Flutter: sliverAppBar resize issue on list scroll - flutter

Question

I want to make sliverAppBar resized while scrolling list below it.
Now there are two issues:
1) sliverAppBar doesn't resize while I am scrolling list (screenshot)
2) I can't find example/solution how to resize child content of sliverAppBar when it change height (screenshot)
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: CustomScrollView(
slivers: <Widget>[
SliverAppBar( // <-- how to resize on scrolling ListView?
expandedHeight: 200.0,
floating: false,
pinned: true,
flexibleSpace: SafeArea(
child: Column(
children: [
Row( // <-- how to make it flexible/resizable?
mainAxisAlignment: MainAxisAlignment.center,
children: [
Image.asset(
'assets/images/user.png',
fit: BoxFit.cover,
width: 120,
)
],
),
],
),
)
),
SliverFillRemaining(
child: ListView.builder(
shrinkWrap: false,
itemCount: widget.europeanCountries.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(widget.europeanCountries[index]),
);
},
),
)
],
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}

Answer 1

Use [FlexibleSpaceBar] and [SliverList]
[SliverList] can change the size of [sliverAppBar] when scrolling the list
[FlexibleSpaceBar] prevents border overflow
import 'dart:math';
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: HomePage(),
);
}
}
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
ScrollController controller = ScrollController();
#override
Widget build(BuildContext context) {
return Scaffold(
body: CustomScrollView(
slivers: <Widget>[
SliverAppBar(
expandedHeight: 200.0,
floating: true,
pinned: true,
flexibleSpace: LayoutBuilder(
builder: (context, bc) {
double size = min(
// bc.constrainHeight() - MediaQuery.of(context).padding.top,
bc.constrainHeight(),
120);
return FlexibleSpaceBar(
centerTitle: true,
// title: Container(
// width: size,
// height: size,
// decoration: BoxDecoration(
// shape: BoxShape.circle,
// image: DecorationImage(
// image: NetworkImage(
// 'https://i.loli.net/2019/08/09/OvVzMqpF3jmI8lE.jpg'),
// fit: BoxFit.cover,
// ),
// ),
// ),
background: Center(
child: Container(
width: size,
height: size,
decoration: BoxDecoration(
shape: BoxShape.circle,
image: DecorationImage(
image: NetworkImage(
'https://i.loli.net/2019/08/09/OvVzMqpF3jmI8lE.jpg'),
fit: BoxFit.cover,
),
),
),
),
);
},
),
),
SliverList(
//
delegate: SliverChildBuilderDelegate(
(context, index) {
return ListTile(
title: Text("Text"),
);
},
childCount: 100,
),
),
],
),
floatingActionButton: FloatingActionButton(
onPressed: () {},
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}