| // 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. |
| |
| import 'package:flutter/material.dart'; |
| |
| /// Flutter code sample for [FadeTransition]. |
| |
| void main() => runApp(const FadeTransitionExampleApp()); |
| |
| class FadeTransitionExampleApp extends StatelessWidget { |
| const FadeTransitionExampleApp({super.key}); |
| |
| static const Duration duration = Duration(seconds: 2); |
| static const Curve curve = Curves.easeIn; |
| |
| @override |
| Widget build(BuildContext context) { |
| return const MaterialApp( |
| home: FadeTransitionExample( |
| duration: duration, |
| curve: curve, |
| ), |
| ); |
| } |
| } |
| |
| class FadeTransitionExample extends StatefulWidget { |
| const FadeTransitionExample({ |
| required this.duration, |
| required this.curve, |
| super.key, |
| }); |
| |
| final Duration duration; |
| |
| final Curve curve; |
| |
| @override |
| State<FadeTransitionExample> createState() => _FadeTransitionExampleState(); |
| } |
| |
| /// [AnimationController]s can be created with `vsync: this` because of |
| /// [TickerProviderStateMixin]. |
| class _FadeTransitionExampleState extends State<FadeTransitionExample> |
| with TickerProviderStateMixin { |
| late final AnimationController _controller = AnimationController( |
| duration: widget.duration, |
| vsync: this, |
| )..repeat(reverse: true); |
| late final CurvedAnimation _animation = CurvedAnimation( |
| parent: _controller, |
| curve: widget.curve, |
| ); |
| |
| @override |
| void didUpdateWidget(FadeTransitionExample oldWidget) { |
| super.didUpdateWidget(oldWidget); |
| |
| if (oldWidget.duration != widget.duration) { |
| _controller |
| ..duration = widget.duration |
| ..repeat(reverse: true); |
| } |
| |
| if (oldWidget.curve != widget.curve) { |
| _animation.curve = widget.curve; |
| } |
| } |
| |
| @override |
| void dispose() { |
| _animation.dispose(); |
| _controller.dispose(); |
| super.dispose(); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| return ColoredBox( |
| color: Colors.white, |
| child: FadeTransition( |
| opacity: _animation, |
| child: const Padding( |
| padding: EdgeInsets.all(8), |
| child: FlutterLogo(), |
| ), |
| ), |
| ); |
| } |
| } |