Flutter 弹出菜单PopupMenuButton

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

//会控菜单项
enum ConferenceItem { AddMember, LockConference, ModifyLayout, TurnoffAll }

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'PopupMenuButton组件示例',
      home: Scaffold(
        appBar: AppBar(
          title: Text('PopupMenuButton组件示例'),
        ),
        body: Center(
          child: FlatButton(
            onPressed: () {},
            child: PopupMenuButton<ConferenceItem>(
              onSelected: (ConferenceItem result) {},
              itemBuilder: (BuildContext context) => //菜单项构造器
              <PopupMenuEntry<ConferenceItem>>[
                const PopupMenuItem<ConferenceItem>(
                  //菜单项
                  value: ConferenceItem.AddMember,
                  child: Text('添加成员'),
                ),
                const PopupMenuItem<ConferenceItem>(
                  value: ConferenceItem.LockConference,
                  child: Text('锁定会议'),
                ),
                const PopupMenuItem<ConferenceItem>(
                  value: ConferenceItem.ModifyLayout,
                  child: Text('修改布局'),
                ),
                const PopupMenuItem<ConferenceItem>(
                  value: ConferenceItem.TurnoffAll,
                  child: Text('挂断所有'),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}