Qt 5.11 | Qt Network | Multicast Sender Example | sender.cpp Example File

Qt 5.11.3 Reference Documentation

# sender.cpp Example File

multicastsender/sender.cpp

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      #include "sender.h"

      Sender::Sender(QWidget *parent)
          : QDialog(parent),
            groupAddress4(QStringLiteral("239.255.43.21")),
            groupAddress6(QStringLiteral("ff12::2115"))
      {
          // force binding to their respective families
          udpSocket4.bind(QHostAddress(QHostAddress::AnyIPv4), 0);
          udpSocket6.bind(QHostAddress(QHostAddress::AnyIPv6), udpSocket4.localPort());

          QString msg = tr("Ready to multicast datagrams to groups %1 and [%2] on port 45454").arg(groupAddress4.toString());
          if (udpSocket6.state() != QAbstractSocket::BoundState)
              msg = tr("IPv6 failed. Ready to multicast datagrams to group %1 on port 45454").arg(groupAddress4.toString());
          else
              msg = msg.arg(groupAddress6.toString());
          statusLabel = new QLabel(msg);

          auto ttlLabel = new QLabel(tr("TTL for IPv4 multicast datagrams:"));
          auto ttlSpinBox = new QSpinBox;
          ttlSpinBox->setRange(0, 255);

          auto ttlLayout = new QHBoxLayout;
          ttlLayout->addWidget(ttlLabel);
          ttlLayout->addWidget(ttlSpinBox);

          startButton = new QPushButton(tr("&Start"));
          auto quitButton = new QPushButton(tr("&Quit"));

          auto buttonBox = new QDialogButtonBox;
          buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);
          buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

          connect(ttlSpinBox, QOverload<int>::of(&QSpinBox::valueChanged), this, &Sender::ttlChanged);
          connect(startButton, &QPushButton::clicked, this, &Sender::startSending);
          connect(quitButton, &QPushButton::clicked, this, &Sender::close);
          connect(&timer, &QTimer::timeout, this, &Sender::sendDatagram);

          auto mainLayout = new QVBoxLayout;
          mainLayout->addWidget(statusLabel);
          mainLayout->addLayout(ttlLayout);
          mainLayout->addWidget(buttonBox);
          setLayout(mainLayout);

          setWindowTitle(tr("Multicast Sender"));
          ttlSpinBox->setValue(1);
      }

      void Sender::ttlChanged(int newTtl)
      {
          // we only set the TTL on the IPv4 socket, as that changes the multicast scope
          udpSocket4.setSocketOption(QAbstractSocket::MulticastTtlOption, newTtl);
      }

      void Sender::startSending()
      {
          startButton->setEnabled(false);
          timer.start(1000);
      }

      void Sender::sendDatagram()
      {
          statusLabel->setText(tr("Now sending datagram %1").arg(messageNo));
          QByteArray datagram = "Multicast message " + QByteArray::number(messageNo);
          udpSocket4.writeDatagram(datagram, groupAddress4, 45454);
          if (udpSocket6.state() == QAbstractSocket::BoundState)
              udpSocket6.writeDatagram(datagram, groupAddress6, 45454);
          ++messageNo;
      }