AnimatedWidget Explained | Flutter for Android Developers

What’s AnimatedWidget?

The AnimatedWidget class is an abstract widget that rebuilds when the value of a given Listenable changes. It is primarily used with Animation objects but can also work with other Listenable types like ChangeNotifier and ValueNotifier. Key properties include ‘listenable’, which specifies the Listenable to listen to, and the ‘build’ method that must be overridden to define the widget’s appearance based on the animation state.

Check the official documentation for more.

AnimatedWidget explained for Android Developers

For Android developers familiar with Kotlin or Jetpack Compose, the AnimatedWidget class can be compared to the View animations in Android. Just as Android uses View properties to animate changes, Flutter’s AnimatedWidget listens to changes in an Animation object and rebuilds the widget accordingly. This is similar to using Kotlin Coroutines to manage state changes in a reactive manner.

Example Code

Here is an example of how to use AnimatedWidget:

class Spinner extends AnimatedWidget {
  Spinner({Key? key, required Animation<double> animation}) : super(key: key, listenable: animation);

  @override
  Widget build(BuildContext context) {
    final animation = listenable as Animation<double>;
    return Transform.rotate(
      angle: animation.value,
      child: Container(
        width: 100,
        height: 100,
        color: Colors.green,
      ),
    );
  }
}

AnimatedWidget Remarks

In conclusion, the AnimatedWidget class provides a powerful way to create animations in Flutter applications. By leveraging the Listenable interface, it allows for efficient updates and smooth transitions, making it an essential tool for any Flutter developer looking to enhance their app’s user experience.