detect failed startups and prompt for safe mode

CHANGES

@@ -16,6 +16,7 @@ Misc:
  - GBA: Improve detection of valid ELF ROMs
  - mGUI: Enable auto-softpatching (closes mgba.io/i/2899)
  - Scripting: Add `callbacks:oneshot` for single-call callbacks
+ - Qt: Detect failed startup and prompt for safe mode
 
 0.10.2: (2023-04-23)
 Emulation fixes:

src/platform/qt/ConfigController.cpp

@@ -7,6 +7,7 @@
 
 #include "ActionMapper.h"
 #include "CoreController.h"
+#include "Display.h"
 
 #include <QDir>
 #include <QMenu>
@@ -114,6 +115,16 @@ ConfigController::ConfigController(QObject* parent)
 	fileName.append("qt.ini");
 	m_settings = std::make_unique<QSettings>(fileName, QSettings::IniFormat);
 
+	if (getQtOption("loadStarted").toBool()) {
+		// If the loadStarted flag is lingering in qt.ini, then that indicates that
+		// the frontend crashed before clearing the flag.
+		// Prompt the user to enter into a safe mode to try to get safely started up.
+		setQtOption("safeModeWarning", true);
+	} else {
+		setQtOption("loadStarted", true);
+		m_settings->sync();
+	}
+
 	mCoreConfigInit(&m_config, PORT);
 
 	m_opts.audioSync = CoreController::AUDIO_SYNC;
@@ -306,6 +317,16 @@ void ConfigController::setQtOption(const QString& key, const QVariant& value, co
 	}
 }
 
+void ConfigController::removeQtOption(const QString& key, const QString& group) {
+	if (!group.isNull()) {
+		m_settings->beginGroup(group);
+	}
+	m_settings->remove(key);
+	if (!group.isNull()) {
+		m_settings->endGroup();
+	}
+}
+
 QStringList ConfigController::getMRU(ConfigController::MRU mruType) const {
 	QStringList mru;
 	m_settings->beginGroup(mruName(mruType));
@@ -354,6 +375,20 @@ void ConfigController::write() {
 	mCoreConfigMap(&m_config, &m_opts);
 }
 
+void ConfigController::setLoadingComplete() {
+	removeQtOption("loadStarted");
+	write();
+}
+
+void ConfigController::setSafeMode() {
+	setQtOption("displayDriver", static_cast<int>(Display::Driver::QT));
+	removeQtOption("safeModeWarning");
+}
+
+void ConfigController::declineSafeMode() {
+	removeQtOption("safeModeWarning");
+}
+
 void ConfigController::makePortable() {
 	mCoreConfigMakePortable(&m_config);
 

src/platform/qt/ConfigController.h

@@ -104,6 +104,10 @@ Q_OBJECT
 	const mGraphicsOpts* graphicsOpts() const { return &m_graphicsOpts; }
 	void usage(const char* arg0) const;
 
+	void setLoadingComplete();
+	void setSafeMode();
+	void declineSafeMode();
+
 	static const QString& configDir();
 	static const QString& cacheDir();
 	static bool isPortable();
@@ -115,6 +119,7 @@ public slots:
 	void setOption(const char* key, const char* value);
 	void setOption(const char* key, const QVariant& value);
 	void setQtOption(const QString& key, const QVariant& value, const QString& group = QString());
+	void removeQtOption(const QString& key, const QString& group = QString());
 
 	void makePortable();
 	void write();
@@ -130,7 +135,7 @@ public slots:
 	mGraphicsOpts m_graphicsOpts{};
 	std::array<mSubParser, 2> m_subparsers;
 	bool m_parsed = false;
-	
+
 	QHash<QString, QVariant> m_argvOptions;
 	QHash<QString, ConfigOption*> m_optionSet;
 	std::unique_ptr<QSettings> m_settings;

src/platform/qt/GBAApp.cpp

@@ -18,6 +18,7 @@
 #include <QFileOpenEvent>
 #include <QFontDatabase>
 #include <QIcon>
+#include <QMessageBox>
 
 #include <mgba/core/version.h>
 #include <mgba/feature/updater.h>
@@ -384,6 +385,19 @@ void GBAApp::finishJob(qint64 jobId) {
 	m_workerJobCallbacks.remove(jobId);
 }
 
+void GBAApp::checkSafeMode() {
+	if (m_configController->getQtOption("safeModeWarning").toBool()) {
+		int choice = QMessageBox::warning(nullptr, tr("Safe Mode"),
+		                                  tr("mGBA detected a problem while starting.\n\nWould you like to reset settings to failsafe values?"),
+		                                  QMessageBox::Yes | QMessageBox::No, QMessageBox::No);
+		if (choice == QMessageBox::Yes) {
+			m_configController->setSafeMode();
+		} else {
+			m_configController->declineSafeMode();
+		}
+	}
+}
+
 GBAApp::WorkerJob::WorkerJob(qint64 id, std::function<void ()> job, GBAApp* owner)
 	: m_id(id)
 	, m_job(job)

src/platform/qt/GBAApp.h

@@ -82,6 +82,8 @@ Q_OBJECT
 	ApplicationUpdater* updater() { return &m_updater; }
 	QString invokeOnExit() { return m_invokeOnExit; }
 
+	void checkSafeMode();
+
 public slots:
 	void restartForUpdate();
 	Window* newWindow();

src/platform/qt/Window.cpp

@@ -122,17 +122,17 @@ Window::Window(CoreManager* manager, ConfigController* config, int playerId, QWi
 			if (value.toBool()) {
 				attachWidget(m_libraryView);
 			} else {
-				attachWidget(m_screenWidget);				
+				attachWidget(m_screenWidget);
 			}
 		}
 	}, this);
 	m_config->updateOption("showLibrary");
 
 	ConfigOption* showFilenameInLibrary = m_config->addOption("showFilenameInLibrary");
 	showFilenameInLibrary->connect([this](const QVariant& value) {
-			m_libraryView->setShowFilename(value.toBool());
-	}, this); 
-    m_config->updateOption("showFilenameInLibrary");
+		m_libraryView->setShowFilename(value.toBool());
+	}, this);
+	m_config->updateOption("showFilenameInLibrary");
 	ConfigOption* libraryStyle = m_config->addOption("libraryStyle");
 	libraryStyle->connect([this](const QVariant& value) {
 		m_libraryView->setViewStyle(static_cast<LibraryStyle>(value.toInt()));
@@ -734,6 +734,7 @@ void Window::showEvent(QShowEvent* event) {
 	}
 	reloadDisplayDriver();
 	setFocus();
+	m_config->setLoadingComplete();
 }
 
 void Window::hideEvent(QHideEvent* event) {

src/platform/qt/main.cpp

@@ -118,6 +118,8 @@ int main(int argc, char* argv[]) {
 	langTranslator.load(locale, binaryName, "-", ":/translations/");
 	application.installTranslator(&langTranslator);
 
+	application.checkSafeMode();
+
 	Window* w = application.newWindow();
 	w->loadConfig();
 	w->argumentsPassed();