Implementation of adaptive color

adaptive_color.dart

import 'package:flutter/material.dart';

enum AdaptiveColor {
  primary,
  secondary,
  background,
  surface,
}

class AdaptiveMaterial extends StatelessWidget {
  AdaptiveMaterial({
    required this.adaptiveColor,
    required this.child,
  });

  final AdaptiveColor adaptiveColor;
  final Widget? child;

  @override
  Widget build(BuildContext context) {
    return _ColorProvider<_OnColor>(
      adaptiveColor,
      _ColorProvider<_Color>(
        adaptiveColor,
        Material(
          color: _toColor(context, adaptiveColor),
          child: child,
        ),
        _toColor(context, adaptiveColor),
      ),
      _toOnColor(context, adaptiveColor),
    );
  }

  static Color? colorOf(BuildContext context) {
    final _ColorProvider? result =
        context.dependOnInheritedWidgetOfExactType<_ColorProvider<_Color>>();
    if (result == null) {
      return null;
    }
    return result._colorFromScheme;
  }

  static Color? onColorOf(BuildContext context) {
    final _ColorProvider? result =
        context.dependOnInheritedWidgetOfExactType<_ColorProvider<_OnColor>>();
    if (result == null) {
      return null;
    }
    return result._colorFromScheme;
  }

  static Color _toColor(
    BuildContext context,
    AdaptiveColor adaptiveColor,
  ) {
    switch (adaptiveColor) {
      case AdaptiveColor.primary:
        return Theme.of(context).colorScheme.primary;
      case AdaptiveColor.secondary:
        return Theme.of(context).colorScheme.secondary;
      case AdaptiveColor.background:
        return Theme.of(context).colorScheme.background;
      case AdaptiveColor.surface:
        return Theme.of(context).colorScheme.surface;
    }
  }

  static Color _toOnColor(
    BuildContext context,
    AdaptiveColor adaptiveColor,
  ) {
    switch (adaptiveColor) {
      case AdaptiveColor.primary:
        return Theme.of(context).colorScheme.onPrimary;
      case AdaptiveColor.secondary:
        return Theme.of(context).colorScheme.onSecondary;
      case AdaptiveColor.background:
        return Theme.of(context).colorScheme.onBackground;
      case AdaptiveColor.surface:
        return Theme.of(context).colorScheme.onSurface;
    }
  }
}

abstract class _ColorProviderType {}

class _Color implements _ColorProviderType {}

class _OnColor implements _ColorProviderType {}

class _ColorProvider<T extends _ColorProviderType> extends InheritedWidget {
  final AdaptiveColor adaptiveColor;
  final Widget child;
  final Color _colorFromScheme;

  _ColorProvider(
    this.adaptiveColor,
    this.child,
    this._colorFromScheme,
  ) : super(child: child);

  @override
  bool updateShouldNotify(covariant _ColorProvider oldWidget) {
    return oldWidget.adaptiveColor != adaptiveColor ||
        oldWidget._colorFromScheme != _colorFromScheme;
  }
}

class AdaptiveIconButton extends StatelessWidget {
  const AdaptiveIconButton({
    Key? key,
    this.iconSize = 24.0,
    this.visualDensity,
    this.padding = const EdgeInsets.all(8.0),
    this.alignment = Alignment.center,
    this.splashRadius,
    this.focusColor,
    this.hoverColor,
    this.highlightColor,
    this.splashColor,
    this.disabledColor,
    required this.onPressed,
    this.mouseCursor = SystemMouseCursors.click,
    this.focusNode,
    this.autofocus = false,
    this.tooltip,
    this.enableFeedback = true,
    this.constraints,
    required this.icon,
  }) : super(key: key);

  final double iconSize;
  final VisualDensity? visualDensity;
  final EdgeInsets padding;
  final Alignment alignment;
  final double? splashRadius;
  final Color? focusColor;
  final Color? hoverColor;
  final Color? highlightColor;
  final Color? splashColor;
  final Color? disabledColor;
  final VoidCallback? onPressed;
  final MouseCursor mouseCursor;
  final FocusNode? focusNode;
  final bool autofocus;
  final String? tooltip;
  final bool enableFeedback;
  final BoxConstraints? constraints;
  final Widget icon;

  @override
  Widget build(BuildContext context) {
    final Color? onColor = AdaptiveMaterial.onColorOf(context);
    assert(
      onColor != null,
      'The current `context` did not contain a parent `AdaptiveColor`. To use '
      'and adaptive widget, place an `AdaptiveColor` widget above this one in '
      'the widget tree.',
    );
    return IconButton(
      iconSize: iconSize,
      visualDensity: visualDensity,
      padding: padding,
      alignment: alignment,
      splashRadius: splashRadius,
      color: onColor,

      /// TODO(caseycrogers): These colors should reflect `onColor` too.
      focusColor: focusColor,
      hoverColor: hoverColor,
      highlightColor: highlightColor,
      splashColor: splashColor,
      disabledColor: disabledColor,
      onPressed: onPressed,
      mouseCursor: mouseCursor,
      focusNode: focusNode,
      autofocus: autofocus,
      tooltip: tooltip,
      enableFeedback: enableFeedback,
      constraints: constraints,
      icon: icon,
    );
  }
}