How can i make pageView.Builder occupy all available space in flutter? - flutter

Question

I am trying to swap two widgets on button click OR is there any other way to do this?
When i set
SizedBox(
height: double.infinity,
width: double.infinity, )
it gives error: BoxConstraints forces an infinite height. it works when manually set height and width.
I tried using
Expanded and flexible it gives error like this
RenderBox was not laid out: RenderRepaintBoundary#8b1a5 relayoutBoundary=up14 NEEDS-PAINT
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1785 pos 12: 'hasSize'
Code
class _MyHomePageState extends State<MyHomePage> {
TextEditingController _uri = TextEditingController();
bool flag=false;
bool swap = false;
int _index = 0;
#override
void initState() {
swap = widget.swap;
super.initState();
}
#override
Widget build(BuildContext context) {
Widget swapWidget;
if (!swap) {
swapWidget = Center(
child: Expanded(
// card height
child: PageView.builder(
itemCount: 2,
controller: PageController(viewportFraction: 0.95),
onPageChanged: (int index) => setState(() => _index = index),
itemBuilder: (_, i) {
return Transform.scale(
scale: i == _index ? 1 : 0.9,
child: Card(
elevation: 6,
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
child: Center(
child: Text(
"Card ${i + 1}",
style: TextStyle(fontSize: 32),
),
),
),
);
},
)
)
);
} else {
swapWidget =new Card(
child:Text('Nothing To show')
);
}
var swapTile = new ListTile(
title: swapWidget,
);
return new Scaffold(
appBar: AppBar( title: Text('My APP')),
body: new ListView(
children: <Widget>[
swapTile,
],
),
);
}
}
What i am doing Wrong?
Thankyou

Answer 1

I am not entirely sure what you are trying to do here, but Few things. PageView widget expands to the maximum allowed space by default, so you don't need the Expanded or Center widget around it.
Second, I don't know why you would want to wrap Card widget with ListTile. You certainly can, but that's not how ListTile and Card are designed.
Third, because PageView widget can expand, it needs some size constraints, so it cannot be put inside a infinitely large widget like ListView, so you can remove that, and here is what I have. I hope it is close to what you were looking for.
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
bool swap = true;
int _index = 0;
#override
Widget build(BuildContext context) {
Widget swapWidget;
if (swap) {
swapWidget = PageView.builder(
itemCount: 2,
controller: PageController(viewportFraction: 0.95),
itemBuilder: (_, i) {
return Transform.scale(
scale: i == _index ? 1 : 0.9,
child: Card(
elevation: 6,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(20)),
child: Center(
child: Text(
"Card ${i + 1}",
style: TextStyle(fontSize: 32),
),
),
),
);
},
);
} else {
swapWidget = Card(child: Text('Nothing To show'));
}
return Scaffold(
body: swapWidget,
);
}
}