations so that one starts after another finishes. This creates a flowing sequence of visual events.

Example: Slide-in and Rotate Animation

This example shows an element sliding in from the left and then starting to rotate.

In C#, you can chain animations by controlling their BeginTime or by using event handlers like Completed to start the next animation.

// Example of chaining using BeginTime
var slideAnimation = new DoubleAnimation
{
    From = -100,
    To = 0,
    Duration = TimeSpan.FromSeconds(0.8),
    EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }
};
slideAnimation.BeginTime = TimeSpan.FromSeconds(0.5); // Stagger the start

var rotateAnimation = new DoubleAnimation
{
    From = 0,
    To = 360,
    Duration = TimeSpan.FromSeconds(2),
    RepeatBehavior = RepeatBehavior.Forever,
    EasingFunction = new LinearEase()
};
rotateAnimation.BeginTime = TimeSpan.FromSeconds(1.3); // Start after slide and a small delay

var transform = new CompositeTransform();
myElement.RenderTransform = transform;

// Apply animations to the transform properties
transform.BeginAnimation(CompositeTransform.TranslateXProperty, slideAnimation);
transform.BeginAnimation(CompositeTransform.RotationProperty, rotateAnimation);

Leveraging Built-in Animation System

WinUI offers a set of pre-defined animations and easing functions that can significantly enhance the feel of your UI. Experiment with different EasingFunction types (e.g., BounceEase, ElasticEase) to achieve various subtle and pronounced effects.

Custom Animation Scenarios

For highly custom animations, you can utilize the Composition API directly. This provides low-level access to the rendering pipeline, enabling powerful visual effects like parallax scrolling, physics-based motion, and more.