citra_qt: load translation from resource

src/citra_qt/configuration/config.cpp

@@ -182,6 +182,7 @@ void Config::ReadValues() {
     UISettings::values.gamedir = qt_config->value("gameListRootDir", ".").toString();
     UISettings::values.gamedir_deepscan = qt_config->value("gameListDeepScan", false).toBool();
     UISettings::values.recent_files = qt_config->value("recentFiles").toStringList();
+    UISettings::values.language = qt_config->value("language", "").toString();
     qt_config->endGroup();
 
     qt_config->beginGroup("Shortcuts");
@@ -333,6 +334,7 @@ void Config::SaveValues() {
     qt_config->setValue("gameListRootDir", UISettings::values.gamedir);
     qt_config->setValue("gameListDeepScan", UISettings::values.gamedir_deepscan);
     qt_config->setValue("recentFiles", UISettings::values.recent_files);
+    qt_config->setValue("language", UISettings::values.language);
     qt_config->endGroup();
 
     qt_config->beginGroup("Shortcuts");

src/citra_qt/configuration/configure_audio.cpp

@@ -75,3 +75,7 @@ void ConfigureAudio::updateAudioDevices(int sink_index) {
         ui->audio_device_combo_box->addItem(device.c_str());
     }
 }
+
+void ConfigureAudio::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_audio.h

@@ -19,6 +19,7 @@ public:
     ~ConfigureAudio();
 
     void applyConfiguration();
+    void retranslateUi();
 
 public slots:
     void updateAudioDevices(int sink_index);

src/citra_qt/configuration/configure_debug.cpp

@@ -24,3 +24,7 @@ void ConfigureDebug::applyConfiguration() {
     Settings::values.gdbstub_port = ui->gdbport_spinbox->value();
     Settings::Apply();
 }
+
+void ConfigureDebug::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_debug.h

@@ -19,6 +19,7 @@ public:
     ~ConfigureDebug();
 
     void applyConfiguration();
+    void retranslateUi();
 
 private:
     void setConfiguration();

src/citra_qt/configuration/configure_dialog.cpp

@@ -10,6 +10,8 @@
 ConfigureDialog::ConfigureDialog(QWidget* parent) : QDialog(parent), ui(new Ui::ConfigureDialog) {
     ui->setupUi(this);
     this->setConfiguration();
+    connect(ui->generalTab, &ConfigureGeneral::languageChanged, this,
+            &ConfigureDialog::onLanguageChanged);
 }
 
 ConfigureDialog::~ConfigureDialog() {}
@@ -26,3 +28,15 @@ void ConfigureDialog::applyConfiguration() {
     ui->webTab->applyConfiguration();
     Settings::Apply();
 }
+
+void ConfigureDialog::onLanguageChanged(const QString& locale) {
+    emit languageChanged(locale);
+    ui->retranslateUi(this);
+    ui->generalTab->retranslateUi();
+    ui->systemTab->retranslateUi();
+    ui->inputTab->retranslateUi();
+    ui->graphicsTab->retranslateUi();
+    ui->audioTab->retranslateUi();
+    ui->debugTab->retranslateUi();
+    ui->webTab->retranslateUi();
+}

src/citra_qt/configuration/configure_dialog.h

@@ -20,6 +20,12 @@ public:
 
     void applyConfiguration();
 
+private slots:
+    void onLanguageChanged(const QString& locale);
+
+signals:
+    void languageChanged(const QString& locale);
+
 private:
     void setConfiguration();
 

src/citra_qt/configuration/configure_general.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <QDirIterator>
 #include "citra_qt/configuration/configure_general.h"
 #include "citra_qt/ui_settings.h"
 #include "core/core.h"
@@ -12,6 +13,23 @@ ConfigureGeneral::ConfigureGeneral(QWidget* parent)
     : QWidget(parent), ui(new Ui::ConfigureGeneral) {
 
     ui->setupUi(this);
+    ui->language_combobox->addItem(tr("<System>"), QString(""));
+    ui->language_combobox->addItem(tr("English"), QString("en"));
+    QDirIterator it(":/languages", QDirIterator::NoIteratorFlags);
+    while (it.hasNext()) {
+        QString locale = it.next();
+        locale.truncate(locale.lastIndexOf('.'));
+        locale.remove(0, locale.lastIndexOf('/') + 1);
+        QString lang = QLocale::languageToString(QLocale(locale).language());
+        ui->language_combobox->addItem(lang, locale);
+    }
+
+    // Unlike other configuration, interface language change need to be reflect on the interface
+    // immediately. This is done by passing a signal to the main window, and then retranslating when
+    // passing back.
+    connect(ui->language_combobox,
+            static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this,
+            &ConfigureGeneral::onLanguageChanged);
 
     for (auto theme : UISettings::themes) {
         ui->theme_combobox->addItem(theme.first, theme.second);
@@ -37,6 +55,8 @@ void ConfigureGeneral::setConfiguration() {
     ui->region_combobox->setCurrentIndex(Settings::values.region_value + 1);
 
     ui->theme_combobox->setCurrentIndex(ui->theme_combobox->findData(UISettings::values.theme));
+    ui->language_combobox->setCurrentIndex(
+        ui->language_combobox->findData(UISettings::values.language));
 }
 
 void ConfigureGeneral::applyConfiguration() {
@@ -52,3 +72,14 @@ void ConfigureGeneral::applyConfiguration() {
     Settings::values.use_cpu_jit = ui->toggle_cpu_jit->isChecked();
     Settings::Apply();
 }
+
+void ConfigureGeneral::onLanguageChanged(int index) {
+    if (index == -1)
+        return;
+
+    emit languageChanged(ui->language_combobox->itemData(index).toString());
+}
+
+void ConfigureGeneral::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_general.h

@@ -19,6 +19,13 @@ public:
     ~ConfigureGeneral();
 
     void applyConfiguration();
+    void retranslateUi();
+
+private slots:
+    void onLanguageChanged(int index);
+
+signals:
+    void languageChanged(const QString& locale);
 
 private:
     void setConfiguration();

src/citra_qt/configuration/configure_general.ui

@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>300</width>
-    <height>377</height>
+    <width>345</width>
+    <height>493</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -38,6 +38,20 @@
             </property>
            </widget>
           </item>
+          <item>
+           <layout class="QHBoxLayout" name="horizontalLayout_2">
+            <item>
+             <widget class="QLabel" name="language_label">
+              <property name="text">
+               <string>Interface language</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="QComboBox" name="language_combobox"/>
+            </item>
+           </layout>
+          </item>
          </layout>
         </item>
        </layout>

src/citra_qt/configuration/configure_graphics.cpp

@@ -113,3 +113,7 @@ void ConfigureGraphics::applyConfiguration() {
     Settings::values.swap_screen = ui->swap_screen->isChecked();
     Settings::Apply();
 }
+
+void ConfigureGraphics::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_graphics.h

@@ -19,6 +19,7 @@ public:
     ~ConfigureGraphics();
 
     void applyConfiguration();
+    void retranslateUi();
 
 private:
     void setConfiguration();

src/citra_qt/configuration/configure_input.cpp

@@ -277,3 +277,7 @@ void ConfigureInput::keyPressEvent(QKeyEvent* event) {
     }
     setPollingResult({}, true);
 }
+
+void ConfigureInput::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_input.h

@@ -33,6 +33,7 @@ public:
 
     /// Save all button configurations to settings file
     void applyConfiguration();
+    void retranslateUi();
 
 private:
     std::unique_ptr<Ui::ConfigureInput> ui;

src/citra_qt/configuration/configure_system.cpp

@@ -167,3 +167,7 @@ void ConfigureSystem::refreshConsoleID() {
     Service::CFG::UpdateConfigNANDSavegame();
     ui->label_console_id->setText("Console ID: 0x" + QString::number(console_id, 16).toUpper());
 }
+
+void ConfigureSystem::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_system.h

@@ -20,6 +20,7 @@ public:
 
     void applyConfiguration();
     void setConfiguration();
+    void retranslateUi();
 
 public slots:
     void updateBirthdayComboBox(int birthmonth_index);

src/citra_qt/configuration/configure_web.cpp

@@ -100,3 +100,7 @@ void ConfigureWeb::OnLoginVerified() {
                "correctly, and that your internet connection is working."));
     }
 }
+
+void ConfigureWeb::retranslateUi() {
+    ui->retranslateUi(this);
+}

src/citra_qt/configuration/configure_web.h

@@ -20,6 +20,7 @@ public:
     ~ConfigureWeb();
 
     void applyConfiguration();
+    void retranslateUi();
 
 public slots:
     void RefreshTelemetryID();

src/citra_qt/main.cpp

@@ -97,6 +97,8 @@ GMainWindow::GMainWindow() : config(new Config()), emu_thread(nullptr) {
     // register size_t to use in slots and signals
     qRegisterMetaType<size_t>("size_t");
 
+    LoadTranslation();
+
     Pica::g_debug_context = Pica::DebugContext::Construct();
     setAcceptDrops(true);
     ui.setupUi(this);
@@ -114,8 +116,8 @@ GMainWindow::GMainWindow() : config(new Config()), emu_thread(nullptr) {
     ConnectMenuEvents();
     ConnectWidgetEvents();
 
-    setWindowTitle(QString("Citra %1| %2-%3")
-                       .arg(Common::g_build_name, Common::g_scm_branch, Common::g_scm_desc));
+    SetupUIStrings();
+
     show();
 
     game_list->PopulateAsync(UISettings::values.gamedir, UISettings::values.gamedir_deepscan);
@@ -871,6 +873,8 @@ void GMainWindow::ToggleWindowMode() {
 
 void GMainWindow::OnConfigure() {
     ConfigureDialog configureDialog(this);
+    connect(&configureDialog, &ConfigureDialog::languageChanged, this,
+            &GMainWindow::OnLanguageChanged);
     auto result = configureDialog.exec();
     if (result == QDialog::Accepted) {
         configureDialog.applyConfiguration();
@@ -1084,6 +1088,45 @@ void GMainWindow::UpdateUITheme() {
     }
 }
 
+void GMainWindow::LoadTranslation() {
+    // If the selected language is English, no need to install any translation
+    if (UISettings::values.language == "en") {
+        return;
+    }
+
+    bool loaded;
+
+    if (UISettings::values.language.isEmpty()) {
+        // If the selected language is empty, use system locale
+        loaded = translator.load(QLocale(), "", "", ":/languages/");
+    } else {
+        // Otherwise load from the specified file
+        loaded = translator.load(UISettings::values.language, ":/languages/");
+    }
+
+    if (loaded) {
+        qApp->installTranslator(&translator);
+    } else {
+        UISettings::values.language = "en";
+    }
+}
+
+void GMainWindow::OnLanguageChanged(const QString& locale) {
+    if (UISettings::values.language != "en") {
+        qApp->removeTranslator(&translator);
+    }
+
+    UISettings::values.language = locale;
+    LoadTranslation();
+    ui.retranslateUi(this);
+    SetupUIStrings();
+}
+
+void GMainWindow::SetupUIStrings() {
+    setWindowTitle(
+        tr("Citra %1| %2-%3").arg(Common::g_build_name, Common::g_scm_branch, Common::g_scm_desc));
+}
+
 #ifdef main
 #undef main
 #endif

src/citra_qt/main.h

@@ -7,6 +7,7 @@
 #include <memory>
 #include <QMainWindow>
 #include <QTimer>
+#include <QTranslator>
 #include "core/core.h"
 #include "core/hle/service/am/am.h"
 #include "ui_main.h"
@@ -151,9 +152,12 @@ private slots:
     void OnUpdateFound(bool found, bool error);
     void OnCheckForUpdates();
     void OnOpenUpdater();
+    void OnLanguageChanged(const QString& locale);
 
 private:
     void UpdateStatusBar();
+    void LoadTranslation();
+    void SetupUIStrings();
 
     Ui::MainWindow ui;
 
@@ -192,6 +196,8 @@ private:
 
     QAction* actions_recent_files[max_recent_files_item];
 
+    QTranslator translator;
+
 protected:
     void dropEvent(QDropEvent* event) override;
     void dragEnterEvent(QDragEnterEvent* event) override;

src/citra_qt/ui_settings.h

@@ -48,6 +48,7 @@ struct Values {
     QString gamedir;
     bool gamedir_deepscan;
     QStringList recent_files;
+    QString language;
 
     QString theme;