blob: c3ca67d926dd3a5a6eee6414588291f9eba10780 [file] [log] [blame]
// Copyright 2017 The Chromium 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';
class ExpansionTileSample extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
home: new Scaffold(
appBar: new AppBar(
title: const Text('ExpansionTile'),
),
body: new ListView.builder(
itemBuilder: (BuildContext context, int index) => new EntryItem(data[index]),
itemCount: data.length,
),
),
);
}
}
// One entry in the multilevel list displayed by this app.
class Entry {
Entry(this.title, [this.children = const <Entry>[]]);
final String title;
final List<Entry> children;
}
// The entire multilevel list displayed by this app.
final List<Entry> data = <Entry>[
new Entry('Chapter A',
<Entry>[
new Entry('Section A0',
<Entry>[
new Entry('Item A0.1'),
new Entry('Item A0.2'),
new Entry('Item A0.3'),
],
),
new Entry('Section A1'),
new Entry('Section A2'),
],
),
new Entry('Chapter B',
<Entry>[
new Entry('Section B0'),
new Entry('Section B1'),
],
),
new Entry('Chapter C',
<Entry>[
new Entry('Section C0'),
new Entry('Section C1'),
new Entry('Section C2',
<Entry>[
new Entry('Item C2.0'),
new Entry('Item C2.1'),
new Entry('Item C2.2'),
new Entry('Item C2.3'),
],
),
],
),
];
// Displays one Entry. If the entry has children then it's displayed
// with an ExpansionTile.
class EntryItem extends StatelessWidget {
const EntryItem(this.entry);
final Entry entry;
Widget _buildTiles(Entry root) {
if (root.children.isEmpty)
return new ListTile(title: new Text(root.title));
return new ExpansionTile(
key: new PageStorageKey<Entry>(root),
title: new Text(root.title),
children: root.children.map(_buildTiles).toList(),
);
}
@override
Widget build(BuildContext context) {
return _buildTiles(entry);
}
}
void main() {
runApp(new ExpansionTileSample());
}
/*
Sample Catalog
Title: ExpansionTile
Summary: An ExpansionTile for building nested lists, with two or more levels.
Description:
This app displays hierarchical data with ExpansionTiles. Tapping a tile
expands or collapses the view of its children. When a tile is collapsed
its children are disposed so that the widget footprint of the list only
reflects what's visible.
When displayed within a scrollable that creates its list items lazily,
like a scrollable list created with `ListView.builder()`, ExpansionTiles
can be quite efficient, particularly for material design "expand/collapse"
lists.
Classes: ExpansionTile, ListView
Sample: ExpansionTileSample
See also:
- The "expand/collapse" part of the material design specification:
<https://material.io/guidelines/components/lists-controls.html#lists-controls-types-of-list-controls>
*/