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Real-Time System Theme Detection Implementation

Overview

The LBA app now automatically detects and responds to system theme changes in real-time, meaning when a user changes their device's theme setting (from light to dark or vice versa), the app immediately reflects this change without requiring a restart.

How It Works

1. System Theme Detection

Flutter's ThemeMode.system: When users haven't manually overridden theme settings, the app uses Flutter's built-in ThemeMode.system which automatically follows the device's system theme.
Real-time Updates: The app listens to system brightness changes using WidgetsBindingObserver and updates the UI immediately.

2. Implementation Details

Files Modified:

lib/main.dart: Updated to use dynamic theme mode selection
lib/utils/theme_manager.dart: Enhanced with real-time system theme detection

Key Features:

// In ThemeManager class
class ThemeManager extends ChangeNotifier with WidgetsBindingObserver {
  
  // Returns appropriate theme mode
  ThemeMode getThemeMode() {
    if (_hasManualOverride) {
      return _isDarkMode ? ThemeMode.dark : ThemeMode.light;
    } else {
      return ThemeMode.system; // Follows system theme automatically
    }
  }

  // Listens to system brightness changes
  @override
  void didChangePlatformBrightness() {
    if (!_hasManualOverride) {
      bool systemIsDark = _getSystemTheme();
      if (_isDarkMode != systemIsDark) {
        _isDarkMode = systemIsDark;
        AppColors.setDarkMode(_isDarkMode);
        _updateSystemUIOverlay();
        notifyListeners(); // Updates UI immediately
      }
    }
  }
}

3. User Experience

When User Has NOT Set Manual Theme:

✅ App automatically follows system theme
✅ Real-time updates when system theme changes
✅ No app restart required
✅ Immediate UI response

When User Has Set Manual Theme:

✅ App respects user's manual choice
✅ System theme changes are ignored
✅ User can reset to system theme anytime

Usage Scenarios

Scenario 1: Following System Theme (Default)

User opens app for first time
App automatically matches device theme (light/dark)
User changes device theme in system settings
App immediately updates to match new system theme

Scenario 2: Manual Theme Override

User manually sets theme in Profile → General settings
App uses selected theme regardless of system changes
User can choose "Reset to System Theme" to return to automatic behavior

Scenario 3: Real-time Detection

User has app open and active
User switches device theme (pull down control center → dark mode toggle)
App theme changes instantly without any delay

Technical Implementation

Key Components:

1. WidgetsBindingObserver

class ThemeManager extends ChangeNotifier with WidgetsBindingObserver {
  ThemeManager() {
    WidgetsBinding.instance.addObserver(this); // Start listening
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this); // Clean up
    super.dispose();
  }
}

2. Platform Brightness Detection

bool _getSystemTheme() {
  return WidgetsBinding.instance.platformDispatcher.platformBrightness == Brightness.dark;
}

3. Dynamic Theme Mode

// In MaterialApp widget
themeMode: themeManager.getThemeMode(), // Dynamic based on user preference

4. State Management

Uses Provider pattern for theme state management
Automatic persistence to SharedPreferences
Immediate UI updates via notifyListeners()

Benefits

1. Seamless User Experience

No manual theme switching needed
Automatic adaptation to user preferences
Consistent with system-wide theme behavior

2. Real-time Response

Instant theme changes
No app restart required
Smooth transitions with animations

3. User Control

Option to override system theme
Ability to reset to system behavior
Persistent user preferences

4. Performance Optimized

Efficient system listening
Minimal resource usage
Clean observer pattern implementation

Testing Instructions

Test Real-time Theme Switching:

Open the LBA app
Ensure no manual theme override is set (go to Profile → General → Theme should follow system)
While app is open and visible:
- On iOS: Swipe down → Control Center → Toggle Dark Mode
- On Android: Quick Settings → Toggle Dark Theme
Observe: App theme should change immediately

Test Manual Override:

Set manual theme in Profile → General settings
Change system theme while app is open
Observe: App should NOT change (respects manual setting)
Reset to system theme in settings
Change system theme again
Observe: App should now follow system changes

Code Examples

How to Add Real-time Theme Detection to Any Screen:

class MyScreen extends StatefulWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<ThemeManager>(
      builder: (context, themeManager, child) {
        return Scaffold(
          backgroundColor: AppColors.scaffoldBackground, // Auto-updates
          body: Text(
            'This text color updates automatically!',
            style: TextStyle(color: AppColors.textPrimary), // Auto-updates
          ),
        );
      },
    );
  }
}

How to Check Current Theme State:

// Get current theme mode
ThemeMode currentMode = themeManager.getThemeMode();

// Check if following system
bool isFollowingSystem = currentMode == ThemeMode.system;

// Check if dark mode is active
bool isDark = themeManager.isDarkMode;

Migration Notes

Breaking Changes: None

All existing functionality preserved
Backward compatibility maintained
No API changes for existing screens

Enhanced Features:

Real-time system theme detection
Improved user experience
Better system integration

Future Enhancements

Potential Improvements:

Theme Scheduling: Set different themes for day/night
Location-based Themes: Auto-dark mode based on sunset/sunrise
Custom Theme Colors: User-defined color palettes
Theme Animations: Enhanced transition effects

Troubleshooting

If Real-time Switching Doesn't Work:

Check if manual theme override is enabled
Ensure app has proper system permissions
Restart app to reinitialize observers
Verify device supports theme switching

Common Issues:

Delay in Updates: Normal on some Android devices (1-2 second delay)
Not Following System: Check if manual override is set
Partial Updates: Ensure all screens use AppColors class

Summary

The LBA app now provides a complete real-time theme switching experience that automatically follows the user's system theme preferences while still allowing manual overrides when desired. This enhancement makes the app feel more integrated with the device's overall user experience and eliminates the need for users to manually sync their app themes with their system preferences.

Key Achievement: ✅ Real-time system theme detection with zero user intervention required

7.1 KiB Raw Blame History