| // 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 PositionedTransition |
| // |
| //*************************************************************************** |
| //* ▼▼▼▼▼▼▼▼ description ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) |
| |
| // The following code implements the [PositionedTransition] as seen in the video |
| // above: |
| |
| //* ▲▲▲▲▲▲▲▲ description ▲▲▲▲▲▲▲▲ (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(), |
| ); |
| } |
| } |
| |
| /// This is the stateful widget that the main application instantiates. |
| class MyStatefulWidget extends StatefulWidget { |
| const MyStatefulWidget({Key? key}) : super(key: key); |
| |
| @override |
| State<MyStatefulWidget> 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<MyStatefulWidget> |
| with TickerProviderStateMixin { |
| //******************************************************************** |
| //* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) |
| |
| 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()), |
| ), |
| ], |
| ); |
| }, |
| ); |
| } |
| |
| //* ▲▲▲▲▲▲▲▲ code ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) |
| //******************************************************************** |
| |
| } |