在颤动中更改 TabBar 形状

Question

我制作了一个底部应用栏，其 shape 属性设置为“CircularNotchedRectangle”，效果非常棒！问题是我正在寻找 TabBar 提供的“滑动以更改页面”功能，但我看不到任何方法可以将其形状更改为 CircularNotchedRectangle。我可以改变它的形状吗？还是我应该尝试制作自己的“滑动以更改页面”功能？ 谢谢！

我目前的BottomNavigationBar：

BottomAppBar(
    shape: CircularNotchedRectangle(),
    notchMargin: 2.0,
    child: Stack(
        children: [
          Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                IconButton(
                    icon: Icon(Icons.search),
                    iconSize: 35,
                    color: widget.currentTab == 0 ? Colors.purple[500] : Colors.black,
                    onPressed: (){
                      setState(() {
                        widget.currentTab = 0;
                      });
                    }
                ),
                IconButton(
                    icon: Icon(Icons.account_circle),
                    iconSize: 35,
                    color: widget.currentTab == 1 ? Colors.purple[500] : Colors.black,
                    onPressed: (){
                      setState(() {
                        widget.currentTab = 1;
                      });
                    }
                ),
                SizedBox(width: 40),
                IconButton(
                    icon: Icon(Icons.group),
                    iconSize: 35,
                    color: widget.currentTab == 2 ? Colors.purple[500] : Colors.black,
                    onPressed: (){
                      setState(() {
                        widget.currentTab = 2;
                      });
                    }
                ),
                IconButton(
                    icon: Icon(Icons.chat_bubble),
                    iconSize: 35,
                    color: widget.currentTab == 3 ? Colors.purple[500] : Colors.black,
                    onPressed: (){
                      setState(() {
                        widget.currentTab = 3;
                      });
                    }
                ),
              ]
          )
        ]
    )
);

这是我想通过 TabBar 获得的形状

Answer 1

您可以在下面复制粘贴运行完整代码
使用当前代码实现 swipe to change page 功能
可以直接使用PageView
代码sn-p

PageController pageController = PageController(
    initialPage: 0,
    keepPage: true,
  );

  Widget buildPageView() {
    return PageView(
      controller: pageController,
      onPageChanged: (index) {
        pageChanged(index);
      },
      children: <Widget>[
        Red(),
        Blue(),
        Yellow(),
        Green(),
      ],
    );
  }
...
void bottomTapped(int index) {
    setState(() {
      currentTab = index;
      pageController.animateToPage(index,
          duration: Duration(milliseconds: 500), curve: Curves.ease);
    });
  }  
...
IconButton(
              icon: Icon(Icons.search),
              iconSize: 35,
              color: currentTab == 0 ? Colors.purple[500] : Colors.black,
              onPressed: () {
                bottomTapped(0);
              }),   

工作演示

完整代码

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  double width;
  Color primaryColor = Colors.blue;

  int currentTab = 0;

  PageController pageController = PageController(
    initialPage: 0,
    keepPage: true,
  );

  Widget buildPageView() {
    return PageView(
      controller: pageController,
      onPageChanged: (index) {
        pageChanged(index);
      },
      children: <Widget>[
        Red(),
        Blue(),
        Yellow(),
        Green(),
      ],
    );
  }

  @override
  void initState() {
    super.initState();
  }

  void pageChanged(int index) {
    setState(() {
      currentTab = index;
    });
  }

  void bottomTapped(int index) {
    setState(() {
      currentTab = index;
      pageController.animateToPage(index,
          duration: Duration(milliseconds: 500), curve: Curves.ease);
    });
  }

  @override
  Widget build(BuildContext context) {
    width = MediaQuery.of(context).size.width;
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: buildPageView(),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.red,
        child: const Icon(
          Icons.add,
        ),
        onPressed: () {},
      ),
      bottomNavigationBar: BottomAppBar(
          shape: CircularNotchedRectangle(),
          notchMargin: 2.0,
          child: Stack(children: [
            Row(mainAxisAlignment: MainAxisAlignment.spaceAround, children: [
              IconButton(
                  icon: Icon(Icons.search),
                  iconSize: 35,
                  color: currentTab == 0 ? Colors.purple[500] : Colors.black,
                  onPressed: () {
                    bottomTapped(0);
                  }),
              IconButton(
                  icon: Icon(Icons.account_circle),
                  iconSize: 35,
                  color: currentTab == 1 ? Colors.purple[500] : Colors.black,
                  onPressed: () {
                    bottomTapped(1);
                  }),
              SizedBox(width: 40),
              IconButton(
                  icon: Icon(Icons.group),
                  iconSize: 35,
                  color: currentTab == 2 ? Colors.purple[500] : Colors.black,
                  onPressed: () {
                    bottomTapped(2);
                  }),
              IconButton(
                  icon: Icon(Icons.chat_bubble),
                  iconSize: 35,
                  color: currentTab == 3 ? Colors.purple[500] : Colors.black,
                  onPressed: () {
                    bottomTapped(3);
                  }),
            ])
          ])),
    );
  }
}

class Red extends StatefulWidget {
  @override
  _RedState createState() => _RedState();
}

class _RedState extends State<Red> {
  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.purple,
    );
  }
}

class Blue extends StatefulWidget {
  @override
  _BlueState createState() => _BlueState();
}

class _BlueState extends State<Blue> {
  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.blueAccent,
    );
  }
}

class Yellow extends StatefulWidget {
  @override
  _YellowState createState() => _YellowState();
}

class _YellowState extends State<Yellow> {
  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.yellowAccent,
    );
  }
}

class Green extends StatefulWidget {
  @override
  _GreenState createState() => _GreenState();
}

class _GreenState extends State<Green> {
  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.greenAccent,
    );
  }
}

Answer 2

您需要做的就是像这样在 Scaffold 中定义 Fab 位置：

floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,