How to create a dynamic TabBarView/ Render a new Tab with a function in Flutter?
Problems arise if you need to modify the arrays. They consist in the fact that when modifying an array you do not have the opportunity to use the same controller.
You can use the next custom widget for this case:
import 'package:flutter/material.dart'; void main() => runApp(MyApp()); class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Flutter Demo', home: MyHomePage(), ); } } class MyHomePage extends StatefulWidget { @override _MyHomePageState createState() => _MyHomePageState(); } class _MyHomePageState extends State<MyHomePage> { List<String> data = ['Page 0', 'Page 1', 'Page 2']; int initPosition = 1; @override Widget build(BuildContext context) { return Scaffold( body: SafeArea( child: CustomTabView( initPosition: initPosition, itemCount: data.length, tabBuilder: (context, index) => Tab(text: data[index]), pageBuilder: (context, index) => Center(child: Text(data[index])), onPositionChange: (index){ print('current position: $index'); initPosition = index; }, onScroll: (position) => print('$position'), ), ), floatingActionButton: FloatingActionButton( onPressed: () { setState(() { data.add('Page ${data.length}'); }); }, child: Icon(Icons.add), ), ); } } /// Implementation class CustomTabView extends StatefulWidget { final int itemCount; final IndexedWidgetBuilder tabBuilder; final IndexedWidgetBuilder pageBuilder; final Widget stub; final ValueChanged<int> onPositionChange; final ValueChanged<double> onScroll; final int initPosition; CustomTabView({ @required this.itemCount, @required this.tabBuilder, @required this.pageBuilder, this.stub, this.onPositionChange, this.onScroll, this.initPosition, }); @override _CustomTabsState createState() => _CustomTabsState(); } class _CustomTabsState extends State<CustomTabView> with TickerProviderStateMixin { TabController controller; int _currentCount; int _currentPosition; @override void initState() { _currentPosition = widget.initPosition ?? 0; controller = TabController( length: widget.itemCount, vsync: this, initialIndex: _currentPosition, ); controller.addListener(onPositionChange); controller.animation.addListener(onScroll); _currentCount = widget.itemCount; super.initState(); } @override void didUpdateWidget(CustomTabView oldWidget) { if (_currentCount != widget.itemCount) { controller.animation.removeListener(onScroll); controller.removeListener(onPositionChange); controller.dispose(); if (widget.initPosition != null) { _currentPosition = widget.initPosition; } if (_currentPosition > widget.itemCount - 1) { _currentPosition = widget.itemCount - 1; _currentPosition = _currentPosition < 0 ? 0 : _currentPosition; if (widget.onPositionChange is ValueChanged<int>) { WidgetsBinding.instance.addPostFrameCallback((_){ if(mounted) { widget.onPositionChange(_currentPosition); } }); } } _currentCount = widget.itemCount; setState(() { controller = TabController( length: widget.itemCount, vsync: this, initialIndex: _currentPosition, ); controller.addListener(onPositionChange); controller.animation.addListener(onScroll); }); } else if (widget.initPosition != null) { controller.animateTo(widget.initPosition); } super.didUpdateWidget(oldWidget); } @override void dispose() { controller.animation.removeListener(onScroll); controller.removeListener(onPositionChange); controller.dispose(); super.dispose(); } @override Widget build(BuildContext context) { if (widget.itemCount < 1) return widget.stub ?? Container(); return Column( crossAxisAlignment: CrossAxisAlignment.stretch, children: <Widget>[ Container( alignment: Alignment.center, child: TabBar( isScrollable: true, controller: controller, labelColor: Theme.of(context).primaryColor, unselectedLabelColor: Theme.of(context).hintColor, indicator: BoxDecoration( border: Border( bottom: BorderSide( color: Theme.of(context).primaryColor, width: 2, ), ), ), tabs: List.generate( widget.itemCount, (index) => widget.tabBuilder(context, index), ), ), ), Expanded( child: TabBarView( controller: controller, children: List.generate( widget.itemCount, (index) => widget.pageBuilder(context, index), ), ), ), ], ); } onPositionChange() { if (!controller.indexIsChanging) { _currentPosition = controller.index; if (widget.onPositionChange is ValueChanged<int>) { widget.onPositionChange(_currentPosition); } } } onScroll() { if (widget.onScroll is ValueChanged<double>) { widget.onScroll(controller.animation.value); } } }
To make dynamic tab you can use a List and keep appending the list on every button click.
Trick: Clear List and redraw an empty widget and again draw the widgets as per your list.
import 'package:flutter/material.dart';void main() { runApp(new MaterialApp( home: new CardStack(), ));}class DynamicTabContent { IconData icon; String tooTip; DynamicTabContent.name(this.icon, this.tooTip);}class CardStack extends StatefulWidget { @override _MainState createState() => new _MainState();}class _MainState extends State<CardStack> with TickerProviderStateMixin { List<DynamicTabContent> myList = new List(); TabController _cardController; TabPageSelector _tabPageSelector; @override void initState() { super.initState(); myList.add(new DynamicTabContent.name(Icons.favorite, "Favorited")); myList.add(new DynamicTabContent.name(Icons.local_pizza, "local pizza")); _cardController = new TabController(vsync: this, length: myList.length); _tabPageSelector = new TabPageSelector(controller: _cardController); } @override void dispose() { _cardController.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return new Scaffold( backgroundColor: Colors.grey[300], appBar: new AppBar( actions: <Widget>[ new Padding( padding: const EdgeInsets.all(1.0), child: new IconButton( icon: const Icon( Icons.add, size: 30.0, color: Colors.white, ), tooltip: 'Add Tabs', onPressed: () { List<DynamicTabContent> tempList = new List(); myList.forEach((dynamicContent) { tempList.add(dynamicContent); }); setState(() { myList.clear(); }); if (tempList.length % 2 == 0) { myList.add(new DynamicTabContent.name(Icons.shopping_cart, "shopping cart")); } else { myList.add(new DynamicTabContent.name(Icons.camera, "camera")); } tempList.forEach((dynamicContent) { myList.add(dynamicContent); }); setState(() { _cardController = new TabController(vsync: this, length: myList.length); _tabPageSelector = new TabPageSelector(controller: _cardController); }); }, ), ), ], title: new Text("Title Here"), bottom: new PreferredSize( preferredSize: const Size.fromHeight(10.0), child: new Theme( data: Theme.of(context).copyWith(accentColor: Colors.grey), child: myList.isEmpty ? new Container( height: 30.0, ) : new Container( height: 30.0, alignment: Alignment.center, child: _tabPageSelector, ), ))), body: new TabBarView( controller: _cardController, children: myList.isEmpty ? <Widget>[] : myList.map((dynamicContent) { return new Card( child: new Container( height: 450.0, width: 300.0, child: new IconButton( icon: new Icon(dynamicContent.icon, size: 100.0), tooltip: dynamicContent.tooTip, onPressed: null, )), ); }).toList(), ), ); }}
Hope this helps :)