Question

我想在用户单击第四个（more_vert）图标时显示一个抽屉，但是我无法实现它。在我当前的实现中，当单击第4个图标时，flutter将我带到一个新页面，并且在其中显示抽屉不在当前屏幕上方。我究竟做错了什么？另外BottomNavigationBar和BottomAppBar之间有什么区别，我在任何地方都找不到。我查看了几篇文章，我认为BottomAppBar用于显示Fab在底部appbar中浮动。两者之间还有其他区别吗？何时应该使用另一种。

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  List<Widget> _widgetOptions = <Widget>[
    Page1(),
    Page2(),
    Page3(),
    Page4(),   // this page implements the drawer

  ];
  int _currentSelected = 0;

  void _onItemTapped(int index) {
    setState(() {
      _currentSelected = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: _widgetOptions.elementAt(_currentSelected),
      bottomNavigationBar: BottomNavigationBar(
        type: BottomNavigationBarType.fixed,
        onTap: _onItemTapped,
        currentIndex: _currentSelected,
        showUnselectedLabels: true,
        unselectedItemColor: Colors.grey[800],
        selectedItemColor: Color.fromRGBO(10, 135, 255, 1),
        items: <BottomNavigationBarItem>[
          BottomNavigationBarItem(
             icon: Icon(AntDesign.carryout),
          ),
          BottomNavigationBarItem(
             icon: Icon(MaterialCommunityIcons.sack),
          ),
          BottomNavigationBarItem(
             icon: Icon(Octicons.archive),
          ),
          BottomNavigationBarItem(
             icon: Icon(Icons.more_vert),
          )
        ],
      ),
      // backgroundColor: Colors.black,
    );
  }
}

Answer 1

BottomNavigationBar不会像AppBar一样显示抽屉图标。

要以编程方式打开抽屉：

将此变量创建为state：

GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey();

将其设置为脚手架的钥匙：

Scaffold(
      key: _scaffoldKey,

然后，您可以使用键状态打开抽屉：

_scaffoldKey.currentState.openDrawer();

Answer 2

您不需要额外的页面。您可以这样做：

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  List<Widget> _widgetOptions = <Widget>[
    Page(),
    Page(),
    Page(),
  ];
  int _currentSelected = 0;
  GlobalKey<ScaffoldState> _drawerKey = GlobalKey();

  void _onItemTapped(int index) {
    index == 3
        ? _drawerKey.currentState.openDrawer()
        : setState(() {
            _currentSelected = index;
          });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _drawerKey,
      body: _widgetOptions.elementAt(_currentSelected),
      drawer: Drawer(),
      bottomNavigationBar: BottomNavigationBar(
        type: BottomNavigationBarType.fixed,
        onTap: _onItemTapped,
        currentIndex: _currentSelected,
        showUnselectedLabels: true,
        unselectedItemColor: Colors.grey[800],
        selectedItemColor: Color.fromRGBO(10, 135, 255, 1),
        items: <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            title: Text('Page 1'),
            icon: Icon(Icons.access_alarm),
          ),
          BottomNavigationBarItem(
            title: Text('Page 2'),
            icon: Icon(Icons.accessible),
          ),
          BottomNavigationBarItem(
            title: Text('Page 3'),
            icon: Icon(Icons.adb),
          ),
          BottomNavigationBarItem(
            title: Text('Drawer'),
            icon: Icon(Icons.more_vert),
          )
        ],
      ),
    );
  }
}

class Page extends StatelessWidget {
  const Page({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

为用于实现抽屉的脚手架添加GlobalKey并在根支架中实现抽屉。

如何在Flutter底部导航栏中添加抽屉？

2 个答案: