feat: i18n text support

l10n.yaml

@@ -0,0 +1,6 @@
+arb-dir: lib/l10n
+template-arb-file: app_en.arb
+output-class: AppLocalizations
+output-localization-file: app_localizations.dart
+nullable-getter: false
+untranslated-messages-file: build/l10n_missing.txt

lib/app.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:pdf_signature/l10n/app_localizations.dart';
 import 'package:pdf_signature/ui/features/pdf/widgets/pdf_screen.dart';
 import 'ui/features/preferences/providers.dart';
 
@@ -18,13 +18,28 @@ class MyApp extends StatelessWidget {
             loading: () => const SizedBox.shrink(),
             error:
                 (e, st) => MaterialApp(
-                  home: Scaffold(body: Center(child: Text('Error: $e'))),
+                  onGenerateTitle: (ctx) => AppLocalizations.of(ctx).appTitle,
+                  supportedLocales: AppLocalizations.supportedLocales,
+                  localizationsDelegates:
+                      AppLocalizations.localizationsDelegates,
+                  home: Builder(
+                    builder:
+                        (ctx) => Scaffold(
+                          body: Center(
+                            child: Text(
+                              AppLocalizations.of(
+                                ctx,
+                              ).errorWithMessage(e.toString()),
+                            ),
+                          ),
+                        ),
+                  ),
                 ),
             data: (_) {
               final themeMode = ref.watch(themeModeProvider);
               final appLocale = ref.watch(localeProvider);
               return MaterialApp(
-                title: 'PDF Signature',
+                onGenerateTitle: (ctx) => AppLocalizations.of(ctx).appTitle,
                 theme: ThemeData(
                   colorScheme: ColorScheme.fromSeed(
                     seedColor: Colors.indigo,
@@ -39,12 +54,8 @@ class MyApp extends StatelessWidget {
                 ),
                 themeMode: themeMode,
                 locale: appLocale,
-                supportedLocales: supportedLocales,
+                supportedLocales: AppLocalizations.supportedLocales,
-                localizationsDelegates: const [
+                localizationsDelegates: AppLocalizations.localizationsDelegates,
-                  GlobalMaterialLocalizations.delegate,
-                  GlobalWidgetsLocalizations.delegate,
-                  GlobalCupertinoLocalizations.delegate,
-                ],
                 home: const PdfSignatureHomePage(),
               );
             },

lib/l10n/app_en.arb

@@ -0,0 +1,61 @@
+{
+  "@@locale": "en",
+  "appTitle": "PDF Signature",
+  "errorWithMessage": "Error: {message}",
+  "@errorWithMessage": {
+    "description": "Generic error text with message",
+    "placeholders": {"message": {"type": "String"}}
+  },
+
+  "settings": "Settings",
+  "theme": "Theme",
+  "themeLight": "Light",
+  "themeDark": "Dark",
+  "themeSystem": "System",
+  "language": "Language",
+  "languageEnglish": "English",
+  "languageChineseTraditional": "Traditional Chinese",
+  "languageSpanish": "Spanish",
+  "resetToDefaults": "Reset to defaults",
+
+  "openPdf": "Open PDF...",
+  "prev": "Prev",
+  "next": "Next",
+  "pageInfo": "Page {current}/{total}",
+  "@pageInfo": {
+    "description": "Label showing current page and total",
+    "placeholders": {
+      "current": {"type": "int"},
+      "total": {"type": "int"}
+    }
+  },
+  "goTo": "Go to:",
+  "dpi": "DPI:",
+  "markForSigning": "Mark for Signing",
+  "unmarkSigning": "Unmark Signing",
+  "saveSignedPdf": "Save Signed PDF",
+  "loadSignatureFromFile": "Load Signature from file",
+  "drawSignature": "Draw Signature",
+  "noPdfLoaded": "No PDF loaded",
+  "signature": "Signature",
+  "lockAspectRatio": "Lock aspect ratio",
+  "backgroundRemoval": "Background removal",
+  "contrast": "Contrast",
+  "brightness": "Brightness",
+  "exportingPleaseWait": "Exporting... Please wait",
+
+  "nothingToSaveYet": "Nothing to save yet",
+  "savedWithPath": "Saved: {path}",
+  "@savedWithPath": {
+    "description": "Snackbar text showing where file saved",
+    "placeholders": {"path": {"type": "String"}}
+  },
+  "failedToSavePdf": "Failed to save PDF",
+  "downloadStarted": "Download started",
+  "failedToGeneratePdf": "Failed to generate PDF",
+  "invalidOrUnsupportedFile": "Invalid or unsupported file",
+
+  "confirm": "Confirm",
+  "undo": "Undo",
+  "clear": "Clear"
+}

lib/l10n/app_es.arb

@@ -0,0 +1,46 @@
+{
+  "@@locale": "es",
+  "appTitle": "Firma PDF",
+  "errorWithMessage": "Error: {message}",
+
+  "settings": "Ajustes",
+  "theme": "Tema",
+  "themeLight": "Claro",
+  "themeDark": "Oscuro",
+  "themeSystem": "Del sistema",
+  "language": "Idioma",
+  "languageEnglish": "Inglés",
+  "languageChineseTraditional": "Chino tradicional",
+  "languageSpanish": "Español",
+  "resetToDefaults": "Restablecer valores",
+
+  "openPdf": "Abrir PDF…",
+  "prev": "Anterior",
+  "next": "Siguiente",
+  "pageInfo": "Página {current}/{total}",
+  "goTo": "Ir a:",
+  "dpi": "DPI:",
+  "markForSigning": "Marcar para firmar",
+  "unmarkSigning": "Quitar marca",
+  "saveSignedPdf": "Guardar PDF firmado",
+  "loadSignatureFromFile": "Cargar firma desde archivo",
+  "drawSignature": "Dibujar firma",
+  "noPdfLoaded": "No hay PDF cargado",
+  "signature": "Firma",
+  "lockAspectRatio": "Bloquear relación de aspecto",
+  "backgroundRemoval": "Eliminación de fondo",
+  "contrast": "Contraste",
+  "brightness": "Brillo",
+  "exportingPleaseWait": "Exportando... Por favor espera",
+
+  "nothingToSaveYet": "Nada que guardar todavía",
+  "savedWithPath": "Guardado: {path}",
+  "failedToSavePdf": "Error al guardar el PDF",
+  "downloadStarted": "Descarga iniciada",
+  "failedToGeneratePdf": "Error al generar el PDF",
+  "invalidOrUnsupportedFile": "Archivo no válido o no compatible",
+
+  "confirm": "Confirmar",
+  "undo": "Deshacer",
+  "clear": "Limpiar"
+}

lib/l10n/app_localizations.dart

@@ -0,0 +1,385 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:intl/intl.dart' as intl;
+
+import 'app_localizations_en.dart';
+import 'app_localizations_es.dart';
+import 'app_localizations_zh.dart';
+
+// ignore_for_file: type=lint
+
+/// Callers can lookup localized strings with an instance of AppLocalizations
+/// returned by `AppLocalizations.of(context)`.
+///
+/// Applications need to include `AppLocalizations.delegate()` in their app's
+/// `localizationDelegates` list, and the locales they support in the app's
+/// `supportedLocales` list. For example:
+///
+/// ```dart
+/// import 'l10n/app_localizations.dart';
+///
+/// return MaterialApp(
+///   localizationsDelegates: AppLocalizations.localizationsDelegates,
+///   supportedLocales: AppLocalizations.supportedLocales,
+///   home: MyApplicationHome(),
+/// );
+/// ```
+///
+/// ## Update pubspec.yaml
+///
+/// Please make sure to update your pubspec.yaml to include the following
+/// packages:
+///
+/// ```yaml
+/// dependencies:
+///   # Internationalization support.
+///   flutter_localizations:
+///     sdk: flutter
+///   intl: any # Use the pinned version from flutter_localizations
+///
+///   # Rest of dependencies
+/// ```
+///
+/// ## iOS Applications
+///
+/// iOS applications define key application metadata, including supported
+/// locales, in an Info.plist file that is built into the application bundle.
+/// To configure the locales supported by your app, you’ll need to edit this
+/// file.
+///
+/// First, open your project’s ios/Runner.xcworkspace Xcode workspace file.
+/// Then, in the Project Navigator, open the Info.plist file under the Runner
+/// project’s Runner folder.
+///
+/// Next, select the Information Property List item, select Add Item from the
+/// Editor menu, then select Localizations from the pop-up menu.
+///
+/// Select and expand the newly-created Localizations item then, for each
+/// locale your application supports, add a new item and select the locale
+/// you wish to add from the pop-up menu in the Value field. This list should
+/// be consistent with the languages listed in the AppLocalizations.supportedLocales
+/// property.
+abstract class AppLocalizations {
+  AppLocalizations(String locale)
+    : localeName = intl.Intl.canonicalizedLocale(locale.toString());
+
+  final String localeName;
+
+  static AppLocalizations of(BuildContext context) {
+    return Localizations.of<AppLocalizations>(context, AppLocalizations)!;
+  }
+
+  static const LocalizationsDelegate<AppLocalizations> delegate =
+      _AppLocalizationsDelegate();
+
+  /// A list of this localizations delegate along with the default localizations
+  /// delegates.
+  ///
+  /// Returns a list of localizations delegates containing this delegate along with
+  /// GlobalMaterialLocalizations.delegate, GlobalCupertinoLocalizations.delegate,
+  /// and GlobalWidgetsLocalizations.delegate.
+  ///
+  /// Additional delegates can be added by appending to this list in
+  /// MaterialApp. This list does not have to be used at all if a custom list
+  /// of delegates is preferred or required.
+  static const List<LocalizationsDelegate<dynamic>> localizationsDelegates =
+      <LocalizationsDelegate<dynamic>>[
+        delegate,
+        GlobalMaterialLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+      ];
+
+  /// A list of this localizations delegate's supported locales.
+  static const List<Locale> supportedLocales = <Locale>[
+    Locale('en'),
+    Locale('es'),
+    Locale('zh'),
+    Locale('zh', 'TW'),
+  ];
+
+  /// No description provided for @appTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'PDF Signature'**
+  String get appTitle;
+
+  /// Generic error text with message
+  ///
+  /// In en, this message translates to:
+  /// **'Error: {message}'**
+  String errorWithMessage(String message);
+
+  /// No description provided for @settings.
+  ///
+  /// In en, this message translates to:
+  /// **'Settings'**
+  String get settings;
+
+  /// No description provided for @theme.
+  ///
+  /// In en, this message translates to:
+  /// **'Theme'**
+  String get theme;
+
+  /// No description provided for @themeLight.
+  ///
+  /// In en, this message translates to:
+  /// **'Light'**
+  String get themeLight;
+
+  /// No description provided for @themeDark.
+  ///
+  /// In en, this message translates to:
+  /// **'Dark'**
+  String get themeDark;
+
+  /// No description provided for @themeSystem.
+  ///
+  /// In en, this message translates to:
+  /// **'System'**
+  String get themeSystem;
+
+  /// No description provided for @language.
+  ///
+  /// In en, this message translates to:
+  /// **'Language'**
+  String get language;
+
+  /// No description provided for @languageEnglish.
+  ///
+  /// In en, this message translates to:
+  /// **'English'**
+  String get languageEnglish;
+
+  /// No description provided for @languageChineseTraditional.
+  ///
+  /// In en, this message translates to:
+  /// **'Traditional Chinese'**
+  String get languageChineseTraditional;
+
+  /// No description provided for @languageSpanish.
+  ///
+  /// In en, this message translates to:
+  /// **'Spanish'**
+  String get languageSpanish;
+
+  /// No description provided for @resetToDefaults.
+  ///
+  /// In en, this message translates to:
+  /// **'Reset to defaults'**
+  String get resetToDefaults;
+
+  /// No description provided for @openPdf.
+  ///
+  /// In en, this message translates to:
+  /// **'Open PDF...'**
+  String get openPdf;
+
+  /// No description provided for @prev.
+  ///
+  /// In en, this message translates to:
+  /// **'Prev'**
+  String get prev;
+
+  /// No description provided for @next.
+  ///
+  /// In en, this message translates to:
+  /// **'Next'**
+  String get next;
+
+  /// Label showing current page and total
+  ///
+  /// In en, this message translates to:
+  /// **'Page {current}/{total}'**
+  String pageInfo(int current, int total);
+
+  /// No description provided for @goTo.
+  ///
+  /// In en, this message translates to:
+  /// **'Go to:'**
+  String get goTo;
+
+  /// No description provided for @dpi.
+  ///
+  /// In en, this message translates to:
+  /// **'DPI:'**
+  String get dpi;
+
+  /// No description provided for @markForSigning.
+  ///
+  /// In en, this message translates to:
+  /// **'Mark for Signing'**
+  String get markForSigning;
+
+  /// No description provided for @unmarkSigning.
+  ///
+  /// In en, this message translates to:
+  /// **'Unmark Signing'**
+  String get unmarkSigning;
+
+  /// No description provided for @saveSignedPdf.
+  ///
+  /// In en, this message translates to:
+  /// **'Save Signed PDF'**
+  String get saveSignedPdf;
+
+  /// No description provided for @loadSignatureFromFile.
+  ///
+  /// In en, this message translates to:
+  /// **'Load Signature from file'**
+  String get loadSignatureFromFile;
+
+  /// No description provided for @drawSignature.
+  ///
+  /// In en, this message translates to:
+  /// **'Draw Signature'**
+  String get drawSignature;
+
+  /// No description provided for @noPdfLoaded.
+  ///
+  /// In en, this message translates to:
+  /// **'No PDF loaded'**
+  String get noPdfLoaded;
+
+  /// No description provided for @signature.
+  ///
+  /// In en, this message translates to:
+  /// **'Signature'**
+  String get signature;
+
+  /// No description provided for @lockAspectRatio.
+  ///
+  /// In en, this message translates to:
+  /// **'Lock aspect ratio'**
+  String get lockAspectRatio;
+
+  /// No description provided for @backgroundRemoval.
+  ///
+  /// In en, this message translates to:
+  /// **'Background removal'**
+  String get backgroundRemoval;
+
+  /// No description provided for @contrast.
+  ///
+  /// In en, this message translates to:
+  /// **'Contrast'**
+  String get contrast;
+
+  /// No description provided for @brightness.
+  ///
+  /// In en, this message translates to:
+  /// **'Brightness'**
+  String get brightness;
+
+  /// No description provided for @exportingPleaseWait.
+  ///
+  /// In en, this message translates to:
+  /// **'Exporting... Please wait'**
+  String get exportingPleaseWait;
+
+  /// No description provided for @nothingToSaveYet.
+  ///
+  /// In en, this message translates to:
+  /// **'Nothing to save yet'**
+  String get nothingToSaveYet;
+
+  /// Snackbar text showing where file saved
+  ///
+  /// In en, this message translates to:
+  /// **'Saved: {path}'**
+  String savedWithPath(String path);
+
+  /// No description provided for @failedToSavePdf.
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to save PDF'**
+  String get failedToSavePdf;
+
+  /// No description provided for @downloadStarted.
+  ///
+  /// In en, this message translates to:
+  /// **'Download started'**
+  String get downloadStarted;
+
+  /// No description provided for @failedToGeneratePdf.
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to generate PDF'**
+  String get failedToGeneratePdf;
+
+  /// No description provided for @invalidOrUnsupportedFile.
+  ///
+  /// In en, this message translates to:
+  /// **'Invalid or unsupported file'**
+  String get invalidOrUnsupportedFile;
+
+  /// No description provided for @confirm.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm'**
+  String get confirm;
+
+  /// No description provided for @undo.
+  ///
+  /// In en, this message translates to:
+  /// **'Undo'**
+  String get undo;
+
+  /// No description provided for @clear.
+  ///
+  /// In en, this message translates to:
+  /// **'Clear'**
+  String get clear;
+}
+
+class _AppLocalizationsDelegate
+    extends LocalizationsDelegate<AppLocalizations> {
+  const _AppLocalizationsDelegate();
+
+  @override
+  Future<AppLocalizations> load(Locale locale) {
+    return SynchronousFuture<AppLocalizations>(lookupAppLocalizations(locale));
+  }
+
+  @override
+  bool isSupported(Locale locale) =>
+      <String>['en', 'es', 'zh'].contains(locale.languageCode);
+
+  @override
+  bool shouldReload(_AppLocalizationsDelegate old) => false;
+}
+
+AppLocalizations lookupAppLocalizations(Locale locale) {
+  // Lookup logic when language+country codes are specified.
+  switch (locale.languageCode) {
+    case 'zh':
+      {
+        switch (locale.countryCode) {
+          case 'TW':
+            return AppLocalizationsZhTw();
+        }
+        break;
+      }
+  }
+
+  // Lookup logic when only language code is specified.
+  switch (locale.languageCode) {
+    case 'en':
+      return AppLocalizationsEn();
+    case 'es':
+      return AppLocalizationsEs();
+    case 'zh':
+      return AppLocalizationsZh();
+  }
+
+  throw FlutterError(
+    'AppLocalizations.delegate failed to load unsupported locale "$locale". This is likely '
+    'an issue with the localizations generation tool. Please file an issue '
+    'on GitHub with a reproducible sample app and the gen-l10n configuration '
+    'that was used.',
+  );
+}

lib/l10n/app_localizations_en.dart

@@ -0,0 +1,133 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for English (`en`).
+class AppLocalizationsEn extends AppLocalizations {
+  AppLocalizationsEn([String locale = 'en']) : super(locale);
+
+  @override
+  String get appTitle => 'PDF Signature';
+
+  @override
+  String errorWithMessage(String message) {
+    return 'Error: $message';
+  }
+
+  @override
+  String get settings => 'Settings';
+
+  @override
+  String get theme => 'Theme';
+
+  @override
+  String get themeLight => 'Light';
+
+  @override
+  String get themeDark => 'Dark';
+
+  @override
+  String get themeSystem => 'System';
+
+  @override
+  String get language => 'Language';
+
+  @override
+  String get languageEnglish => 'English';
+
+  @override
+  String get languageChineseTraditional => 'Traditional Chinese';
+
+  @override
+  String get languageSpanish => 'Spanish';
+
+  @override
+  String get resetToDefaults => 'Reset to defaults';
+
+  @override
+  String get openPdf => 'Open PDF...';
+
+  @override
+  String get prev => 'Prev';
+
+  @override
+  String get next => 'Next';
+
+  @override
+  String pageInfo(int current, int total) {
+    return 'Page $current/$total';
+  }
+
+  @override
+  String get goTo => 'Go to:';
+
+  @override
+  String get dpi => 'DPI:';
+
+  @override
+  String get markForSigning => 'Mark for Signing';
+
+  @override
+  String get unmarkSigning => 'Unmark Signing';
+
+  @override
+  String get saveSignedPdf => 'Save Signed PDF';
+
+  @override
+  String get loadSignatureFromFile => 'Load Signature from file';
+
+  @override
+  String get drawSignature => 'Draw Signature';
+
+  @override
+  String get noPdfLoaded => 'No PDF loaded';
+
+  @override
+  String get signature => 'Signature';
+
+  @override
+  String get lockAspectRatio => 'Lock aspect ratio';
+
+  @override
+  String get backgroundRemoval => 'Background removal';
+
+  @override
+  String get contrast => 'Contrast';
+
+  @override
+  String get brightness => 'Brightness';
+
+  @override
+  String get exportingPleaseWait => 'Exporting... Please wait';
+
+  @override
+  String get nothingToSaveYet => 'Nothing to save yet';
+
+  @override
+  String savedWithPath(String path) {
+    return 'Saved: $path';
+  }
+
+  @override
+  String get failedToSavePdf => 'Failed to save PDF';
+
+  @override
+  String get downloadStarted => 'Download started';
+
+  @override
+  String get failedToGeneratePdf => 'Failed to generate PDF';
+
+  @override
+  String get invalidOrUnsupportedFile => 'Invalid or unsupported file';
+
+  @override
+  String get confirm => 'Confirm';
+
+  @override
+  String get undo => 'Undo';
+
+  @override
+  String get clear => 'Clear';
+}

lib/l10n/app_localizations_es.dart

@@ -0,0 +1,133 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for Spanish Castilian (`es`).
+class AppLocalizationsEs extends AppLocalizations {
+  AppLocalizationsEs([String locale = 'es']) : super(locale);
+
+  @override
+  String get appTitle => 'Firma PDF';
+
+  @override
+  String errorWithMessage(String message) {
+    return 'Error: $message';
+  }
+
+  @override
+  String get settings => 'Ajustes';
+
+  @override
+  String get theme => 'Tema';
+
+  @override
+  String get themeLight => 'Claro';
+
+  @override
+  String get themeDark => 'Oscuro';
+
+  @override
+  String get themeSystem => 'Del sistema';
+
+  @override
+  String get language => 'Idioma';
+
+  @override
+  String get languageEnglish => 'Inglés';
+
+  @override
+  String get languageChineseTraditional => 'Chino tradicional';
+
+  @override
+  String get languageSpanish => 'Español';
+
+  @override
+  String get resetToDefaults => 'Restablecer valores';
+
+  @override
+  String get openPdf => 'Abrir PDF…';
+
+  @override
+  String get prev => 'Anterior';
+
+  @override
+  String get next => 'Siguiente';
+
+  @override
+  String pageInfo(int current, int total) {
+    return 'Página $current/$total';
+  }
+
+  @override
+  String get goTo => 'Ir a:';
+
+  @override
+  String get dpi => 'DPI:';
+
+  @override
+  String get markForSigning => 'Marcar para firmar';
+
+  @override
+  String get unmarkSigning => 'Quitar marca';
+
+  @override
+  String get saveSignedPdf => 'Guardar PDF firmado';
+
+  @override
+  String get loadSignatureFromFile => 'Cargar firma desde archivo';
+
+  @override
+  String get drawSignature => 'Dibujar firma';
+
+  @override
+  String get noPdfLoaded => 'No hay PDF cargado';
+
+  @override
+  String get signature => 'Firma';
+
+  @override
+  String get lockAspectRatio => 'Bloquear relación de aspecto';
+
+  @override
+  String get backgroundRemoval => 'Eliminación de fondo';
+
+  @override
+  String get contrast => 'Contraste';
+
+  @override
+  String get brightness => 'Brillo';
+
+  @override
+  String get exportingPleaseWait => 'Exportando... Por favor espera';
+
+  @override
+  String get nothingToSaveYet => 'Nada que guardar todavía';
+
+  @override
+  String savedWithPath(String path) {
+    return 'Guardado: $path';
+  }
+
+  @override
+  String get failedToSavePdf => 'Error al guardar el PDF';
+
+  @override
+  String get downloadStarted => 'Descarga iniciada';
+
+  @override
+  String get failedToGeneratePdf => 'Error al generar el PDF';
+
+  @override
+  String get invalidOrUnsupportedFile => 'Archivo no válido o no compatible';
+
+  @override
+  String get confirm => 'Confirmar';
+
+  @override
+  String get undo => 'Deshacer';
+
+  @override
+  String get clear => 'Limpiar';
+}

lib/l10n/app_localizations_zh.dart

@@ -0,0 +1,261 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for Chinese (`zh`).
+class AppLocalizationsZh extends AppLocalizations {
+  AppLocalizationsZh([String locale = 'zh']) : super(locale);
+
+  @override
+  String get appTitle => 'PDF 簽名';
+
+  @override
+  String errorWithMessage(String message) {
+    return '錯誤：$message';
+  }
+
+  @override
+  String get settings => '設定';
+
+  @override
+  String get theme => '主題';
+
+  @override
+  String get themeLight => '淺色';
+
+  @override
+  String get themeDark => '深色';
+
+  @override
+  String get themeSystem => '系統';
+
+  @override
+  String get language => '語言';
+
+  @override
+  String get languageEnglish => '英文';
+
+  @override
+  String get languageChineseTraditional => '繁體中文';
+
+  @override
+  String get languageSpanish => '西班牙文';
+
+  @override
+  String get resetToDefaults => '重設為預設值';
+
+  @override
+  String get openPdf => '開啟 PDF…';
+
+  @override
+  String get prev => '上一頁';
+
+  @override
+  String get next => '下一頁';
+
+  @override
+  String pageInfo(int current, int total) {
+    return '第 $current/$total 頁';
+  }
+
+  @override
+  String get goTo => '前往：';
+
+  @override
+  String get dpi => 'DPI：';
+
+  @override
+  String get markForSigning => '標記簽署';
+
+  @override
+  String get unmarkSigning => '取消標記';
+
+  @override
+  String get saveSignedPdf => '儲存已簽名 PDF';
+
+  @override
+  String get loadSignatureFromFile => '從檔案載入簽名';
+
+  @override
+  String get drawSignature => '手寫簽名';
+
+  @override
+  String get noPdfLoaded => '尚未載入 PDF';
+
+  @override
+  String get signature => '簽名';
+
+  @override
+  String get lockAspectRatio => '鎖定長寬比';
+
+  @override
+  String get backgroundRemoval => '去除背景';
+
+  @override
+  String get contrast => '對比';
+
+  @override
+  String get brightness => '亮度';
+
+  @override
+  String get exportingPleaseWait => '匯出中…請稍候';
+
+  @override
+  String get nothingToSaveYet => '尚無可儲存的內容';
+
+  @override
+  String savedWithPath(String path) {
+    return '已儲存：$path';
+  }
+
+  @override
+  String get failedToSavePdf => '儲存 PDF 失敗';
+
+  @override
+  String get downloadStarted => '已開始下載';
+
+  @override
+  String get failedToGeneratePdf => '產生 PDF 失敗';
+
+  @override
+  String get invalidOrUnsupportedFile => '無效或不支援的檔案';
+
+  @override
+  String get confirm => '確認';
+
+  @override
+  String get undo => '復原';
+
+  @override
+  String get clear => '清除';
+}
+
+/// The translations for Chinese, as used in Taiwan (`zh_TW`).
+class AppLocalizationsZhTw extends AppLocalizationsZh {
+  AppLocalizationsZhTw() : super('zh_TW');
+
+  @override
+  String get appTitle => 'PDF 簽名';
+
+  @override
+  String errorWithMessage(String message) {
+    return '錯誤：$message';
+  }
+
+  @override
+  String get settings => '設定';
+
+  @override
+  String get theme => '主題';
+
+  @override
+  String get themeLight => '淺色';
+
+  @override
+  String get themeDark => '深色';
+
+  @override
+  String get themeSystem => '系統';
+
+  @override
+  String get language => '語言';
+
+  @override
+  String get languageEnglish => '英文';
+
+  @override
+  String get languageChineseTraditional => '繁體中文';
+
+  @override
+  String get languageSpanish => '西班牙文';
+
+  @override
+  String get resetToDefaults => '重設為預設值';
+
+  @override
+  String get openPdf => '開啟 PDF…';
+
+  @override
+  String get prev => '上一頁';
+
+  @override
+  String get next => '下一頁';
+
+  @override
+  String pageInfo(int current, int total) {
+    return '第 $current/$total 頁';
+  }
+
+  @override
+  String get goTo => '前往：';
+
+  @override
+  String get dpi => 'DPI：';
+
+  @override
+  String get markForSigning => '標記簽署';
+
+  @override
+  String get unmarkSigning => '取消標記';
+
+  @override
+  String get saveSignedPdf => '儲存已簽名 PDF';
+
+  @override
+  String get loadSignatureFromFile => '從檔案載入簽名';
+
+  @override
+  String get drawSignature => '手寫簽名';
+
+  @override
+  String get noPdfLoaded => '尚未載入 PDF';
+
+  @override
+  String get signature => '簽名';
+
+  @override
+  String get lockAspectRatio => '鎖定長寬比';
+
+  @override
+  String get backgroundRemoval => '去除背景';
+
+  @override
+  String get contrast => '對比';
+
+  @override
+  String get brightness => '亮度';
+
+  @override
+  String get exportingPleaseWait => '匯出中…請稍候';
+
+  @override
+  String get nothingToSaveYet => '尚無可儲存的內容';
+
+  @override
+  String savedWithPath(String path) {
+    return '已儲存：$path';
+  }
+
+  @override
+  String get failedToSavePdf => '儲存 PDF 失敗';
+
+  @override
+  String get downloadStarted => '已開始下載';
+
+  @override
+  String get failedToGeneratePdf => '產生 PDF 失敗';
+
+  @override
+  String get invalidOrUnsupportedFile => '無效或不支援的檔案';
+
+  @override
+  String get confirm => '確認';
+
+  @override
+  String get undo => '復原';
+
+  @override
+  String get clear => '清除';
+}

lib/l10n/app_zh.arb

@@ -0,0 +1,46 @@
+{
+  "@@locale": "zh",
+  "appTitle": "PDF 簽名",
+  "errorWithMessage": "錯誤：{message}",
+
+  "settings": "設定",
+  "theme": "主題",
+  "themeLight": "淺色",
+  "themeDark": "深色",
+  "themeSystem": "系統",
+  "language": "語言",
+  "languageEnglish": "英文",
+  "languageChineseTraditional": "繁體中文",
+  "languageSpanish": "西班牙文",
+  "resetToDefaults": "重設為預設值",
+
+  "openPdf": "開啟 PDF…",
+  "prev": "上一頁",
+  "next": "下一頁",
+  "pageInfo": "第 {current}/{total} 頁",
+  "goTo": "前往：",
+  "dpi": "DPI：",
+  "markForSigning": "標記簽署",
+  "unmarkSigning": "取消標記",
+  "saveSignedPdf": "儲存已簽名 PDF",
+  "loadSignatureFromFile": "從檔案載入簽名",
+  "drawSignature": "手寫簽名",
+  "noPdfLoaded": "尚未載入 PDF",
+  "signature": "簽名",
+  "lockAspectRatio": "鎖定長寬比",
+  "backgroundRemoval": "去除背景",
+  "contrast": "對比",
+  "brightness": "亮度",
+  "exportingPleaseWait": "匯出中…請稍候",
+
+  "nothingToSaveYet": "尚無可儲存的內容",
+  "savedWithPath": "已儲存：{path}",
+  "failedToSavePdf": "儲存 PDF 失敗",
+  "downloadStarted": "已開始下載",
+  "failedToGeneratePdf": "產生 PDF 失敗",
+  "invalidOrUnsupportedFile": "無效或不支援的檔案",
+
+  "confirm": "確認",
+  "undo": "復原",
+  "clear": "清除"
+}

lib/l10n/app_zh_TW.arb

@@ -0,0 +1,46 @@
+{
+  "@@locale": "zh_TW",
+  "appTitle": "PDF 簽名",
+  "errorWithMessage": "錯誤：{message}",
+
+  "settings": "設定",
+  "theme": "主題",
+  "themeLight": "淺色",
+  "themeDark": "深色",
+  "themeSystem": "系統",
+  "language": "語言",
+  "languageEnglish": "英文",
+  "languageChineseTraditional": "繁體中文",
+  "languageSpanish": "西班牙文",
+  "resetToDefaults": "重設為預設值",
+
+  "openPdf": "開啟 PDF…",
+  "prev": "上一頁",
+  "next": "下一頁",
+  "pageInfo": "第 {current}/{total} 頁",
+  "goTo": "前往：",
+  "dpi": "DPI：",
+  "markForSigning": "標記簽署",
+  "unmarkSigning": "取消標記",
+  "saveSignedPdf": "儲存已簽名 PDF",
+  "loadSignatureFromFile": "從檔案載入簽名",
+  "drawSignature": "手寫簽名",
+  "noPdfLoaded": "尚未載入 PDF",
+  "signature": "簽名",
+  "lockAspectRatio": "鎖定長寬比",
+  "backgroundRemoval": "去除背景",
+  "contrast": "對比",
+  "brightness": "亮度",
+  "exportingPleaseWait": "匯出中…請稍候",
+
+  "nothingToSaveYet": "尚無可儲存的內容",
+  "savedWithPath": "已儲存：{path}",
+  "failedToSavePdf": "儲存 PDF 失敗",
+  "downloadStarted": "已開始下載",
+  "failedToGeneratePdf": "產生 PDF 失敗",
+  "invalidOrUnsupportedFile": "無效或不支援的檔案",
+
+  "confirm": "確認",
+  "undo": "復原",
+  "clear": "清除"
+}

lib/ui/features/pdf/view_model/view_model.dart

@@ -2,6 +2,7 @@ import 'dart:math' as math;
 import 'dart:typed_data';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:pdf_signature/l10n/app_localizations.dart';
 import 'package:image/image.dart' as img;
 
 import '../../../../data/model/model.dart';
@@ -96,9 +97,10 @@ class SignatureController extends StateNotifier<SignatureState> {
   }
 
   void setInvalidSelected(BuildContext context) {
-    ScaffoldMessenger.of(context).showSnackBar(
+    final l = AppLocalizations.of(context);
-      const SnackBar(content: Text('Invalid or unsupported file')),
+    ScaffoldMessenger.of(
-    );
+      context,
+    ).showSnackBar(SnackBar(content: Text(l.invalidOrUnsupportedFile)));
   }
 
   void drag(Offset delta) {

lib/ui/features/pdf/widgets/draw_canvas.dart

@@ -1,6 +1,7 @@
 import 'dart:math' as math;
 import 'dart:typed_data';
 import 'package:flutter/material.dart';
+import 'package:pdf_signature/l10n/app_localizations.dart';
 import 'package:hand_signature/signature.dart' as hand;
 
 class DrawCanvas extends StatefulWidget {
@@ -35,6 +36,7 @@ class _DrawCanvasState extends State<DrawCanvas> {
 
   @override
   Widget build(BuildContext context) {
+    final l = AppLocalizations.of(context);
     return SafeArea(
       child: Padding(
         padding: const EdgeInsets.all(12),
@@ -64,19 +66,19 @@ class _DrawCanvasState extends State<DrawCanvas> {
                       }
                     }
                   },
-                  child: const Text('Confirm'),
+                  child: Text(l.confirm),
                 ),
                 const SizedBox(width: 8),
                 OutlinedButton(
                   key: const Key('btn_canvas_undo'),
                   onPressed: () => _control.stepBack(),
-                  child: const Text('Undo'),
+                  child: Text(l.undo),
                 ),
                 const SizedBox(width: 8),
                 OutlinedButton(
                   key: const Key('btn_canvas_clear'),
                   onPressed: () => _control.clear(),
-                  child: const Text('Clear'),
+                  child: Text(l.clear),
                 ),
               ],
             ),

lib/ui/features/pdf/widgets/pdf_screen.dart

@@ -4,6 +4,7 @@ import 'package:file_selector/file_selector.dart' as fs;
 import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:pdf_signature/l10n/app_localizations.dart';
 import 'package:pdfrx/pdfrx.dart';
 import 'package:printing/printing.dart' as printing;
 
@@ -101,8 +102,8 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
       final messenger = ScaffoldMessenger.of(context);
       if (!pdf.loaded || sig.rect == null) {
         messenger.showSnackBar(
-          const SnackBar(
+          SnackBar(
-            content: Text('Nothing to save yet'),
+            content: Text(AppLocalizations.of(context).nothingToSaveYet),
           ), // guard per use-case
         );
         return;
@@ -193,22 +194,32 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
         // Desktop/mobile: we had a concrete path
         if (ok) {
           messenger.showSnackBar(
-            SnackBar(content: Text('Saved: ${savedPath ?? ''}')),
+            SnackBar(
+              content: Text(
+                AppLocalizations.of(context).savedWithPath(savedPath ?? ''),
+              ),
+            ),
           );
         } else {
           messenger.showSnackBar(
-            const SnackBar(content: Text('Failed to save PDF')),
+            SnackBar(
+              content: Text(AppLocalizations.of(context).failedToSavePdf),
+            ),
           );
         }
       } else {
         // Web: indicate whether we triggered a download dialog
         if (ok) {
           messenger.showSnackBar(
-            const SnackBar(content: Text('Download started')),
+            SnackBar(
+              content: Text(AppLocalizations.of(context).downloadStarted),
+            ),
           );
         } else {
           messenger.showSnackBar(
-            const SnackBar(content: Text('Failed to generate PDF')),
+            SnackBar(
+              content: Text(AppLocalizations.of(context).failedToGeneratePdf),
+            ),
           );
         }
       }
@@ -227,8 +238,9 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
   Widget build(BuildContext context) {
     final pdf = ref.watch(pdfProvider);
     final isExporting = ref.watch(exportingProvider);
+    final l = AppLocalizations.of(context);
     return Scaffold(
-      appBar: AppBar(title: const Text('PDF Signature')),
+      appBar: AppBar(title: Text(l.appTitle)),
       body: Padding(
         padding: const EdgeInsets.all(12),
         child: Stack(
@@ -260,15 +272,15 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
               Positioned.fill(
                 child: Container(
                   color: Colors.black45,
-                  child: const Center(
+                  child: Center(
                     child: Column(
                       mainAxisSize: MainAxisSize.min,
                       children: [
                         CircularProgressIndicator(),
                         SizedBox(height: 12),
                         Text(
-                          'Exporting... Please wait',
+                          l.exportingPleaseWait,
-                          style: TextStyle(color: Colors.white),
+                          style: const TextStyle(color: Colors.white),
                         ),
                       ],
                     ),
@@ -283,7 +295,8 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
 
   Widget _buildToolbar(PdfState pdf, {bool disabled = false}) {
     final dpi = ref.watch(exportDpiProvider);
-    final pageInfo = 'Page ${pdf.currentPage}/${pdf.pageCount}';
+    final l = AppLocalizations.of(context);
+    final pageInfo = l.pageInfo(pdf.currentPage, pdf.pageCount);
     return Wrap(
       spacing: 8,
       runSpacing: 8,
@@ -299,12 +312,12 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                       MaterialPageRoute(builder: (_) => const SettingsScreen()),
                     );
                   },
-          child: const Text('Settings'),
+          child: Text(l.settings),
         ),
         OutlinedButton(
           key: const Key('btn_open_pdf_picker'),
           onPressed: disabled ? null : _pickPdf,
-          child: const Text('Open PDF...'),
+          child: Text(l.openPdf),
         ),
         if (pdf.loaded) ...[
           Row(
@@ -315,7 +328,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                 onPressed:
                     disabled ? null : () => _jumpToPage(pdf.currentPage - 1),
                 icon: const Icon(Icons.chevron_left),
-                tooltip: 'Prev',
+                tooltip: l.prev,
               ),
               Text(pageInfo, key: const Key('lbl_page_info')),
               IconButton(
@@ -323,14 +336,14 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                 onPressed:
                     disabled ? null : () => _jumpToPage(pdf.currentPage + 1),
                 icon: const Icon(Icons.chevron_right),
-                tooltip: 'Next',
+                tooltip: l.next,
               ),
             ],
           ),
           Row(
             mainAxisSize: MainAxisSize.min,
             children: [
-              const Text('Go to:'),
+              Text(l.goTo),
               SizedBox(
                 width: 60,
                 child: TextField(
@@ -348,7 +361,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
           Row(
             mainAxisSize: MainAxisSize.min,
             children: [
-              const Text('DPI:'),
+              Text(l.dpi),
               const SizedBox(width: 8),
               DropdownButton<double>(
                 key: const Key('ddl_export_dpi'),
@@ -377,25 +390,25 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
             key: const Key('btn_mark_signing'),
             onPressed: disabled ? null : _toggleMarkForSigning,
             child: Text(
-              pdf.markedForSigning ? 'Unmark Signing' : 'Mark for Signing',
+              pdf.markedForSigning ? l.unmarkSigning : l.markForSigning,
             ),
           ),
           if (pdf.loaded)
             ElevatedButton(
               key: const Key('btn_save_pdf'),
               onPressed: disabled ? null : _saveSignedPdf,
-              child: const Text('Save Signed PDF'),
+              child: Text(l.saveSignedPdf),
             ),
           if (pdf.markedForSigning) ...[
             OutlinedButton(
               key: const Key('btn_load_signature_picker'),
               onPressed: disabled ? null : _loadSignatureFromFile,
-              child: const Text('Load Signature from file'),
+              child: Text(l.loadSignatureFromFile),
             ),
             ElevatedButton(
               key: const Key('btn_draw_signature'),
               onPressed: disabled ? null : _openDrawCanvas,
-              child: const Text('Draw Signature'),
+              child: Text(l.drawSignature),
             ),
           ],
         ],
@@ -405,7 +418,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
 
   Widget _buildPageArea(PdfState pdf) {
     if (!pdf.loaded) {
-      return const Center(child: Text('No PDF loaded'));
+      return Center(child: Text(AppLocalizations.of(context).noPdfLoaded));
     }
     final useMock = ref.watch(useMockViewerProvider);
     if (useMock) {
@@ -422,7 +435,9 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                   color: Colors.grey.shade200,
                   child: Center(
                     child: Text(
-                      'Page ${pdf.currentPage}/${pdf.pageCount}',
+                      AppLocalizations.of(
+                        context,
+                      ).pageInfo(pdf.currentPage, pdf.pageCount),
                       style: const TextStyle(
                         fontSize: 24,
                         color: Colors.black54,
@@ -544,7 +559,11 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                           );
                           final bytes = processed ?? sig.imageBytes;
                           if (bytes == null) {
-                            return const Center(child: Text('Signature'));
+                            return Center(
+                              child: Text(
+                                AppLocalizations.of(context).signature,
+                              ),
+                            );
                           }
                           return Image.memory(bytes, fit: BoxFit.contain);
                         },
@@ -590,7 +609,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                       .read(signatureProvider.notifier)
                       .toggleAspect(v ?? false),
             ),
-            const Text('Lock aspect ratio'),
+            Text(AppLocalizations.of(context).lockAspectRatio),
             const SizedBox(width: 16),
             Switch(
               key: const Key('swt_bg_removal'),
@@ -598,12 +617,12 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
               onChanged:
                   (v) => ref.read(signatureProvider.notifier).setBgRemoval(v),
             ),
-            const Text('Background removal'),
+            Text(AppLocalizations.of(context).backgroundRemoval),
           ],
         ),
         Row(
           children: [
-            const Text('Contrast'),
+            Text(AppLocalizations.of(context).contrast),
             Expanded(
               child: Slider(
                 key: const Key('sld_contrast'),
@@ -619,7 +638,7 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
         ),
         Row(
           children: [
-            const Text('Brightness'),
+            Text(AppLocalizations.of(context).brightness),
             Expanded(
               child: Slider(
                 key: const Key('sld_brightness'),

lib/ui/features/preferences/widgets/settings_screen.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:pdf_signature/l10n/app_localizations.dart';
 import '../providers.dart';
 
 class SettingsScreen extends ConsumerWidget {
@@ -8,22 +9,23 @@ class SettingsScreen extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final prefs = ref.watch(preferencesProvider);
+    final l = AppLocalizations.of(context);
     return Scaffold(
-      appBar: AppBar(title: const Text('Settings')),
+      appBar: AppBar(title: Text(l.settings)),
       body: Padding(
         padding: const EdgeInsets.all(16.0),
         child: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
-            const Text('Theme', style: TextStyle(fontWeight: FontWeight.bold)),
+            Text(l.theme, style: const TextStyle(fontWeight: FontWeight.bold)),
             const SizedBox(height: 8),
             DropdownButton<String>(
               key: const Key('ddl_theme'),
               value: prefs.theme,
-              items: const [
+              items: [
-                DropdownMenuItem(value: 'light', child: Text('Light')),
+                DropdownMenuItem(value: 'light', child: Text(l.themeLight)),
-                DropdownMenuItem(value: 'dark', child: Text('Dark')),
+                DropdownMenuItem(value: 'dark', child: Text(l.themeDark)),
-                DropdownMenuItem(value: 'system', child: Text('System')),
+                DropdownMenuItem(value: 'system', child: Text(l.themeSystem)),
               ],
               onChanged:
                   (v) =>
@@ -32,18 +34,21 @@ class SettingsScreen extends ConsumerWidget {
                           : ref.read(preferencesProvider.notifier).setTheme(v),
             ),
             const SizedBox(height: 16),
-            const Text(
+            Text(
-              'Language',
+              l.language,
-              style: TextStyle(fontWeight: FontWeight.bold),
+              style: const TextStyle(fontWeight: FontWeight.bold),
             ),
             const SizedBox(height: 8),
             DropdownButton<String>(
               key: const Key('ddl_language'),
               value: prefs.language,
-              items: const [
+              items: [
-                DropdownMenuItem(value: 'en', child: Text('English')),
+                DropdownMenuItem(value: 'en', child: Text(l.languageEnglish)),
-                DropdownMenuItem(value: 'zh-TW', child: Text('繁體中文')),
+                DropdownMenuItem(
-                DropdownMenuItem(value: 'es', child: Text('Español')),
+                  value: 'zh-TW',
+                  child: Text(l.languageChineseTraditional),
+                ),
+                DropdownMenuItem(value: 'es', child: Text(l.languageSpanish)),
               ],
               onChanged:
                   (v) =>
@@ -63,7 +68,7 @@ class SettingsScreen extends ConsumerWidget {
                         ref
                             .read(preferencesProvider.notifier)
                             .resetToDefaults(),
-                child: const Text('Reset to defaults'),
+                child: Text(l.resetToDefaults),
               ),
             ),
           ],

pubspec.yaml

@@ -73,6 +73,7 @@ dev_dependencies:
 
 # The following section is specific to Flutter packages.
 flutter:
+  generate: true
 
   # The following line ensures that the Material Icons font is
   # included with your application, so that you can use the icons in