// 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 InheritedNotifier 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 SpinModel extends InheritedNotifier { const SpinModel({ Key? key, AnimationController? notifier, required Widget child, }) : super(key: key, notifier: notifier, child: child); static double of(BuildContext context) { return context .dependOnInheritedWidgetOfExactType()! .notifier! .value; } } class Spinner extends StatelessWidget { const Spinner({Key? key}) : super(key: key); @override Widget build(BuildContext context) { return Transform.rotate( angle: SpinModel.of(context) * 2.0 * math.pi, child: Container( width: 100, height: 100, color: Colors.green, child: const Center( child: Text('Whee!'), ), ), ); } } class MyStatefulWidget extends StatefulWidget { const MyStatefulWidget({Key? key}) : super(key: key); @override State createState() => _MyStatefulWidgetState(); } /// AnimationControllers can be created with `vsync: this` because of TickerProviderStateMixin. class _MyStatefulWidgetState extends State with TickerProviderStateMixin { late AnimationController _controller; @override void initState() { super.initState(); _controller = AnimationController( duration: const Duration(seconds: 10), vsync: this, )..repeat(); } @override void dispose() { _controller.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return SpinModel( notifier: _controller, child: Row( mainAxisAlignment: MainAxisAlignment.spaceAround, children: const [ Spinner(), Spinner(), Spinner(), ], ), ); } }