// 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 [RelativePositionedTransition]. 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>[ RelativePositionedTransition( size: biggest, rect: RectTween( begin: const Rect.fromLTWH(0, 0, bigLogo, bigLogo), end: Rect.fromLTWH(biggest.width - smallLogo, biggest.height - smallLogo, smallLogo, smallLogo), ).animate(CurvedAnimation( parent: _controller, curve: Curves.elasticInOut, )), child: const Padding( padding: EdgeInsets.all(8), child: FlutterLogo()), ), ], ); }, ); } }