dart - 如何在没有可见的 appBar flutter 的情况下保持汉堡包图标

Question

我最近尝试在没有 AppBar 或至少完全不可见的情况下为我的菜单 slider 保留汉堡包图标。第一次尝试使用 SafeArea，但清空了 Scaffold。然后我尝试将不透明度设置为 0.0，如下面的代码所示。但它给出了与 SafeArea 相同的结果，但 Scaffold 上没有任何内容。请问有人可以帮忙吗？

    import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => MyAppState();
}

class MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      theme: ThemeData(
        // Define the default Brightness and Colors
        brightness: Brightness.dark,
        primaryColor: Colors.lightBlue[800],
        accentColor: Colors.cyan[600],
      ),
      home: Scaffold(
          Opacity(
            opacity: 0.0,
            appBar: AppBar(),
          ),
          drawer: new Drawer(
            child: new ListView(),
          ),
          body: new Center(
              child: new Column(
            children: <Widget>[],
          ))),
    );
  }
}

Answer 1

如果我没听错，你想显示一个菜单按钮来显示 Drawer，而不显示任何 AppBar。

一种选择是使用 Stack 作为 Scaffold 的主体。

import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => MyAppState();
}

class MyAppState extends State<MyApp> {
  var scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      theme: ThemeData(
        // Define the default Brightness and Colors
        brightness: Brightness.dark,
        primaryColor: Colors.lightBlue[800],
        accentColor: Colors.cyan[600],
      ),
      home: Scaffold(
        key: scaffoldKey,
        drawer: new Drawer(
          child: new ListView(),
        ),
        body: Stack(
          children: <Widget>[
            new Center(
                child: new Column(
              children: <Widget>[],
            )),
            Positioned(
              left: 10,
              top: 20,
              child: IconButton(
                icon: Icon(Icons.menu),
                onPressed: () => scaffoldKey.currentState.openDrawer(),
              ),
            ),
          ],
        ),
      ),
    );
  }
}