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@boeledi
Last active July 31, 2019 13:52
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Module to handle multi-lingual
import 'dart:async';
import 'dart:convert';
import 'dart:ui';
import 'package:flutter/services.dart';
import 'package:shared_preferences/shared_preferences.dart';
///
/// Preferences related
///
const String _storageKey = "MyApplication_";
const List<String> _supportedLanguages = ['en','fr'];
Future<SharedPreferences> _prefs = SharedPreferences.getInstance();
class GlobalTranslations {
Locale _locale;
Map<dynamic, dynamic> _localizedValues;
VoidCallback _onLocaleChangedCallback;
///
/// Returns the list of supported Locales
///
Iterable<Locale> supportedLocales() => _supportedLanguages.map<Locale>((lang) => new Locale(lang, ''));
///
/// Returns the translation that corresponds to the [key]
///
String text(String key) {
// Return the requested string
return (_localizedValues == null || _localizedValues[key] == null) ? '** $key not found' : _localizedValues[key];
}
///
/// Returns the current language code
///
get currentLanguage => _locale == null ? '' : _locale.languageCode;
///
/// Returns the current Locale
///
get locale => _locale;
///
/// One-time initialization
///
Future<Null> init([String language]) async {
if (_locale == null){
await setNewLanguage(language);
}
return null;
}
/// ----------------------------------------------------------
/// Method that saves/restores the preferred language
/// ----------------------------------------------------------
getPreferredLanguage() async {
return _getApplicationSavedInformation('language');
}
setPreferredLanguage(String lang) async {
return _setApplicationSavedInformation('language', lang);
}
///
/// Routine to change the language
///
Future<Null> setNewLanguage([String newLanguage, bool saveInPrefs = false]) async {
String language = newLanguage;
if (language == null){
language = await getPreferredLanguage();
}
// Set the locale
if (language == ""){
language = "en";
}
_locale = Locale(language, "");
// Load the language strings
String jsonContent = await rootBundle.loadString("locale/i18n_${_locale.languageCode}.json");
_localizedValues = json.decode(jsonContent);
// If we are asked to save the new language in the application preferences
if (saveInPrefs){
await setPreferredLanguage(language);
}
// If there is a callback to invoke to notify that a language has changed
if (_onLocaleChangedCallback != null){
_onLocaleChangedCallback();
}
return null;
}
///
/// Callback to be invoked when the user changes the language
///
set onLocaleChangedCallback(VoidCallback callback){
_onLocaleChangedCallback = callback;
}
///
/// Application Preferences related
///
/// ----------------------------------------------------------
/// Generic routine to fetch an application preference
/// ----------------------------------------------------------
Future<String> _getApplicationSavedInformation(String name) async {
final SharedPreferences prefs = await _prefs;
return prefs.getString(_storageKey + name) ?? '';
}
/// ----------------------------------------------------------
/// Generic routine to saves an application preference
/// ----------------------------------------------------------
Future<bool> _setApplicationSavedInformation(String name, String value) async {
final SharedPreferences prefs = await _prefs;
return prefs.setString(_storageKey + name, value);
}
///
/// Singleton Factory
///
static final GlobalTranslations _translations = new GlobalTranslations._internal();
factory GlobalTranslations() {
return _translations;
}
GlobalTranslations._internal();
}
GlobalTranslations allTranslations = new GlobalTranslations();
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