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98 lines
2.8 KiB
Dart
98 lines
2.8 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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// Flutter code sample for RestorationMixin
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import 'package:flutter/material.dart';
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void main() => runApp(const RestorationExampleApp());
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class RestorationExampleApp extends StatelessWidget {
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const RestorationExampleApp({super.key});
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@override
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Widget build(BuildContext context) {
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return const MaterialApp(
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restorationScopeId: 'app',
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title: 'Restorable Counter',
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home: RestorableCounter(restorationId: 'counter'),
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);
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}
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}
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class RestorableCounter extends StatefulWidget {
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const RestorableCounter({super.key, this.restorationId});
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final String? restorationId;
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@override
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State<RestorableCounter> createState() => _RestorableCounterState();
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}
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// The [State] object uses the [RestorationMixin] to make the current value
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// of the counter restorable.
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class _RestorableCounterState extends State<RestorableCounter>
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with RestorationMixin {
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// The current value of the counter is stored in a [RestorableProperty].
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// During state restoration it is automatically restored to its old value.
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// If no restoration data is available to restore the counter from, it is
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// initialized to the specified default value of zero.
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final RestorableInt _counter = RestorableInt(0);
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// In this example, the restoration ID for the mixin is passed in through
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// the [StatefulWidget]'s constructor.
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@override
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String? get restorationId => widget.restorationId;
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@override
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void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
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// All restorable properties must be registered with the mixin. After
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// registration, the counter either has its old value restored or is
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// initialized to its default value.
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registerForRestoration(_counter, 'count');
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}
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void _incrementCounter() {
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setState(() {
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// The current value of the property can be accessed and modified via
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// the value getter and setter.
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_counter.value++;
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});
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}
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@override
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void dispose() {
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_counter.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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return Scaffold(
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appBar: AppBar(
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title: const Text('Restorable Counter'),
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),
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body: Center(
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child: Column(
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mainAxisAlignment: MainAxisAlignment.center,
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children: <Widget>[
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const Text(
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'You have pushed the button this many times:',
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),
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Text(
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'${_counter.value}',
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style: Theme.of(context).textTheme.headlineMedium,
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),
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],
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),
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),
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floatingActionButton: FloatingActionButton(
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onPressed: _incrementCounter,
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tooltip: 'Increment',
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child: const Icon(Icons.add),
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),
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);
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}
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}
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