Как добавить число значков как часть BottomNavigationBarItem в flutter

Попробуйте это:

 import 'dart:async'; import 'package:flutter/material.dart'; import 'badge_icon.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(), ); } } class MyHomePage extends StatefulWidget { @override _MyHomePageState createState() => _MyHomePageState(); } class _MyHomePageState extends State { StreamController _countController = StreamController(); int _currentIndex = 0; int _tabBarCount = 0; List _pages; Widget _tabBar() { return BottomNavigationBar( items: [ const BottomNavigationBarItem( icon: Icon(Icons.home, size: 25), title: const Text("Increment"), ), BottomNavigationBarItem( icon: StreamBuilder( initialData: _tabBarCount, stream: _countController.stream, builder: (_, snapshot) => BadgeIcon( icon: Icon(Icons.chat, size: 25), badgeCount: snapshot.data, ), ), title: const Text("Decrement"), ), ], currentIndex: _currentIndex, onTap: (index) => setState(() => _currentIndex = index), ); } @override void initState() { _pages = [ Container( child: Center( child: FlatButton( child: Text('Increment'), onPressed: () { _tabBarCount = _tabBarCount + 1; _countController.sink.add(_tabBarCount); }, ), ), ), Container( child: Center( child: FlatButton( child: Text('Decrement'), onPressed: () { _tabBarCount = _tabBarCount - 1; _countController.sink.add(_tabBarCount); }, ), ), ), ]; super.initState(); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('Tab Bar Icon Badge'), ), body: _pages[_currentIndex], bottomNavigationBar: _tabBar(), ); } @override void dispose() { _countController.close(); super.dispose(); } } 

Виджет BadgeIcon:

 import 'package:flutter/material.dart'; class BadgeIcon extends StatelessWidget { BadgeIcon( {this.icon, this.badgeCount = 0, this.showIfZero = false, this.badgeColor = Colors.red, TextStyle badgeTextStyle}) : this.badgeTextStyle = badgeTextStyle ?? TextStyle( color: Colors.white, fontSize: 8, ); final Widget icon; final int badgeCount; final bool showIfZero; final Color badgeColor; final TextStyle badgeTextStyle; @override Widget build(BuildContext context) { return new Stack(children: [ icon, if (badgeCount > 0 || showIfZero) badge(badgeCount), ]); } Widget badge(int count) => Positioned( right: 0, top: 0, child: new Container( padding: EdgeInsets.all(1), decoration: new BoxDecoration( color: badgeColor, borderRadius: BorderRadius.circular(8.5), ), constraints: BoxConstraints( minWidth: 15, minHeight: 15, ), child: Text( count.toString(), style: new TextStyle( color: Colors.white, fontSize: 10, ), textAlign: TextAlign.center, ), ), ); } 

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