NestedScrollView
sample.packages.flutter.lib.src.widgets.nested_scroll_view.144.
This simple example shows a [NestedScrollView] whose header contains a snapping, floating [SliverAppBar]. Without setting any additional flags, e.g [NestedScrollView.floatHeaderSlivers], the [SliverAppBar] will animate in and out without floating. The [SliverOverlapAbsorber] and [SliverOverlapInjector] maintain the proper alignment between the two separate scroll views.
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
static const String _title = 'Flutter Code Sample';
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: _title,
home: MyStatelessWidget(),
);
}
}
class MyStatelessWidget extends StatelessWidget {
const MyStatelessWidget({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
body: NestedScrollView(headerSliverBuilder:
(BuildContext context, bool innerBoxIsScrolled) {
return [
SliverOverlapAbsorber(
handle: NestedScrollView.sliverOverlapAbsorberHandleFor(context),
sliver: SliverAppBar(
title: const Text('Snapping Nested SliverAppBar'),
floating: true,
snap: true,
expandedHeight: 200.0,
forceElevated: innerBoxIsScrolled,
),
),
];
}, body: Builder(builder: (BuildContext context) {
return CustomScrollView(
// The "controller" and "primary" members should be left
// unset, so that the NestedScrollView can control this
// inner scroll view.
// If the "controller" property is set, then this scroll
// view will not be associated with the NestedScrollView.
slivers: [
SliverOverlapInjector(
handle: NestedScrollView.sliverOverlapAbsorberHandleFor(context)),
SliverFixedExtentList(
itemExtent: 48.0,
delegate: SliverChildBuilderDelegate(
(BuildContext context, int index) =>
ListTile(title: Text('Item $index')),
childCount: 30,
),
),
],
);
})));
}
}
SHARE: