// 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. // Template: dev/snippets/config/templates/stateful_widget_material_ticker.tmpl // // Comment lines marked with "▼▼▼" and "▲▲▲" are used for authoring // of samples, and may be ignored if you are just exploring the sample. // Flutter code sample for AnimatedWidget // //*************************************************************************** //* ▼▼▼▼▼▼▼▼ description ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) // This code defines a widget called `Spinner` that spins a green square // continually. It is built with an [AnimatedWidget]. //* ▲▲▲▲▲▲▲▲ description ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //*************************************************************************** //******************************************************************************** //* ▼▼▼▼▼▼▼▼ code-dartImports ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) import 'dart:math' as math; //* ▲▲▲▲▲▲▲▲ code-dartImports ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //******************************************************************************** import 'package:flutter/material.dart'; void main() => runApp(const MyApp()); /// This is the main application widget. 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(), ); } } //***************************************************************************** //* ▼▼▼▼▼▼▼▼ code-preamble ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) class SpinningContainer extends AnimatedWidget { const SpinningContainer({ Key? key, required AnimationController controller, }) : super(key: key, listenable: controller); Animation get _progress => listenable as Animation; @override Widget build(BuildContext context) { return Transform.rotate( angle: _progress.value * 2.0 * math.pi, child: Container(width: 200.0, height: 200.0, color: Colors.green), ); } } //* ▲▲▲▲▲▲▲▲ code-preamble ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //***************************************************************************** /// This is the stateful widget that the main application instantiates. class MyStatefulWidget extends StatefulWidget { const MyStatefulWidget({Key? key}) : super(key: key); @override State createState() => _MyStatefulWidgetState(); } /// This is the private State class that goes with MyStatefulWidget. /// AnimationControllers can be created with `vsync: this` because of TickerProviderStateMixin. class _MyStatefulWidgetState extends State with TickerProviderStateMixin { //******************************************************************** //* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) 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 SpinningContainer(controller: _controller); } //* ▲▲▲▲▲▲▲▲ code ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //******************************************************************** }