- Qt 5.5
- Qt D-Bus
- D-Bus Complex Ping Pong Example
- complexping.cpp Example File
- Qt 5.5.1 Reference Documentation

# complexping.cpp Example File

complexpingpong/complexping.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
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    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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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, const QString &oldValue, const QString &newValue)
    {
        Q_UNUSED(oldValue);

        if (name != SERVICE_NAME || newValue.isEmpty())
            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;
        }

        Ping ping;
        ping.connect(QDBusConnection::sessionBus().interface(),
                     SIGNAL(serviceOwnerChanged(QString,QString,QString)),
                     SLOT(start(QString,QString,QString)));

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

        app.exec();
    }