text_button.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 'dart:math' as math;
import 'dart:ui' show lerpDouble;

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

import 'button_style.dart';
import 'button_style_button.dart';
import 'color_scheme.dart';
import 'colors.dart';
import 'constants.dart';
import 'ink_ripple.dart';
import 'ink_well.dart';
import 'material_state.dart';
import 'text_button_theme.dart';
import 'theme.dart';
import 'theme_data.dart';

/// A Material Design "Text Button".
///
/// Use text buttons on toolbars, in dialogs, or inline with other
/// content but offset from that content with padding so that the
/// button's presence is obvious. Text buttons do not have visible
/// borders and must therefore rely on their position relative to
/// other content for context. In dialogs and cards, they should be
/// grouped together in one of the bottom corners. Avoid using text
/// buttons where they would blend in with other content, for example
/// in the middle of lists.
///
/// A text button is a label [child] displayed on a (zero elevation)
/// [Material] widget. The label's [Text] and [Icon] widgets are
/// displayed in the [style]'s [ButtonStyle.foregroundColor]. The
/// button reacts to touches by filling with the [style]'s
/// [ButtonStyle.backgroundColor].
///
/// The text button's default style is defined by [defaultStyleOf].
/// The style of this text button can be overridden with its [style]
/// parameter. The style of all text buttons in a subtree can be
/// overridden with the [TextButtonTheme] and the style of all of the
/// text buttons in an app can be overridden with the [Theme]'s
/// [ThemeData.textButtonTheme] property.
///
/// The static [styleFrom] method is a convenient way to create a
/// text button [ButtonStyle] from simple values.
///
/// If the [onPressed] and [onLongPress] callbacks are null, then this
/// button will be disabled, it will not react to touch.
///
/// {@tool dartpad}
/// This sample shows how to render a disabled TextButton, an enabled TextButton
/// and lastly a TextButton with gradient background.
///
/// ** See code in examples/api/lib/material/text_button/text_button.0.dart **
/// {@end-tool}
///
/// {@tool dartpad}
/// This sample demonstrates using the [statesController] parameter to create a button
/// that adds support for [MaterialState.selected].
///
/// ** See code in examples/api/lib/material/text_button/text_button.1.dart **
/// {@end-tool}
///
/// See also:
///
///  * [ElevatedButton], a filled button whose material elevates when pressed.
///  * [FilledButton], a filled button that doesn't elevate when pressed.
///  * [FilledButton.tonal], a filled button variant that uses a secondary fill color.
///  * [OutlinedButton], a button with an outlined border and no fill color.
///  * <https://material.io/design/components/buttons.html>
///  * <https://m3.material.io/components/buttons>
class TextButton extends ButtonStyleButton {
  /// Create a TextButton.
  ///
  /// The [autofocus] and [clipBehavior] arguments must not be null.
  const TextButton({
    super.key,
    required super.onPressed,
    super.onLongPress,
    super.onHover,
    super.onFocusChange,
    super.style,
    super.focusNode,
    super.autofocus = false,
    super.clipBehavior = Clip.none,
    super.statesController,
    required Widget super.child,
  });

  /// Create a text button from a pair of widgets that serve as the button's
  /// [icon] and [label].
  ///
  /// The icon and label are arranged in a row and padded by 8 logical pixels
  /// at the ends, with an 8 pixel gap in between.
  ///
  /// The [icon] and [label] arguments must not be null.
  factory TextButton.icon({
    Key? key,
    required VoidCallback? onPressed,
    VoidCallback? onLongPress,
    ValueChanged<bool>? onHover,
    ValueChanged<bool>? onFocusChange,
    ButtonStyle? style,
    FocusNode? focusNode,
    bool? autofocus,
    Clip? clipBehavior,
    required Widget icon,
    required Widget label,
  }) = _TextButtonWithIcon;

  /// A static convenience method that constructs a text button
  /// [ButtonStyle] given simple values.
  ///
  /// The [foregroundColor] and [disabledForegroundColor] colors are used
  /// to create a [MaterialStateProperty] [ButtonStyle.foregroundColor], and
  /// a derived [ButtonStyle.overlayColor].
  ///
  /// The [backgroundColor] and [disabledBackgroundColor] colors are
  /// used to create a [MaterialStateProperty] [ButtonStyle.backgroundColor].
  ///
  /// Similarly, the [enabledMouseCursor] and [disabledMouseCursor]
  /// parameters are used to construct [ButtonStyle.mouseCursor].
  ///
  /// All of the other parameters are either used directly or used to
  /// create a [MaterialStateProperty] with a single value for all
  /// states.
  ///
  /// All parameters default to null. By default this method returns
  /// a [ButtonStyle] that doesn't override anything.
  ///
  /// For example, to override the default text and icon colors for a
  /// [TextButton], as well as its overlay color, with all of the
  /// standard opacity adjustments for the pressed, focused, and
  /// hovered states, one could write:
  ///
  /// ```dart
  /// TextButton(
  ///   style: TextButton.styleFrom(foregroundColor: Colors.green),
  ///   child: const Text('Give Kate a mix tape'),
  ///   onPressed: () {
  ///     // ...
  ///   },
  /// ),
  /// ```
  static ButtonStyle styleFrom({
    Color? foregroundColor,
    Color? backgroundColor,
    Color? disabledForegroundColor,
    Color? disabledBackgroundColor,
    Color? shadowColor,
    Color? surfaceTintColor,
    double? elevation,
    TextStyle? textStyle,
    EdgeInsetsGeometry? padding,
    Size? minimumSize,
    Size? fixedSize,
    Size? maximumSize,
    BorderSide? side,
    OutlinedBorder? shape,
    MouseCursor? enabledMouseCursor,
    MouseCursor? disabledMouseCursor,
    VisualDensity? visualDensity,
    MaterialTapTargetSize? tapTargetSize,
    Duration? animationDuration,
    bool? enableFeedback,
    AlignmentGeometry? alignment,
    InteractiveInkFeatureFactory? splashFactory,
    @Deprecated(
      'Use foregroundColor instead. '
      'This feature was deprecated after v3.1.0.'
    )
    Color? primary,
    @Deprecated(
      'Use disabledForegroundColor instead. '
      'This feature was deprecated after v3.1.0.'
    )
    Color? onSurface,
  }) {
    final Color? foreground = foregroundColor ?? primary;
    final Color? disabledForeground = disabledForegroundColor ?? onSurface?.withOpacity(0.38);
    final MaterialStateProperty<Color?>? foregroundColorProp = (foreground == null && disabledForeground == null)
      ? null
      : _TextButtonDefaultColor(foreground, disabledForeground);
    final MaterialStateProperty<Color?>? backgroundColorProp = (backgroundColor == null && disabledBackgroundColor == null)
      ? null
      : disabledBackgroundColor == null
        ? ButtonStyleButton.allOrNull<Color?>(backgroundColor)
        : _TextButtonDefaultColor(backgroundColor, disabledBackgroundColor);
    final MaterialStateProperty<Color?>? overlayColor = (foreground == null)
      ? null
      : _TextButtonDefaultOverlay(foreground);
    final MaterialStateProperty<MouseCursor>? mouseCursor = (enabledMouseCursor == null && disabledMouseCursor == null)
      ? null
      : _TextButtonDefaultMouseCursor(enabledMouseCursor!, disabledMouseCursor!);

    return ButtonStyle(
      textStyle: ButtonStyleButton.allOrNull<TextStyle>(textStyle),
      foregroundColor: foregroundColorProp,
      backgroundColor: backgroundColorProp,
      overlayColor: overlayColor,
      shadowColor: ButtonStyleButton.allOrNull<Color>(shadowColor),
      surfaceTintColor: ButtonStyleButton.allOrNull<Color>(surfaceTintColor),
      elevation: ButtonStyleButton.allOrNull<double>(elevation),
      padding: ButtonStyleButton.allOrNull<EdgeInsetsGeometry>(padding),
      minimumSize: ButtonStyleButton.allOrNull<Size>(minimumSize),
      fixedSize: ButtonStyleButton.allOrNull<Size>(fixedSize),
      maximumSize: ButtonStyleButton.allOrNull<Size>(maximumSize),
      side: ButtonStyleButton.allOrNull<BorderSide>(side),
      shape: ButtonStyleButton.allOrNull<OutlinedBorder>(shape),
      mouseCursor: mouseCursor,
      visualDensity: visualDensity,
      tapTargetSize: tapTargetSize,
      animationDuration: animationDuration,
      enableFeedback: enableFeedback,
      alignment: alignment,
      splashFactory: splashFactory,
    );
  }

  /// Defines the button's default appearance.
  ///
  /// {@template flutter.material.text_button.default_style_of}
  /// The button [child]'s [Text] and [Icon] widgets are rendered with
  /// the [ButtonStyle]'s foreground color. The button's [InkWell] adds
  /// the style's overlay color when the button is focused, hovered
  /// or pressed. The button's background color becomes its [Material]
  /// color and is transparent by default.
  ///
  /// All of the [ButtonStyle]'s defaults appear below.
  ///
  /// In this list "Theme.foo" is shorthand for
  /// `Theme.of(context).foo`. Color scheme values like
  /// "onSurface(0.38)" are shorthand for
  /// `onSurface.withOpacity(0.38)`. [MaterialStateProperty] valued
  /// properties that are not followed by a sublist have the same
  /// value for all states, otherwise the values are as specified for
  /// each state and "others" means all other states.
  ///
  /// The `textScaleFactor` is the value of
  /// `MediaQuery.of(context).textScaleFactor` and the names of the
  /// EdgeInsets constructors and `EdgeInsetsGeometry.lerp` have been
  /// abbreviated for readability.
  ///
  /// The color of the [ButtonStyle.textStyle] is not used, the
  /// [ButtonStyle.foregroundColor] color is used instead.
  /// {@endtemplate}
  ///
  /// ## Material 2 defaults
  ///
  /// * `textStyle` - Theme.textTheme.button
  /// * `backgroundColor` - transparent
  /// * `foregroundColor`
  ///   * disabled - Theme.colorScheme.onSurface(0.38)
  ///   * others - Theme.colorScheme.primary
  /// * `overlayColor`
  ///   * hovered - Theme.colorScheme.primary(0.04)
  ///   * focused or pressed - Theme.colorScheme.primary(0.12)
  /// * `shadowColor` - Theme.shadowColor
  /// * `elevation` - 0
  /// * `padding`
  ///   * `textScaleFactor <= 1` - all(8)
  ///   * `1 < textScaleFactor <= 2` - lerp(all(8), horizontal(8))
  ///   * `2 < textScaleFactor <= 3` - lerp(horizontal(8), horizontal(4))
  ///   * `3 < textScaleFactor` - horizontal(4)
  /// * `minimumSize` - Size(64, 36)
  /// * `fixedSize` - null
  /// * `maximumSize` - Size.infinite
  /// * `side` - null
  /// * `shape` - RoundedRectangleBorder(borderRadius: BorderRadius.circular(4))
  /// * `mouseCursor`
  ///   * disabled - SystemMouseCursors.basic
  ///   * others - SystemMouseCursors.click
  /// * `visualDensity` - theme.visualDensity
  /// * `tapTargetSize` - theme.materialTapTargetSize
  /// * `animationDuration` - kThemeChangeDuration
  /// * `enableFeedback` - true
  /// * `alignment` - Alignment.center
  /// * `splashFactory` - InkRipple.splashFactory
  ///
  /// The default padding values for the [TextButton.icon] factory are slightly different:
  ///
  /// * `padding`
  ///   * `textScaleFactor <= 1` - all(8)
  ///   * `1 < textScaleFactor <= 2 `- lerp(all(8), horizontal(4))
  ///   * `2 < textScaleFactor` - horizontal(4)
  ///
  /// The default value for `side`, which defines the appearance of the button's
  /// outline, is null. That means that the outline is defined by the button
  /// shape's [OutlinedBorder.side]. Typically the default value of an
  /// [OutlinedBorder]'s side is [BorderSide.none], so an outline is not drawn.
  ///
  /// ## Material 3 defaults
  ///
  /// If [ThemeData.useMaterial3] is set to true the following defaults will
  /// be used:
  ///
  /// {@template flutter.material.text_button.material3_defaults}
  /// * `textStyle` - Theme.textTheme.labelLarge
  /// * `backgroundColor` - transparent
  /// * `foregroundColor`
  ///   * disabled - Theme.colorScheme.onSurface(0.38)
  ///   * others - Theme.colorScheme.primary
  /// * `overlayColor`
  ///   * hovered - Theme.colorScheme.primary(0.08)
  ///   * focused or pressed - Theme.colorScheme.primary(0.12)
  ///   * others - null
  /// * `shadowColor` - null
  /// * `surfaceTintColor` - null
  /// * `elevation` - 0
  /// * `padding`
  ///   * `textScaleFactor <= 1` - all(8)
  ///   * `1 < textScaleFactor <= 2` - lerp(all(8), horizontal(8))
  ///   * `2 < textScaleFactor <= 3` - lerp(horizontal(8), horizontal(4))
  ///   * `3 < textScaleFactor` - horizontal(4)
  /// * `minimumSize` - Size(64, 40)
  /// * `fixedSize` - null
  /// * `maximumSize` - Size.infinite
  /// * `side` - null
  /// * `shape` - StadiumBorder()
  /// * `mouseCursor`
  ///   * disabled - SystemMouseCursors.basic
  ///   * others - SystemMouseCursors.click
  /// * `visualDensity` - theme.visualDensity
  /// * `tapTargetSize` - theme.materialTapTargetSize
  /// * `animationDuration` - kThemeChangeDuration
  /// * `enableFeedback` - true
  /// * `alignment` - Alignment.center
  /// * `splashFactory` - Theme.splashFactory
  /// {@endtemplate}
  @override
  ButtonStyle defaultStyleOf(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    final ColorScheme colorScheme = theme.colorScheme;

    return Theme.of(context).useMaterial3
      ? _TextButtonDefaultsM3(context)
      : styleFrom(
          foregroundColor: colorScheme.primary,
          disabledForegroundColor: colorScheme.onSurface.withOpacity(0.38),
          backgroundColor: Colors.transparent,
          disabledBackgroundColor: Colors.transparent,
          shadowColor: theme.shadowColor,
          elevation: 0,
          textStyle: theme.textTheme.labelLarge,
          padding: _scaledPadding(context),
          minimumSize: const Size(64, 36),
          maximumSize: Size.infinite,
          shape: const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(4))),
          enabledMouseCursor: SystemMouseCursors.click,
          disabledMouseCursor: SystemMouseCursors.basic,
          visualDensity: theme.visualDensity,
          tapTargetSize: theme.materialTapTargetSize,
          animationDuration: kThemeChangeDuration,
          enableFeedback: true,
          alignment: Alignment.center,
          splashFactory: InkRipple.splashFactory,
        );
  }

  /// Returns the [TextButtonThemeData.style] of the closest
  /// [TextButtonTheme] ancestor.
  @override
  ButtonStyle? themeStyleOf(BuildContext context) {
    return TextButtonTheme.of(context).style;
  }
}

EdgeInsetsGeometry _scaledPadding(BuildContext context) {
  return ButtonStyleButton.scaledPadding(
    const EdgeInsets.all(8),
    const EdgeInsets.symmetric(horizontal: 8),
    const EdgeInsets.symmetric(horizontal: 4),
    MediaQuery.maybeOf(context)?.textScaleFactor ?? 1,
  );
}

@immutable
class _TextButtonDefaultColor extends MaterialStateProperty<Color?> {
  _TextButtonDefaultColor(this.color, this.disabled);

  final Color? color;
  final Color? disabled;

  @override
  Color? resolve(Set<MaterialState> states) {
    if (states.contains(MaterialState.disabled)) {
      return disabled;
    }
    return color;
  }

  @override
  String toString() {
    return '{disabled: $disabled, otherwise: $color}';
  }
}

@immutable
class _TextButtonDefaultOverlay extends MaterialStateProperty<Color?> {
  _TextButtonDefaultOverlay(this.primary);

  final Color primary;

  @override
  Color? resolve(Set<MaterialState> states) {
    if (states.contains(MaterialState.hovered)) {
      return primary.withOpacity(0.04);
    }
    if (states.contains(MaterialState.focused) || states.contains(MaterialState.pressed)) {
      return primary.withOpacity(0.12);
    }
    return null;
  }

  @override
  String toString() {
    return '{hovered: ${primary.withOpacity(0.04)}, focused,pressed: ${primary.withOpacity(0.12)}, otherwise: null}';
  }
}

@immutable
class _TextButtonDefaultMouseCursor extends MaterialStateProperty<MouseCursor> with Diagnosticable {
  _TextButtonDefaultMouseCursor(this.enabledCursor, this.disabledCursor);

  final MouseCursor enabledCursor;
  final MouseCursor disabledCursor;

  @override
  MouseCursor resolve(Set<MaterialState> states) {
    if (states.contains(MaterialState.disabled)) {
      return disabledCursor;
    }
    return enabledCursor;
  }
}

class _TextButtonWithIcon extends TextButton {
  _TextButtonWithIcon({
    super.key,
    required super.onPressed,
    super.onLongPress,
    super.onHover,
    super.onFocusChange,
    super.style,
    super.focusNode,
    bool? autofocus,
    Clip? clipBehavior,
    required Widget icon,
    required Widget label,
  }) : assert(icon != null),
       assert(label != null),
       super(
         autofocus: autofocus ?? false,
         clipBehavior: clipBehavior ?? Clip.none,
         child: _TextButtonWithIconChild(icon: icon, label: label),
      );

  @override
  ButtonStyle defaultStyleOf(BuildContext context) {
    final EdgeInsetsGeometry scaledPadding = ButtonStyleButton.scaledPadding(
      const EdgeInsets.all(8),
      const EdgeInsets.symmetric(horizontal: 4),
      const EdgeInsets.symmetric(horizontal: 4),
      MediaQuery.maybeOf(context)?.textScaleFactor ?? 1,
    );
    return super.defaultStyleOf(context).copyWith(
      padding: MaterialStatePropertyAll<EdgeInsetsGeometry>(scaledPadding),
    );
  }
}

class _TextButtonWithIconChild extends StatelessWidget {
  const _TextButtonWithIconChild({
    required this.label,
    required this.icon,
  });

  final Widget label;
  final Widget icon;

  @override
  Widget build(BuildContext context) {
    final double scale = MediaQuery.maybeOf(context)?.textScaleFactor ?? 1;
    final double gap = scale <= 1 ? 8 : lerpDouble(8, 4, math.min(scale - 1, 1))!;
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: <Widget>[icon, SizedBox(width: gap), Flexible(child: label)],
    );
  }
}

// BEGIN GENERATED TOKEN PROPERTIES - TextButton

// Do not edit by hand. The code between the "BEGIN GENERATED" and
// "END GENERATED" comments are generated from data in the Material
// Design token database by the script:
//   dev/tools/gen_defaults/bin/gen_defaults.dart.

// Token database version: v0_132

class _TextButtonDefaultsM3 extends ButtonStyle {
  _TextButtonDefaultsM3(this.context)
   : super(
       animationDuration: kThemeChangeDuration,
       enableFeedback: true,
       alignment: Alignment.center,
     );

  final BuildContext context;
  late final ColorScheme _colors = Theme.of(context).colorScheme;

  @override
  MaterialStateProperty<TextStyle?> get textStyle =>
    MaterialStatePropertyAll<TextStyle?>(Theme.of(context).textTheme.labelLarge);

  @override
  MaterialStateProperty<Color?>? get backgroundColor =>
    const MaterialStatePropertyAll<Color>(Colors.transparent);

  @override
  MaterialStateProperty<Color?>? get foregroundColor =>
    MaterialStateProperty.resolveWith((Set<MaterialState> states) {
      if (states.contains(MaterialState.disabled)) {
        return _colors.onSurface.withOpacity(0.38);
      }
      return _colors.primary;
    });

  @override
  MaterialStateProperty<Color?>? get overlayColor =>
    MaterialStateProperty.resolveWith((Set<MaterialState> states) {
      if (states.contains(MaterialState.hovered)) {
        return _colors.primary.withOpacity(0.08);
      }
      if (states.contains(MaterialState.focused)) {
        return _colors.primary.withOpacity(0.12);
      }
      if (states.contains(MaterialState.pressed)) {
        return _colors.primary.withOpacity(0.12);
      }
      return null;
    });

  @override
  MaterialStateProperty<Color>? get shadowColor =>
    const MaterialStatePropertyAll<Color>(Colors.transparent);

  @override
  MaterialStateProperty<Color>? get surfaceTintColor =>
    const MaterialStatePropertyAll<Color>(Colors.transparent);

  @override
  MaterialStateProperty<double>? get elevation =>
    const MaterialStatePropertyAll<double>(0.0);

  @override
  MaterialStateProperty<EdgeInsetsGeometry>? get padding =>
    MaterialStatePropertyAll<EdgeInsetsGeometry>(_scaledPadding(context));

  @override
  MaterialStateProperty<Size>? get minimumSize =>
    const MaterialStatePropertyAll<Size>(Size(64.0, 40.0));

  // No default fixedSize

  @override
  MaterialStateProperty<Size>? get maximumSize =>
    const MaterialStatePropertyAll<Size>(Size.infinite);

  // No default side

  @override
  MaterialStateProperty<OutlinedBorder>? get shape =>
    const MaterialStatePropertyAll<OutlinedBorder>(StadiumBorder());

  @override
  MaterialStateProperty<MouseCursor?>? get mouseCursor =>
    MaterialStateProperty.resolveWith((Set<MaterialState> states) {
      if (states.contains(MaterialState.disabled)) {
        return SystemMouseCursors.basic;
      }
      return SystemMouseCursors.click;
    });

  @override
  VisualDensity? get visualDensity => Theme.of(context).visualDensity;

  @override
  MaterialTapTargetSize? get tapTargetSize => Theme.of(context).materialTapTargetSize;

  @override
  InteractiveInkFeatureFactory? get splashFactory => Theme.of(context).splashFactory;
}

// END GENERATED TOKEN PROPERTIES - TextButton