- Qt 5.5
- Qt Network
- Multicast Receiver Example
- receiver.cpp Example File
- Qt 5.5.1 Reference Documentation

# receiver.cpp Example File

multicastreceiver/receiver.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include <QtWidgets>
    #include <QtNetwork>

    #include "receiver.h"

    Receiver::Receiver(QWidget *parent)
        : QDialog(parent)
    {
        groupAddress = QHostAddress("239.255.43.21");

        statusLabel = new QLabel(tr("Listening for multicasted messages"));
        quitButton = new QPushButton(tr("&Quit"));

        udpSocket = new QUdpSocket(this);
        udpSocket->bind(QHostAddress::AnyIPv4, 45454, QUdpSocket::ShareAddress);
        udpSocket->joinMulticastGroup(groupAddress);

        connect(udpSocket, SIGNAL(readyRead()),
                this, SLOT(processPendingDatagrams()));
        connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));

        QHBoxLayout *buttonLayout = new QHBoxLayout;
        buttonLayout->addStretch(1);
        buttonLayout->addWidget(quitButton);
        buttonLayout->addStretch(1);

        QVBoxLayout *mainLayout = new QVBoxLayout;
        mainLayout->addWidget(statusLabel);
        mainLayout->addLayout(buttonLayout);
        setLayout(mainLayout);

        setWindowTitle(tr("Multicast Receiver"));
    }

    void Receiver::processPendingDatagrams()
    {
        while (udpSocket->hasPendingDatagrams()) {
            QByteArray datagram;
            datagram.resize(udpSocket->pendingDatagramSize());
            udpSocket->readDatagram(datagram.data(), datagram.size());
            statusLabel->setText(tr("Received datagram: \"%1\"")
                                 .arg(datagram.data()));
        }
    }