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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 'package:flutter/widgets.dart';
import 'list_tile.dart';
import 'switch.dart';
import 'theme.dart';
import 'theme_data.dart';
// Examples can assume:
// void setState(VoidCallback fn) { }
// bool _isSelected;
enum _SwitchListTileType { material, adaptive }
/// A [ListTile] with a [Switch]. In other words, a switch with a label.
///
/// The entire list tile is interactive: tapping anywhere in the tile toggles
/// the switch. Tapping and dragging the [Switch] also triggers the [onChanged]
/// callback.
///
/// To ensure that [onChanged] correctly triggers, the state passed
/// into [value] must be properly managed. This is typically done by invoking
/// [State.setState] in [onChanged] to toggle the state value.
///
/// The [value], [onChanged], [activeColor], [activeThumbImage], and
/// [inactiveThumbImage] properties of this widget are identical to the
/// similarly-named properties on the [Switch] widget.
///
/// 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 [value] state; to have the list tile
/// appear selected when the switch is on, pass the same value to both.
///
/// The switch is shown on the right by default in left-to-right languages (i.e.
/// in the [ListTile.trailing] slot). The [secondary] widget is placed in the
/// [ListTile.leading] slot. This cannot be changed; there is not sufficient
/// space in a [ListTile]'s [ListTile.leading] slot for a [Switch].
///
/// To show the [SwitchListTile] as disabled, pass null as the [onChanged]
/// callback.
///
/// {@tool dartpad --template=stateful_widget_scaffold_center}
///
/// ![SwitchListTile sample](https://flutter.github.io/assets-for-api-docs/assets/material/switch_list_tile.png)
///
/// This widget shows a switch that, when toggled, changes the state of a [bool]
/// member field called `_lights`.
///
/// ```dart
/// bool _lights = false;
///
/// @override
/// Widget build(BuildContext context) {
/// return SwitchListTile(
/// title: const Text('Lights'),
/// value: _lights,
/// onChanged: (bool value) { setState(() { _lights = value; }); },
/// secondary: const Icon(Icons.lightbulb_outline),
/// );
/// }
/// ```
/// {@end-tool}
///
/// ## Semantics in SwitchListTile
///
/// Since the entirety of the SwitchListTile is interactive, it should represent
/// itself as a single interactive entity.
///
/// To do so, a SwitchListTile 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, SwitchListTile 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
/// SwitchListTile. [RichText] has an embedded gesture recognizer that
/// requires its own [Semantics] node, which directly conflicts with
/// SwitchListTile'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_center}
///
/// ![Switch list tile semantics sample](https://flutter.github.io/assets-for-api-docs/assets/material/switch_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 LinkedLabelSwitch extends StatelessWidget {
/// const LinkedLabelSwitch({
/// this.label,
/// this.padding,
/// this.value,
/// this.onChanged,
/// });
///
/// final String label;
/// final EdgeInsets padding;
/// final bool value;
/// final Function onChanged;
///
/// @override
/// Widget build(BuildContext context) {
/// return Padding(
/// padding: padding,
/// child: Row(
/// children: <Widget>[
/// Expanded(
/// child: RichText(
/// text: TextSpan(
/// text: label,
/// style: TextStyle(
/// color: Colors.blueAccent,
/// decoration: TextDecoration.underline,
/// ),
/// recognizer: TapGestureRecognizer()
/// ..onTap = () {
/// print('Label has been tapped.');
/// },
/// ),
/// ),
/// ),
/// Switch(
/// value: value,
/// onChanged: (bool newValue) {
/// onChanged(newValue);
/// },
/// ),
/// ],
/// ),
/// );
/// }
/// }
/// ```
/// ```dart
/// bool _isSelected = false;
///
/// @override
/// Widget build(BuildContext context) {
/// return LinkedLabelSwitch(
/// label: 'Linked, tappable label text',
/// padding: const EdgeInsets.symmetric(horizontal: 20.0),
/// value: _isSelected,
/// onChanged: (bool newValue) {
/// setState(() {
/// _isSelected = newValue;
/// });
/// },
/// );
/// }
/// ```
/// {@end-tool}
///
/// ## SwitchListTile isn't exactly what I want
///
/// If the way SwitchListTile pads and positions its elements isn't quite what
/// you're looking for, you can create custom labeled switch widgets by
/// combining [Switch] with other widgets, such as [Text], [Padding] and
/// [InkWell].
///
/// {@tool dartpad --template=stateful_widget_scaffold_center}
///
/// ![Custom switch list tile sample](https://flutter.github.io/assets-for-api-docs/assets/material/switch_list_tile_custom.png)
///
/// Here is an example of a custom LabeledSwitch widget, but you can easily
/// make your own configurable widget.
///
/// ```dart preamble
/// class LabeledSwitch extends StatelessWidget {
/// const LabeledSwitch({
/// 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: () {
/// onChanged(!value);
/// },
/// child: Padding(
/// padding: padding,
/// child: Row(
/// children: <Widget>[
/// Expanded(child: Text(label)),
/// Switch(
/// value: value,
/// onChanged: (bool newValue) {
/// onChanged(newValue);
/// },
/// ),
/// ],
/// ),
/// ),
/// );
/// }
/// }
/// ```
/// ```dart
/// bool _isSelected = false;
///
/// @override
/// Widget build(BuildContext context) {
/// return LabeledSwitch(
/// label: 'This is the label text',
/// padding: const EdgeInsets.symmetric(horizontal: 20.0),
/// value: _isSelected,
/// onChanged: (bool newValue) {
/// setState(() {
/// _isSelected = newValue;
/// });
/// },
/// );
/// }
/// ```
/// {@end-tool}
///
/// See also:
///
/// * [ListTileTheme], which can be used to affect the style of list tiles,
/// including switch list tiles.
/// * [CheckboxListTile], a similar widget for checkboxes.
/// * [RadioListTile], a similar widget for radio buttons.
/// * [ListTile] and [Switch], the widgets from which this widget is made.
class SwitchListTile extends StatelessWidget {
/// Creates a combination of a list tile and a switch.
///
/// The switch tile itself does not maintain any state. Instead, when the
/// state of the switch changes, the widget calls the [onChanged] callback.
/// Most widgets that use a switch will listen for the [onChanged] callback
/// and rebuild the switch tile with a new [value] to update the visual
/// appearance of the switch.
///
/// The following arguments are required:
///
/// * [value] determines whether this switch is on or off.
/// * [onChanged] is called when the user toggles the switch on or off.
const SwitchListTile({
Key key,
@required this.value,
@required this.onChanged,
this.activeColor,
this.activeTrackColor,
this.inactiveThumbColor,
this.inactiveTrackColor,
this.activeThumbImage,
this.inactiveThumbImage,
this.title,
this.subtitle,
this.isThreeLine = false,
this.dense,
this.contentPadding,
this.secondary,
this.selected = false,
}) : _switchListTileType = _SwitchListTileType.material,
assert(value != null),
assert(isThreeLine != null),
assert(!isThreeLine || subtitle != null),
assert(selected != null),
super(key: key);
/// Creates the wrapped switch with [Switch.adaptive].
///
/// Creates a [CupertinoSwitch] if the target platform is iOS, creates a
/// material design switch otherwise.
///
/// If a [CupertinoSwitch] is created, the following parameters are
/// ignored: [activeTrackColor], [inactiveThumbColor], [inactiveTrackColor],
/// [activeThumbImage], [inactiveThumbImage], [materialTapTargetSize].
const SwitchListTile.adaptive({
Key key,
@required this.value,
@required this.onChanged,
this.activeColor,
this.activeTrackColor,
this.inactiveThumbColor,
this.inactiveTrackColor,
this.activeThumbImage,
this.inactiveThumbImage,
this.title,
this.subtitle,
this.isThreeLine = false,
this.dense,
this.contentPadding,
this.secondary,
this.selected = false,
}) : _switchListTileType = _SwitchListTileType.adaptive,
assert(value != null),
assert(isThreeLine != null),
assert(!isThreeLine || subtitle != null),
assert(selected != null),
super(key: key);
/// Whether this switch is checked.
///
/// This property must not be null.
final bool value;
/// Called when the user toggles the switch on or off.
///
/// The switch passes the new value to the callback but does not actually
/// change state until the parent widget rebuilds the switch tile with the
/// new value.
///
/// If null, the switch will be displayed as disabled.
///
/// 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
/// SwitchListTile(
/// value: _isSelected,
/// onChanged: (bool newValue) {
/// setState(() {
/// _isSelected = newValue;
/// });
/// },
/// title: Text('Selection'),
/// )
/// ```
final ValueChanged<bool> onChanged;
/// The color to use when this switch is on.
///
/// Defaults to accent color of the current [Theme].
final Color activeColor;
/// The color to use on the track when this switch is on.
///
/// Defaults to [ThemeData.toggleableActiveColor] with the opacity set at 50%.
///
/// Ignored if created with [SwitchListTile.adaptive].
final Color activeTrackColor;
/// The color to use on the thumb when this switch is off.
///
/// Defaults to the colors described in the Material design specification.
///
/// Ignored if created with [SwitchListTile.adaptive].
final Color inactiveThumbColor;
/// The color to use on the track when this switch is off.
///
/// Defaults to the colors described in the Material design specification.
///
/// Ignored if created with [SwitchListTile.adaptive].
final Color inactiveTrackColor;
/// An image to use on the thumb of this switch when the switch is on.
final ImageProvider activeThumbImage;
/// An image to use on the thumb of this switch when the switch is off.
///
/// Ignored if created with [SwitchListTile.adaptive].
final ImageProvider inactiveThumbImage;
/// 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 switch.
///
/// 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;
/// The tile's internal padding.
///
/// Insets a [SwitchListTile]'s contents: its [title], [subtitle],
/// [secondary], and [Switch] widgets.
///
/// If null, [ListTile]'s default of `EdgeInsets.symmetric(horizontal: 16.0)`
/// is used.
final EdgeInsetsGeometry contentPadding;
/// Whether to render icons and text in the [activeColor].
///
/// No effort is made to automatically coordinate the [selected] state and the
/// [value] state. To have the list tile appear selected when the switch is
/// on, pass the same value to both.
///
/// Normally, this property is left to its default value, false.
final bool selected;
/// If adaptive, creates the switch with [Switch.adaptive].
final _SwitchListTileType _switchListTileType;
@override
Widget build(BuildContext context) {
Widget control;
switch (_switchListTileType) {
case _SwitchListTileType.adaptive:
control = Switch.adaptive(
value: value,
onChanged: onChanged,
activeColor: activeColor,
activeThumbImage: activeThumbImage,
inactiveThumbImage: inactiveThumbImage,
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
activeTrackColor: activeTrackColor,
inactiveTrackColor: inactiveTrackColor,
inactiveThumbColor: inactiveThumbColor,
);
break;
case _SwitchListTileType.material:
control = Switch(
value: value,
onChanged: onChanged,
activeColor: activeColor,
activeThumbImage: activeThumbImage,
inactiveThumbImage: inactiveThumbImage,
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
activeTrackColor: activeTrackColor,
inactiveTrackColor: inactiveTrackColor,
inactiveThumbColor: inactiveThumbColor,
);
}
return MergeSemantics(
child: ListTileTheme.merge(
selectedColor: activeColor ?? Theme.of(context).accentColor,
child: ListTile(
leading: secondary,
title: title,
subtitle: subtitle,
trailing: control,
isThreeLine: isThreeLine,
dense: dense,
contentPadding: contentPadding,
enabled: onChanged != null,
onTap: onChanged != null ? () { onChanged(!value); } : null,
selected: selected,
),
),
);
}
}