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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flutter/material.dart';
/// Flutter code sample for [SliverAppBar].
void main() {
runApp(const StretchableSliverAppBar());
}
class StretchableSliverAppBar extends StatefulWidget {
const StretchableSliverAppBar({super.key});
@override
State<StretchableSliverAppBar> createState() =>
_StretchableSliverAppBarState();
}
class _StretchableSliverAppBarState extends State<StretchableSliverAppBar> {
bool _stretch = true;
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: CustomScrollView(
physics: const BouncingScrollPhysics(),
slivers: <Widget>[
SliverAppBar(
stretch: _stretch,
onStretchTrigger: () async {
// Triggers when stretching
},
// [stretchTriggerOffset] describes the amount of overscroll that must occur
// to trigger [onStretchTrigger]
//
// Setting [stretchTriggerOffset] to a value of 300.0 will trigger
// [onStretchTrigger] when the user has overscrolled by 300.0 pixels.
stretchTriggerOffset: 300.0,
expandedHeight: 200.0,
flexibleSpace: const FlexibleSpaceBar(
title: Text('SliverAppBar'),
background: FlutterLogo(),
),
),
SliverList(
delegate: SliverChildBuilderDelegate(
(BuildContext context, int index) {
return Container(
color: index.isOdd ? Colors.white : Colors.black12,
height: 100.0,
child: Center(
child: Text('$index', textScaleFactor: 5),
),
);
},
childCount: 20,
),
),
],
),
bottomNavigationBar: BottomAppBar(
child: Padding(
padding: const EdgeInsets.all(8),
child: OverflowBar(
overflowAlignment: OverflowBarAlignment.center,
alignment: MainAxisAlignment.center,
children: <Widget>[
Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
const Text('stretch'),
Switch(
onChanged: (bool val) {
setState(() {
_stretch = val;
});
},
value: _stretch,
),
],
),
],
),
),
),
));
}
}