easy_theme_extension 0.1.0+1

A zero-boilerplate code generator for Flutter ThemeExtension classes.

easy_theme_extension

A zero-boilerplate generator for Flutter ThemeExtension classes.

Define your theme as an annotated abstract class. The generator creates the full immutable implementation with constructor, fields, copyWith, lerp and more.

Before	After

---

Installation

flutter pub add \
  easy_theme_extension \
  dev:easy_theme_extension_builder \
  dev:build_runner

---

Usage

1. Define your theme contract

part 'my_colors.g.dart';

@easyTheme
abstract class _MyColors {
  Color get primary;
  Color get secondary;
  Color get textBody;
  Color get textTitle;
  Color get textLabel;
}

2. Run the generator

dart run build_runner build

my_colors.g.dart

part of 'my_colors.dart';

@immutable
class MyColors extends ThemeExtension<MyColors> with Diagnosticable implements _MyColors {
  const MyColors({
    required this.primary,
    required this.secondary,
    required this.textBody,
    required this.textTitle,
    required this.textLabel,
  });

  @override
  final Color primary;

  @override
  final Color secondary;

  @override
  final Color textBody;

  @override
  final Color textTitle;

  @override
  final Color textLabel;

  @override
  MyColors copyWith({
    Color? primary,
    Color? secondary,
    Color? textBody,
    Color? textTitle,
    Color? textLabel,
  }) => MyColors(
    primary: primary ?? this.primary,
    secondary: secondary ?? this.secondary,
    textBody: textBody ?? this.textBody,
    textTitle: textTitle ?? this.textTitle,
    textLabel: textLabel ?? this.textLabel,
  );

  @override
  MyColors lerp(MyColors? other, double t) {
    if (other is! MyColors) return this;
    return MyColors(
      primary: Color.lerp(primary, other.primary, t)!,
      secondary: Color.lerp(secondary, other.secondary, t)!,
      textBody: Color.lerp(textBody, other.textBody, t)!,
      textTitle: Color.lerp(textTitle, other.textTitle, t)!,
      textLabel: Color.lerp(textLabel, other.textLabel, t)!,
    );
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    if (other.runtimeType != runtimeType) return false;
    return other is MyColors &&
        other.primary == primary &&
        other.secondary == secondary &&
        other.textBody == textBody &&
        other.textTitle == textTitle &&
        other.textLabel == textLabel;
  }

  @override
  int get hashCode => Object.hash(
    runtimeType,
    primary,
    secondary,
    textBody,
    textTitle,
    textLabel,
  );

  @override
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
    properties
      ..add(DiagnosticsProperty<Color>('primary', primary))
      ..add(DiagnosticsProperty<Color>('secondary', secondary))
      ..add(DiagnosticsProperty<Color>('textBody', textBody))
      ..add(DiagnosticsProperty<Color>('textTitle', textTitle))
      ..add(DiagnosticsProperty<Color>('textLabel', textLabel));
  }
}

extension MyColorsBuildContextExtension on BuildContext {
  MyColors get myColors => Theme.of(this).extension<MyColors>()!;
}

3. Use the generated extension

return MaterialApp(
  theme: ThemeData(
    extensions: const [
      MyColors(
        primary: Colors.blue,
        secondary: Colors.red,
        textBody: Colors.black,
        textTitle: Colors.black,
        textLabel: Colors.grey,
      ),
    ],
  ),
);

// Context extension
context.myColors.secondary;

---

Default Instance

If all fields provide values, the generator creates a static $default instance.

@easyTheme
abstract class _AppColors {
  Color get primary => Colors.blue;
  Color get textColor => Colors.orange;
}

You can use it directly when configuring the theme:

return MaterialApp(
  theme: ThemeData(
    extensions: const [
      AppColors.$default, // instance with default values
    ],
  ),
);

---

Annotation Options

@EasyTheme(contextExtensionName: 'color')
abstract class _MyColors { ... }

Option	Type	Default	Description
contextExtension	bool?	true	Generates an extension on BuildContext for accessing the theme.
contextExtensionName	String?	<className>	Custom name for the generated BuildContext accessor.
defaultStaticInstance	bool?	true	Generates a static default instance ($default).
defaultStaticInstanceAsConst	bool?	true	Generates a static default instance ($default) as const.
diagnosticable	bool?	true	Mixes in Diagnosticable on the generated class.
equals	bool?	true	Generates == and hashCode implementations.

---

Supported Types

See the example app for the full list of supported types and current limitations here.

---

Contributing

Contributions, issues, and suggestions are welcome. Open an issue or submit a pull request on GitHub

Package page on pub.dev

License

Released under the MIT License