| // 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 [PositionedTransition]. |
| |
| 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 { |
| late final AnimationController _controller = AnimationController( |
| duration: const Duration(seconds: 2), |
| vsync: this, |
| )..repeat(reverse: true); |
| |
| @override |
| void dispose() { |
| _controller.dispose(); |
| super.dispose(); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| const double smallLogo = 100; |
| const double bigLogo = 200; |
| |
| return LayoutBuilder( |
| builder: (BuildContext context, BoxConstraints constraints) { |
| final Size biggest = constraints.biggest; |
| return Stack( |
| children: <Widget>[ |
| PositionedTransition( |
| rect: RelativeRectTween( |
| begin: RelativeRect.fromSize( |
| const Rect.fromLTWH(0, 0, smallLogo, smallLogo), biggest), |
| end: RelativeRect.fromSize( |
| Rect.fromLTWH(biggest.width - bigLogo, |
| biggest.height - bigLogo, bigLogo, bigLogo), |
| biggest), |
| ).animate(CurvedAnimation( |
| parent: _controller, |
| curve: Curves.elasticInOut, |
| )), |
| child: const Padding( |
| padding: EdgeInsets.all(8), child: FlutterLogo()), |
| ), |
| ], |
| ); |
| }, |
| ); |
| } |
| } |