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interactive example
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<code_start>
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import 'package:flutter/material.dart';
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void main() {
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runApp(
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MyApp(
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items: List<String>.generate(10000, (i) => 'item $i'),
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),
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);
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}
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class MyApp extends StatelessWidget {
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final List<String> items;
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const MyApp({super.key, required this.items});
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@override
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widget build(BuildContext context) {
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const title = 'long list';
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return MaterialApp(
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title: title,
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home: scaffold(
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appBar: AppBar(
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title: const text(title),
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),
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body: ListView.builder(
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itemCount: items.length,
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prototypeItem: ListTile(
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title: text(items.first),
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),
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itemBuilder: (context, index) {
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return ListTile(
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title: text(items[index]),
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);
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},
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),
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),
|
);
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}
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}
|
<code_end>
|
<topic_end>
|
<topic_start>
|
children’s extent
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to specify each item’s extent, you can use either itemExtent or prototypeItem.
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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
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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
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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
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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
|
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