Bearer Cloud Example

Responding to changes

Each network session and associated network configuration known to the system is represented in the scene as a Cloud object.

In the Cloud constructor we first initialize member variables. Then we create a new QNetworkSession object bound to the network configuration. Next we connect the QNetworkSession signals which we use to monitor it for state changes.

Next we set some QGraphicsItem properties. The QGraphicsItem::ItemIsMovable flag enables mouse interaction with the Cloud object.

The Cloud object consists of an icon and a text caption, these are constructed here. We will assign values to them later, as these will change as the sessions state changes.

Next we set the initial animation state and call our newConfigurationActivated() slot to finish setting up the Cloud object based on the state of network session.

 Cloud::Cloud(const QNetworkConfiguration &config, QGraphicsItem *parent)
 :   QGraphicsItem(parent), configuration(config), deleteAfterAnimation(false)
 {
     session = new QNetworkSession(configuration, this);
     connect(session, SIGNAL(newConfigurationActivated()),
             this, SLOT(newConfigurationActivated()));
     connect(session, SIGNAL(stateChanged(QNetworkSession::State)),
             this, SLOT(stateChanged(QNetworkSession::State)));

     setFlag(ItemIsMovable);
 #if (QT_VERSION >= QT_VERSION_CHECK(4, 6, 0))
     setFlag(ItemSendsGeometryChanges);
 #endif
     setZValue(1);

     icon = new QGraphicsSvgItem(this);
     text = new QGraphicsTextItem(this);

     currentScale = 0;
     finalScale = 1;
     setTransform(QTransform::fromScale(currentScale, currentScale), false);
     setOpacity(0);

     newConfigurationActivated();
 }

The newConfigurationActivated() slot is called when a session has successfully roamed from one access point to another.

The first thing we do is set the icon, inserting it into a shared SVG renderer cache if it is not already available. Next we set the text caption to the name of the network configuration.

We then set the position of the icon and text caption so that they are centered horizontally.

Finally we call our stateChanged() slot.

 void Cloud::newConfigurationActivated()
 {
     QNetworkConfiguration::BearerType bearerType = configuration.bearerType();
     if (!svgCache.contains(bearerType)) {
         QSvgRenderer *renderer = 0;
         switch (bearerType) {
         case QNetworkConfiguration::BearerWLAN:
             renderer = new QSvgRenderer(QLatin1String(":wlan.svg"));
             break;
         case QNetworkConfiguration::BearerEthernet:
             renderer = new QSvgRenderer(QLatin1String(":lan.svg"));
             break;
         case QNetworkConfiguration::Bearer2G:
             renderer = new QSvgRenderer(QLatin1String(":cell.svg"));
             break;
         case QNetworkConfiguration::BearerBluetooth:
             renderer = new QSvgRenderer(QLatin1String(":bluetooth.svg"));
             break;
         case QNetworkConfiguration::BearerCDMA2000:
         case QNetworkConfiguration::BearerWCDMA:
         case QNetworkConfiguration::BearerHSPA:
             renderer = new QSvgRenderer(QLatin1String(":umts.svg"));
             break;
         default:
             renderer = new QSvgRenderer(QLatin1String(":unknown.svg"));
         }

         if (renderer)
             svgCache.insert(bearerType, renderer);
     }

     icon->setSharedRenderer(svgCache[bearerType]);

     if (configuration.name().isEmpty()) {
         text->setPlainText(tr("HIDDEN NETWORK"));
     } else {
         if (configuration.type() == QNetworkConfiguration::ServiceNetwork)
             text->setHtml("<b>" + configuration.name() + "</b>");
         else
             text->setPlainText(configuration.name());
     }

     const qreal height = icon->boundingRect().height() + text->boundingRect().height();

     icon->setPos(icon->boundingRect().width() / -2, height / -2);

     text->setPos(text->boundingRect().width() / -2,
                  height / 2 - text->boundingRect().height());

     stateChanged(session->state());
 }

The stateChanged() slot is called when the session state changes.

In this slot we set lower the opacity of Cloud objects with network sessions that cannot be opened, and set a detailed tool tip describing the sessions state.

 void Cloud::stateChanged(QNetworkSession::State state)
 {
     if (configuration.name().isEmpty())
         finalOpacity = qreal(0.1);
     else if (session->state() == QNetworkSession::NotAvailable)
         finalOpacity = 0.5;
     else
         finalOpacity = 1.0;

 #if !defined(Q_WS_MAEMO_5) && !defined(Q_WS_MAEMO_6) && \
     !defined(Q_OS_SYMBIAN) && !defined(Q_OS_WINCE)
     QString tooltip;

     if (configuration.name().isEmpty())
         tooltip += tr("<b>HIDDEN NETWORK</b><br>");
     else
         tooltip += tr("<b>%1</b><br>").arg(configuration.name());

 #ifndef QT_NO_NETWORKINTERFACE
     const QNetworkInterface interface = session->interface();
     if (interface.isValid())
         tooltip += tr("<br>Interface: %1").arg(interface.humanReadableName());
     tooltip += tr("<br>Id: %1").arg(configuration.identifier());
 #endif

     const QString bearerTypeName = configuration.bearerTypeName();
     if (!bearerTypeName.isEmpty())
         tooltip += tr("<br>Bearer: %1").arg(bearerTypeName);

     QString s = tr("<br>State: %1 (%2)");
     switch (state) {
     case QNetworkSession::Invalid:
         s = s.arg(tr("Invalid"));
         break;
     case QNetworkSession::NotAvailable:
         s = s.arg(tr("Not Available"));
         break;
     case QNetworkSession::Connecting:
         s = s.arg(tr("Connecting"));
         break;
     case QNetworkSession::Connected:
         s = s.arg(tr("Connected"));
         break;
     case QNetworkSession::Closing:
         s = s.arg(tr("Closing"));
         break;
     case QNetworkSession::Disconnected:
         s = s.arg(tr("Disconnected"));
         break;
     case QNetworkSession::Roaming:
         s = s.arg(tr("Roaming"));
         break;
     default:
         s = s.arg(tr("Unknown"));
     }

     if (session->isOpen())
         s = s.arg(tr("Open"));
     else
         s = s.arg(tr("Closed"));

     tooltip += s;

     tooltip += tr("<br><br>Active time: %1 seconds").arg(session->activeTime());
     tooltip += tr("<br>Received data: %1 bytes").arg(session->bytesReceived());
     tooltip += tr("<br>Sent data: %1 bytes").arg(session->bytesWritten());

     setToolTip(tooltip);
 #else
     Q_UNUSED(state);
 #endif
 }

In our reimplementation of the QGraphicsItem::mouseDoubleClickEvent() function we call QNetworkSession::open() or QNetworkSession::close() to open or close the session in response to a double left click.

 void Cloud::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event)
 {
     if (event->button() == Qt::LeftButton) {
         if (session->isOpen())
             session->close();
         else
             session->open();

         event->accept();
     }
 }

As we support the user dragging Cloud objects around we need to restart animations when the position of the Cloud object changes. This is accomplished by reimplementing the QGraphicsItem::itemChanged() function and calling the cloudMoved() function of the BearerCloud object.

 QVariant Cloud::itemChange(GraphicsItemChange change, const QVariant &value)
 {
     switch (change) {
     case ItemPositionHasChanged:
         if (BearerCloud *bearercloud = qobject_cast<BearerCloud *>(scene()))
             bearercloud->cloudMoved();
     default:
         ;
     };

     return QGraphicsItem::itemChange(change, value);
 }

The remainder of the code for the Cloud object implements the animations. The calculateForces() function calculates the new position of the Cloud object based on the position of all the other Cloud objects in the scene. The new position is set when the advance() function is called to update the Cloud object for the current animation frame.