Sender.cpp Example File

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    #include "Sender.hpp"

    #include <QtCore/QTimer>
    #include <QtNetwork/QUdpSocket>

    Sender::Sender(QObject *parent)
        : QObject(parent), m_ttl(0)
    {
        // Initialize the multicast address
        m_groupAddress = QHostAddress("239.255.43.21");

        /**
         * Initialize the 'status' property with some data, it will
         * be shown in the UI until the first datagram is sent.
         */
        m_status = tr("Ready to multicast datagrams to group %1 on port 45454").arg(m_groupAddress.toString());

        // Create the timer that triggers the sending of the multicast datagrams
        m_timer = new QTimer(this);

        // Create the UDP socket object.
        m_udpSocket = new QUdpSocket(this);

        // Initialize the datagram counter
        m_messageNo = 1;

        // Initialize the TTL
        setTtl("1");

        /**
         * Create a signal/slot connection so that whenever the timer times out, the sendDatagram()
         * method is invoked.
         */
        connect(m_timer, SIGNAL(timeout()), this, SLOT(sendDatagram()));
    }

    void Sender::startSending()
    {
        // Start the timer with an interval of 1 second
        m_timer->start(1000);
    }

    void Sender::sendDatagram()
    {
        // Update the status message and signal that it has changed
        m_status = tr("Now sending datagram %1").arg(m_messageNo);
        emit statusChanged();

        // Assemble the content of the datagram
        const QByteArray datagram = "Multicast message " + QByteArray::number(m_messageNo);

        // Send the multicast datagram with the given content to port 45454
        m_udpSocket->writeDatagram(datagram.data(), datagram.size(), m_groupAddress, 45454);

        // Increase the datagram counter, so that the next sent datagram will have a different content
        ++m_messageNo;
    }

    QString Sender::status() const
    {
        return m_status;
    }

    QString Sender::ttl() const
    {
        return QString::number(m_ttl);
    }

    void Sender::setTtl(const QString &ttlString)
    {
        bool ok = false;

        // Convert the input string to an integer value
        const int ttl = ttlString.toInt(&ok);

        // Ignore invalid values or if the new TTL is the same as the current one
        if (!ok || (m_ttl == ttl))
            return;

        // Update the internal TTL value ...
        m_ttl = ttl;

        // ... and set it on the multicast UDP socket.
        m_udpSocket->setSocketOption(QAbstractSocket::MulticastTtlOption, m_ttl);

        emit ttlChanged();
    }