Qt: Add translation support (#664)

* Translation PoC

* i18n but better

* More Greek translation

* Add proper translation UI

* Linux CI: Install qt6-tools-dev

src/panda_qt/config_window.cpp

@@ -12,7 +12,7 @@ ConfigWindow::ConfigWindow(ConfigCallback configCallback, MainWindowCallback win
 
 	// Set the window title of the main window appropriately if we enable showing the app version on the window
 	if (config.windowSettings.showAppVersion) {
-		getMainWindow()->setWindowTitle("Alber v" PANDA3DS_VERSION);
+		getMainWindow()->setWindowTitle(tr("Alber v%1").arg(PANDA3DS_VERSION));
 	}
 
 	// Initialize the widget list and the widget container widgets
@@ -96,6 +96,9 @@ ConfigWindow::ConfigWindow(ConfigCallback configCallback, MainWindowCallback win
 	});
 	guiLayout->addRow(tr("Window icon"), iconSelect);
 
+	QComboBox* languageSelect = createLanguageSelect();
+	guiLayout->addRow(tr("Language"), languageSelect);
+
 	QCheckBox* showAppVersion = new QCheckBox(tr("Show version on window title"));
 	showAppVersion->setChecked(config.windowSettings.showAppVersion);
 	connect(showAppVersion, &QCheckBox::toggled, this, [&](bool checked) {
@@ -103,7 +106,7 @@ ConfigWindow::ConfigWindow(ConfigCallback configCallback, MainWindowCallback win
 		updateConfig();
 
 		// Update main window title
-		getMainWindow()->setWindowTitle(checked ? "Alber v" PANDA3DS_VERSION : "Alber");
+		getMainWindow()->setWindowTitle(checked ? tr("Alber v%1").arg(PANDA3DS_VERSION) : tr("Alber"));
 	});
 	connectCheckbox(showAppVersion, config.windowSettings.showAppVersion);
 	guiLayout->addRow(showAppVersion);

src/panda_qt/main_window.cpp

@@ -14,6 +14,9 @@
 #include "version.hpp"
 
 MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent), keyboardMappings(InputMappings::defaultKeyboardMappings()) {
+	emu = new Emulator();
+
+	loadTranslation();
 	setWindowTitle(tr("Alber"));
 
 	// Enable drop events for loading ROMs
@@ -75,7 +78,6 @@ MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent)
 	auto aboutAction = aboutMenu->addAction(tr("About Panda3DS"));
 	connect(aboutAction, &QAction::triggered, this, &MainWindow::showAboutMenu);
 
-	emu = new Emulator();
 	emu->setOutputSize(screen->surfaceWidth, screen->surfaceHeight);
 
 	// Set up misc objects
@@ -678,4 +680,4 @@ void MainWindow::setupControllerSensors(SDL_GameController* controller) {
 	if (haveAccelerometer) {
 		SDL_GameControllerSetSensorEnabled(controller, SDL_SENSOR_ACCEL, SDL_TRUE);
 	}
-}
+}

src/panda_qt/translations.cpp

@@ -0,0 +1,91 @@
+#include <QFile>
+#include <QTranslator>
+#include <array>
+#include <cstdio>
+
+#include "panda_qt/config_window.hpp"
+#include "panda_qt/main_window.hpp"
+
+void MainWindow::loadTranslation() {
+	// TODO: This should become a member variable when we allow changing language at runtime.
+	QTranslator* translator = nullptr;
+
+	// Fetch the .qm file for our language and load it
+	auto language = QString::fromStdString(emu->getConfig().frontendSettings.language);
+	const QString baseDir = QStringLiteral(":/translations");
+	const QString basePath = QStringLiteral("%1/%2.qm").arg(baseDir).arg(language);
+
+	if (QFile::exists(basePath)) {
+		if (translator != nullptr) {
+			qApp->removeTranslator(translator);
+		}
+
+		translator = new QTranslator(qApp);
+		if (!translator->load(basePath)) {
+			QMessageBox::warning(
+				nullptr, QStringLiteral("Translation Error"),
+				QStringLiteral("Failed to find load translation file for '%1':\n%2").arg(language).arg(basePath)
+			);
+			delete translator;
+		} else {
+			qApp->installTranslator(translator);
+		}
+	} else {
+		printf("Language file %s does not exist. Defaulting to English\n", basePath.toStdString().c_str());
+	}
+}
+
+struct LanguageInfo {
+	QString name;      // Full name of the language (for example "English (US)")
+	const char* code;  // ISO 639 language code (for example "en_us")
+
+	explicit LanguageInfo(const QString& name, const char* code) : name(name), code(code) {}
+};
+
+// List of languages in the order they should appear in the menu
+// Please keep this list mostly in alphabetical order.
+// Also, for Unicode characters in language names, use Unicode keycodes instead of writing out the name,
+// as some compilers/toolchains may not enjoy Unicode in source files.
+static std::array<LanguageInfo, 2> languages = {
+	LanguageInfo(QStringLiteral(u"English"), "en"),                                           // English
+	LanguageInfo(QStringLiteral(u"\u0395\u03BB\u03BB\u03B7\u03BD\u03B9\u03BA\u03AC"), "el"),  // Greek
+};
+
+QComboBox* ConfigWindow::createLanguageSelect() {
+	QComboBox* select = new QComboBox();
+
+	for (usize i = 0; i < languages.size(); i++) {
+		const auto& lang = languages[i];
+		select->addItem(lang.name);
+
+		if (config.frontendSettings.language == lang.code) {
+			select->setCurrentIndex(i);
+		}
+	}
+
+	connect(select, &QComboBox::currentIndexChanged, this, [&](int index) {
+		const QString baseDir = QStringLiteral(":/translations");
+		const QString basePath = QStringLiteral("%1/%2.qm").arg(baseDir).arg(languages[index].code);
+
+		if (QFile::exists(basePath)) {
+			config.frontendSettings.language = languages[index].code;
+			updateConfig();
+
+			QMessageBox messageBox(
+				QMessageBox::Icon::Information, tr("Language change successful"),
+				tr("Restart Panda3DS for the new language to be used.")
+			);
+
+			messageBox.exec();
+		} else {
+			QMessageBox messageBox(
+				QMessageBox::Icon::Warning, tr("Language change failed"),
+				tr("The language you selected is not included in Panda3DS. If you're seeing this, someone messed up the language UI code...")
+			);
+
+			messageBox.exec();
+		}
+	});
+
+	return select;
+}