如何在DefaulfTabController上对齐左Tab？

Question

如何对齐左侧的标签？

DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: Row(
            children: <Widget>[
              ...
            ],
          ),
          actions: <Widget>[
            ...
          ],
          bottom: TabBar(
              isScrollable: true,
              tabs: [
                Tab(text: 'Chat'),
                Tab(child: Row(
                  children: <Widget>[
                   ...
                  ],
                )),
              ]
          ),
        ),
      ),
    );

我也尝试过FlexibleSpace。它向左对齐，但是我需要在bottom

上添加TabBar

Answer 1

您可以在下面复制粘贴运行完整代码
您可以使用PreferredSize和Align
代码段

appBar: AppBar(
        title: Text(widget.title),
        bottom: PreferredSize(
          preferredSize: const Size.fromHeight(20.0),
          child: Align(
            alignment: Alignment.centerLeft,
            child: Container(
              width: MediaQuery.of(context).size.width / 2,
              child: TabBar(
                isScrollable: true,
                controller: _tabController,
                tabs: [
                  Tab(text: 'Tab 1'),
                  Tab(text: 'Tab 2'),
                  Tab(text: 'Tab 3'),
                  Tab(text: 'Tab 4'),
                  Tab(text: 'Tab 5'),
                ],
              ),
            ),
          ),
        ),
      )

工作演示

完整代码

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final appTitle = 'Tabs Demo';
    return MaterialApp(
      title: appTitle,
      home: MyHomePage(title: appTitle),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({Key key, this.title}) : super(key: key);

  @override
  State<StatefulWidget> createState() {
    return _MyHomePageState();
  }
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  int _tabIndex = 0;

  TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(vsync: this, length: 5);
  }

  void _toggleTab() {
    _tabIndex = _tabController.index + 1;
    _tabController.animateTo(_tabIndex);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      bottomNavigationBar: BottomAppBar(
        notchMargin: 20,
        child: new Row(
          // mainAxisSize: MainAxisSize.max,
          mainAxisAlignment: MainAxisAlignment.end,
          children: <Widget>[
            InkWell(
              onTap: () {
                _toggleTab();
              },
              child: Text(
                'Next >',
                style: TextStyle(fontSize: 20, color: Colors.red),
              ),
            )
          ],
        ),
      ),
      appBar: AppBar(
        title: Text(widget.title),
        bottom: PreferredSize(
          preferredSize: const Size.fromHeight(20.0),
          child: Align(
            alignment: Alignment.centerLeft,
            child: Container(
              width: MediaQuery.of(context).size.width / 2,
              child: TabBar(
                isScrollable: true,
                controller: _tabController,
                tabs: [
                  Tab(text: 'Tab 1'),
                  Tab(text: 'Tab 2'),
                  Tab(text: 'Tab 3'),
                  Tab(text: 'Tab 4'),
                  Tab(text: 'Tab 5'),
                ],
              ),
            ),
          ),
        ),
      ),
      body: TabBarView(
        controller: _tabController,
        children: [
          Card(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                ListTile(
                  leading: Icon(Icons.album),
                  title: Text('Hello 1'),
                  subtitle: Text('Click on Next Button to go to Tab 2.'),
                ),
              ],
            ),
          ),
          Card(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                ListTile(
                  leading: Icon(Icons.album),
                  title: Text('Hello 2'),
                  subtitle: Text('Click on Next Button to go to Tab 3'),
                ),
              ],
            ),
          ),
          Card(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                ListTile(
                  leading: Icon(Icons.album),
                  title: Text('Hello 3'),
                  subtitle: Text('The End'),
                ),
              ],
            ),
          ),
          Card(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                ListTile(
                  leading: Icon(Icons.album),
                  title: Text('Hello 4'),
                  subtitle: Text('The End'),
                ),
              ],
            ),
          ),
          Card(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                ListTile(
                  leading: Icon(Icons.album),
                  title: Text('Hello 5'),
                  subtitle: Text('The End'),
                ),
              ],
            ),
          ),
        ],
      ),
    ));
  }
}