Flutter Widget: set width to leftover width without using absolute number - flutter

Question

I have the following Flutter Widget. On the right side to "+", we still see a lot of free gray space. How can I set the width of the white box to use all the leftover space, without using the absolute number?
import 'package:flutter/material.dart';
class QtyWidget extends StatefulWidget {
String title;
QtyWidget({this.title});
#override
_QtyWidgetState createState() => new _QtyWidgetState();
}
class _QtyWidgetState extends State<QtyWidget> {
int _itemCount = 1;
#override
Widget build(BuildContext context) {
return Container(
padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
color: Colors.grey[200],
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
width: 100,
padding: EdgeInsets.fromLTRB(0, 0, 10, 0),
child: Text(
'Qty',
style: TextStyle(
fontWeight: FontWeight.normal,
fontSize: 16,
color: Colors.grey[600]),
),
),
Container(
padding: EdgeInsets.fromLTRB(15, 0, 15, 0),
decoration: BoxDecoration(
color: Colors.white,
border: Border.all(
color: Colors.amber[800],
),
borderRadius: BorderRadius.all(Radius.circular(10))
),
child: Row(
children: <Widget>[
IconButton(icon: new Icon(Icons.remove),
onPressed: () {
setState(() {
_itemCount = _itemCount - 1 ;
if (_itemCount < 0) {
_itemCount = 1;
}
});
}),
Text(_itemCount.toString()),
IconButton(icon: new Icon(Icons.add),
onPressed: ()=>setState(()=>_itemCount++))
],
),
),
]),
);
}
}

Answer 1

You can copy paste run full code below
You can use wrap Container with Expanded and Row use MainAxisAlignment.center and CrossAxisAlignment.center
code snippet
Expanded(
child: Container(
padding: EdgeInsets.fromLTRB(15, 0, 15, 0),
decoration: BoxDecoration(
color: Colors.white,
border: Border.all(
color: Colors.amber[800],
),
borderRadius: BorderRadius.all(Radius.circular(10))),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
working demo
full code
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
class QtyWidget extends StatefulWidget {
String title;
QtyWidget({this.title});
#override
_QtyWidgetState createState() => new _QtyWidgetState();
}
class _QtyWidgetState extends State<QtyWidget> {
int _itemCount = 1;
#override
Widget build(BuildContext context) {
return Container(
padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
color: Colors.grey[200],
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
width: 100,
padding: EdgeInsets.fromLTRB(0, 0, 10, 0),
child: Text(
'Qty',
style: TextStyle(
fontWeight: FontWeight.normal,
fontSize: 16,
color: Colors.grey[600]),
),
),
Expanded(
child: Container(
padding: EdgeInsets.fromLTRB(15, 0, 15, 0),
decoration: BoxDecoration(
color: Colors.white,
border: Border.all(
color: Colors.amber[800],
),
borderRadius: BorderRadius.all(Radius.circular(10))),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
IconButton(
icon: new Icon(Icons.remove),
onPressed: () {
setState(() {
_itemCount = _itemCount - 1;
if (_itemCount < 0) {
_itemCount = 1;
}
});
}),
Text(_itemCount.toString()),
IconButton(
icon: new Icon(Icons.add),
onPressed: () => setState(() => _itemCount++))
],
),
),
),
]),
);
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
QtyWidget(),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}