Create Theme

codegen for flutter ThemeExtension

Installing

flutter pub add create_theme_annotation
flutter pub add --dev create_theme

Example

my_widget.dart

import 'package:create_theme_annotation/create_theme_annotation.dart';
import 'package:flutter/material.dart';

part 'my_widget.g.dart';

MyWidgetThemeData _createDefault(ThemeData theme) {
  return MyWidgetThemeData(
    headerColor: theme.colorScheme.primary,
    headerTextStyle: TextStyle(
      color: theme.colorScheme.onPrimary,
    ),
    backgroundColor: theme.scaffoldBackgroundColor,
  );
}

@CreateTheme(
  themeProperties: {
    'headerColor': CreateThemeColor(),
    'headerTextStyle': CreateThemeTextStyle(),
    'backgroundColor': CreateThemeColor(),
  },
  createDefault: _createDefault,
)
class MyWidget extends StatelessWidget {
  const MyWidget({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final theme = MyWidgetTheme.of(context);

    return Column(
      children: [
        Material(
          color: theme.headerColor,
          child: DefaultTextStyle.merge(
            style: theme.headerTextStyle,
            child: const Padding(
              padding: EdgeInsets.all(8.0),
              child: Center(
                child: Text('Header'),
              ),
            ),
          ),
        ),
        Expanded(
          child: Material(
            color: theme.backgroundColor,
            child: const Padding(
              padding: EdgeInsets.all(8.0),
              child: Center(
                child: Text('Body'),
              ),
            ),
          ),
        ),
      ],
    );
  }
}

class CreateThemeColor extends CreateThemeProperties<Color> {
  const CreateThemeColor() : super(propertiesType: Color, lerp: Color.lerp);
}

class CreateThemeTextStyle extends CreateThemeProperties<TextStyle> {
  const CreateThemeTextStyle()
      : super(propertiesType: TextStyle, lerp: TextStyle.lerp);
}

my_widget.g.dart

// GENERATED CODE - DO NOT MODIFY BY HAND

part of 'my_widget.dart';

// **************************************************************************
// CreateThemeGenerator
// **************************************************************************

class MyWidgetThemeData extends ThemeExtension<MyWidgetThemeData> {
  const MyWidgetThemeData({
    this.headerColor,
    this.headerTextStyle,
    this.backgroundColor,
  });

  final Color? headerColor;
  final TextStyle? headerTextStyle;
  final Color? backgroundColor;

  @override
  MyWidgetThemeData copyWith({
    Color? headerColor,
    TextStyle? headerTextStyle,
    Color? backgroundColor,
  }) {
    return MyWidgetThemeData(
      headerColor: headerColor ?? this.headerColor,
      headerTextStyle: headerTextStyle ?? this.headerTextStyle,
      backgroundColor: backgroundColor ?? this.backgroundColor,
    );
  }

  @override
  MyWidgetThemeData lerp(
    ThemeExtension<MyWidgetThemeData>? other,
    double t,
  ) {
    if (other is! MyWidgetThemeData) return this;

    return MyWidgetThemeData(
      headerColor: Color.lerp(headerColor, other.headerColor, t),
      headerTextStyle:
          TextStyle.lerp(headerTextStyle, other.headerTextStyle, t),
      backgroundColor: Color.lerp(backgroundColor, other.backgroundColor, t),
    );
  }

  MyWidgetThemeData merge(MyWidgetThemeData? other) {
    if (other == null) return this;

    return copyWith(
      headerColor: other.headerColor,
      headerTextStyle: other.headerTextStyle,
      backgroundColor: other.backgroundColor,
    );
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;

    return other is MyWidgetThemeData &&
        other.headerColor == headerColor &&
        other.headerTextStyle == headerTextStyle &&
        other.backgroundColor == backgroundColor;
  }

  @override
  int get hashCode {
    return Object.hashAll([
      headerColor,
      headerTextStyle,
      backgroundColor,
    ]);
  }
}

class MyWidgetTheme extends InheritedWidget {
  const MyWidgetTheme({
    super.key,
    required this.theme,
    required super.child,
  });

  final MyWidgetThemeData theme;

  @override
  bool updateShouldNotify(MyWidgetTheme oldWidget) {
    return oldWidget.theme != theme;
  }

  static MyWidgetThemeData of(BuildContext context) {
    final widget = context.dependOnInheritedWidgetOfExactType<MyWidgetTheme>();
    final localTheme = widget?.theme;

    final theme = Theme.of(context);
    final rootTheme = theme.extensions[MyWidgetThemeData] as MyWidgetThemeData?;

    final MyWidgetThemeData defaultTheme = _createDefault(theme);
    final result = defaultTheme.merge(rootTheme?.merge(localTheme));

    return result;
  }
}