forked from lxm_flutter/FlutterUnit
63 lines
2.1 KiB
Dart
63 lines
2.1 KiB
Dart
import 'package:flutter/material.dart';
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/// create by 张风捷特烈 on 2020/9/21
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/// contact me by email 1981462002@qq.com
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/// 说明: 346 InheritedWidget 传承组件
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/// 该类是抽象类，作用是可以在本上下文存储数据，在其后续节点的上下文中共享该数据。有很多实现类，包括各种主题组件、MediaQuery等。
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/// link: 167,319,328,324,331
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///
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// {
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// "widgetId": 346,
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// "name": 'InheritedWidget 使用',
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// "priority": 1,
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// "subtitle":
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// "【child】 : 子组件 【Widget】\n"
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// "下面是一个简单的自定义 InheritedWidget，实现信息的子树共享。",
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// }
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class InheritedWidgetDemo extends StatelessWidget {
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final String info =
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'InheritedWidget 是一个抽象类，不可以直接使用。可以自定义对应共享数据的子类，如这里的通过 InfoInheritedWidget 实现：当前这段话可以在任意子树节点上下文获取。'
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'一般都会定义一个 XXX.of(context) 的方法来获取数据，如 MediaQuery.of，Theme.of 等。';
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const InheritedWidgetDemo({Key? key}) : super(key: key);
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@override
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Widget build(BuildContext context) {
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return InfoInheritedWidget(
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info: info,
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child: const InfoWidget(),
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);
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}
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}
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class InfoWidget extends StatelessWidget {
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const InfoWidget({Key? key}) : super(key: key);
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@override
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Widget build(BuildContext context) {
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String info = InfoInheritedWidget.of(context)?.info??'';
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return Container(
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color: Colors.blue.withOpacity(0.1),
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padding: const EdgeInsets.all(10),
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margin: const EdgeInsets.all(10),
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child: Text(info),
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);
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}
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}
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class InfoInheritedWidget extends InheritedWidget {
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final String info;
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const InfoInheritedWidget({Key? key,required this.info, required Widget child})
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: super(key: key, child: child);
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@override
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bool updateShouldNotify(covariant InfoInheritedWidget oldWidget) =>
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info != oldWidget.info;
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static InfoInheritedWidget? of(BuildContext context) =>
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context.dependOnInheritedWidgetOfExactType<InfoInheritedWidget>();
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}
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