Animations play a crucial role in modern mobile applications. They make the user interface more engaging, provide visual feedback, and guide users through the application workflow. Flutter, as a powerful UI toolkit, offers two types of animations: implicit and explicit. While implicit animations are easy to use and require minimal code, explicit animations provide developers with full control over the animation process.

Explicit animations in Flutter are those animations where developers manually control the animation lifecycle, including its duration, curve, repetition, and callbacks. By using objects like AnimationController, Tween, and Animation, developers can create sophisticated, responsive, and interactive animations that respond dynamically to user input or application state changes.

Introduction to Explicit Animations

In Flutter, an explicit animation requires developers to take charge of the animation process. Unlike implicit animations, where you simply change a property of a widget and Flutter handles the animation automatically, explicit animations give you precise control over every frame of the animation.

Explicit animations are ideal when:

Animations need to run in sequences or with delays.
The animation must respond to user interactions, such as gestures or scroll events.
Complex animations involve multiple properties changing simultaneously.
Fine-grained control over curves, repetitions, or durations is required.

Understanding explicit animations is essential for building advanced, polished, and interactive user experiences in Flutter applications.

Core Components of Explicit Animations

Explicit animations in Flutter are built using a few core components: AnimationController, Animation, and Tween. Each of these plays a unique role in the animation lifecycle.

AnimationController

The AnimationController is the backbone of any explicit animation. It manages the animation’s state, duration, and progress. The controller emits values between 0.0 and 1.0 over a specified duration.

Key properties and methods of AnimationController include:

duration: Defines how long the animation should run.
forward(): Starts the animation from the beginning.
reverse(): Plays the animation backward.
repeat(): Repeats the animation indefinitely or for a set number of cycles.
value: Current value of the animation, ranging from 0.0 to 1.0.

The AnimationController must be disposed of properly to avoid memory leaks, usually in the dispose() method of a StatefulWidget.

Tween

A Tween (short for “in-between”) defines the range of values an animation can take. For example, if you want to animate a widget’s opacity from 0 to 1, you would define a Tween as Tween<double>(begin: 0.0, end: 1.0).

Tweens are responsible for mapping the controller’s 0.0 to 1.0 value to a more meaningful range, such as positions, sizes, colors, or rotations.

Animation

The Animation object connects the AnimationController and the Tween. It produces the interpolated value at every frame, which can then be applied to widgets. Animations can also be chained, combined, and transformed using various built-in methods.

Creating a Basic Explicit Animation

To illustrate how explicit animations work, let us create a simple example: animating a container’s width from 100 to 200 pixels.

import 'package:flutter/material.dart';

class ExplicitAnimationExample extends StatefulWidget {
  @override
  _ExplicitAnimationExampleState createState() => _ExplicitAnimationExampleState();
}

class _ExplicitAnimationExampleState extends State<ExplicitAnimationExample> with SingleTickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<double> _widthAnimation;

  @override
  void initState() {
super.initState();
_controller = AnimationController(
  vsync: this,
  duration: Duration(seconds: 2),
);
_widthAnimation = Tween&lt;double&gt;(begin: 100.0, end: 200.0).animate(_controller)
  ..addListener(() {
    setState(() {});
  });
_controller.forward();  }

  @override
  void dispose() {
_controller.dispose();
super.dispose();  }

  @override
  Widget build(BuildContext context) {
return Scaffold(
  body: Center(
    child: Container(
      width: _widthAnimation.value,
      height: 100,
      color: Colors.blue,
    ),
  ),
);  }
}

In this example:

The AnimationController defines the duration of the animation.
The Tween specifies the starting and ending width.
The Animation listens to changes from the controller and updates the UI accordingly.
setState() rebuilds the widget whenever the animation value changes.

This simple example demonstrates how explicit animations provide full control over the animation lifecycle.

Using Curves in Explicit Animations

Curves allow developers to modify the animation’s speed and timing, creating more natural and visually appealing motion. Flutter provides several predefined curves in the Curves class, such as easeIn, easeOut, bounceIn, and elasticOut.

To apply a curve, wrap the animation with a CurvedAnimation:

_widthAnimation = Tween<double>(begin: 100.0, end: 200.0).animate(
  CurvedAnimation(
parent: _controller,
curve: Curves.easeInOut,  ),
);

This changes the animation’s progression so that it accelerates at the start and decelerates at the end, making the motion more dynamic.

Repeating and Reversing Animations

Explicit animations can be looped or reversed to create continuous effects.

To repeat an animation indefinitely:

_controller.repeat();

To reverse the animation back and forth:

_controller.repeat(reverse: true);

To play the animation backward manually:

_controller.reverse();

These features are useful for animations like pulsating buttons, loading indicators, or continuous background effects.

Staggered Animations

One of the most powerful features of explicit animations is the ability to create staggered animations, where multiple animations start at different times or overlap. This is useful for animating lists, cards, or complex UI sequences.

For example, animating three containers one after another:

Animation<double> animation1 = Tween<double>(begin: 0, end: 100).animate(
  CurvedAnimation(parent: _controller, curve: Interval(0.0, 0.33, curve: Curves.easeIn)),
);

Animation<double> animation2 = Tween<double>(begin: 0, end: 100).animate(
  CurvedAnimation(parent: _controller, curve: Interval(0.33, 0.66, curve: Curves.easeIn)),
);

Animation<double> animation3 = Tween<double>(begin: 0, end: 100).animate(
  CurvedAnimation(parent: _controller, curve: Interval(0.66, 1.0, curve: Curves.easeIn)),
);

Using Interval, you control when each animation starts and ends relative to the controller’s timeline, creating a sequence effect.

Animations Responding to User Input

Explicit animations are ideal for user-driven interactions. For example, a drag gesture can control the animation’s progress. Using the controller’s value property, developers can tie the animation to user input:

GestureDetector(
  onHorizontalDragUpdate: (details) {
_controller.value += details.primaryDelta! / 200;  },
  child: Container(
width: _widthAnimation.value,
height: 100,
color: Colors.red,  ),
);

This approach allows for highly interactive animations that respond fluidly to user gestures, creating a more immersive experience.

Combining Multiple Animations

With explicit animations, it is possible to animate multiple properties simultaneously, such as size, color, position, or rotation.

Example:

Animation<double> widthAnimation = Tween<double>(begin: 100, end: 200).animate(_controller);
Animation<double> heightAnimation = Tween<double>(begin: 100, end: 150).animate(_controller);
Animation<Color?> colorAnimation = ColorTween(begin: Colors.blue, end: Colors.green).animate(_controller);

In the widget:

Container(
  width: widthAnimation.value,
  height: heightAnimation.value,
  color: colorAnimation.value,
);

This flexibility allows for sophisticated visual effects that enhance the app’s user experience.

Callbacks in Explicit Animations

The AnimationController provides several callbacks to monitor the animation lifecycle:

addListener: Called every time the animation value changes.
addStatusListener: Called when the animation status changes, such as completed, dismissed, forward, or reverse.

Example:

_controller.addStatusListener((status) {
  if (status == AnimationStatus.completed) {
print("Animation completed!");  }
});

This enables developers to chain animations, trigger events, or synchronize UI updates based on animation progress.

Performance Considerations

Explicit animations give developers fine-grained control, but they also require careful management to maintain performance:

Always dispose of controllers to prevent memory leaks.
Avoid heavy computations inside addListener.
Use AnimatedBuilder or AnimatedWidget to reduce unnecessary setState() calls.
For long-running or continuous animations, consider using TickerProvider efficiently.

Following these practices ensures smooth, high-performance animations even on lower-end devices.

Real-World Use Cases for Explicit Animations

Explicit animations are widely used in production Flutter apps for:

Complex onboarding screens with sequential elements.
Interactive sliders and progress bars controlled by gestures.
Loading animations with multiple layers or staggered effects.
Animated transitions between screens or tabs.
Games and interactive apps requiring precise timing.
Buttons, cards, or widgets with multi-property animations.

These use cases demonstrate the versatility of explicit animations in enhancing user engagement.

Advantages of Explicit Animations

Full control over duration, curve, and progress.
Ability to create complex sequences and staggered animations.
Interactivity with user input.
Reusability through controllers and tweens.
Callbacks for responding to animation events.
Fine-grained control over multiple properties simultaneously.

Limitations of Explicit Animations

Requires more code compared to implicit animations.
Manual management of controllers and disposal.
More complex logic for sequences or chained animations.
Risk of performance issues if listeners or setState are misused.

What are Explicit Animations