Flutter AnimatedBuilder example

main.dart

import 'dart:math';

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Animation Course',
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Explicit Animations'),
        ),
        body: const Center(
          child: AnimatedBuilderExample(),
        ),
      ),
    );
  }
}

class AnimatedBuilderExample extends StatefulWidget {
  const AnimatedBuilderExample({Key? key}) : super(key: key);

  @override
  _AnimatedBuilderExampleState createState() => _AnimatedBuilderExampleState();
}

class _AnimatedBuilderExampleState extends State<AnimatedBuilderExample>
    with SingleTickerProviderStateMixin {
  late AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller =
        AnimationController(vsync: this, duration: const Duration(seconds: 10));
    _controller.repeat();
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      builder: (context, child) {
        return Transform.rotate(
          angle: _controller.value * 2 * pi,
          child: child,
        );
      },
      child: Container(color: Colors.red, width: 100, height: 100),
    );
  }
}