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import 'package:flutter/material.dart'; | |
import 'package:sliver_appbar_example/sliver_items.dart'; | |
void main() { | |
runApp(MyApp()); | |
} | |
class MyApp extends StatelessWidget { | |
@override | |
Widget build(BuildContext context) { | |
return MaterialApp( | |
home: const MyHomePage(), | |
); | |
} | |
} | |
class MyHomePage extends StatelessWidget { | |
const MyHomePage({Key key}) : super(key: key); | |
@override | |
Widget build(BuildContext context) { | |
return Scaffold( | |
body: CustomScrollView( | |
slivers: [ | |
SliverPersistentHeader( | |
pinned: true, | |
delegate: const MyHeaderDelegate(), | |
), | |
const SliverItems(), | |
], | |
), | |
); | |
} | |
} | |
class MyHeaderDelegate extends SliverPersistentHeaderDelegate { | |
const MyHeaderDelegate(); | |
@override | |
Widget build( | |
BuildContext context, | |
double shrinkOffset, | |
bool overlapsContent, | |
) { | |
final progress = shrinkOffset / maxExtent; | |
return Material( | |
child: Stack( | |
fit: StackFit.expand, | |
children: [ | |
AnimatedOpacity( | |
duration: const Duration(milliseconds: 150), | |
opacity: progress, | |
child: ColoredBox( | |
color: const Color(0xBE7A81FF), | |
), | |
), | |
AnimatedOpacity( | |
duration: const Duration(milliseconds: 150), | |
opacity: 1 - progress, | |
child: Image.asset( | |
'assets/images/mountains.jpg', | |
fit: BoxFit.cover, | |
), | |
), | |
AnimatedContainer( | |
duration: const Duration(milliseconds: 100), | |
padding: EdgeInsets.lerp( | |
EdgeInsets.symmetric(horizontal: 16, vertical: 16), | |
EdgeInsets.only(bottom: 16), | |
progress, | |
), | |
alignment: Alignment.lerp( | |
Alignment.bottomLeft, | |
Alignment.bottomCenter, | |
progress, | |
), | |
child: Text( | |
'Mountains', | |
style: TextStyle.lerp( | |
Theme.of(context) | |
.textTheme | |
.headline4 | |
.copyWith(color: Colors.white), | |
Theme.of(context) | |
.textTheme | |
.headline6 | |
.copyWith(color: Colors.white), | |
progress, | |
), | |
), | |
), | |
AppBar( | |
backgroundColor: Colors.transparent, | |
leading: BackButton(), | |
actions: [ | |
IconButton( | |
icon: const Icon(Icons.search), | |
onPressed: () {}, | |
), | |
IconButton( | |
icon: const Icon(Icons.more_vert), | |
onPressed: () {}, | |
), | |
], | |
elevation: 0, | |
), | |
], | |
), | |
); | |
} | |
@override | |
double get maxExtent => 264; | |
@override | |
double get minExtent => 84; | |
@override | |
bool shouldRebuild(covariant SliverPersistentHeaderDelegate oldDelegate) => | |
true; | |
} |
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