Qt 5.11 | Qt D-Bus | D-Bus Complex Ping Pong Example | complexping.cpp Example File

Qt 5.11.3 Reference Documentation

# complexping.cpp Example File

complexpingpong/complexping.cpp

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      #include <stdio.h>

      #include <QtCore/QCoreApplication>
      #include <QtCore/QFile>
      #include <QtCore/QDebug>
      #include <QtCore/QProcess>
      #include <QtDBus/QtDBus>

      #include "ping-common.h"
      #include "complexping.h"

      void Ping::start(const QString &name)
      {
          if (name != SERVICE_NAME)
              return;

          // open stdin for reading
          qstdin.open(stdin, QIODevice::ReadOnly);

          // find our remote
          iface = new QDBusInterface(SERVICE_NAME, "/", "org.example.QtDBus.ComplexPong.Pong",
                                     QDBusConnection::sessionBus(), this);
          if (!iface->isValid()) {
              fprintf(stderr, "%s\n",
                      qPrintable(QDBusConnection::sessionBus().lastError().message()));
              QCoreApplication::instance()->quit();
          }

          connect(iface, SIGNAL(aboutToQuit()), QCoreApplication::instance(), SLOT(quit()));

          while (true) {
              printf("Ask your question: ");

              QString line = QString::fromLocal8Bit(qstdin.readLine()).trimmed();
              if (line.isEmpty()) {
                  iface->call("quit");
                  return;
              } else if (line == "value") {
                  QVariant reply = iface->property("value");
                  if (!reply.isNull())
                      printf("value = %s\n", qPrintable(reply.toString()));
              } else if (line.startsWith("value=")) {
                  iface->setProperty("value", line.mid(6));
              } else {
                  QDBusReply<QDBusVariant> reply = iface->call("query", line);
                  if (reply.isValid())
                      printf("Reply was: %s\n", qPrintable(reply.value().variant().toString()));
              }

              if (iface->lastError().isValid())
                  fprintf(stderr, "Call failed: %s\n", qPrintable(iface->lastError().message()));
          }
      }

      int main(int argc, char **argv)
      {
          QCoreApplication app(argc, argv);

          if (!QDBusConnection::sessionBus().isConnected()) {
              fprintf(stderr, "Cannot connect to the D-Bus session bus.\n"
                      "To start it, run:\n"
                      "\teval `dbus-launch --auto-syntax`\n");
              return 1;
          }

          QDBusServiceWatcher serviceWatcher(SERVICE_NAME, QDBusConnection::sessionBus(),
                                             QDBusServiceWatcher::WatchForRegistration);

          Ping ping;
          QObject::connect(&serviceWatcher, &QDBusServiceWatcher::serviceRegistered,
                           &ping, &Ping::start);

          QProcess pong;
          pong.start("./complexpong");

          app.exec();
      }