86 lines
2.5 KiB
Dart
86 lines
2.5 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/material.dart';
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/// Flutter code sample for [PositionedTransition].
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void main() => runApp(const PositionedTransitionExampleApp());
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class PositionedTransitionExampleApp extends StatelessWidget {
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const PositionedTransitionExampleApp({super.key});
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@override
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Widget build(BuildContext context) {
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return const MaterialApp(home: PositionedTransitionExample());
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}
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}
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class PositionedTransitionExample extends StatefulWidget {
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const PositionedTransitionExample({super.key});
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@override
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State<PositionedTransitionExample> createState() =>
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_PositionedTransitionExampleState();
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}
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/// [AnimationController]s can be created with `vsync: this` because of
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/// [TickerProviderStateMixin].
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class _PositionedTransitionExampleState
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extends State<PositionedTransitionExample>
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with TickerProviderStateMixin {
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late final AnimationController _controller = AnimationController(
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duration: const Duration(seconds: 2),
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vsync: this,
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)..repeat(reverse: true);
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@override
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void dispose() {
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_controller.dispose();
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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const double smallLogo = 100;
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const double bigLogo = 200;
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return LayoutBuilder(
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builder: (BuildContext context, BoxConstraints constraints) {
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final Size biggest = constraints.biggest;
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return Stack(
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children: <Widget>[
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PositionedTransition(
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rect:
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RelativeRectTween(
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begin: RelativeRect.fromSize(
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const Rect.fromLTWH(0, 0, smallLogo, smallLogo),
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biggest,
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),
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end: RelativeRect.fromSize(
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Rect.fromLTWH(
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biggest.width - bigLogo,
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biggest.height - bigLogo,
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bigLogo,
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bigLogo,
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),
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biggest,
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),
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).animate(
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CurvedAnimation(
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parent: _controller,
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curve: Curves.elasticInOut,
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),
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),
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child: const Padding(
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padding: EdgeInsets.all(8),
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child: FlutterLogo(),
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),
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),
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],
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);
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},
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);
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}
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}
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