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****************************************************************************/

#include "qcvdisplaylink.h"

#include <QtCore/qcoreapplication.h>

#include <QtCore/qdebug.h>

QT_USE_NAMESPACE

static CVReturn CVDisplayLinkCallback(CVDisplayLinkRef displayLink,

                                 const CVTimeStamp *inNow,

                                 const CVTimeStamp *inOutputTime,

                                 CVOptionFlags flagsIn,

                                 CVOptionFlags *flagsOut,

                                 void *displayLinkContext)

{

    Q_UNUSED(displayLink);

    Q_UNUSED(inNow);

    Q_UNUSED(flagsIn);

    Q_UNUSED(flagsOut);

    QCvDisplayLink *link = (QCvDisplayLink *)displayLinkContext;

    link->displayLinkEvent(inOutputTime);

    return kCVReturnSuccess;

}

QCvDisplayLink::QCvDisplayLink(QObject *parent)

    :QObject(parent),

    m_pendingDisplayLinkEvent(false),

    m_isActive(false)

{

    // create display link for the main display

    CVDisplayLinkCreateWithCGDisplay(kCGDirectMainDisplay, &m_displayLink);

    if (m_displayLink) {

        // set the current display of a display link.

        CVDisplayLinkSetCurrentCGDisplay(m_displayLink, kCGDirectMainDisplay);

        // set the renderer output callback function

        CVDisplayLinkSetOutputCallback(m_displayLink, &CVDisplayLinkCallback, this);

    }

}

QCvDisplayLink::~QCvDisplayLink()

{

    if (m_displayLink) {

        CVDisplayLinkStop(m_displayLink);

        CVDisplayLinkRelease(m_displayLink);

        m_displayLink = NULL;

    }

}

bool QCvDisplayLink::isValid()

{

    return m_displayLink != 0;

}

bool QCvDisplayLink::isActive() const

{

    return m_isActive;

}

void QCvDisplayLink::start()

{

     if (m_displayLink && !m_isActive) {

        CVDisplayLinkStart(m_displayLink);

        m_isActive = true;

     }

}

void QCvDisplayLink::stop()

{

    if (m_displayLink && m_isActive) {

        CVDisplayLinkStop(m_displayLink);

        m_isActive = false;

    }

}

void QCvDisplayLink::displayLinkEvent(const CVTimeStamp *ts)

{

    // This function is called from a

    // thread != gui thread. So we post the event.

    // But we need to make sure that we don't post faster

    // than the event loop can eat:

    m_displayLinkMutex.lock();

    bool pending = m_pendingDisplayLinkEvent;

    m_pendingDisplayLinkEvent = true;

    m_frameTimeStamp = *ts;

    m_displayLinkMutex.unlock();

    if (!pending)

        qApp->postEvent(this, new QEvent(QEvent::User), Qt::HighEventPriority);

}

bool QCvDisplayLink::event(QEvent *event)

{

    switch (event->type()){

        case QEvent::User:  {

                m_displayLinkMutex.lock();

                m_pendingDisplayLinkEvent = false;

                CVTimeStamp ts = m_frameTimeStamp;

                m_displayLinkMutex.unlock();

                emit tick(ts);

                return false;

            }

            break;

        default:

            break;

    }

    return QObject::event(event);

}

#include "moc_qcvdisplaylink.cpp"