Show a message dialog before navigation to next tab flutter - flutter

Question

I have a TabBarView(), and i need to show a MessageDialog (showDialog) asking if really want to leave this tab. is there any way to do it?
this is the body of my code
child: Scaffold(
drawer: SideMenu(),
appBar: AppBar(
title: Text("Antecedentes"),
bottom: TabBar(
isScrollable: true,
controller: _controller,
tabs: [
Tab(text: 'Tab # 1'),
Tab(text: 'Tab # 2'),
Tab(text: 'Tab # 3'),
),
),
body: TabBarView(
controller: _controller,
children: [
TabOnePage(),
TabTwoPage(),
TabThreePage(),
],
),
),
Im using version 2.2.3 of Flutter.
I appreciate help on this .

Answer 1

Show AlertDialog on Tabbar onTap action, and set TabBar index to previous one(this will allow TabBar to stay on the same tab):
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Tabbar Demo"),
bottom: TabBar(
onTap: (index) {
print(index);
showAlert(tabController.index);
tabController.index = tabController.previousIndex;
},
unselectedLabelColor: Colors.white,
labelColor: Colors.black,
tabs: [
Tab(icon: Icon(Icons.chat)),
Tab(icon: Icon(Icons.drafts)),
Tab(icon: Icon(Icons.ac_unit))
],
controller: tabController,
indicatorColor: Colors.black,
indicatorSize: TabBarIndicatorSize.tab,
),
),
body: TabBarView(
children: <Widget>[
CustomView("First"),
CustomView("Second"),
CustomView("Third"),
],
controller: tabController,
));
}
And upon selection of the "OK" button in the AlertDialog, set Tabbar index to the new one.
void showAlert(int newIndex) {
AlertDialog alertDialog = new AlertDialog(
content: new Container(
height: 80.0,
child: new Column(
children: <Widget>[
new Text("Want to leave this tab?"),
new RaisedButton(
child: new Text("OK"),
onPressed: () {
tabController.index = newIndex;
Navigator.pop(context);
},
)
],
),
),
);
showDialog(context: context, child: alertDialog);
}