packages/flutter/lib/src/material/chip_choice.dart

// 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 'chip.dart';
import 'chip_theme.dart';
import 'debug.dart';
import 'theme_data.dart';

/// A Material Design choice chip.
///
/// [ChoiceChip]s represent a single choice from a set. Choice chips contain
/// related descriptive text or categories.
///
/// Requires one of its ancestors to be a [Material] widget. The [selected] and
/// [label] arguments must not be null.
///
/// {@tool snippet}
///
/// ```dart
/// class MyThreeOptions extends StatefulWidget {
///   const MyThreeOptions({super.key});
///
///   @override
///   State<MyThreeOptions> createState() => _MyThreeOptionsState();
/// }
///
/// class _MyThreeOptionsState extends State<MyThreeOptions> {
///   int? _value = 1;
///
///   @override
///   Widget build(BuildContext context) {
///     return Wrap(
///       children: List<Widget>.generate(
///         3,
///         (int index) {
///           return ChoiceChip(
///             label: Text('Item $index'),
///             selected: _value == index,
///             onSelected: (bool selected) {
///               setState(() {
///                 _value = selected ? index : null;
///               });
///             },
///           );
///         },
///       ).toList(),
///     );
///   }
/// }
/// ```
/// {@end-tool}
///
/// See also:
///
///  * [Chip], a chip that displays information and can be deleted.
///  * [InputChip], a chip that represents a complex piece of information, such
///    as an entity (person, place, or thing) or conversational text, in a
///    compact form.
///  * [FilterChip], uses tags or descriptive words as a way to filter content.
///  * [ActionChip], represents an action related to primary content.
///  * [CircleAvatar], which shows images or initials of people.
///  * [Wrap], A widget that displays its children in multiple horizontal or
///    vertical runs.
///  * <https://material.io/design/components/chips.html>
class ChoiceChip extends StatelessWidget
    implements
        ChipAttributes,
        SelectableChipAttributes,
        DisabledChipAttributes {
  /// Create a chip that acts like a radio button.
  ///
  /// The [label], [selected], [autofocus], and [clipBehavior] arguments must
  /// not be null. The [pressElevation] and [elevation] must be null or
  /// non-negative. Typically, [pressElevation] is greater than [elevation].
  const ChoiceChip({
    super.key,
    this.avatar,
    required this.label,
    this.labelStyle,
    this.labelPadding,
    this.onSelected,
    this.pressElevation,
    required this.selected,
    this.selectedColor,
    this.disabledColor,
    this.tooltip,
    this.side,
    this.shape,
    this.clipBehavior = Clip.none,
    this.focusNode,
    this.autofocus = false,
    this.backgroundColor,
    this.padding,
    this.visualDensity,
    this.materialTapTargetSize,
    this.elevation,
    this.shadowColor,
    this.selectedShadowColor,
    this.avatarBorder = const CircleBorder(),
  }) : assert(selected != null),
       assert(label != null),
       assert(clipBehavior != null),
       assert(autofocus != null),
       assert(pressElevation == null || pressElevation >= 0.0),
       assert(elevation == null || elevation >= 0.0);

  @override
  final Widget? avatar;
  @override
  final Widget label;
  @override
  final TextStyle? labelStyle;
  @override
  final EdgeInsetsGeometry? labelPadding;
  @override
  final ValueChanged<bool>? onSelected;
  @override
  final double? pressElevation;
  @override
  final bool selected;
  @override
  final Color? disabledColor;
  @override
  final Color? selectedColor;
  @override
  final String? tooltip;
  @override
  final BorderSide? side;
  @override
  final OutlinedBorder? shape;
  @override
  final Clip clipBehavior;
  @override
  final FocusNode? focusNode;
  @override
  final bool autofocus;
  @override
  final Color? backgroundColor;
  @override
  final EdgeInsetsGeometry? padding;
  @override
  final VisualDensity? visualDensity;
  @override
  final MaterialTapTargetSize? materialTapTargetSize;
  @override
  final double? elevation;
  @override
  final Color? shadowColor;
  @override
  final Color? selectedShadowColor;
  @override
  final ShapeBorder avatarBorder;

  @override
  bool get isEnabled => onSelected != null;

  @override
  Widget build(BuildContext context) {
    assert(debugCheckHasMaterial(context));
    final ChipThemeData chipTheme = ChipTheme.of(context);
    return RawChip(
      avatar: avatar,
      label: label,
      labelStyle: labelStyle ?? (selected ? chipTheme.secondaryLabelStyle : null),
      labelPadding: labelPadding,
      onSelected: onSelected,
      pressElevation: pressElevation,
      selected: selected,
      showCheckmark: false,
      tooltip: tooltip,
      side: side,
      shape: shape,
      clipBehavior: clipBehavior,
      focusNode: focusNode,
      autofocus: autofocus,
      disabledColor: disabledColor,
      selectedColor: selectedColor ?? chipTheme.secondarySelectedColor,
      backgroundColor: backgroundColor,
      padding: padding,
      visualDensity: visualDensity,
      isEnabled: isEnabled,
      materialTapTargetSize: materialTapTargetSize,
      elevation: elevation,
      shadowColor: shadowColor,
      selectedShadowColor: selectedShadowColor,
      avatarBorder: avatarBorder,
    );
  }
}