Set display language

lib/event/event.dart

@@ -70,6 +70,8 @@ class FileRemovedEvent {
 
 class ThemeChangedEvent {}
 
+class LanguageChangedEvent {}
+
 extension FilePropertyUpdatedEventExtension on FilePropertyUpdatedEvent {
   bool hasAnyProperties(List<int> properties) =>
       properties.any((p) => this.properties & p != 0);

lib/l10n/app_en.arb

@@ -309,6 +309,10 @@
 	"@settingsWidgetTitle": {
 		"description": "Title of the Settings widget"
 	},
+	"settingsLanguageTitle": "Language",
+	"@settingsLanguageTitle": {
+		"description": "Set display language"
+	},
 	"settingsExifSupportTitle": "EXIF support",
 	"@settingsExifSupportTitle": {
 		"description": "Title of the EXIF support setting"

lib/language_util.dart

@@ -0,0 +1,40 @@
+import 'package:flutter/widgets.dart';
+import 'package:nc_photos/pref.dart';
+
+class AppLanguage {
+  const AppLanguage(this.langId, this.nativeName, this.locale);
+
+  final int langId;
+  final String nativeName;
+  final Locale locale;
+}
+
+String getSelectedLanguageName(BuildContext context) =>
+    _getSelectedLanguage(context).nativeName;
+Locale getSelectedLocale(BuildContext context) =>
+    _getSelectedLanguage(context).locale;
+
+final supportedLanguages = {
+  _AppLanguageEnum.systemDefault.index:
+      AppLanguage(_AppLanguageEnum.systemDefault.index, "System default", null),
+  _AppLanguageEnum.english.index: AppLanguage(
+      _AppLanguageEnum.english.index, "English", const Locale("en")),
+  _AppLanguageEnum.spanish.index: AppLanguage(
+      _AppLanguageEnum.spanish.index, "Español", const Locale("es")),
+};
+
+enum _AppLanguageEnum {
+  // the order must not be changed
+  systemDefault,
+  english,
+  spanish,
+}
+
+AppLanguage _getSelectedLanguage(BuildContext context) {
+  try {
+    final lang = Pref.inst().getLanguage();
+    return supportedLanguages[lang];
+  } catch (_) {
+    return supportedLanguages[_AppLanguageEnum.systemDefault.index];
+  }
+}

lib/pref.dart

@@ -60,6 +60,9 @@ class Pref {
 
   Future<bool> setDarkTheme(bool value) => _pref.setBool("isDarkTheme", value);
 
+  int getLanguage([int def = 0]) => _pref.getInt("language") ?? def;
+  Future<bool> setLanguage(int value) => _pref.setInt("language", value);
+
   Pref._();
 
   static final _inst = Pref._();

lib/widget/my_app.dart

@@ -3,6 +3,7 @@ import 'package:flutter/widgets.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 import 'package:logging/logging.dart';
 import 'package:nc_photos/event/event.dart';
+import 'package:nc_photos/language_util.dart' as language_util;
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
@@ -29,6 +30,8 @@ class _MyAppState extends State<MyApp> implements SnackBarHandler {
     SnackBarManager().registerHandler(this);
     _themeChangedListener =
         AppEventListener<ThemeChangedEvent>(_onThemeChangedEvent)..begin();
+    _langChangedListener =
+        AppEventListener<LanguageChangedEvent>(_onLangChangedEvent)..begin();
   }
 
   @override
@@ -41,6 +44,7 @@ class _MyAppState extends State<MyApp> implements SnackBarHandler {
       initialRoute: Splash.routeName,
       onGenerateRoute: _onGenerateRoute,
       scaffoldMessengerKey: _scaffoldMessengerKey,
+      locale: language_util.getSelectedLocale(context),
       localizationsDelegates: AppLocalizations.localizationsDelegates,
       supportedLocales: AppLocalizations.supportedLocales,
       debugShowCheckedModeBanner: false,
@@ -52,6 +56,7 @@ class _MyAppState extends State<MyApp> implements SnackBarHandler {
     super.dispose();
     SnackBarManager().unregisterHandler(this);
     _themeChangedListener.end();
+    _langChangedListener.end();
   }
 
   @override
@@ -92,6 +97,10 @@ class _MyAppState extends State<MyApp> implements SnackBarHandler {
     setState(() {});
   }
 
+  void _onLangChangedEvent(LanguageChangedEvent ev) {
+    setState(() {});
+  }
+
   Route<dynamic> _handleBasicRoute(RouteSettings settings) {
     for (final e in _getRouter().entries) {
       if (e.key == settings.name) {
@@ -206,6 +215,7 @@ class _MyAppState extends State<MyApp> implements SnackBarHandler {
   final _scaffoldMessengerKey = GlobalKey<ScaffoldMessengerState>();
 
   AppEventListener<ThemeChangedEvent> _themeChangedListener;
+  AppEventListener<LanguageChangedEvent> _langChangedListener;
 
   static final _log = Logger("widget.my_app.MyAppState");
 }

lib/widget/settings.dart

@@ -1,10 +1,14 @@
+import 'package:event_bus/event_bus.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 import 'package:kiwi/kiwi.dart';
 import 'package:logging/logging.dart';
 import 'package:nc_photos/account.dart';
+import 'package:nc_photos/app_db.dart';
+import 'package:nc_photos/event/event.dart';
 import 'package:nc_photos/k.dart' as k;
+import 'package:nc_photos/language_util.dart' as language_util;
 import 'package:nc_photos/metadata_task_manager.dart';
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
@@ -65,6 +69,11 @@ class _SettingsState extends State<Settings> {
         SliverList(
           delegate: SliverChildListDelegate(
             [
+              ListTile(
+                title: Text(AppLocalizations.of(context).settingsLanguageTitle),
+                subtitle: Text(language_util.getSelectedLanguageName(context)),
+                onTap: () => _onLanguageTap(context),
+              ),
               SwitchListTile(
                 title:
                     Text(AppLocalizations.of(context).settingsExifSupportTitle),
@@ -128,6 +137,32 @@ class _SettingsState extends State<Settings> {
     );
   }
 
+  void _onLanguageTap(BuildContext context) {
+    showDialog(
+      context: context,
+      builder: (context) => SimpleDialog(
+        children: language_util.supportedLanguages.values
+            .map<Widget>((lang) => SimpleDialogOption(
+                  onPressed: () {
+                    _log.info(
+                        "[_onLanguageTap] Set language: ${lang.nativeName}");
+                    Navigator.of(context).pop(lang.langId);
+                  },
+                  child: ListTile(
+                    title: Text(lang.nativeName),
+                  ),
+                ))
+            .toList(),
+      ),
+    ).then((value) {
+      if (value != null) {
+        Pref.inst().setLanguage(value).then((_) {
+          KiwiContainer().resolve<EventBus>().fire(LanguageChangedEvent());
+        });
+      }
+    });
+  }
+
   void _onExifSupportChanged(BuildContext context, bool value) {
     if (value) {
       showDialog(