qt-everywhere-src-5.15.1/qtmultimedia/src/gsttools/qgstreamerbushelper.cpp

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#include <QtCore/qmap.h>
#include <QtCore/qtimer.h>
#include <QtCore/qmutex.h>
#include <QtCore/qlist.h>
#include <QtCore/qabstracteventdispatcher.h>
#include <QtCore/qcoreapplication.h>

#include "qgstreamerbushelper_p.h"

QT_BEGIN_NAMESPACE


class QGstreamerBusHelperPrivate : public QObject
{
    Q_OBJECT
public:
    QGstreamerBusHelperPrivate(QGstreamerBusHelper *parent, GstBus* bus) :
        QObject(parent),
        m_tag(0),
        m_bus(bus),
        m_helper(parent),
        m_intervalTimer(nullptr)
    {
        // glib event loop can be disabled either by env variable or QT_NO_GLIB define, so check the dispacher
        QAbstractEventDispatcher *dispatcher = QCoreApplication::eventDispatcher();
        const bool hasGlib = dispatcher && dispatcher->inherits("QEventDispatcherGlib");
        if (!hasGlib) {
            m_intervalTimer = new QTimer(this);
            m_intervalTimer->setInterval(250);
            connect(m_intervalTimer, SIGNAL(timeout()), SLOT(interval()));
            m_intervalTimer->start();
        } else {
            m_tag = gst_bus_add_watch_full(bus, G_PRIORITY_DEFAULT, busCallback, this, nullptr);
        }
    }

    ~QGstreamerBusHelperPrivate()
    {
        m_helper = 0;
        delete m_intervalTimer;

        if (m_tag)
#if GST_CHECK_VERSION(1, 6, 0)
            gst_bus_remove_watch(m_bus);
#else
            g_source_remove(m_tag);
#endif
    }

    GstBus* bus() const { return m_bus; }

private slots:
    void interval()
    {
        GstMessage* message;
        while ((message = gst_bus_poll(m_bus, GST_MESSAGE_ANY, 0)) != 0) {
            processMessage(message);
            gst_message_unref(message);
        }
    }

private:
    void processMessage(GstMessage* message)
    {
        QGstreamerMessage msg(message);
        doProcessMessage(msg);
    }

    void queueMessage(GstMessage* message)
    {
        QGstreamerMessage msg(message);
        QMetaObject::invokeMethod(this, "doProcessMessage", Qt::QueuedConnection,
                                  Q_ARG(QGstreamerMessage, msg));
    }

    static gboolean busCallback(GstBus *bus, GstMessage *message, gpointer data)
    {
        Q_UNUSED(bus);
        reinterpret_cast<QGstreamerBusHelperPrivate*>(data)->queueMessage(message);
        return TRUE;
    }

    guint m_tag;
    GstBus* m_bus;
    QGstreamerBusHelper*  m_helper;
    QTimer*     m_intervalTimer;

private slots:
    void doProcessMessage(const QGstreamerMessage& msg)
    {
        for (QGstreamerBusMessageFilter *filter : qAsConst(busFilters)) {
            if (filter->processBusMessage(msg))
                break;
        }
        emit m_helper->message(msg);
    }

public:
    QMutex filterMutex;
    QList<QGstreamerSyncMessageFilter*> syncFilters;
    QList<QGstreamerBusMessageFilter*> busFilters;
};


static GstBusSyncReply syncGstBusFilter(GstBus* bus, GstMessage* message, QGstreamerBusHelperPrivate *d)
{
    Q_UNUSED(bus);
    QMutexLocker lock(&d->filterMutex);

    for (QGstreamerSyncMessageFilter *filter : qAsConst(d->syncFilters)) {
        if (filter->processSyncMessage(QGstreamerMessage(message))) {
            gst_message_unref(message);
            return GST_BUS_DROP;
        }
    }

    return GST_BUS_PASS;
}


/*!
    \class QGstreamerBusHelper
    \internal
*/

QGstreamerBusHelper::QGstreamerBusHelper(GstBus* bus, QObject* parent):
    QObject(parent)
{
    d = new QGstreamerBusHelperPrivate(this, bus);
#if GST_CHECK_VERSION(1,0,0)
    gst_bus_set_sync_handler(bus, (GstBusSyncHandler)syncGstBusFilter, d, 0);
#else
    gst_bus_set_sync_handler(bus, (GstBusSyncHandler)syncGstBusFilter, d);
#endif
    gst_object_ref(GST_OBJECT(bus));
}

QGstreamerBusHelper::~QGstreamerBusHelper()
{
#if GST_CHECK_VERSION(1,0,0)
    gst_bus_set_sync_handler(d->bus(), 0, 0, 0);
#else
    gst_bus_set_sync_handler(d->bus(),0,0);
#endif
    gst_object_unref(GST_OBJECT(d->bus()));
}

void QGstreamerBusHelper::installMessageFilter(QObject *filter)
{
    auto syncFilter = qobject_cast<QGstreamerSyncMessageFilter*>(filter);
    if (syncFilter) {
        QMutexLocker lock(&d->filterMutex);
        if (!d->syncFilters.contains(syncFilter))
            d->syncFilters.append(syncFilter);
    }

    auto busFilter = qobject_cast<QGstreamerBusMessageFilter*>(filter);
    if (busFilter && !d->busFilters.contains(busFilter))
        d->busFilters.append(busFilter);
}

void QGstreamerBusHelper::removeMessageFilter(QObject *filter)
{
    auto syncFilter = qobject_cast<QGstreamerSyncMessageFilter*>(filter);
    if (syncFilter) {
        QMutexLocker lock(&d->filterMutex);
        d->syncFilters.removeAll(syncFilter);
    }

    auto busFilter = qobject_cast<QGstreamerBusMessageFilter*>(filter);
    if (busFilter)
        d->busFilters.removeAll(busFilter);
}

QT_END_NAMESPACE

#include "qgstreamerbushelper.moc"