packages/flutter/lib/src/material/list_tile.dart - mirrors/flutter - Git at Google

 // 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) {
     TextStyle style;
     if (tileTheme != null) {
       switch (tileTheme.style) {
         case ListTileStyle.drawer:
           style = theme.textTheme.body2;
           break;
         case ListTileStyle.list:
           style = theme.textTheme.subhead;
           break;
       }
     } else {
       style = 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 ConstrainedBox(
         constraints: new BoxConstraints(minHeight: tileHeight),
         child: new Padding(
           padding: const EdgeInsets.symmetric(horizontal: 16.0),
           child: new UnconstrainedBox(
             constrainedAxis: Axis.horizontal,
             child: new Row(children: children),
           ),
         )
       ),
     );
   }
 }
	// 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) {
	TextStyle style;
	if (tileTheme != null) {
	switch (tileTheme.style) {
	case ListTileStyle.drawer:
	style = theme.textTheme.body2;
	break;
	case ListTileStyle.list:
	style = theme.textTheme.subhead;
	break;
	}
	} else {
	style = 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 ConstrainedBox(
	constraints: new BoxConstraints(minHeight: tileHeight),
	child: new Padding(
	padding: const EdgeInsets.symmetric(horizontal: 16.0),
	child: new UnconstrainedBox(
	constrainedAxis: Axis.horizontal,
	child: new Row(children: children),
	),
	)
	),
	);
	}
	}