FlutterExpansionTile 可折叠列表

Posted 2021-09-11 韩曙亮

文章目录

• 一、ExpansionTile 构造方法
• 二、完整代码示例
• 三、相关资源

一、ExpansionTile 构造方法

---

下面是 ExpansionTile 的构造方法 ;

其中 required this.title 是必须要设置的参数 ;

class ExpansionTile extends StatefulWidget {
  /// Creates a single-line [ListTile] with a trailing button that expands or collapses
  /// the tile to reveal or hide the [children]. The [initiallyExpanded] property must
  /// be non-null.
  const ExpansionTile({
    Key? key,
    this.leading,						// 标题左侧的 Widget 组件
    required this.title,				// 展示的列表标题 Widget 
    this.subtitle,						// 子标题 
    this.onExpansionChanged,			// 列表 展开/折叠 回调函数
    this.children = const <Widget>[],	// 列表展示时显示的 Widget 组件集合
    this.trailing,						// 标题右侧的 Widget 组件
    this.initiallyExpanded = false,		// 默认状态下是否展开 , 默认不展开 
    this.maintainState = false,
    this.tilePadding,
    this.expandedCrossAxisAlignment,
    this.expandedAlignment,
    this.childrenPadding,
    this.backgroundColor,				// 背景沿着
    this.collapsedBackgroundColor,
    this.textColor,
    this.collapsedTextColor,
    this.iconColor,
    this.collapsedIconColor,
  }) : assert(initiallyExpanded != null),
       assert(maintainState != null),
       assert(
       expandedCrossAxisAlignment != CrossAxisAlignment.baseline,
       'CrossAxisAlignment.baseline is not supported since the expanded children '
           'are aligned in a column, not a row. Try to use another constant.',
       ),
       super(key: key);
}

二、完整代码示例

---

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

const NAMES = {
  '三十六天罡' : [ '宋江', '卢俊义', '吴用', '公孙胜', '关胜' ],
  '七十二地煞' : [ '陈继真', '黄景元', '贾成', '呼颜', '鲁修德' ]
};



void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    /// 材料设计主题
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          /// 标题组件
          title: Text("ListView 示例"),
        ),

        /// 列表组件
        body: ListView(
          children: _buildList(),
        ),
      ),
    );
  }

  /// 创建列表 , 每个元素都是一个 ExpansionTile 组件
  List<Widget> _buildList(){
    List<Widget> widgets = [];
    NAMES.keys.forEach((key) {
      widgets.add(_generateExpansionTileWidget(key, NAMES[key]));
    });
    return widgets;
  }

  /// 生成 ExpansionTile 组件 , children 是 List<Widget> 组件
  Widget _generateExpansionTileWidget(tittle, List<String>? names){
    return ExpansionTile(
      title: Text(
        tittle,
        style: TextStyle(
          color: Colors.black54,
          fontSize: 20
        ),
      ),
      children: names!.map((name) => _generateWidget(name)).toList(),
    );
  }

  /// 生成 ExpansionTile 下的 ListView 的单个组件
  Widget _generateWidget(name){
    /// 使用该组件可以使宽度撑满
    return FractionallySizedBox(
      widthFactor: 1,
      child: Container(
        height: 80,
        //width: 80,
        margin: EdgeInsets.only(bottom: 5),
        //margin: EdgeInsets.only(right: 5),
        alignment: Alignment.center,
        decoration: BoxDecoration(color: Colors.black),
        child: Text(
          name,
          style: TextStyle(
              color: Colors.yellowAccent,
              fontSize: 20
          ),
        ),
      ),
    );
  }
}

执行效果 :

三、相关资源

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参考资料 :

• Flutter 官网 : https://flutter.dev/
• Flutter 插件下载地址 : https://pub.dev/packages
• Flutter 开发文档 : https://flutter.cn/docs ( 强烈推荐 )
• 官方 GitHub 地址 : https://github.com/flutter
• Flutter 中文社区 : https://flutter.cn/
• Flutter 实用教程 : https://flutter.cn/docs/cookbook
• Flutter CodeLab : https://codelabs.flutter-io.cn/
• Dart 中文文档 : https://dart.cn/
• Dart 开发者官网 : https://api.dart.dev/
• Flutter 中文网 : https://flutterchina.club/ , http://flutter.axuer.com/docs/
• Flutter 相关问题 : https://flutterchina.club/faq/ ( 入门阶段推荐看一遍 )
• GitHub 上的 Flutter 开源示例 : https://download.csdn.net/download/han1202012/15989510
• Flutter 实战电子书 : https://book.flutterchina.club/chapter1/
• Dart 语言练习网站 : https://dartpad.dartlang.org/

重要的专题 :

• Flutter 动画参考文档 : https://flutterchina.club/animations/

博客源码下载 :

• GitHub 地址 : https://github.com/han1202012/flutter_listview ( 随博客进度一直更新 , 有可能没有本博客的源码 )

• 博客源码快照 : https://download.csdn.net/download/han1202012/21590425 ( 本篇博客的源码快照 , 可以找到本博客的源码 )