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// 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 [PositionedTransition].
void main() => runApp(const PositionedTransitionExampleApp());
class PositionedTransitionExampleApp extends StatelessWidget {
const PositionedTransitionExampleApp({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(
home: PositionedTransitionExample(),
);
}
}
class PositionedTransitionExample extends StatefulWidget {
const PositionedTransitionExample({super.key});
@override
State<PositionedTransitionExample> createState() => _PositionedTransitionExampleState();
}
/// [AnimationController]s can be created with `vsync: this` because of
/// [TickerProviderStateMixin].
class _PositionedTransitionExampleState extends State<PositionedTransitionExample> 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(),
),
),
],
);
},
);
}
}