Flutter 手動控制drawer（抽屜）打開關閉

• GlobalKey 方式打開

  import "package:flutter/material.dart";
   
  class MyTest extends StatefulWidget {
    @override
    _MyTestState createState() => new _MyTestState ();
  }
   
  class _MyTestState extends State<MyTest> {
    final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
    @override
    Widget build(BuildContext context) {
      return new Scaffold(
        key: _scaffoldKey,
        drawer: new Drawer(),
        appBar: new AppBar(
          leading: new IconButton(
              icon: new Icon(Icons.settings),
              onPressed: () => _scaffoldKey.currentState.openDrawer()),
        ),
      );
    }
  }

• builder方式

• class _MyTestState extends State<MyTest> {
    @override
    Widget build(BuildContext context) {
      return new Scaffold(
        drawer: new Drawer(),
        appBar: new AppBar(
          leading: Builder(
              builder: (context) => IconButton(
                    icon: new Icon(Icons.settings),
                    onPressed: () => Scaffold.of(context).openDrawer(),
                  ),
          ),
        ),
      );
    }
  }