// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // Flutter code sample for AnimatedBuilder import 'dart:math' as math; import 'package:flutter/material.dart'; void main() => runApp(const MyApp()); class MyApp extends StatelessWidget { const MyApp({Key? key}) : super(key: key); static const String _title = 'Flutter Code Sample'; @override Widget build(BuildContext context) { return const MaterialApp( title: _title, home: MyStatefulWidget(), ); } } class MyStatefulWidget extends StatefulWidget { const MyStatefulWidget({Key? key}) : super(key: key); @override State<MyStatefulWidget> createState() => _MyStatefulWidgetState(); } /// AnimationControllers can be created with `vsync: this` because of TickerProviderStateMixin. class _MyStatefulWidgetState extends State<MyStatefulWidget> with TickerProviderStateMixin { late final AnimationController _controller = AnimationController( duration: const Duration(seconds: 10), vsync: this, )..repeat(); @override void dispose() { _controller.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return AnimatedBuilder( animation: _controller, child: Container( width: 200.0, height: 200.0, color: Colors.green, child: const Center( child: Text('Whee!'), ), ), builder: (BuildContext context, Widget? child) { return Transform.rotate( angle: _controller.value * 2.0 * math.pi, child: child, ); }, ); } }