// 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. import 'dart:math' as math; import 'package:flutter/material.dart'; /// Flutter code sample for [InheritedNotifier]. void main() => runApp(const InheritedNotifierExampleApp()); class InheritedNotifierExampleApp extends StatelessWidget { const InheritedNotifierExampleApp({super.key}); @override Widget build(BuildContext context) { return const MaterialApp( home: InheritedNotifierExample(), ); } } class SpinModel extends InheritedNotifier<AnimationController> { const SpinModel({ super.key, super.notifier, required super.child, }); static double of(BuildContext context) { return context.dependOnInheritedWidgetOfExactType<SpinModel>()!.notifier!.value; } } class Spinner extends StatelessWidget { const Spinner({super.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 InheritedNotifierExample extends StatefulWidget { const InheritedNotifierExample({super.key}); @override State<InheritedNotifierExample> createState() => _InheritedNotifierExampleState(); } /// [AnimationController]s can be created with `vsync: this` because of /// [TickerProviderStateMixin]. class _InheritedNotifierExampleState extends State<InheritedNotifierExample> 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: const Row( mainAxisAlignment: MainAxisAlignment.spaceAround, children: <Widget>[ Spinner(), Spinner(), Spinner(), ], ), ); } }