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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 'dart:math' as math;
import 'package:flutter/widgets.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'colors.dart';
import 'constants.dart';
import 'debug.dart';
import 'divider.dart';
import 'ink_well.dart';
import 'theme.dart';
/// Defines the title font used for [ListTile] descendants of a [ListTileTheme].
///
/// List tiles that appear in a [Drawer] use the theme's [TextTheme.bodyText1]
/// text style, which is a little smaller than the theme's [TextTheme.subtitle1]
/// text style, which is used by default.
enum ListTileStyle {
/// Use a title font that's appropriate for a [ListTile] in a list.
list,
/// Use a title font that's appropriate for a [ListTile] that appears in a [Drawer].
drawer,
}
/// An inherited widget that defines color and style parameters for [ListTile]s
/// in this widget's subtree.
///
/// Values specified here are used for [ListTile] properties that are not given
/// an explicit non-null value.
///
/// The [Drawer] widget specifies a tile theme for its children which sets
/// [style] to [ListTileStyle.drawer].
class ListTileTheme extends InheritedTheme {
/// Creates a list tile theme that controls the color and style parameters for
/// [ListTile]s.
const ListTileTheme({
Key key,
this.dense = false,
this.style = ListTileStyle.list,
this.selectedColor,
this.iconColor,
this.textColor,
this.contentPadding,
Widget child,
}) : super(key: key, child: child);
/// Creates a list tile theme that controls the color and style parameters for
/// [ListTile]s, and merges in the current list tile theme, if any.
///
/// The [child] argument must not be null.
static Widget merge({
Key key,
bool dense,
ListTileStyle style,
Color selectedColor,
Color iconColor,
Color textColor,
EdgeInsetsGeometry contentPadding,
@required Widget child,
}) {
assert(child != null);
return Builder(
builder: (BuildContext context) {
final ListTileTheme parent = ListTileTheme.of(context);
return ListTileTheme(
key: key,
dense: dense ?? parent.dense,
style: style ?? parent.style,
selectedColor: selectedColor ?? parent.selectedColor,
iconColor: iconColor ?? parent.iconColor,
textColor: textColor ?? parent.textColor,
contentPadding: contentPadding ?? parent.contentPadding,
child: child,
);
},
);
}
/// If true then [ListTile]s will have the vertically dense layout.
final bool dense;
/// If specified, [style] defines the font used for [ListTile] titles.
final ListTileStyle style;
/// If specified, the color used for icons and text when a [ListTile] is selected.
final Color selectedColor;
/// If specified, the icon color used for enabled [ListTile]s that are not selected.
final Color iconColor;
/// If specified, the text color used for enabled [ListTile]s that are not selected.
final Color textColor;
/// The tile's internal padding.
///
/// Insets a [ListTile]'s contents: its [leading], [title], [subtitle],
/// and [trailing] widgets.
final EdgeInsetsGeometry contentPadding;
/// The closest instance of this class that encloses the given context.
///
/// Typical usage is as follows:
///
/// ```dart
/// ListTileTheme theme = ListTileTheme.of(context);
/// ```
static ListTileTheme of(BuildContext context) {
final ListTileTheme result = context.dependOnInheritedWidgetOfExactType<ListTileTheme>();
return result ?? const ListTileTheme();
}
@override
Widget wrap(BuildContext context, Widget child) {
final ListTileTheme ancestorTheme = context.findAncestorWidgetOfExactType<ListTileTheme>();
return identical(this, ancestorTheme) ? child : ListTileTheme(
dense: dense,
style: style,
selectedColor: selectedColor,
iconColor: iconColor,
textColor: textColor,
contentPadding: contentPadding,
child: child,
);
}
@override
bool updateShouldNotify(ListTileTheme oldWidget) {
return dense != oldWidget.dense
|| style != oldWidget.style
|| selectedColor != oldWidget.selectedColor
|| iconColor != oldWidget.iconColor
|| textColor != oldWidget.textColor
|| contentPadding != oldWidget.contentPadding;
}
}
/// Where to place the control in widgets that use [ListTile] to position a
/// control next to a label.
///
/// See also:
///
/// * [CheckboxListTile], which combines a [ListTile] with a [Checkbox].
/// * [RadioListTile], which combines a [ListTile] with a [Radio] button.
enum ListTileControlAffinity {
/// Position the control on the leading edge, and the secondary widget, if
/// any, on the trailing edge.
leading,
/// Position the control on the trailing edge, and the secondary widget, if
/// any, on the leading edge.
trailing,
/// Position the control relative to the text in the fashion that is typical
/// for the current platform, and place the secondary widget on the opposite
/// side.
platform,
}
/// A single fixed-height row that typically contains some text as well as
/// a leading or trailing icon.
///
/// {@youtube 560 315 https://www.youtube.com/watch?v=l8dj0yPBvgQ}
///
/// A list tile contains one to three lines of text optionally flanked by icons or
/// other widgets, such as check boxes. The icons (or other widgets) for the
/// tile are defined with the [leading] and [trailing] parameters. The first
/// line of text is not optional and is specified with [title]. The value of
/// [subtitle], which _is_ optional, will occupy the space allocated for an
/// additional line of text, or two lines if [isThreeLine] is true. If [dense]
/// is true then the overall height of this tile and the size of the
/// [DefaultTextStyle]s that wrap the [title] and [subtitle] widget are reduced.
///
/// It is the responsibility of the caller to ensure that [title] does not wrap,
/// and to ensure that [subtitle] doesn't wrap (if [isThreeLine] is false) or
/// wraps to two lines (if it is true).
///
/// The heights of the [leading] and [trailing] widgets are constrained
/// according to the
/// [Material spec](https://material.io/design/components/lists.html).
/// An exception is made for one-line ListTiles for accessibility. Please
/// see the example below to see how to adhere to both Material spec and
/// accessibility requirements.
///
/// Note that [leading] and [trailing] widgets can expand as far as they wish
/// horizontally, so ensure that they are properly constrained.
///
/// List tiles are typically used in [ListView]s, or arranged in [Column]s in
/// [Drawer]s and [Card]s.
///
/// Requires one of its ancestors to be a [Material] widget.
///
/// {@tool snippet}
///
/// This example uses a [ListView] to demonstrate different configurations of
/// [ListTile]s in [Card]s.
///
/// ![Different variations of ListTile](https://flutter.github.io/assets-for-api-docs/assets/material/list_tile.png)
///
/// ```dart
/// ListView(
/// children: const <Widget>[
/// Card(child: ListTile(title: Text('One-line ListTile'))),
/// Card(
/// child: ListTile(
/// leading: FlutterLogo(),
/// title: Text('One-line with leading widget'),
/// ),
/// ),
/// Card(
/// child: ListTile(
/// title: Text('One-line with trailing widget'),
/// trailing: Icon(Icons.more_vert),
/// ),
/// ),
/// Card(
/// child: ListTile(
/// leading: FlutterLogo(),
/// title: Text('One-line with both widgets'),
/// trailing: Icon(Icons.more_vert),
/// ),
/// ),
/// Card(
/// child: ListTile(
/// title: Text('One-line dense ListTile'),
/// dense: true,
/// ),
/// ),
/// Card(
/// child: ListTile(
/// leading: FlutterLogo(size: 56.0),
/// title: Text('Two-line ListTile'),
/// subtitle: Text('Here is a second line'),
/// trailing: Icon(Icons.more_vert),
/// ),
/// ),
/// Card(
/// child: ListTile(
/// leading: FlutterLogo(size: 72.0),
/// title: Text('Three-line ListTile'),
/// subtitle: Text(
/// 'A sufficiently long subtitle warrants three lines.'
/// ),
/// trailing: Icon(Icons.more_vert),
/// isThreeLine: true,
/// ),
/// ),
/// ],
/// )
/// ```
/// {@end-tool}
/// {@tool snippet}
///
/// Tiles can be much more elaborate. Here is a tile which can be tapped, but
/// which is disabled when the `_act` variable is not 2. When the tile is
/// tapped, the whole row has an ink splash effect (see [InkWell]).
///
/// ```dart
/// int _act = 1;
/// // ...
/// ListTile(
/// leading: const Icon(Icons.flight_land),
/// title: const Text("Trix's airplane"),
/// subtitle: _act != 2 ? const Text('The airplane is only in Act II.') : null,
/// enabled: _act == 2,
/// onTap: () { /* react to the tile being tapped */ }
/// )
/// ```
/// {@end-tool}
///
/// To be accessible, tappable [leading] and [trailing] widgets have to
/// be at least 48x48 in size. However, to adhere to the Material spec,
/// [trailing] and [leading] widgets in one-line ListTiles should visually be
/// at most 32 ([dense]: true) or 40 ([dense]: false) in height, which may
/// conflict with the accessibility requirement.
///
/// For this reason, a one-line ListTile allows the height of [leading]
/// and [trailing] widgets to be constrained by the height of the ListTile.
/// This allows for the creation of tappable [leading] and [trailing] widgets
/// that are large enough, but it is up to the developer to ensure that
/// their widgets follow the Material spec.
///
/// {@tool snippet}
///
/// Here is an example of a one-line, non-[dense] ListTile with a
/// tappable leading widget that adheres to accessibility requirements and
/// the Material spec. To adjust the use case below for a one-line, [dense]
/// ListTile, adjust the vertical padding to 8.0.
///
/// ```dart
/// ListTile(
/// leading: GestureDetector(
/// behavior: HitTestBehavior.translucent,
/// onTap: () {},
/// child: Container(
/// width: 48,
/// height: 48,
/// padding: EdgeInsets.symmetric(vertical: 4.0),
/// alignment: Alignment.center,
/// child: CircleAvatar(),
/// ),
/// ),
/// title: Text('title'),
/// dense: false,
/// ),
/// ```
/// {@end-tool}
///
/// ## The ListTile layout isn't exactly what I want
///
/// If the way ListTile pads and positions its elements isn't quite what
/// you're looking for, it's easy to create custom list items with a
/// combination of other widgets, such as [Row]s and [Column]s.
///
/// {@tool dartpad --template=stateless_widget_scaffold}
///
/// Here is an example of a custom list item that resembles a Youtube related
/// video list item created with [Expanded] and [Container] widgets.
///
/// ![Custom list item a](https://flutter.github.io/assets-for-api-docs/assets/widgets/custom_list_item_a.png)
///
/// ```dart preamble
/// class CustomListItem extends StatelessWidget {
/// const CustomListItem({
/// this.thumbnail,
/// this.title,
/// this.user,
/// this.viewCount,
/// });
///
/// final Widget thumbnail;
/// final String title;
/// final String user;
/// final int viewCount;
///
/// @override
/// Widget build(BuildContext context) {
/// return Padding(
/// padding: const EdgeInsets.symmetric(vertical: 5.0),
/// child: Row(
/// crossAxisAlignment: CrossAxisAlignment.start,
/// children: <Widget>[
/// Expanded(
/// flex: 2,
/// child: thumbnail,
/// ),
/// Expanded(
/// flex: 3,
/// child: _VideoDescription(
/// title: title,
/// user: user,
/// viewCount: viewCount,
/// ),
/// ),
/// const Icon(
/// Icons.more_vert,
/// size: 16.0,
/// ),
/// ],
/// ),
/// );
/// }
/// }
///
/// class _VideoDescription extends StatelessWidget {
/// const _VideoDescription({
/// Key key,
/// this.title,
/// this.user,
/// this.viewCount,
/// }) : super(key: key);
///
/// final String title;
/// final String user;
/// final int viewCount;
///
/// @override
/// Widget build(BuildContext context) {
/// return Padding(
/// padding: const EdgeInsets.fromLTRB(5.0, 0.0, 0.0, 0.0),
/// child: Column(
/// crossAxisAlignment: CrossAxisAlignment.start,
/// children: <Widget>[
/// Text(
/// title,
/// style: const TextStyle(
/// fontWeight: FontWeight.w500,
/// fontSize: 14.0,
/// ),
/// ),
/// const Padding(padding: EdgeInsets.symmetric(vertical: 2.0)),
/// Text(
/// user,
/// style: const TextStyle(fontSize: 10.0),
/// ),
/// const Padding(padding: EdgeInsets.symmetric(vertical: 1.0)),
/// Text(
/// '$viewCount views',
/// style: const TextStyle(fontSize: 10.0),
/// ),
/// ],
/// ),
/// );
/// }
/// }
/// ```
///
/// ```dart
/// Widget build(BuildContext context) {
/// return ListView(
/// padding: const EdgeInsets.all(8.0),
/// itemExtent: 106.0,
/// children: <CustomListItem>[
/// CustomListItem(
/// user: 'Flutter',
/// viewCount: 999000,
/// thumbnail: Container(
/// decoration: const BoxDecoration(color: Colors.blue),
/// ),
/// title: 'The Flutter YouTube Channel',
/// ),
/// CustomListItem(
/// user: 'Dash',
/// viewCount: 884000,
/// thumbnail: Container(
/// decoration: const BoxDecoration(color: Colors.yellow),
/// ),
/// title: 'Announcing Flutter 1.0',
/// ),
/// ],
/// );
/// }
/// ```
/// {@end-tool}
///
/// {@tool dartpad --template=stateless_widget_scaffold}
///
/// Here is an example of an article list item with multiline titles and
/// subtitles. It utilizes [Row]s and [Column]s, as well as [Expanded] and
/// [AspectRatio] widgets to organize its layout.
///
/// ![Custom list item b](https://flutter.github.io/assets-for-api-docs/assets/widgets/custom_list_item_b.png)
///
/// ```dart preamble
/// class _ArticleDescription extends StatelessWidget {
/// _ArticleDescription({
/// Key key,
/// this.title,
/// this.subtitle,
/// this.author,
/// this.publishDate,
/// this.readDuration,
/// }) : super(key: key);
///
/// final String title;
/// final String subtitle;
/// final String author;
/// final String publishDate;
/// final String readDuration;
///
/// @override
/// Widget build(BuildContext context) {
/// return Column(
/// crossAxisAlignment: CrossAxisAlignment.start,
/// children: <Widget>[
/// Expanded(
/// flex: 1,
/// child: Column(
/// crossAxisAlignment: CrossAxisAlignment.start,
/// children: <Widget>[
/// Text(
/// '$title',
/// maxLines: 2,
/// overflow: TextOverflow.ellipsis,
/// style: const TextStyle(
/// fontWeight: FontWeight.bold,
/// ),
/// ),
/// const Padding(padding: EdgeInsets.only(bottom: 2.0)),
/// Text(
/// '$subtitle',
/// maxLines: 2,
/// overflow: TextOverflow.ellipsis,
/// style: const TextStyle(
/// fontSize: 12.0,
/// color: Colors.black54,
/// ),
/// ),
/// ],
/// ),
/// ),
/// Expanded(
/// flex: 1,
/// child: Column(
/// crossAxisAlignment: CrossAxisAlignment.start,
/// mainAxisAlignment: MainAxisAlignment.end,
/// children: <Widget>[
/// Text(
/// '$author',
/// style: const TextStyle(
/// fontSize: 12.0,
/// color: Colors.black87,
/// ),
/// ),
/// Text(
/// '$publishDate - $readDuration',
/// style: const TextStyle(
/// fontSize: 12.0,
/// color: Colors.black54,
/// ),
/// ),
/// ],
/// ),
/// ),
/// ],
/// );
/// }
/// }
///
/// class CustomListItemTwo extends StatelessWidget {
/// CustomListItemTwo({
/// Key key,
/// this.thumbnail,
/// this.title,
/// this.subtitle,
/// this.author,
/// this.publishDate,
/// this.readDuration,
/// }) : super(key: key);
///
/// final Widget thumbnail;
/// final String title;
/// final String subtitle;
/// final String author;
/// final String publishDate;
/// final String readDuration;
///
/// @override
/// Widget build(BuildContext context) {
/// return Padding(
/// padding: const EdgeInsets.symmetric(vertical: 10.0),
/// child: SizedBox(
/// height: 100,
/// child: Row(
/// crossAxisAlignment: CrossAxisAlignment.start,
/// children: <Widget>[
/// AspectRatio(
/// aspectRatio: 1.0,
/// child: thumbnail,
/// ),
/// Expanded(
/// child: Padding(
/// padding: const EdgeInsets.fromLTRB(20.0, 0.0, 2.0, 0.0),
/// child: _ArticleDescription(
/// title: title,
/// subtitle: subtitle,
/// author: author,
/// publishDate: publishDate,
/// readDuration: readDuration,
/// ),
/// ),
/// )
/// ],
/// ),
/// ),
/// );
/// }
/// }
/// ```
///
/// ```dart
/// Widget build(BuildContext context) {
/// return ListView(
/// padding: const EdgeInsets.all(10.0),
/// children: <Widget>[
/// CustomListItemTwo(
/// thumbnail: Container(
/// decoration: const BoxDecoration(color: Colors.pink),
/// ),
/// title: 'Flutter 1.0 Launch',
/// subtitle:
/// 'Flutter continues to improve and expand its horizons.'
/// 'This text should max out at two lines and clip',
/// author: 'Dash',
/// publishDate: 'Dec 28',
/// readDuration: '5 mins',
/// ),
/// CustomListItemTwo(
/// thumbnail: Container(
/// decoration: const BoxDecoration(color: Colors.blue),
/// ),
/// title: 'Flutter 1.2 Release - Continual updates to the framework',
/// subtitle: 'Flutter once again improves and makes updates.',
/// author: 'Flutter',
/// publishDate: 'Feb 26',
/// readDuration: '12 mins',
/// ),
/// ],
/// );
/// }
/// ```
/// {@end-tool}
///
/// See also:
///
/// * [ListTileTheme], which defines visual properties for [ListTile]s.
/// * [ListView], which can display an arbitrary number of [ListTile]s
/// in a scrolling list.
/// * [CircleAvatar], which shows an icon representing a person and is often
/// used as the [leading] element of a ListTile.
/// * [Card], which can be used with [Column] to show a few [ListTile]s.
/// * [Divider], which can be used to separate [ListTile]s.
/// * [ListTile.divideTiles], a utility for inserting [Divider]s in between [ListTile]s.
/// * [CheckboxListTile], [RadioListTile], and [SwitchListTile], widgets
/// that combine [ListTile] with other controls.
/// * <https://material.io/design/components/lists.html>
class ListTile extends StatelessWidget {
/// Creates a list tile.
///
/// If [isThreeLine] is true, then [subtitle] must not be null.
///
/// Requires one of its ancestors to be a [Material] widget.
const ListTile({
Key key,
this.leading,
this.title,
this.subtitle,
this.trailing,
this.isThreeLine = false,
this.dense,
this.contentPadding,
this.enabled = true,
this.onTap,
this.onLongPress,
this.selected = false,
}) : assert(isThreeLine != null),
assert(enabled != null),
assert(selected != null),
assert(!isThreeLine || subtitle != null),
super(key: key);
/// A widget to display before the title.
///
/// Typically an [Icon] or a [CircleAvatar] widget.
final Widget leading;
/// The primary content of the list tile.
///
/// Typically a [Text] widget.
///
/// This should not wrap.
final Widget title;
/// Additional content displayed below the title.
///
/// Typically a [Text] widget.
///
/// If [isThreeLine] is false, this should not wrap.
///
/// If [isThreeLine] is true, this should be configured to take a maximum of
/// two lines.
final Widget subtitle;
/// A widget to display after the title.
///
/// Typically an [Icon] widget.
///
/// To show right-aligned metadata (assuming left-to-right reading order;
/// left-aligned for right-to-left reading order), consider using a [Row] with
/// [MainAxisAlign.baseline] alignment whose first item is [Expanded] and
/// whose second child is the metadata text, instead of using the [trailing]
/// property.
final Widget trailing;
/// Whether this list tile is intended to display three lines of text.
///
/// If true, then [subtitle] must be non-null (since it is expected to give
/// the second and third lines of text).
///
/// If false, the list tile is treated as having one line if the subtitle is
/// null and treated as having two lines if the subtitle is non-null.
final bool isThreeLine;
/// Whether this list tile is part of a vertically dense list.
///
/// If this property is null then its value is based on [ListTileTheme.dense].
///
/// Dense list tiles default to a smaller height.
final bool dense;
/// The tile's internal padding.
///
/// Insets a [ListTile]'s contents: its [leading], [title], [subtitle],
/// and [trailing] widgets.
///
/// If null, `EdgeInsets.symmetric(horizontal: 16.0)` is used.
final EdgeInsetsGeometry contentPadding;
/// Whether this list tile is interactive.
///
/// If false, this list tile is styled with the disabled color from the
/// current [Theme] and the [onTap] and [onLongPress] callbacks are
/// inoperative.
final bool enabled;
/// Called when the user taps this list tile.
///
/// Inoperative if [enabled] is false.
final GestureTapCallback onTap;
/// Called when the user long-presses on this list tile.
///
/// Inoperative if [enabled] is false.
final GestureLongPressCallback onLongPress;
/// If this tile is also [enabled] then icons and text are rendered with the same color.
///
/// By default the selected color is the theme's primary color. The selected color
/// can be overridden with a [ListTileTheme].
final bool selected;
/// Add a one pixel border in between each tile. If color isn't specified the
/// [ThemeData.dividerColor] of the context's [Theme] is used.
///
/// See also:
///
/// * [Divider], which you can use to obtain this effect manually.
static Iterable<Widget> divideTiles({ BuildContext context, @required Iterable<Widget> tiles, Color color }) sync* {
assert(tiles != null);
assert(color != null || context != null);
final Iterator<Widget> iterator = tiles.iterator;
final bool isNotEmpty = iterator.moveNext();
final Decoration decoration = BoxDecoration(
border: Border(
bottom: Divider.createBorderSide(context, color: color),
),
);
Widget tile = iterator.current;
while (iterator.moveNext()) {
yield DecoratedBox(
position: DecorationPosition.foreground,
decoration: decoration,
child: tile,
);
tile = iterator.current;
}
if (isNotEmpty)
yield tile;
}
Color _iconColor(ThemeData theme, ListTileTheme tileTheme) {
if (!enabled)
return theme.disabledColor;
if (selected && tileTheme?.selectedColor != null)
return tileTheme.selectedColor;
if (!selected && tileTheme?.iconColor != null)
return tileTheme.iconColor;
switch (theme.brightness) {
case Brightness.light:
return selected ? theme.primaryColor : Colors.black45;
case Brightness.dark:
return selected ? theme.accentColor : null; // null - use current icon theme color
}
assert(theme.brightness != null);
return null;
}
Color _textColor(ThemeData theme, ListTileTheme tileTheme, Color defaultColor) {
if (!enabled)
return theme.disabledColor;
if (selected && tileTheme?.selectedColor != null)
return tileTheme.selectedColor;
if (!selected && tileTheme?.textColor != null)
return tileTheme.textColor;
if (selected) {
switch (theme.brightness) {
case Brightness.light:
return theme.primaryColor;
case Brightness.dark:
return theme.accentColor;
}
}
return defaultColor;
}
bool _isDenseLayout(ListTileTheme tileTheme) {
return dense ?? tileTheme?.dense ?? false;
}
TextStyle _titleTextStyle(ThemeData theme, ListTileTheme tileTheme) {
TextStyle style;
if (tileTheme != null) {
switch (tileTheme.style) {
case ListTileStyle.drawer:
style = theme.textTheme.bodyText1;
break;
case ListTileStyle.list:
style = theme.textTheme.subtitle1;
break;
}
} else {
style = theme.textTheme.subtitle1;
}
final Color color = _textColor(theme, tileTheme, style.color);
return _isDenseLayout(tileTheme)
? style.copyWith(fontSize: 13.0, color: color)
: style.copyWith(color: color);
}
TextStyle _subtitleTextStyle(ThemeData theme, ListTileTheme tileTheme) {
final TextStyle style = theme.textTheme.bodyText2;
final Color color = _textColor(theme, tileTheme, theme.textTheme.caption.color);
return _isDenseLayout(tileTheme)
? style.copyWith(color: color, fontSize: 12.0)
: style.copyWith(color: color);
}
@override
Widget build(BuildContext context) {
assert(debugCheckHasMaterial(context));
final ThemeData theme = Theme.of(context);
final ListTileTheme tileTheme = ListTileTheme.of(context);
IconThemeData iconThemeData;
if (leading != null || trailing != null)
iconThemeData = IconThemeData(color: _iconColor(theme, tileTheme));
Widget leadingIcon;
if (leading != null) {
leadingIcon = IconTheme.merge(
data: iconThemeData,
child: leading,
);
}
final TextStyle titleStyle = _titleTextStyle(theme, tileTheme);
final Widget titleText = AnimatedDefaultTextStyle(
style: titleStyle,
duration: kThemeChangeDuration,
child: title ?? const SizedBox(),
);
Widget subtitleText;
TextStyle subtitleStyle;
if (subtitle != null) {
subtitleStyle = _subtitleTextStyle(theme, tileTheme);
subtitleText = AnimatedDefaultTextStyle(
style: subtitleStyle,
duration: kThemeChangeDuration,
child: subtitle,
);
}
Widget trailingIcon;
if (trailing != null) {
trailingIcon = IconTheme.merge(
data: iconThemeData,
child: trailing,
);
}
const EdgeInsets _defaultContentPadding = EdgeInsets.symmetric(horizontal: 16.0);
final TextDirection textDirection = Directionality.of(context);
final EdgeInsets resolvedContentPadding = contentPadding?.resolve(textDirection)
?? tileTheme?.contentPadding?.resolve(textDirection)
?? _defaultContentPadding;
return InkWell(
onTap: enabled ? onTap : null,
onLongPress: enabled ? onLongPress : null,
canRequestFocus: enabled,
child: Semantics(
selected: selected,
enabled: enabled,
child: SafeArea(
top: false,
bottom: false,
minimum: resolvedContentPadding,
child: _ListTile(
leading: leadingIcon,
title: titleText,
subtitle: subtitleText,
trailing: trailingIcon,
isDense: _isDenseLayout(tileTheme),
isThreeLine: isThreeLine,
textDirection: textDirection,
titleBaselineType: titleStyle.textBaseline,
subtitleBaselineType: subtitleStyle?.textBaseline,
),
),
),
);
}
}
// Identifies the children of a _ListTileElement.
enum _ListTileSlot {
leading,
title,
subtitle,
trailing,
}
class _ListTile extends RenderObjectWidget {
const _ListTile({
Key key,
this.leading,
this.title,
this.subtitle,
this.trailing,
@required this.isThreeLine,
@required this.isDense,
@required this.textDirection,
@required this.titleBaselineType,
this.subtitleBaselineType,
}) : assert(isThreeLine != null),
assert(isDense != null),
assert(textDirection != null),
assert(titleBaselineType != null),
super(key: key);
final Widget leading;
final Widget title;
final Widget subtitle;
final Widget trailing;
final bool isThreeLine;
final bool isDense;
final TextDirection textDirection;
final TextBaseline titleBaselineType;
final TextBaseline subtitleBaselineType;
@override
_ListTileElement createElement() => _ListTileElement(this);
@override
_RenderListTile createRenderObject(BuildContext context) {
return _RenderListTile(
isThreeLine: isThreeLine,
isDense: isDense,
textDirection: textDirection,
titleBaselineType: titleBaselineType,
subtitleBaselineType: subtitleBaselineType,
);
}
@override
void updateRenderObject(BuildContext context, _RenderListTile renderObject) {
renderObject
..isThreeLine = isThreeLine
..isDense = isDense
..textDirection = textDirection
..titleBaselineType = titleBaselineType
..subtitleBaselineType = subtitleBaselineType;
}
}
class _ListTileElement extends RenderObjectElement {
_ListTileElement(_ListTile widget) : super(widget);
final Map<_ListTileSlot, Element> slotToChild = <_ListTileSlot, Element>{};
final Map<Element, _ListTileSlot> childToSlot = <Element, _ListTileSlot>{};
@override
_ListTile get widget => super.widget as _ListTile;
@override
_RenderListTile get renderObject => super.renderObject as _RenderListTile;
@override
void visitChildren(ElementVisitor visitor) {
slotToChild.values.forEach(visitor);
}
@override
void forgetChild(Element child) {
assert(slotToChild.values.contains(child));
assert(childToSlot.keys.contains(child));
final _ListTileSlot slot = childToSlot[child];
childToSlot.remove(child);
slotToChild.remove(slot);
super.forgetChild(child);
}
void _mountChild(Widget widget, _ListTileSlot slot) {
final Element oldChild = slotToChild[slot];
final Element newChild = updateChild(oldChild, widget, slot);
if (oldChild != null) {
slotToChild.remove(slot);
childToSlot.remove(oldChild);
}
if (newChild != null) {
slotToChild[slot] = newChild;
childToSlot[newChild] = slot;
}
}
@override
void mount(Element parent, dynamic newSlot) {
super.mount(parent, newSlot);
_mountChild(widget.leading, _ListTileSlot.leading);
_mountChild(widget.title, _ListTileSlot.title);
_mountChild(widget.subtitle, _ListTileSlot.subtitle);
_mountChild(widget.trailing, _ListTileSlot.trailing);
}
void _updateChild(Widget widget, _ListTileSlot slot) {
final Element oldChild = slotToChild[slot];
final Element newChild = updateChild(oldChild, widget, slot);
if (oldChild != null) {
childToSlot.remove(oldChild);
slotToChild.remove(slot);
}
if (newChild != null) {
slotToChild[slot] = newChild;
childToSlot[newChild] = slot;
}
}
@override
void update(_ListTile newWidget) {
super.update(newWidget);
assert(widget == newWidget);
_updateChild(widget.leading, _ListTileSlot.leading);
_updateChild(widget.title, _ListTileSlot.title);
_updateChild(widget.subtitle, _ListTileSlot.subtitle);
_updateChild(widget.trailing, _ListTileSlot.trailing);
}
void _updateRenderObject(RenderBox child, _ListTileSlot slot) {
switch (slot) {
case _ListTileSlot.leading:
renderObject.leading = child;
break;
case _ListTileSlot.title:
renderObject.title = child;
break;
case _ListTileSlot.subtitle:
renderObject.subtitle = child;
break;
case _ListTileSlot.trailing:
renderObject.trailing = child;
break;
}
}
@override
void insertChildRenderObject(RenderObject child, dynamic slotValue) {
assert(child is RenderBox);
assert(slotValue is _ListTileSlot);
final _ListTileSlot slot = slotValue as _ListTileSlot;
_updateRenderObject(child as RenderBox, slot);
assert(renderObject.childToSlot.keys.contains(child));
assert(renderObject.slotToChild.keys.contains(slot));
}
@override
void removeChildRenderObject(RenderObject child) {
assert(child is RenderBox);
assert(renderObject.childToSlot.keys.contains(child));
_updateRenderObject(null, renderObject.childToSlot[child]);
assert(!renderObject.childToSlot.keys.contains(child));
assert(!renderObject.slotToChild.keys.contains(slot));
}
@override
void moveChildRenderObject(RenderObject child, dynamic slotValue) {
assert(false, 'not reachable');
}
}
class _RenderListTile extends RenderBox {
_RenderListTile({
@required bool isDense,
@required bool isThreeLine,
@required TextDirection textDirection,
@required TextBaseline titleBaselineType,
TextBaseline subtitleBaselineType,
}) : assert(isDense != null),
assert(isThreeLine != null),
assert(textDirection != null),
assert(titleBaselineType != null),
_isDense = isDense,
_isThreeLine = isThreeLine,
_textDirection = textDirection,
_titleBaselineType = titleBaselineType,
_subtitleBaselineType = subtitleBaselineType;
static const double _minLeadingWidth = 40.0;
// The horizontal gap between the titles and the leading/trailing widgets
static const double _horizontalTitleGap = 16.0;
// The minimum padding on the top and bottom of the title and subtitle widgets.
static const double _minVerticalPadding = 4.0;
final Map<_ListTileSlot, RenderBox> slotToChild = <_ListTileSlot, RenderBox>{};
final Map<RenderBox, _ListTileSlot> childToSlot = <RenderBox, _ListTileSlot>{};
RenderBox _updateChild(RenderBox oldChild, RenderBox newChild, _ListTileSlot slot) {
if (oldChild != null) {
dropChild(oldChild);
childToSlot.remove(oldChild);
slotToChild.remove(slot);
}
if (newChild != null) {
childToSlot[newChild] = slot;
slotToChild[slot] = newChild;
adoptChild(newChild);
}
return newChild;
}
RenderBox _leading;
RenderBox get leading => _leading;
set leading(RenderBox value) {
_leading = _updateChild(_leading, value, _ListTileSlot.leading);
}
RenderBox _title;
RenderBox get title => _title;
set title(RenderBox value) {
_title = _updateChild(_title, value, _ListTileSlot.title);
}
RenderBox _subtitle;
RenderBox get subtitle => _subtitle;
set subtitle(RenderBox value) {
_subtitle = _updateChild(_subtitle, value, _ListTileSlot.subtitle);
}
RenderBox _trailing;
RenderBox get trailing => _trailing;
set trailing(RenderBox value) {
_trailing = _updateChild(_trailing, value, _ListTileSlot.trailing);
}
// The returned list is ordered for hit testing.
Iterable<RenderBox> get _children sync* {
if (leading != null)
yield leading;
if (title != null)
yield title;
if (subtitle != null)
yield subtitle;
if (trailing != null)
yield trailing;
}
bool get isDense => _isDense;
bool _isDense;
set isDense(bool value) {
assert(value != null);
if (_isDense == value)
return;
_isDense = value;
markNeedsLayout();
}
bool get isThreeLine => _isThreeLine;
bool _isThreeLine;
set isThreeLine(bool value) {
assert(value != null);
if (_isThreeLine == value)
return;
_isThreeLine = value;
markNeedsLayout();
}
TextDirection get textDirection => _textDirection;
TextDirection _textDirection;
set textDirection(TextDirection value) {
assert(value != null);
if (_textDirection == value)
return;
_textDirection = value;
markNeedsLayout();
}
TextBaseline get titleBaselineType => _titleBaselineType;
TextBaseline _titleBaselineType;
set titleBaselineType(TextBaseline value) {
assert(value != null);
if (_titleBaselineType == value)
return;
_titleBaselineType = value;
markNeedsLayout();
}
TextBaseline get subtitleBaselineType => _subtitleBaselineType;
TextBaseline _subtitleBaselineType;
set subtitleBaselineType(TextBaseline value) {
if (_subtitleBaselineType == value)
return;
_subtitleBaselineType = value;
markNeedsLayout();
}
@override
void attach(PipelineOwner owner) {
super.attach(owner);
for (final RenderBox child in _children)
child.attach(owner);
}
@override
void detach() {
super.detach();
for (final RenderBox child in _children)
child.detach();
}
@override
void redepthChildren() {
_children.forEach(redepthChild);
}
@override
void visitChildren(RenderObjectVisitor visitor) {
_children.forEach(visitor);
}
@override
List<DiagnosticsNode> debugDescribeChildren() {
final List<DiagnosticsNode> value = <DiagnosticsNode>[];
void add(RenderBox child, String name) {
if (child != null)
value.add(child.toDiagnosticsNode(name: name));
}
add(leading, 'leading');
add(title, 'title');
add(subtitle, 'subtitle');
add(trailing, 'trailing');
return value;
}
@override
bool get sizedByParent => false;
static double _minWidth(RenderBox box, double height) {
return box == null ? 0.0 : box.getMinIntrinsicWidth(height);
}
static double _maxWidth(RenderBox box, double height) {
return box == null ? 0.0 : box.getMaxIntrinsicWidth(height);
}
@override
double computeMinIntrinsicWidth(double height) {
final double leadingWidth = leading != null
? math.max(leading.getMinIntrinsicWidth(height), _minLeadingWidth) + _horizontalTitleGap
: 0.0;
return leadingWidth
+ math.max(_minWidth(title, height), _minWidth(subtitle, height))
+ _maxWidth(trailing, height);
}
@override
double computeMaxIntrinsicWidth(double height) {
final double leadingWidth = leading != null
? math.max(leading.getMaxIntrinsicWidth(height), _minLeadingWidth) + _horizontalTitleGap
: 0.0;
return leadingWidth
+ math.max(_maxWidth(title, height), _maxWidth(subtitle, height))
+ _maxWidth(trailing, height);
}
double get _defaultTileHeight {
final bool hasSubtitle = subtitle != null;
final bool isTwoLine = !isThreeLine && hasSubtitle;
final bool isOneLine = !isThreeLine && !hasSubtitle;
if (isOneLine)
return isDense ? 48.0 : 56.0;
if (isTwoLine)
return isDense ? 64.0 : 72.0;
return isDense ? 76.0 : 88.0;
}
@override
double computeMinIntrinsicHeight(double width) {
return math.max(
_defaultTileHeight,
title.getMinIntrinsicHeight(width) + (subtitle?.getMinIntrinsicHeight(width) ?? 0.0),
);
}
@override
double computeMaxIntrinsicHeight(double width) {
return computeMinIntrinsicHeight(width);
}
@override
double computeDistanceToActualBaseline(TextBaseline baseline) {
assert(title != null);
final BoxParentData parentData = title.parentData as BoxParentData;
return parentData.offset.dy + title.getDistanceToActualBaseline(baseline);
}
static double _boxBaseline(RenderBox box, TextBaseline baseline) {
return box.getDistanceToBaseline(baseline);
}
static Size _layoutBox(RenderBox box, BoxConstraints constraints) {
if (box == null)
return Size.zero;
box.layout(constraints, parentUsesSize: true);
return box.size;
}
static void _positionBox(RenderBox box, Offset offset) {
final BoxParentData parentData = box.parentData as BoxParentData;
parentData.offset = offset;
}
// All of the dimensions below were taken from the Material Design spec:
// https://material.io/design/components/lists.html#specs
@override
void performLayout() {
final BoxConstraints constraints = this.constraints;
final bool hasLeading = leading != null;
final bool hasSubtitle = subtitle != null;
final bool hasTrailing = trailing != null;
final bool isTwoLine = !isThreeLine && hasSubtitle;
final bool isOneLine = !isThreeLine && !hasSubtitle;
final BoxConstraints maxIconHeightConstraint = BoxConstraints(
// One-line trailing and leading widget heights do not follow
// Material specifications, but this sizing is required to adhere
// to accessibility requirements for smallest tappable widget.
// Two- and three-line trailing widget heights are constrained
// properly according to the Material spec.
maxHeight: isDense ? 48.0 : 56.0,
);
final BoxConstraints looseConstraints = constraints.loosen();
final BoxConstraints iconConstraints = looseConstraints.enforce(maxIconHeightConstraint);
final double tileWidth = looseConstraints.maxWidth;
final Size leadingSize = _layoutBox(leading, iconConstraints);
final Size trailingSize = _layoutBox(trailing, iconConstraints);
assert(
tileWidth != leadingSize.width,
'Leading widget consumes entire tile width. Please use a sized widget.'
);
assert(
tileWidth != trailingSize.width,
'Trailing widget consumes entire tile width. Please use a sized widget.'
);
final double titleStart = hasLeading
? math.max(_minLeadingWidth, leadingSize.width) + _horizontalTitleGap
: 0.0;
final BoxConstraints textConstraints = looseConstraints.tighten(
width: tileWidth - titleStart - (hasTrailing ? trailingSize.width + _horizontalTitleGap : 0.0),
);
final Size titleSize = _layoutBox(title, textConstraints);
final Size subtitleSize = _layoutBox(subtitle, textConstraints);
double titleBaseline;
double subtitleBaseline;
if (isTwoLine) {
titleBaseline = isDense ? 28.0 : 32.0;
subtitleBaseline = isDense ? 48.0 : 52.0;
} else if (isThreeLine) {
titleBaseline = isDense ? 22.0 : 28.0;
subtitleBaseline = isDense ? 42.0 : 48.0;
} else {
assert(isOneLine);
}
final double defaultTileHeight = _defaultTileHeight;
double tileHeight;
double titleY;
double subtitleY;
if (!hasSubtitle) {
tileHeight = math.max(defaultTileHeight, titleSize.height + 2.0 * _minVerticalPadding);
titleY = (tileHeight - titleSize.height) / 2.0;
} else {
assert(subtitleBaselineType != null);
titleY = titleBaseline - _boxBaseline(title, titleBaselineType);
subtitleY = subtitleBaseline - _boxBaseline(subtitle, subtitleBaselineType);
tileHeight = defaultTileHeight;
// If the title and subtitle overlap, move the title upwards by half
// the overlap and the subtitle down by the same amount, and adjust
// tileHeight so that both titles fit.
final double titleOverlap = titleY + titleSize.height - subtitleY;
if (titleOverlap > 0.0) {
titleY -= titleOverlap / 2.0;
subtitleY += titleOverlap / 2.0;
}
// If the title or subtitle overflow tileHeight then punt: title
// and subtitle are arranged in a column, tileHeight = column height plus
// _minVerticalPadding on top and bottom.
if (titleY < _minVerticalPadding ||
(subtitleY + subtitleSize.height + _minVerticalPadding) > tileHeight) {
tileHeight = titleSize.height + subtitleSize.height + 2.0 * _minVerticalPadding;
titleY = _minVerticalPadding;
subtitleY = titleSize.height + _minVerticalPadding;
}
}
// This attempts to implement the redlines for the vertical position of the
// leading and trailing icons on the spec page:
// https://material.io/design/components/lists.html#specs
// The interpretation for these redlines is as follows:
// - For large tiles (> 72dp), both leading and trailing controls should be
// a fixed distance from top. As per guidelines this is set to 16dp.
// - For smaller tiles, trailing should always be centered. Leading can be
// centered or closer to the top. It should never be further than 16dp
// to the top.
double leadingY;
double trailingY;
if (tileHeight > 72.0) {
leadingY = 16.0;
trailingY = 16.0;
} else {
leadingY = math.min((tileHeight - leadingSize.height) / 2.0, 16.0);
trailingY = (tileHeight - trailingSize.height) / 2.0;
}
switch (textDirection) {
case TextDirection.rtl: {
if (hasLeading)
_positionBox(leading, Offset(tileWidth - leadingSize.width, leadingY));
final double titleX = hasTrailing ? trailingSize.width + _horizontalTitleGap : 0.0;
_positionBox(title, Offset(titleX, titleY));
if (hasSubtitle)
_positionBox(subtitle, Offset(titleX, subtitleY));
if (hasTrailing)
_positionBox(trailing, Offset(0.0, trailingY));
break;
}
case TextDirection.ltr: {
if (hasLeading)
_positionBox(leading, Offset(0.0, leadingY));
_positionBox(title, Offset(titleStart, titleY));
if (hasSubtitle)
_positionBox(subtitle, Offset(titleStart, subtitleY));
if (hasTrailing)
_positionBox(trailing, Offset(tileWidth - trailingSize.width, trailingY));
break;
}
}
size = constraints.constrain(Size(tileWidth, tileHeight));
assert(size.width == constraints.constrainWidth(tileWidth));
assert(size.height == constraints.constrainHeight(tileHeight));
}
@override
void paint(PaintingContext context, Offset offset) {
void doPaint(RenderBox child) {
if (child != null) {
final BoxParentData parentData = child.parentData as BoxParentData;
context.paintChild(child, parentData.offset + offset);
}
}
doPaint(leading);
doPaint(title);
doPaint(subtitle);
doPaint(trailing);
}
@override
bool hitTestSelf(Offset position) => true;
@override
bool hitTestChildren(BoxHitTestResult result, { @required Offset position }) {
assert(position != null);
for (final RenderBox child in _children) {
final BoxParentData parentData = child.parentData as BoxParentData;
final bool isHit = result.addWithPaintOffset(
offset: parentData.offset,
position: position,
hitTest: (BoxHitTestResult result, Offset transformed) {
assert(transformed == position - parentData.offset);
return child.hitTest(result, position: transformed);
},
);
if (isHit)
return true;
}
return false;
}
}