GT Theme

A production-ready Flutter theme management package with Material 3 & Cupertino support, system theme detection, light/dark mode switching, and theme persistence.

✨ Features

🎨 Material 3 & Cupertino Support - Beautiful pre-configured themes for both design systems
🌓 Light/Dark/System Modes - Complete theme mode switching with persistence
📱 System Theme Detection - Real-time sync with device theme changes (no context needed!)
💾 Theme Persistence - Automatically saves user preference via SharedPreferences
⚡ High Performance - Minimal rebuilds using ValueNotifier pattern
🔌 Zero-Dependency State Management - Works with GetX, Provider, Bloc, Riverpod, or none!
🧩 Ready-to-Use Widgets - ThemeModeSelector, BrightnessIndicator, ThemeInfoCard

📦 Installation

Add to your pubspec.yaml:

dependencies:
  gt_theme: ^1.0.0

Then run:

flutter pub get

🚀 Quick Start

1. Initialize in main()

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

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  ThemeService.instance.startListening();
  runApp(const MyApp());
}

2. Configure MaterialApp

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder<ThemeMode>(
      valueListenable: ThemeService.instance.themeModeNotifier,
      builder: (context, themeMode, child) {
        return MaterialApp(
          title: 'My App',
          themeMode: themeMode,
          theme: ThemeService.instance.getMaterialTheme(Brightness.light),
          darkTheme: ThemeService.instance.getMaterialTheme(Brightness.dark),
          home: const HomePage(),
        );
      },
    );
  }
}

3. Use Theme Widgets

class SettingsPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          // Theme mode selector (Light/Dark/System)
          ThemeModeSelector(
            themeService: ThemeService.instance,
            onThemeModeChanged: () => print('Theme changed!'),
          ),
          
          // Shows current system brightness
          BrightnessIndicator(themeService: ThemeService.instance),
          
          // Shows detailed theme info
          ThemeInfoCard(themeService: ThemeService.instance),
        ],
      ),
    );
  }
}

📖 API Reference

ThemeService

The core singleton service for theme management.

Property/Method	Description
`ThemeService.instance`	Global singleton instance
`startListening()`	Start listening to system brightness changes
`setThemeMode(ThemeMode)`	Set theme mode (light/dark/system)
`currentThemeMode`	Get current ThemeMode
`effectiveBrightness`	Get effective Brightness based on mode
`themeModeNotifier`	ValueNotifier for theme mode changes
`systemBrightnessNotifier`	ValueNotifier for system brightness
`getMaterialTheme(Brightness)`	Get Material ThemeData
`getCupertinoTheme(Brightness)`	Get CupertinoThemeData

Widgets

Widget	Description
`ThemeConsumer`	Efficiently consume theme data with minimal rebuilds
`ThemeModeSelector`	UI for switching between Light/Dark/System modes
`BrightnessIndicator`	Display current system brightness
`ThemeInfoCard`	Display current theme information

🎯 Advanced Usage

Manual Theme Switching

// Switch to dark mode
ThemeService.instance.setThemeMode(ThemeMode.dark);

// Switch to light mode
ThemeService.instance.setThemeMode(ThemeMode.light);

// Follow system theme
ThemeService.instance.setThemeMode(ThemeMode.system);

Using ThemeConsumer for Optimized Rebuilds

ThemeConsumer(
  themeService: ThemeService.instance,
  builder: (context, service, child) {
    final isDark = service.effectiveBrightness == Brightness.dark;
    return Container(
      color: isDark ? Colors.black : Colors.white,
      child: child, // This child won't rebuild!
    );
  },
  child: const ExpensiveWidget(), // Won't rebuild on theme change
)

Cupertino App Support

CupertinoApp(
  theme: ThemeService.instance.getCupertinoTheme(
    ThemeService.instance.effectiveBrightness,
  ),
  home: const HomePage(),
)

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

👨‍💻 Author

Gaurav Technical

GitHub: @GauravTechnical24