Qt: Enable switching of languages without restarting app

src/duckstation-qt/mainwindow.cpp

@@ -970,8 +970,8 @@ void MainWindow::setupAdditionalUi()
     connect(action, &QAction::triggered, [this, action]() {
       const QString new_language = action->data().toString();
       m_host_interface->SetStringSettingValue("Main", "Language", new_language.toUtf8().constData());
-      QMessageBox::information(this, tr("DuckStation"),
-                               tr("Language changed. Please restart the application to apply."));
+      m_host_interface->reinstallTranslator();
+      recreate();
     });
   }
 

src/duckstation-qt/qthostinterface.cpp

@@ -158,7 +158,20 @@ void QtHostInterface::installTranslator()
   }
 
   Log_InfoPrintf("Loaded translation file for language '%s'", language.c_str());
-  qApp->installTranslator(translator.release());
+  qApp->installTranslator(translator.get());
+  m_translators.push_back(translator.release());
+}
+
+void QtHostInterface::reinstallTranslator()
+{
+  for (QTranslator* translator : m_translators)
+  {
+    qApp->removeTranslator(translator);
+    translator->deleteLater();
+  }
+  m_translators.clear();
+
+  installTranslator();
 }
 
 void QtHostInterface::ReportError(const char* message)

src/duckstation-qt/qthostinterface.h

@@ -91,6 +91,7 @@ public:
   void setMainWindow(MainWindow* window);
   HostDisplay* createHostDisplay();
   void connectDisplaySignals(QtDisplayWidget* widget);
+  void reinstallTranslator();
 
   void populateLoadStateMenu(const char* game_code, QMenu* menu);
   void populateSaveStateMenu(const char* game_code, QMenu* menu);
@@ -285,6 +286,7 @@ private:
 
   QTimer* m_background_controller_polling_timer = nullptr;
   std::unique_ptr<QTimer> m_settings_save_timer;
+  std::vector<QTranslator*> m_translators;
 
   bool m_is_rendering_to_main = false;
   bool m_is_fullscreen = false;