Flutter: Create a rectangle that fills the title area of the app bar - flutter

Question

In Flutter I want to create an app bar that looks as follows:
I've easily managed to add the 2 icons on the left and right, but I am struggling to create a rectangle in the middle.
I've tried the following code:
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.white,
leading: IconButton(
icon: Image.asset('assets/images/maps.png'),
onPressed: () => {},
),
title: Expanded( // The bit that's not working. A rectangle that fills the middle area.
child: Container(
color: Colors.blue,
),
),
actions: <Widget>[
IconButton(
icon: Image.asset('assets/images/search.png'),
onPressed: () => {},
),
],
),
);
but I get the following exception:
Expanded widgets must be placed inside Flex widgets.
Expanded(no depth, flex: 1, dirty) has no Flex ancestor at all.
Thanks for the help.

Answer 1

You can achieve this by setting the centerTile attribute of the AppBar to true
Like this
import 'package:flutter/material.dart';
class Home extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.white,
centerTitle: true,
leading: IconButton(
icon: Icon(
Icons.location_on,
color: Colors.grey,
),
onPressed: () => {},
),
title: Container(
padding: EdgeInsets.all(10),
child: Row(
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Icon(Icons.refresh),
Expanded(
child: Center(
child: Text("London"),
),
),
Opacity(child: Icon(Icons.refresh), opacity: 0,),
],
),
decoration: BoxDecoration(
color: Colors.grey, borderRadius: BorderRadius.circular(10)),
),
actions: <Widget>[
IconButton(
icon: Icon(
Icons.search,
color: Colors.grey,
),
onPressed: () => {},
),
],
),
);
}
}
The output:

Answer 2

An alternative solution (inspired by #Josteve Adekanbi answer), to create a rectangle that fills the title area is:
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.white,
leading: ...
title: Container(
width: double.infinity,
height: 40,
child: Container(
color: Colors.blue,
),
),
actions: ...
),
);