How to customize the SliverAppBar widget in flutter? - dart

Question

I would like to add some more information in the green area, but when user scrolls up, I keep the _ SliverAppBar on the top..., like this:
Here is my current source code:
body: new CustomScrollView(slivers: <Widget>[
const SliverAppBar(
pinned: true,
expandedHeight: 300.0, // TODO: check out later
flexibleSpace: const FlexibleSpaceBar(
title: const Text('_SliverAppBar')
),
),
new SliverList(delegate: new SliverChildListDelegate(_galleryListItems()))
]),

Answer 1

The FlexibleSpaceBar has a background property the accepts any Widget
Use to build the information you need:
FlexibleSpaceBar(
title: Text('_SliverAppBar'),
background: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('Info'),
],
),
),
Here is a more complete example that adds a subtitle and hides it when the user scrolls.

Answer 2

import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(title: 'My Flutter Pad'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => new _MyHomePageState();
}
const kExpandedHeight = 300.0;
class _MyHomePageState extends State<MyHomePage> {
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: NestedScrollView(
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
return <Widget>[
SliverAppBar(
leading: Icon(Icons.menu),
actions: <Widget>[
new IconButton(
icon: new Icon(Icons.search),
highlightColor: Colors.white,
onPressed: () {},
),
],
expandedHeight: 200.0,
floating: false,
pinned: true,
flexibleSpace: FlexibleSpaceBar(
centerTitle: true,
background: Container(
decoration: BoxDecoration(
image: DecorationImage(
image: AssetImage("assets/images/bar.jpg"),
fit: BoxFit.cover)),
child: Column(
children: [
Expanded(
child: Align(
alignment: Alignment.bottomCenter,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('NEW GAME'),
Text('Sekiro: Shadows Dies Twice'),
RaisedButton(
onPressed: () {},
child: Text('Play'),
),
],
),
),
),
],
),
)),
),
];
},
body: Center(
child: Text("Sample Text"),
),
),
);
}
}