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import 'package:flutter/material.dart'; | |
void main() => runApp(new MyApp()); | |
class MyApp extends StatelessWidget { | |
@override | |
Widget build(BuildContext context) { | |
return new MaterialApp( | |
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> { | |
ScrollController _scrollController; | |
@override | |
void initState() { | |
super.initState(); | |
_scrollController = ScrollController() | |
..addListener(() => setState(() {})); | |
} | |
bool get _showTitle { | |
return _scrollController.hasClients | |
&& _scrollController.offset > kExpandedHeight - kToolbarHeight; | |
} | |
@override | |
Widget build(BuildContext context) { | |
return Scaffold( | |
body: CustomScrollView( | |
controller: _scrollController, | |
slivers: <Widget>[ | |
SliverAppBar( | |
pinned: true, | |
leading: IconButton(icon: Icon(Icons.menu), onPressed: () {},), | |
expandedHeight: kExpandedHeight, | |
title: _showTitle ? Text('_SliverAppBar') : null, | |
flexibleSpace: _showTitle ? null : FlexibleSpaceBar( | |
title: new Column( | |
mainAxisAlignment: MainAxisAlignment.end, | |
children: <Widget>[ | |
Text('_SliverAppBar'), | |
Text('subtitle'), | |
], | |
), | |
background: Column( | |
mainAxisAlignment: MainAxisAlignment.center, | |
children: <Widget>[ | |
Text('Info'), | |
], | |
), | |
), | |
), | |
SliverList( | |
delegate: SliverChildListDelegate(List<Text>.generate(100, (int i) { | |
return Text("List item $i"); | |
})), | |
), | |
] | |
), | |
); | |
} | |
} |
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@zgramming you will maybe have better luck following @fattiger00's gist. Your widget just needs to rebuild when the colour will in fact change. Maybe putting the scroll logic and list logic in separate widgets would be wise.