19Flutter 基础Widget —— 菜单按钮.pdfVIP

Flutter 基础Widget —— 菜单按 钮 本节讲 Flutter 菜单按钮的使⽤。 菜单按钮的 Widget 是：PopupMenuButton (https://docs.flutter.io/flutter/material/PopupMenuButton- class.html) PopupMenuButton PopupMenuButton 是⼀个按钮，当你点击按钮的时候，就会弹出 类似 Android 选项菜单的框。 代码所在位置 flutter_ idget_demo/lib/menu/PopupMenuButtonWidget.dart PopupMenuButton 的快速上⼿ PopupMenuButton 是点击 会弹出菜单选项的按钮，其 child 参 数是⽤来显示按钮的内容，itemBuilder 参数是⽤来显示弹出的菜 单，onSelected 参数⽤于处理菜单点击事件： PopupMenuButton<MenuItem>( child: Text('更多'), onSelected: (MenuItem result) { print('click ' result.toString()); }, itemBuilder: (BuildContext context) => <PopupMenuEntry<MenuItem>>[ const PopupMenuItem<MenuItem>( value: MenuItem.menuA, child: Text('menu A '), ), const PopupMenuItem<MenuItem>( value: MenuItem.menuB, child: Text('menu B'), ), const PopupMenuItem<MenuItem>( value: MenuItem.menuC, child: Text('menu C'), ), const PopupMenuItem<MenuItem>( value: MenuItem.menuD, child: Text('menu D'), ), ], ) PopupMenuButton 在⼀个⻚⾯使⽤的完整 Demo 如下： import 'package:flutter/material.dart'; void main() => runApp(PopupMenuButtonWidget()); class PopupMenuButtonWidget extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: "Flutter Demo", theme: ThemeData( primaryColor: Colors.blue, ), home: Scaffold( appBar: AppBar(title: Text("Flutter UI基 础Widget -- 按钮")), body : PopupMenuButton<MenuItem>( child: Text('更多'), onSelected: (MenuItem result) { print('click ' result.toString()); }, itemBuilder: (BuildContext context) => <PopupMenuEntry<MenuItem>>[ const PopupMenuItem<MenuItem>( value: MenuItem.menuA, child: Text('menu A '), ),