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// Copyright 2015 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/foundation.dart';
import 'package:flutter/widgets.dart';
import 'colors.dart';
import 'constants.dart';
import 'debug.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.body2]
/// text style, which is a little smaller than the theme's [TextTheme.subhead]
/// 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 InheritedWidget {
/// 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,
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,
@required Widget child,
}) {
assert(child != null);
return new Builder(
builder: (BuildContext context) {
final ListTileTheme parent = ListTileTheme.of(context);
return new ListTileTheme(
key: key,
dense: dense ?? parent.dense,
style: style ?? parent.style,
selectedColor: selectedColor ?? parent.selectedColor,
iconColor: iconColor ?? parent.iconColor,
textColor: textColor ?? parent.textColor,
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 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.inheritFromWidgetOfExactType(ListTileTheme);
return result ?? const ListTileTheme();
}
@override
bool updateShouldNotify(ListTileTheme oldTheme) {
return dense != oldTheme.dense
|| style != oldTheme.style
|| selectedColor != oldTheme.selectedColor
|| iconColor != oldTheme.iconColor
|| textColor != oldTheme.textColor;
}
}
/// 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.
///
/// 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.
///
/// List tiles are always a fixed height (which height depends on how
/// [isThreeLine], [dense], and [subtitle] are configured); they do not grow in
/// height based on their contents. If you are looking for a widget that allows
/// for arbitrary layout in a row, consider [Row].
///
/// 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.
///
/// ## Sample code
///
/// Here is a simple tile with an icon and some text.
///
/// ```dart
/// new ListTile(
/// leading: const Icon(Icons.event_seat),
/// title: const Text('The seat for the narrator'),
/// )
/// ```
///
/// 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;
/// // ...
/// new 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 */ }
/// )
/// ```
///
/// 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.google.com/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.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.
final Widget title;
/// Additional content displayed below the title.
///
/// Typically a [Text] widget.
final Widget subtitle;
/// A widget to display after the title.
///
/// Typically an [Icon] widget.
final Widget trailing;
/// Whether this list tile is intended to display three 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].
final bool dense;
/// 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 Color dividerColor = color ?? Theme.of(context).dividerColor;
final Iterator<Widget> iterator = tiles.iterator;
final bool isNotEmpty = iterator.moveNext();
Widget tile = iterator.current;
while (iterator.moveNext()) {
yield new DecoratedBox(
position: DecorationPosition.foreground,
decoration: new BoxDecoration(
border: new Border(
bottom: new BorderSide(color: dividerColor, width: 0.0),
),
),
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 _denseLayout(ListTileTheme tileTheme) {
return dense != null ? dense : (tileTheme?.dense ?? false);
}
TextStyle _titleTextStyle(ThemeData theme, ListTileTheme tileTheme) {
final TextStyle style = tileTheme?.style == ListTileStyle.drawer
? theme.textTheme.body2
: theme.textTheme.subhead;
final Color color = _textColor(theme, tileTheme, style.color);
return _denseLayout(tileTheme)
? style.copyWith(fontSize: 13.0, color: color)
: style.copyWith(color: color);
}
TextStyle _subtitleTextStyle(ThemeData theme, ListTileTheme tileTheme) {
final TextStyle style = theme.textTheme.body1;
final Color color = _textColor(theme, tileTheme, theme.textTheme.caption.color);
return _denseLayout(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);
final bool isTwoLine = !isThreeLine && subtitle != null;
final bool isOneLine = !isThreeLine && !isTwoLine;
double tileHeight;
if (isOneLine)
tileHeight = _denseLayout(tileTheme) ? 48.0 : 56.0;
else if (isTwoLine)
tileHeight = _denseLayout(tileTheme) ? 60.0 : 72.0;
else
tileHeight = _denseLayout(tileTheme) ? 76.0 : 88.0;
// Overall, the list tile is a Row() with these children.
final List<Widget> children = <Widget>[];
IconThemeData iconThemeData;
if (leading != null || trailing != null)
iconThemeData = new IconThemeData(color: _iconColor(theme, tileTheme));
if (leading != null) {
children.add(IconTheme.merge(
data: iconThemeData,
child: new Container(
margin: const EdgeInsetsDirectional.only(end: 16.0),
width: 40.0,
alignment: AlignmentDirectional.centerStart,
child: leading,
),
));
}
final Widget primaryLine = new AnimatedDefaultTextStyle(
style: _titleTextStyle(theme, tileTheme),
duration: kThemeChangeDuration,
child: title ?? new Container()
);
Widget center = primaryLine;
if (subtitle != null && (isTwoLine || isThreeLine)) {
center = new Column(
mainAxisSize: MainAxisSize.min,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
primaryLine,
new AnimatedDefaultTextStyle(
style: _subtitleTextStyle(theme, tileTheme),
duration: kThemeChangeDuration,
child: subtitle,
),
],
);
}
children.add(new Expanded(
child: center,
));
if (trailing != null) {
children.add(IconTheme.merge(
data: iconThemeData,
child: new Container(
margin: const EdgeInsetsDirectional.only(start: 16.0),
alignment: AlignmentDirectional.centerEnd,
child: trailing,
),
));
}
return new InkWell(
onTap: enabled ? onTap : null,
onLongPress: enabled ? onLongPress : null,
child: new Container(
height: tileHeight,
padding: const EdgeInsets.symmetric(horizontal: 16.0),
child: new Row(children: children),
)
);
}
}