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

 // 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 'package:flutter/widgets.dart';

 import 'list_tile.dart';
 import 'radio.dart';
 import 'theme.dart';
 import 'theme_data.dart';

 // Examples can assume:
 // void setState(VoidCallback fn) { }

 /// A [ListTile] with a [Radio]. In other words, a radio button with a label.
 ///
 /// The entire list tile is interactive: tapping anywhere in the tile selects
 /// the radio button.
 ///
 /// The [value], [groupValue], [onChanged], and [activeColor] properties of this
 /// widget are identical to the similarly-named properties on the [Radio]
 /// widget. The type parameter `T` serves the same purpose as that of the
 /// [Radio] class' type parameter.
 ///
 /// The [title], [subtitle], [isThreeLine], and [dense] properties are like
 /// those of the same name on [ListTile].
 ///
 /// The [selected] property on this widget is similar to the [ListTile.selected]
 /// property, but the color used is that described by [activeColor], if any,
 /// defaulting to the accent color of the current [Theme]. No effort is made to
 /// coordinate the [selected] state and the [checked] state; to have the list
 /// tile appear selected when the radio button is the selected radio button, set
 /// [selected] to true when [value] matches [groupValue].
 ///
 /// The radio button is shown on the left by default in left-to-right languages
 /// (i.e. the leading edge). This can be changed using [controlAffinity]. The
 /// [secondary] widget is placed on the opposite side. This maps to the
 /// [ListTile.leading] and [ListTile.trailing] properties of [ListTile].
 ///
 /// To show the [RadioListTile] as disabled, pass null as the [onChanged]
 /// callback.
 ///
 /// {@tool dartpad --template=stateful_widget_scaffold}
 ///
 /// ![RadioListTile sample](https://flutter.github.io/assets-for-api-docs/assets/material/radio_list_tile.png)
 ///
 /// This widget shows a pair of radio buttons that control the `_character`
 /// field. The field is of the type `SingingCharacter`, an enum.
 ///
 /// ```dart preamble
 /// enum SingingCharacter { lafayette, jefferson }
 /// ```
 /// ```dart
 /// SingingCharacter _character = SingingCharacter.lafayette;
 ///
 /// @override
 /// Widget build(BuildContext context) {
 ///   return Column(
 ///     children: <Widget>[
 ///       RadioListTile<SingingCharacter>(
 ///         title: const Text('Lafayette'),
 ///         value: SingingCharacter.lafayette,
 ///         groupValue: _character,
 ///         onChanged: (SingingCharacter value) { setState(() { _character = value; }); },
 ///       ),
 ///       RadioListTile<SingingCharacter>(
 ///         title: const Text('Thomas Jefferson'),
 ///         value: SingingCharacter.jefferson,
 ///         groupValue: _character,
 ///         onChanged: (SingingCharacter value) { setState(() { _character = value; }); },
 ///       ),
 ///     ],
 ///   );
 /// }
 /// ```
 /// {@end-tool}
 ///
 /// ## Semantics in RadioListTile
 ///
 /// Since the entirety of the RadioListTile is interactive, it should represent
 /// itself as a single interactive entity.
 ///
 /// To do so, a RadioListTile widget wraps its children with a [MergeSemantics]
 /// widget. [MergeSemantics] will attempt to merge its descendant [Semantics]
 /// nodes into one node in the semantics tree. Therefore, RadioListTile will
 /// throw an error if any of its children requires its own [Semantics] node.
 ///
 /// For example, you cannot nest a [RichText] widget as a descendant of
 /// RadioListTile. [RichText] has an embedded gesture recognizer that
 /// requires its own [Semantics] node, which directly conflicts with
 /// RadioListTile's desire to merge all its descendants' semantic nodes
 /// into one. Therefore, it may be necessary to create a custom radio tile
 /// widget to accommodate similar use cases.
 ///
 /// {@tool dartpad --template=stateful_widget_scaffold}
 ///
 /// ![Radio list tile semantics sample](https://flutter.github.io/assets-for-api-docs/assets/material/radio_list_tile_semantics.png)
 ///
 /// Here is an example of a custom labeled radio widget, called
 /// LinkedLabelRadio, that includes an interactive [RichText] widget that
 /// handles tap gestures.
 ///
 /// ```dart imports
 /// import 'package:flutter/gestures.dart';
 /// ```
 /// ```dart preamble
 /// class LinkedLabelRadio extends StatelessWidget {
 ///   const LinkedLabelRadio({
 ///     this.label,
 ///     this.padding,
 ///     this.groupValue,
 ///     this.value,
 ///     this.onChanged,
 ///   });
 ///
 ///   final String label;
 ///   final EdgeInsets padding;
 ///   final bool groupValue;
 ///   final bool value;
 ///   final Function onChanged;
 ///
 ///   @override
 ///   Widget build(BuildContext context) {
 ///     return Padding(
 ///       padding: padding,
 ///       child: Row(
 ///         children: <Widget>[
 ///           Radio<bool>(
 ///             groupValue: groupValue,
 ///             value: value,
 ///             onChanged: (bool newValue) {
 ///               onChanged(newValue);
 ///             }
 ///           ),
 ///           RichText(
 ///             text: TextSpan(
 ///               text: label,
 ///               style: TextStyle(
 ///                 color: Colors.blueAccent,
 ///                 decoration: TextDecoration.underline,
 ///               ),
 ///               recognizer: TapGestureRecognizer()
 ///                 ..onTap = () {
 ///                 print('Label has been tapped.');
 ///               },
 ///             ),
 ///           ),
 ///         ],
 ///       ),
 ///     );
 ///   }
 /// }
 /// ```
 /// ```dart
 /// bool _isRadioSelected = false;
 ///
 /// @override
 /// Widget build(BuildContext context) {
 ///   return Scaffold(
 ///     body: Column(
 ///       mainAxisAlignment: MainAxisAlignment.center,
 ///       children: <Widget>[
 ///         LinkedLabelRadio(
 ///           label: 'First tappable label text',
 ///           padding: EdgeInsets.symmetric(horizontal: 5.0),
 ///           value: true,
 ///           groupValue: _isRadioSelected,
 ///           onChanged: (bool newValue) {
 ///             setState(() {
 ///               _isRadioSelected = newValue;
 ///             });
 ///           },
 ///         ),
 ///         LinkedLabelRadio(
 ///           label: 'Second tappable label text',
 ///           padding: EdgeInsets.symmetric(horizontal: 5.0),
 ///           value: false,
 ///           groupValue: _isRadioSelected,
 ///           onChanged: (bool newValue) {
 ///             setState(() {
 ///               _isRadioSelected = newValue;
 ///             });
 ///           },
 ///         ),
 ///       ],
 ///     ),
 ///   );
 /// }
 /// ```
 /// {@end-tool}
 ///
 /// ## RadioListTile isn't exactly what I want
 ///
 /// If the way RadioListTile pads and positions its elements isn't quite what
 /// you're looking for, you can create custom labeled radio widgets by
 /// combining [Radio] with other widgets, such as [Text], [Padding] and
 /// [InkWell].
 ///
 /// {@tool dartpad --template=stateful_widget_scaffold}
 ///
 /// ![Custom radio list tile sample](https://flutter.github.io/assets-for-api-docs/assets/material/radio_list_tile_custom.png)
 ///
 /// Here is an example of a custom LabeledRadio widget, but you can easily
 /// make your own configurable widget.
 ///
 /// ```dart preamble
 /// class LabeledRadio extends StatelessWidget {
 ///   const LabeledRadio({
 ///     this.label,
 ///     this.padding,
 ///     this.groupValue,
 ///     this.value,
 ///     this.onChanged,
 ///   });
 ///
 ///   final String label;
 ///   final EdgeInsets padding;
 ///   final bool groupValue;
 ///   final bool value;
 ///   final Function onChanged;
 ///
 ///   @override
 ///   Widget build(BuildContext context) {
 ///     return InkWell(
 ///       onTap: () {
 ///         if (value != groupValue)
 ///           onChanged(value);
 ///       },
 ///       child: Padding(
 ///         padding: padding,
 ///         child: Row(
 ///           children: <Widget>[
 ///             Radio<bool>(
 ///               groupValue: groupValue,
 ///               value: value,
 ///               onChanged: (bool newValue) {
 ///                 onChanged(newValue);
 ///               },
 ///             ),
 ///             Text(label),
 ///           ],
 ///         ),
 ///       ),
 ///     );
 ///   }
 /// }
 /// ```
 /// ```dart
 /// bool _isRadioSelected = false;
 ///
 /// @override
 /// Widget build(BuildContext context) {
 ///   return Scaffold(
 ///     body: Column(
 ///       mainAxisAlignment: MainAxisAlignment.center,
 ///       children: <LabeledRadio>[
 ///         LabeledRadio(
 ///           label: 'This is the first label text',
 ///           padding: const EdgeInsets.symmetric(horizontal: 5.0),
 ///           value: true,
 ///           groupValue: _isRadioSelected,
 ///           onChanged: (bool newValue) {
 ///             setState(() {
 ///               _isRadioSelected = newValue;
 ///             });
 ///           },
 ///         ),
 ///         LabeledRadio(
 ///           label: 'This is the second label text',
 ///           padding: const EdgeInsets.symmetric(horizontal: 5.0),
 ///           value: false,
 ///           groupValue: _isRadioSelected,
 ///           onChanged: (bool newValue) {
 ///             setState(() {
 ///               _isRadioSelected = newValue;
 ///             });
 ///           },
 ///         ),
 ///       ],
 ///     ),
 ///   );
 /// }
 /// ```
 /// {@end-tool}
 ///
 /// See also:
 ///
 ///  * [ListTileTheme], which can be used to affect the style of list tiles,
 ///    including radio list tiles.
 ///  * [CheckboxListTile], a similar widget for checkboxes.
 ///  * [SwitchListTile], a similar widget for switches.
 ///  * [ListTile] and [Radio], the widgets from which this widget is made.
 class RadioListTile<T> extends StatelessWidget {
   /// Creates a combination of a list tile and a radio button.
   ///
   /// The radio tile itself does not maintain any state. Instead, when the radio
   /// button is selected, the widget calls the [onChanged] callback. Most
   /// widgets that use a radio button will listen for the [onChanged] callback
   /// and rebuild the radio tile with a new [groupValue] to update the visual
   /// appearance of the radio button.
   ///
   /// The following arguments are required:
   ///
   /// * [value] and [groupValue] together determine whether the radio button is
   ///   selected.
   /// * [onChanged] is called when the user selects this radio button.
   const RadioListTile({
     Key key,
     @required this.value,
     @required this.groupValue,
     @required this.onChanged,
     this.toggleable = false,
     this.activeColor,
     this.title,
     this.subtitle,
     this.isThreeLine = false,
     this.dense,
     this.secondary,
     this.selected = false,
     this.controlAffinity = ListTileControlAffinity.platform,

   }) : assert(toggleable != null),
        assert(isThreeLine != null),
        assert(!isThreeLine || subtitle != null),
        assert(selected != null),
        assert(controlAffinity != null),
        super(key: key);

   /// The value represented by this radio button.
   final T value;

   /// The currently selected value for this group of radio buttons.
   ///
   /// This radio button is considered selected if its [value] matches the
   /// [groupValue].
   final T groupValue;

   /// Called when the user selects this radio button.
   ///
   /// The radio button passes [value] as a parameter to this callback. The radio
   /// button does not actually change state until the parent widget rebuilds the
   /// radio tile with the new [groupValue].
   ///
   /// If null, the radio button will be displayed as disabled.
   ///
   /// The provided callback will not be invoked if this radio button is already
   /// selected.
   ///
   /// The callback provided to [onChanged] should update the state of the parent
   /// [StatefulWidget] using the [State.setState] method, so that the parent
   /// gets rebuilt; for example:
   ///
   /// ```dart
   /// RadioListTile<SingingCharacter>(
   ///   title: const Text('Lafayette'),
   ///   value: SingingCharacter.lafayette,
   ///   groupValue: _character,
   ///   onChanged: (SingingCharacter newValue) {
   ///     setState(() {
   ///       _character = newValue;
   ///     });
   ///   },
   /// )
   /// ```
   final ValueChanged<T> onChanged;

   /// Set to true if this radio list tile is allowed to be returned to an
   /// indeterminate state by selecting it again when selected.
   ///
   /// To indicate returning to an indeterminate state, [onChanged] will be
   /// called with null.
   ///
   /// If true, [onChanged] can be called with [value] when selected while
   /// [groupValue] != [value], or with null when selected again while
   /// [groupValue] == [value].
   ///
   /// If false, [onChanged] will be called with [value] when it is selected
   /// while [groupValue] != [value], and only by selecting another radio button
   /// in the group (i.e. changing the value of [groupValue]) can this radio
   /// list tile be unselected.
   ///
   /// The default is false.
   ///
   /// {@tool dartpad --template=stateful_widget_scaffold}
   /// This example shows how to enable deselecting a radio button by setting the
   /// [toggleable] attribute.
   ///
   /// ```dart
   /// int groupValue;
   /// static const List<String> selections = <String>[
   ///   'Hercules Mulligan',
   ///   'Eliza Hamilton',
   ///   'Philip Schuyler',
   ///   'Maria Reynolds',
   ///   'Samuel Seabury',
   /// ];
   ///
   /// @override
   /// Widget build(BuildContext context) {
   ///   return Scaffold(
   ///     body: ListView.builder(
   ///       itemBuilder: (context, index) {
   ///         return RadioListTile<int>(
   ///           value: index,
   ///           groupValue: groupValue,
   ///           toggleable: true,
   ///           title: Text(selections[index]),
   ///           onChanged: (int value) {
   ///             setState(() {
   ///               groupValue = value;
   ///             });
   ///           },
   ///         );
   ///       },
   ///       itemCount: selections.length,
   ///     ),
   ///   );
   /// }
   /// ```
   /// {@end-tool}
   final bool toggleable;

   /// The color to use when this radio button is selected.
   ///
   /// Defaults to accent color of the current [Theme].
   final Color activeColor;

   /// 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 on the opposite side of the tile from the radio button.
   ///
   /// Typically an [Icon] widget.
   final Widget secondary;

   /// 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 to render icons and text in the [activeColor].
   ///
   /// No effort is made to automatically coordinate the [selected] state and the
   /// [checked] state. To have the list tile appear selected when the radio
   /// button is the selected radio button, set [selected] to true when [value]
   /// matches [groupValue].
   ///
   /// Normally, this property is left to its default value, false.
   final bool selected;

   /// Where to place the control relative to the text.
   final ListTileControlAffinity controlAffinity;

   /// Whether this radio button is checked.
   ///
   /// To control this value, set [value] and [groupValue] appropriately.
   bool get checked => value == groupValue;

   @override
   Widget build(BuildContext context) {
     final Widget control = Radio<T>(
       value: value,
       groupValue: groupValue,
       onChanged: onChanged,
       toggleable: toggleable,
       activeColor: activeColor,
       materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
     );
     Widget leading, trailing;
     switch (controlAffinity) {
       case ListTileControlAffinity.leading:
       case ListTileControlAffinity.platform:
         leading = control;
         trailing = secondary;
         break;
       case ListTileControlAffinity.trailing:
         leading = secondary;
         trailing = control;
         break;
     }
     return MergeSemantics(
       child: ListTileTheme.merge(
         selectedColor: activeColor ?? Theme.of(context).accentColor,
         child: ListTile(
           leading: leading,
           title: title,
           subtitle: subtitle,
           trailing: trailing,
           isThreeLine: isThreeLine,
           dense: dense,
           enabled: onChanged != null,
           onTap: onChanged != null ? () {
             if (toggleable && checked) {
               onChanged(null);
               return;
             }
             if (!checked) {
               onChanged(value);
             }
           } : null,
           selected: selected,
         ),
       ),
     );
   }
 }
	// 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 'package:flutter/widgets.dart';

	import 'list_tile.dart';
	import 'radio.dart';
	import 'theme.dart';
	import 'theme_data.dart';

	// Examples can assume:
	// void setState(VoidCallback fn) { }

	/// A [ListTile] with a [Radio]. In other words, a radio button with a label.
	///
	/// The entire list tile is interactive: tapping anywhere in the tile selects
	/// the radio button.
	///
	/// The [value], [groupValue], [onChanged], and [activeColor] properties of this
	/// widget are identical to the similarly-named properties on the [Radio]
	/// widget. The type parameter `T` serves the same purpose as that of the
	/// [Radio] class' type parameter.
	///
	/// The [title], [subtitle], [isThreeLine], and [dense] properties are like
	/// those of the same name on [ListTile].
	///
	/// The [selected] property on this widget is similar to the [ListTile.selected]
	/// property, but the color used is that described by [activeColor], if any,
	/// defaulting to the accent color of the current [Theme]. No effort is made to
	/// coordinate the [selected] state and the [checked] state; to have the list
	/// tile appear selected when the radio button is the selected radio button, set
	/// [selected] to true when [value] matches [groupValue].
	///
	/// The radio button is shown on the left by default in left-to-right languages
	/// (i.e. the leading edge). This can be changed using [controlAffinity]. The
	/// [secondary] widget is placed on the opposite side. This maps to the
	/// [ListTile.leading] and [ListTile.trailing] properties of [ListTile].
	///
	/// To show the [RadioListTile] as disabled, pass null as the [onChanged]
	/// callback.
	///
	/// {@tool dartpad --template=stateful_widget_scaffold}
	///
	/// ![RadioListTile sample](https://flutter.github.io/assets-for-api-docs/assets/material/radio_list_tile.png)
	///
	/// This widget shows a pair of radio buttons that control the `_character`
	/// field. The field is of the type `SingingCharacter`, an enum.
	///
	/// ```dart preamble
	/// enum SingingCharacter { lafayette, jefferson }
	/// ```
	/// ```dart
	/// SingingCharacter _character = SingingCharacter.lafayette;
	///
	/// @override
	/// Widget build(BuildContext context) {
	/// return Column(
	/// children: <Widget>[
	/// RadioListTile<SingingCharacter>(
	/// title: const Text('Lafayette'),
	/// value: SingingCharacter.lafayette,
	/// groupValue: _character,
	/// onChanged: (SingingCharacter value) { setState(() { _character = value; }); },
	/// ),
	/// RadioListTile<SingingCharacter>(
	/// title: const Text('Thomas Jefferson'),
	/// value: SingingCharacter.jefferson,
	/// groupValue: _character,
	/// onChanged: (SingingCharacter value) { setState(() { _character = value; }); },
	/// ),
	/// ],
	/// );
	/// }
	/// ```
	/// {@end-tool}
	///
	/// ## Semantics in RadioListTile
	///
	/// Since the entirety of the RadioListTile is interactive, it should represent
	/// itself as a single interactive entity.
	///
	/// To do so, a RadioListTile widget wraps its children with a [MergeSemantics]
	/// widget. [MergeSemantics] will attempt to merge its descendant [Semantics]
	/// nodes into one node in the semantics tree. Therefore, RadioListTile will
	/// throw an error if any of its children requires its own [Semantics] node.
	///
	/// For example, you cannot nest a [RichText] widget as a descendant of
	/// RadioListTile. [RichText] has an embedded gesture recognizer that
	/// requires its own [Semantics] node, which directly conflicts with
	/// RadioListTile's desire to merge all its descendants' semantic nodes
	/// into one. Therefore, it may be necessary to create a custom radio tile
	/// widget to accommodate similar use cases.
	///
	/// {@tool dartpad --template=stateful_widget_scaffold}
	///
	/// ![Radio list tile semantics sample](https://flutter.github.io/assets-for-api-docs/assets/material/radio_list_tile_semantics.png)
	///
	/// Here is an example of a custom labeled radio widget, called
	/// LinkedLabelRadio, that includes an interactive [RichText] widget that
	/// handles tap gestures.
	///
	/// ```dart imports
	/// import 'package:flutter/gestures.dart';
	/// ```
	/// ```dart preamble
	/// class LinkedLabelRadio extends StatelessWidget {
	/// const LinkedLabelRadio({
	/// this.label,
	/// this.padding,
	/// this.groupValue,
	/// this.value,
	/// this.onChanged,
	/// });
	///
	/// final String label;
	/// final EdgeInsets padding;
	/// final bool groupValue;
	/// final bool value;
	/// final Function onChanged;
	///
	/// @override
	/// Widget build(BuildContext context) {
	/// return Padding(
	/// padding: padding,
	/// child: Row(
	/// children: <Widget>[
	/// Radio<bool>(
	/// groupValue: groupValue,
	/// value: value,
	/// onChanged: (bool newValue) {
	/// onChanged(newValue);
	/// }
	/// ),
	/// RichText(
	/// text: TextSpan(
	/// text: label,
	/// style: TextStyle(
	/// color: Colors.blueAccent,
	/// decoration: TextDecoration.underline,
	/// ),
	/// recognizer: TapGestureRecognizer()
	/// ..onTap = () {
	/// print('Label has been tapped.');
	/// },
	/// ),
	/// ),
	/// ],
	/// ),
	/// );
	/// }
	/// }
	/// ```
	/// ```dart
	/// bool _isRadioSelected = false;
	///
	/// @override
	/// Widget build(BuildContext context) {
	/// return Scaffold(
	/// body: Column(
	/// mainAxisAlignment: MainAxisAlignment.center,
	/// children: <Widget>[
	/// LinkedLabelRadio(
	/// label: 'First tappable label text',
	/// padding: EdgeInsets.symmetric(horizontal: 5.0),
	/// value: true,
	/// groupValue: _isRadioSelected,
	/// onChanged: (bool newValue) {
	/// setState(() {
	/// _isRadioSelected = newValue;
	/// });
	/// },
	/// ),
	/// LinkedLabelRadio(
	/// label: 'Second tappable label text',
	/// padding: EdgeInsets.symmetric(horizontal: 5.0),
	/// value: false,
	/// groupValue: _isRadioSelected,
	/// onChanged: (bool newValue) {
	/// setState(() {
	/// _isRadioSelected = newValue;
	/// });
	/// },
	/// ),
	/// ],
	/// ),
	/// );
	/// }
	/// ```
	/// {@end-tool}
	///
	/// ## RadioListTile isn't exactly what I want
	///
	/// If the way RadioListTile pads and positions its elements isn't quite what
	/// you're looking for, you can create custom labeled radio widgets by
	/// combining [Radio] with other widgets, such as [Text], [Padding] and
	/// [InkWell].
	///
	/// {@tool dartpad --template=stateful_widget_scaffold}
	///
	/// ![Custom radio list tile sample](https://flutter.github.io/assets-for-api-docs/assets/material/radio_list_tile_custom.png)
	///
	/// Here is an example of a custom LabeledRadio widget, but you can easily
	/// make your own configurable widget.
	///
	/// ```dart preamble
	/// class LabeledRadio extends StatelessWidget {
	/// const LabeledRadio({
	/// this.label,
	/// this.padding,
	/// this.groupValue,
	/// this.value,
	/// this.onChanged,
	/// });
	///
	/// final String label;
	/// final EdgeInsets padding;
	/// final bool groupValue;
	/// final bool value;
	/// final Function onChanged;
	///
	/// @override
	/// Widget build(BuildContext context) {
	/// return InkWell(
	/// onTap: () {
	/// if (value != groupValue)
	/// onChanged(value);
	/// },
	/// child: Padding(
	/// padding: padding,
	/// child: Row(
	/// children: <Widget>[
	/// Radio<bool>(
	/// groupValue: groupValue,
	/// value: value,
	/// onChanged: (bool newValue) {
	/// onChanged(newValue);
	/// },
	/// ),
	/// Text(label),
	/// ],
	/// ),
	/// ),
	/// );
	/// }
	/// }
	/// ```
	/// ```dart
	/// bool _isRadioSelected = false;
	///
	/// @override
	/// Widget build(BuildContext context) {
	/// return Scaffold(
	/// body: Column(
	/// mainAxisAlignment: MainAxisAlignment.center,
	/// children: <LabeledRadio>[
	/// LabeledRadio(
	/// label: 'This is the first label text',
	/// padding: const EdgeInsets.symmetric(horizontal: 5.0),
	/// value: true,
	/// groupValue: _isRadioSelected,
	/// onChanged: (bool newValue) {
	/// setState(() {
	/// _isRadioSelected = newValue;
	/// });
	/// },
	/// ),
	/// LabeledRadio(
	/// label: 'This is the second label text',
	/// padding: const EdgeInsets.symmetric(horizontal: 5.0),
	/// value: false,
	/// groupValue: _isRadioSelected,
	/// onChanged: (bool newValue) {
	/// setState(() {
	/// _isRadioSelected = newValue;
	/// });
	/// },
	/// ),
	/// ],
	/// ),
	/// );
	/// }
	/// ```
	/// {@end-tool}
	///
	/// See also:
	///
	/// * [ListTileTheme], which can be used to affect the style of list tiles,
	/// including radio list tiles.
	/// * [CheckboxListTile], a similar widget for checkboxes.
	/// * [SwitchListTile], a similar widget for switches.
	/// * [ListTile] and [Radio], the widgets from which this widget is made.
	class RadioListTile<T> extends StatelessWidget {
	/// Creates a combination of a list tile and a radio button.
	///
	/// The radio tile itself does not maintain any state. Instead, when the radio
	/// button is selected, the widget calls the [onChanged] callback. Most
	/// widgets that use a radio button will listen for the [onChanged] callback
	/// and rebuild the radio tile with a new [groupValue] to update the visual
	/// appearance of the radio button.
	///
	/// The following arguments are required:
	///
	/// * [value] and [groupValue] together determine whether the radio button is
	/// selected.
	/// * [onChanged] is called when the user selects this radio button.
	const RadioListTile({
	Key key,
	@required this.value,
	@required this.groupValue,
	@required this.onChanged,
	this.toggleable = false,
	this.activeColor,
	this.title,
	this.subtitle,
	this.isThreeLine = false,
	this.dense,
	this.secondary,
	this.selected = false,
	this.controlAffinity = ListTileControlAffinity.platform,

	}) : assert(toggleable != null),
	assert(isThreeLine != null),
	assert(!isThreeLine \|\| subtitle != null),
	assert(selected != null),
	assert(controlAffinity != null),
	super(key: key);

	/// The value represented by this radio button.
	final T value;

	/// The currently selected value for this group of radio buttons.
	///
	/// This radio button is considered selected if its [value] matches the
	/// [groupValue].
	final T groupValue;

	/// Called when the user selects this radio button.
	///
	/// The radio button passes [value] as a parameter to this callback. The radio
	/// button does not actually change state until the parent widget rebuilds the
	/// radio tile with the new [groupValue].
	///
	/// If null, the radio button will be displayed as disabled.
	///
	/// The provided callback will not be invoked if this radio button is already
	/// selected.
	///
	/// The callback provided to [onChanged] should update the state of the parent
	/// [StatefulWidget] using the [State.setState] method, so that the parent
	/// gets rebuilt; for example:
	///
	/// ```dart
	/// RadioListTile<SingingCharacter>(
	/// title: const Text('Lafayette'),
	/// value: SingingCharacter.lafayette,
	/// groupValue: _character,
	/// onChanged: (SingingCharacter newValue) {
	/// setState(() {
	/// _character = newValue;
	/// });
	/// },
	/// )
	/// ```
	final ValueChanged<T> onChanged;

	/// Set to true if this radio list tile is allowed to be returned to an
	/// indeterminate state by selecting it again when selected.
	///
	/// To indicate returning to an indeterminate state, [onChanged] will be
	/// called with null.
	///
	/// If true, [onChanged] can be called with [value] when selected while
	/// [groupValue] != [value], or with null when selected again while
	/// [groupValue] == [value].
	///
	/// If false, [onChanged] will be called with [value] when it is selected
	/// while [groupValue] != [value], and only by selecting another radio button
	/// in the group (i.e. changing the value of [groupValue]) can this radio
	/// list tile be unselected.
	///
	/// The default is false.
	///
	/// {@tool dartpad --template=stateful_widget_scaffold}
	/// This example shows how to enable deselecting a radio button by setting the
	/// [toggleable] attribute.
	///
	/// ```dart
	/// int groupValue;
	/// static const List<String> selections = <String>[
	/// 'Hercules Mulligan',
	/// 'Eliza Hamilton',
	/// 'Philip Schuyler',
	/// 'Maria Reynolds',
	/// 'Samuel Seabury',
	/// ];
	///
	/// @override
	/// Widget build(BuildContext context) {
	/// return Scaffold(
	/// body: ListView.builder(
	/// itemBuilder: (context, index) {
	/// return RadioListTile<int>(
	/// value: index,
	/// groupValue: groupValue,
	/// toggleable: true,
	/// title: Text(selections[index]),
	/// onChanged: (int value) {
	/// setState(() {
	/// groupValue = value;
	/// });
	/// },
	/// );
	/// },
	/// itemCount: selections.length,
	/// ),
	/// );
	/// }
	/// ```
	/// {@end-tool}
	final bool toggleable;

	/// The color to use when this radio button is selected.
	///
	/// Defaults to accent color of the current [Theme].
	final Color activeColor;

	/// 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 on the opposite side of the tile from the radio button.
	///
	/// Typically an [Icon] widget.
	final Widget secondary;

	/// 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 to render icons and text in the [activeColor].
	///
	/// No effort is made to automatically coordinate the [selected] state and the
	/// [checked] state. To have the list tile appear selected when the radio
	/// button is the selected radio button, set [selected] to true when [value]
	/// matches [groupValue].
	///
	/// Normally, this property is left to its default value, false.
	final bool selected;

	/// Where to place the control relative to the text.
	final ListTileControlAffinity controlAffinity;

	/// Whether this radio button is checked.
	///
	/// To control this value, set [value] and [groupValue] appropriately.
	bool get checked => value == groupValue;

	@override
	Widget build(BuildContext context) {
	final Widget control = Radio<T>(
	value: value,
	groupValue: groupValue,
	onChanged: onChanged,
	toggleable: toggleable,
	activeColor: activeColor,
	materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
	);
	Widget leading, trailing;
	switch (controlAffinity) {
	case ListTileControlAffinity.leading:
	case ListTileControlAffinity.platform:
	leading = control;
	trailing = secondary;
	break;
	case ListTileControlAffinity.trailing:
	leading = secondary;
	trailing = control;
	break;
	}
	return MergeSemantics(
	child: ListTileTheme.merge(
	selectedColor: activeColor ?? Theme.of(context).accentColor,
	child: ListTile(
	leading: leading,
	title: title,
	subtitle: subtitle,
	trailing: trailing,
	isThreeLine: isThreeLine,
	dense: dense,
	enabled: onChanged != null,
	onTap: onChanged != null ? () {
	if (toggleable && checked) {
	onChanged(null);
	return;
	}
	if (!checked) {
	onChanged(value);
	}
	} : null,
	selected: selected,
	),
	),
	);
	}
	}