Explaining code of notificationslistener.cpp

notificationslistener.cpp

NotificationsListener::NotificationsListener(KdeConnectPlugin *aPlugin)
    : QObject(aPlugin)
    , m_plugin(aPlugin)
{
    qRegisterMetaTypeStreamOperators("NotifyingApplication");

    GError *error = nullptr;
    m_gdbusConnection = g_bus_get_sync(G_BUS_TYPE_SESSION, nullptr, &error);
    g_assert_no_error(error);
    m_gdbusFilterId = g_dbus_connection_add_filter(m_gdbusConnection, NotificationsListener::onMessageFiltered, this, nullptr);

    g_autoptr(GDBusMessage) msg =
        g_dbus_message_new_method_call("org.freedesktop.DBus", "/org/freedesktop/DBus", "org.freedesktop.DBus.Monitoring", "BecomeMonitor");

    GVariantBuilder *arrayBuilder = g_variant_builder_new(G_VARIANT_TYPE("as"));
    g_variant_builder_add(arrayBuilder, "s", "interface='org.freedesktop.Notifications'");
    g_variant_builder_add(arrayBuilder, "s", "member='Notify'");

    g_dbus_message_set_body(msg, g_variant_new("(asu)", arrayBuilder, 0u));
    g_dbus_connection_send_message(m_gdbusConnection, msg, GDBusSendMessageFlags::G_DBUS_SEND_MESSAGE_FLAGS_NONE, nullptr, &error);
    g_assert_no_error(error);

    setTranslatedAppName();
    loadApplications();

    connect(m_plugin->config(), &KdeConnectPluginConfig::configChanged, this, &NotificationsListener::loadApplications);
}

This constructor builds a notification message and connects it to the plugin's configChanged signal. It registers the meta type stream operators and creates a DBus filter for the message.

NotificationsListener::~NotificationsListener()
{
    qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Destroying NotificationsListener";
    g_dbus_connection_remove_filter(m_gdbusConnection, m_gdbusFilterId);
    g_object_unref(m_gdbusConnection);
}

This removes the notification filter from the DBus connection.

void NotificationsListener::setTranslatedAppName()
{
    QString filePath =
        QStandardPaths::locate(QStandardPaths::GenericDataLocation, QStringLiteral("knotifications5/kdeconnect.notifyrc"), QStandardPaths::LocateFile);
    if (filePath.isEmpty()) {
        qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Couldn't find kdeconnect.notifyrc to hide kdeconnect notifications on the devices. Using default name.";
        m_translatedAppName = QStringLiteral("KDE Connect");
        return;
    }

    KConfig config(filePath, KConfig::OpenFlag::SimpleConfig);
    KConfigGroup globalgroup(&config, QStringLiteral("Global"));
    m_translatedAppName = globalgroup.readEntry(QStringLiteral("Name"), QStringLiteral("KDE Connect"));
}

This loads the translated app name from the kdeconnect. notifyrc file. It first locates the kdeconnect. notifyrc file, and opens the configuration group and reads the name from it.

void NotificationsListener::loadApplications()
{
    m_applications.clear();
    const QVariantList list = m_plugin->config()->getList(QStringLiteral("applications"));
    for (const auto &a : list) {
        NotifyingApplication app = a.value();
        if (!m_applications.contains(app.name)) {
            m_applications.insert(app.name, app);
        }
    }
    // qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Loaded" << applications.size() << " applications";
}

This loads the applications from the internal list.

bool NotificationsListener::parseImageDataArgument(GVariant *argument,
                                                   int &width,
                                                   int &height,
                                                   int &rowStride,
                                                   int &bitsPerSample,
                                                   int &channels,
                                                   bool &hasAlpha,
                                                   QByteArray &imageData) const
{
    if (g_variant_n_children(argument) != 7) {
        return false;
    }

    g_autoptr(GVariant) variant;

    variant = g_variant_get_child_value(argument, 0);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_INT32)) {
        return false;
    }
    width = g_variant_get_int32(variant);

    variant = g_variant_get_child_value(argument, 1);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_INT32)) {
        return false;
    }
    height = g_variant_get_int32(variant);

    variant = g_variant_get_child_value(argument, 2);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_INT32)) {
        return false;
    }
    rowStride = g_variant_get_int32(variant);

    variant = g_variant_get_child_value(argument, 3);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_BOOLEAN)) {
        return false;
    }
    hasAlpha = g_variant_get_boolean(variant);

    variant = g_variant_get_child_value(argument, 4);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_INT32)) {
        return false;
    }
    bitsPerSample = g_variant_get_int32(variant);

    variant = g_variant_get_child_value(argument, 5);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_INT32)) {
        return false;
    }
    channels = g_variant_get_int32(variant);

    variant = g_variant_get_child_value(argument, 6);
    if (g_variant_is_of_type(variant, G_VARIANT_TYPE_ARRAY)) {
        return false;
    }
    imageData = g_variant_get_bytestring(variant);

    return true;
}

This parses the image data argument of the given type, and returns true if it is a valid image.

QSharedPointer NotificationsListener::iconForImageData(GVariant *argument) const
{
    int width, height, rowStride, bitsPerSample, channels;
    bool hasAlpha;
    QByteArray imageData;

    if (!parseImageDataArgument(argument, width, height, rowStride, bitsPerSample, channels, hasAlpha, imageData))
        return QSharedPointer();

    if (bitsPerSample != 8) {
        qCWarning(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Unsupported image format:"
                                                      << "width=" << width << "height=" << height << "rowStride=" << rowStride
                                                      << "bitsPerSample=" << bitsPerSample << "channels=" << channels << "hasAlpha=" << hasAlpha;
        return QSharedPointer();
    }

    QImage image(reinterpret_cast(imageData.data()), width, height, rowStride, hasAlpha ? QImage::Format_ARGB32 : QImage::Format_RGB32);
    if (hasAlpha)
        image = image.rgbSwapped(); // RGBA --> ARGB

    QSharedPointer buffer = QSharedPointer(new QBuffer);
    if (!buffer || !buffer->open(QIODevice::WriteOnly) || !image.save(buffer.data(), "PNG")) {
        qCWarning(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Could not initialize image buffer";
        return QSharedPointer();
    }

    return buffer;
}

This creates a QBuffer object from an image data buffer. It takes the width height rowStride bitsPerSample channels and image data from the internal buffer. It returns a QSharedPointer object that can be used to manage the icon for the image data.

QSharedPointer NotificationsListener::iconForIconName(const QString &iconName)
{
    int size = KIconLoader::SizeEnormous; // use big size to allow for good
                                          // quality on high-DPI mobile devices
    QString iconPath = KIconLoader::global()->iconPath(iconName, -size, true);
    if (!iconPath.isEmpty()) {
        if (!iconPath.endsWith(QLatin1String(".png")) && KIconLoader::global()->theme()->name() != QLatin1String("hicolor")) {
            // try falling back to hicolor theme:
            KIconTheme hicolor(QStringLiteral("hicolor"));
            if (hicolor.isValid()) {
                iconPath = hicolor.iconPath(iconName + QStringLiteral(".png"), size, KIconLoader::MatchBest);
                // qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Found non-png icon in default theme trying fallback to hicolor:" << iconPath;
            }
        }
    }

    if (iconPath.endsWith(QLatin1String(".png")))
        return QSharedPointer(new QFile(iconPath));
    return QSharedPointer();
}

This method returns a QSharedPointer object that represents the icon of the given icon name. It first tries to find the icon in the global theme, if it doesn't exist, it tries to find it in the hicolor theme. If it doesn't find it, it falls back to the default theme.

GDBusMessage *NotificationsListener::onMessageFiltered(GDBusConnection *, GDBusMessage *msg, int, void *parent)
{
    static unsigned id = 0;
    if (!msg) {
        return msg;
    }

    const gchar *interface = g_dbus_message_get_interface(msg);
    if (!interface || strcmp(interface, "org.freedesktop.Notifications")) {
        // The first message will be from org.freedesktop.DBus.Monitoring
        return msg;
    }
    const gchar *member = g_dbus_message_get_member(msg);
    if (!member || strcmp(member, "Notify")) {
        // Even if member is set, the monitor will still notify messages from other members.
        return nullptr;
    }

    g_autoptr(GVariant) bodyVariant = g_dbus_message_get_body(msg);
    Q_ASSERT(bodyVariant);

    // Data order and types: https://specifications.freedesktop.org/notification-spec/notification-spec-latest.html
    g_autoptr(GVariant) variant = g_variant_get_child_value(bodyVariant, 0);
    const QString appName = QString::fromUtf8(g_variant_get_string(variant, nullptr));
    // skip our own notifications
    auto listener = static_cast(parent);

    if (appName == listener->m_translatedAppName) {
        return nullptr;
    }

    variant = g_variant_get_child_value(bodyVariant, 2);
    const QString appIcon = QString::fromUtf8(g_variant_get_string(variant, nullptr));

    NotifyingApplication app;
    if (!listener->m_applications.contains(appName)) {
        // new application -> add to config
        app.name = appName;
        app.icon = appIcon;
        app.active = true;
        app.blacklistExpression = QRegularExpression();
        listener->m_applications.insert(app.name, app);
        // update config:
        QVariantList list;
        for (const auto &a : std::as_const(listener->m_applications))
            list << QVariant::fromValue(a);
        listener->m_plugin->config()->setList(QStringLiteral("applications"), list);
        // qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Added new application to config:" << app;
    } else {
        app = listener->m_applications.value(appName);
    }

    if (!app.active) {
        return nullptr;
    }

    variant = g_variant_get_child_value(bodyVariant, 7);
    const auto timeout = g_variant_get_int32(variant);
    if (timeout > 0 && listener->m_plugin->config()->getBool(QStringLiteral("generalPersistent"), false)) {
        return nullptr;
    }

    variant = g_variant_get_child_value(bodyVariant, 6);
    std::unordered_map hints;
    GVariantIter *iter;
    const gchar *key;
    GVariant *value = nullptr;
    g_variant_get(variant, "a{sv}", &iter);
    while (g_variant_iter_loop(iter, "{sv}", &key, &value)) {
        hints.emplace(QString::fromUtf8(key), value);
    }
    g_variant_iter_free(iter);

    QScopeGuard cleanupHints([&hints] {
        for (auto &[_, hint] : hints) {
            g_variant_unref(hint);
        }
    });

    int urgency = -1;
    if (auto it = hints.find(QStringLiteral("urgency")); it != hints.end()) {
        if (g_variant_is_of_type(it->second, G_VARIANT_TYPE_BYTE)) {
            urgency = g_variant_get_byte(it->second);
        }
    }
    if (urgency > -1 && urgency < listener->m_plugin->config()->getInt(QStringLiteral("generalUrgency"), 0))
        return nullptr;

    variant = g_variant_get_child_value(bodyVariant, 3);
    QString ticker = QString::fromUtf8(g_variant_get_string(variant, nullptr));

    variant = g_variant_get_child_value(bodyVariant, 4);
    const QString body = QString::fromUtf8(g_variant_get_string(variant, nullptr));

    if (!body.isEmpty() && listener->m_plugin->config()->getBool(QStringLiteral("generalIncludeBody"), true)) {
        ticker += QStringLiteral(": ") + body;
    }

    if (app.blacklistExpression.isValid() && !app.blacklistExpression.pattern().isEmpty() && app.blacklistExpression.match(ticker).hasMatch()) {
        return nullptr;
    }

    variant = g_variant_get_child_value(bodyVariant, 1);
    const unsigned replacesId = g_variant_get_uint32(variant);

    // qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Sending notification from" << appName << ":" < 0 ? replacesId : ++id)},
                      {QStringLiteral("appName"), appName},
                      {QStringLiteral("ticker"), ticker},
                      {QStringLiteral("isClearable"), timeout == 0}}); // KNotifications are persistent if
                                                                       // timeout == 0, for other notifications
                                                                       // clearability is pointless

    // sync any icon data?
    if (listener->m_plugin->config()->getBool(QStringLiteral("generalSynchronizeIcons"), true)) {
        QSharedPointer iconSource;
        // try different image sources according to priorities in notifications-
        // spec version 1.2:
        if (auto it = hints.find(QStringLiteral("image-data")); it != hints.end()) {
            iconSource = listener->iconForImageData(it->second);
        } else if (auto it = hints.find(QStringLiteral("image_data")); it != hints.end()) { // 1.1 backward compatibility
            iconSource = listener->iconForImageData(it->second);
        } else if (auto it = hints.find(QStringLiteral("image-path")); it != hints.end()) {
            iconSource = iconForIconName(QString::fromUtf8(g_variant_get_string(it->second, nullptr)));
        } else if (auto it = hints.find(QStringLiteral("image_path")); it != hints.end()) { // 1.1 backward compatibility
            iconSource = iconForIconName(QString::fromUtf8(g_variant_get_string(it->second, nullptr)));
        } else if (!appIcon.isEmpty()) {
            iconSource = iconForIconName(appIcon);
        } else if (auto it = hints.find(QStringLiteral("icon_data")); it != hints.end()) { // < 1.1 backward compatibility
            iconSource = listener->iconForImageData(it->second);
        }

        if (iconSource)
            np.setPayload(iconSource, iconSource->size());
    }

    listener->m_plugin->sendPacket(np);

    qCDebug(KDECONNECT_PLUGIN_SENDNOTIFICATION) << "Got notification appName=" << appName << "replacesId=" << replacesId << "appIcon=" << appIcon
                                                << "summary=" << ticker << "body=" << body << "hints=" << hints.size() << "urgency=" << urgency
                                                << "timeout=" << timeout;

    return nullptr;
}

This function builds a notification object from an existing message. It returns the message object, if it exists, and creates a notification listener.