sddm returns a QT error

invalidPointer

I am trying to get sddm working under linux. I am trying to make it use the KDE 5 default theme and getting these error messages :

QObject::installEventFilter(): Cannot filter events for objects in a different thread.
QObject: Cannot create children for a parent that is in a different thread.
(Parent is SDDM::GreeterApp(0x7fffba842e70), parent's thread is QThread(0x244ae60), current thread is QThread(0x24876d0).

Why am I getting these messages ?

ambershark

You're going to need to ask sddm devs/support forums on that one. I can tell you why that would be happening Qt wise but it wouldn't help you get sddm working.

That being said I use sddm-0.11.0 with no problems during build. I'm using Qt 5.4.2 for sddm's build if that helps you.

I can try to help you get it working,

what linux distro/ver are you using
how did you install sddm? Did you build it? or use a binary dist?
What version of Qt is sddm built against?
What version of Qt are you running on your system"?
What version of sddm are you trying to use?
What rc system are you using? systemd/openrc?
How did you start sddm?
Are you using a custom sddm config file? i.e. I used sddm --example-config > /etc/sddm.conf to create my config file, then modified that. This may be distro specific though.

invalidPointer

I digged a little into sddm source code to find the code causing this and this is what I found. I added setenv manually so it finds the KDE QML files. Is there some kind of initialization not done ? The messages appear when ScreenModel() is called.

//// GreeterApp.cpp

GreeterApp::GreeterApp(int &argc, char **argv) : QGuiApplication(argc, argv) {
    // point instance to this
    self = this;

    // Parse arguments
    bool testing = false;

    if (arguments().contains("--test-mode"))
        testing = true;

    // get socket name
    QString socket = parameter(arguments(), "--socket", "");

    setenv("QML2_IMPORT_PATH", "/opt/qt5/lib/qt5/qml:/usr/lib/qt5/qml:/lib/qt5/qml:/opt/kf5/lib/qt5/qml", 1);

    setenv("QML_IMPORT_PATH", "/opt/qt5/lib/qt5/qml:/usr/lib/qt5/qml:/lib/qt5/qml:/opt/kf5/lib/qt5/qml", 1);

    // get theme path
    QString themePath = parameter(arguments(), "--theme", "");

    // create view
    m_view = new QQuickView();
    m_view->setResizeMode(QQuickView::SizeRootObjectToView);

    m_view->engine()->addImportPath(IMPORTS_INSTALL_DIR);

    // read theme metadata
    m_metadata = new ThemeMetadata(QString("%1/metadata.desktop").arg(themePath));

    // Translations
    // Components translation
    m_components_tranlator = new QTranslator();
    if (m_components_tranlator->load(QLocale::system(), "", "", COMPONENTS_TRANSLATION_DIR))
        installTranslator(m_components_tranlator);

    // Theme specific translation
    m_theme_translator = new QTranslator();
    if (m_theme_translator->load(QLocale::system(), "", "",
                       QString("%1/%2/").arg(themePath, m_metadata->translationsDirectory())))
        installTranslator(m_theme_translator);

    // get theme config file
    QString configFile = QString("%1/%2").arg(themePath).arg(m_metadata->configFile());

    // read theme config
    m_themeConfig = new ThemeConfig(configFile);

    // set default icon theme from greeter theme
    if (m_themeConfig->contains("iconTheme"))
        QIcon::setThemeName(m_themeConfig->value("iconTheme").toString());

    // set cursor theme according to greeter theme
    if (m_themeConfig->contains("cursorTheme"))
        qputenv("XCURSOR_THEME", m_themeConfig->value("cursorTheme").toString().toUtf8());

    // create models

    m_sessionModel = new SessionModel();
/////////// ScreenModel() is called here
    m_screenModel = new ScreenModel();
    m_userModel = new UserModel();
    m_proxy = new GreeterProxy(socket);
    m_keyboard = new KeyboardModel();

    if(!testing && !m_proxy->isConnected()) {
        qCritical() << "Cannot connect to the daemon - is it running?";
        exit(EXIT_FAILURE);
    }

    // Set numlock upon start
    if (m_keyboard->enabled()) {
        if (mainConfig.Numlock.get() == MainConfig::NUM_SET_ON)
            m_keyboard->setNumLockState(true);
        else if (mainConfig.Numlock.get() == MainConfig::NUM_SET_OFF)
            m_keyboard->setNumLockState(false);
    }

    m_proxy->setSessionModel(m_sessionModel);

    // connect proxy signals
    QObject::connect(m_proxy, SIGNAL(loginSucceeded()), m_view, SLOT(close()));

    // set context properties
    m_view->rootContext()->setContextProperty("sessionModel", m_sessionModel);
    m_view->rootContext()->setContextProperty("screenModel", m_screenModel);
    m_view->rootContext()->setContextProperty("userModel", m_userModel);
    m_view->rootContext()->setContextProperty("config", *m_themeConfig);
    m_view->rootContext()->setContextProperty("sddm", m_proxy);
    m_view->rootContext()->setContextProperty("keyboard", m_keyboard);

    // get theme main script
    QString mainScript = QString("%1/%2").arg(themePath).arg(m_metadata->mainScript());

    // set main script as source
    m_view->setSource(QUrl::fromLocalFile(mainScript));

    // connect screen update signals
    connect(m_screenModel, SIGNAL(primaryChanged()), this, SLOT(show()));

    show();
}

//// ScreenModel.cpp

ScreenModel::ScreenModel(QObject *parent) : QAbstractListModel(parent), d(new ScreenModelPrivate()) {
    // The messages appear at this code
    connect(QGuiApplication::instance(), SIGNAL(screenAdded(QScreen*)), this, SLOT(onScreenAdded(QScreen*)));
    initScreens(true);
}