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Overview

Location: lib/logic/locale_logic.dart The LocaleLogic class manages app localization, loading translations, and handling locale changes. It integrates with Flutter’s AppLocalizations system and detects the system locale.

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Registration

GetIt.I.registerLazySingleton<LocaleLogic>(() => LocaleLogic());
Access via global accessor: 
LocaleLogic get localeLogic => GetIt.I.get<LocaleLogic>();

// Convenient access to localized strings
AppLocalizations get $strings => localeLogic.strings;

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Properties

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strings
AppLocalizations
Access to all localized strings for the current locale.Example:
Text($strings.appTitle)
Text($strings.wonderDetailsTitle)
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isLoaded
bool
Returns true if translations have been loaded, false otherwise.
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isEnglish
bool
Returns true if the current locale is English (en).
bool isEnglish => strings.localeName == 'en';

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Methods

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load()

Loads translations for the appropriate locale. Called during app bootstrap. 
Future<void> load()
Behavior:
  1. Checks settingsLogic.currentLocale.value for saved preference
  2. Falls back to system locale via findSystemLocale()
  3. Validates locale is in AppLocalizations.supportedLocales
  4. Defaults to English (en) if locale not supported
  5. Loads translations via AppLocalizations.delegate.load()
  6. Saves selected locale to settingsLogic
Supported locales:
  • en - English
  • zh - Chinese (Simplified)
Example: 
// During app initialization
await localeLogic.load();

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loadIfChanged()

Reloads translations if the locale has changed. 
Future<void> loadIfChanged(Locale locale)
Parameters:
  • locale: The new locale to load
Behavior:
  • Only reloads if the locale differs from current strings.localeName
  • Validates locale is supported before loading
Example: 
// Called from SettingsLogic.changeLocale()
await localeLogic.loadIfChanged(Locale('zh'));

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Usage Examples

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Access Localized Strings

import 'package:wonders/common_libs.dart';

class WelcomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text($strings.welcomeTitle),
        Text($strings.welcomeSubtitle),
        ElevatedButton(
          onPressed: () {},
          child: Text($strings.continueButton),
        ),
      ],
    );
  }
}

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Check Current Locale

if (localeLogic.isEnglish) {
  // Use English-specific font (Cinzel)
  fontFamily = 'Cinzel';
} else {
  // Use Chinese-specific font (MaShanZheng)
  fontFamily = 'MaShanZheng';
}

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Debug Locale Override

For testing, you can force a locale in debug mode: 
// In lib/logic/locale_logic.dart:18-20
if (kDebugMode) {
  locale = Locale('zh'); // Uncomment to test Chinese
}

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Integration with MaterialApp

From lib/main.dart:56-73: 
class _WondersAppState extends State<WondersApp> with GetItStateMixin {
  @override
  Widget build(BuildContext context) {
    final locale = watchX((SettingsLogic s) => s.currentLocale);
    return MaterialApp.router(
      locale: locale == null ? null : Locale(locale),
      localizationsDelegates: const [
        AppLocalizations.delegate,
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      supportedLocales: AppLocalizations.supportedLocales,
      // ...
    );
  }
}

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Localization Files

Configuration: l10n.yaml 
arb-dir: lib/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart
Translation files:
  • lib/l10n/app_en.arb - English translations
  • lib/l10n/app_zh.arb - Chinese translations
Generated code:
  • lib/l10n/app_localizations.dart - Base class
  • lib/l10n/app_localizations_en.dart - English implementation
  • lib/l10n/app_localizations_zh.dart - Chinese implementation

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System Locale Detection

Uses intl_standalone package to detect the system locale: 
final localeCode = settingsLogic.currentLocale.value ?? await findSystemLocale();
Returns locale code like en_US, zh_CN, etc. The language code is extracted: 
locale = Locale(localeCode.split('_')[0]); // "en" from "en_US"

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Initialization

Locale is loaded during app bootstrap in AppLogic.bootstrap(): 
// From lib/logic/app_logic.dart:64-65
await localeLogic.load();

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