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interactive example
<code_start>
import 'package:flutter/material.dart';
void main() {
runApp(
MyApp(
items: List<String>.generate(10000, (i) => 'item $i'),
),
);
}
class MyApp extends StatelessWidget {
final List<String> items;
const MyApp({super.key, required this.items});
@override
widget build(BuildContext context) {
const title = 'long list';
return MaterialApp(
title: title,
home: scaffold(
appBar: AppBar(
title: const text(title),
),
body: ListView.builder(
itemCount: items.length,
prototypeItem: ListTile(
title: text(items.first),
),
itemBuilder: (context, index) {
return ListTile(
title: text(items[index]),
);
},
),
),
);
}
}
<code_end>
<topic_end>
<topic_start>
children’s extent
to specify each item’s extent, you can use either itemExtent or prototypeItem.
specifying either is more efficient than letting the children determine their own extent
because the scrolling machinery can make use of the foreknowledge of the children’s
extent to save work, for example when the scroll position changes drastically.
<topic_end>
<topic_start>
scrolling
flutter has many built-in widgets that automatically
scroll and also offers a variety of widgets
that you can customize to create specific scrolling
behavior.
<topic_end>
<topic_start>
basic scrolling
many flutter widgets support scrolling out of the box
and do most of the work for you. for example,
SingleChildScrollView automatically scrolls its
child when necessary. other useful widgets include
ListView and GridView.
you can check out more of these widgets on the
scrolling page of the widget catalog.
<topic_end>
<topic_start>
infinite scrolling
when you have a long list of items
in your ListView or GridView (including an infinite list),
you can build the items on demand
as they scroll into view. this provides a much
more performant scrolling experience.
for more information, check out
ListView.builder or GridView.builder.
<topic_end>
<topic_start>
specialized scrollable widgets
the following widgets provide more specific scrolling
behavior.
a video on using DraggableScrollableSheet
turn the scrollable area into a wheel! ListWheelScrollView
<topic_end>
<topic_start>
fancy scrolling
perhaps you want to implement elastic scrolling,
also called scroll bouncing. or maybe you want to
implement other dynamic scrolling effects, like parallax scrolling.
or perhaps you want a scrolling header with very specific behavior,
such as shrinking or disappearing.
you can achieve all this and more using the
flutter sliver* classes.
a sliver refers to a piece of the scrollable area.
you can define and insert a sliver into a CustomScrollView
to have finer-grained control over that area.
for more information, check out
using slivers to achieve fancy scrolling
and the sliver classes.
<topic_end>
<topic_start>
nested scrolling widgets
how do you nest a scrolling widget
inside another scrolling widget