// 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 [AlignTransition]. import 'package:flutter/material.dart'; void main() => runApp(const MyApp()); class MyApp extends StatelessWidget { const MyApp({super.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({super.key}); @override State<MyStatefulWidget> createState() => _MyStatefulWidgetState(); } /// [AnimationController]s can be created with `vsync: this` because of /// [TickerProviderStateMixin]. class _MyStatefulWidgetState extends State<MyStatefulWidget> with TickerProviderStateMixin { // Using `late final` for lazy initialization. See // https://dart.dev/null-safety/understanding-null-safety#lazy-initialization. late final AnimationController _controller = AnimationController( duration: const Duration(seconds: 2), vsync: this, )..repeat(reverse: true); late final Animation<AlignmentGeometry> _animation = Tween<AlignmentGeometry>( begin: Alignment.bottomLeft, end: Alignment.center, ).animate( CurvedAnimation( parent: _controller, curve: Curves.decelerate, ), ); @override void dispose() { _controller.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Container( color: Colors.white, child: AlignTransition( alignment: _animation, child: const Padding( padding: EdgeInsets.all(8), child: FlutterLogo(size: 150.0), ), ), ); } }