Qt 5.9 | Qt Location | Plane Spotter (QML) | main.cpp Example File

Qt 5.9.4 Reference Documentation

# main.cpp Example File

planespotter/main.cpp

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      #include <QGuiApplication>
      #include <QQmlApplicationEngine>
      #include <QQmlContext>
      #include <QObject>
      #include <QTime>
      #include <QBasicTimer>
      #include <QDebug>
      #include <QEasingCurve>
      #include <QGeoCoordinate>
      #include <QtPositioning/private/qwebmercator_p.h>

      #define ANIMATION_DURATION 4000

      class PlaneController: public QObject
      {
          Q_OBJECT
          Q_PROPERTY(QGeoCoordinate position READ position WRITE setPosition NOTIFY positionChanged)
          Q_PROPERTY(QGeoCoordinate from READ from WRITE setFrom NOTIFY fromChanged)
          Q_PROPERTY(QGeoCoordinate to READ to WRITE setTo NOTIFY toChanged)

      public:
          PlaneController()
          {
              easingCurve.setType(QEasingCurve::InOutQuad);
              easingCurve.setPeriod(ANIMATION_DURATION);
          }

          void setFrom(const QGeoCoordinate& from)
          {
              fromCoordinate = from;
          }

          QGeoCoordinate from() const
          {
              return fromCoordinate;
          }

          void setTo(const QGeoCoordinate& to)
          {
              toCoordinate = to;
          }

          QGeoCoordinate to() const
          {
              return toCoordinate;
          }

          void setPosition(const QGeoCoordinate &c) {
              if (currentPosition == c)
                  return;

              currentPosition = c;
              emit positionChanged();
          }

          QGeoCoordinate position() const
          {
              return currentPosition;
          }

          Q_INVOKABLE bool isFlying() const {
              return timer.isActive();
          }

      public slots:
          void startFlight()
          {
              if (timer.isActive())
                  return;

              startTime = QTime::currentTime();
              finishTime = startTime.addMSecs(ANIMATION_DURATION);

              timer.start(15, this);
              emit departed();
          }

          void swapDestinations() {
              if (currentPosition == toCoordinate) {
                  // swap destinations
                  toCoordinate = fromCoordinate;
                  fromCoordinate = currentPosition;
              }
          }

      signals:
          void positionChanged();
          void arrived();
          void departed();
          void toChanged();
          void fromChanged();

      protected:
          void timerEvent(QTimerEvent *event) Q_DECL_OVERRIDE
          {
              if (!event)
                  return;

              if (event->timerId() == timer.timerId())
                  updatePosition();
              else
                  QObject::timerEvent(event);
          }

      private:
          void updatePosition()
          {
              // simple progress animation
              qreal progress;
              QTime current = QTime::currentTime();
              if (current >= finishTime) {
                  progress = 1.0;
                  timer.stop();
              } else {
                  progress = ((qreal)startTime.msecsTo(current) / ANIMATION_DURATION);
              }

              setPosition(QWebMercator::coordinateInterpolation(
                                fromCoordinate, toCoordinate, easingCurve.valueForProgress(progress)));

              if (!timer.isActive())
                  emit arrived();
          }

      private:
          QGeoCoordinate currentPosition;
          QGeoCoordinate fromCoordinate, toCoordinate;
          QBasicTimer timer;
          QTime startTime, finishTime;
          QEasingCurve easingCurve;
          // ...
      };

      int main(int argc, char *argv[])
      {
          QGuiApplication app(argc, argv);

          PlaneController oslo2berlin;
          PlaneController berlin2london;

          QQmlApplicationEngine engine;
          engine.rootContext()->setContextProperty("oslo2Berlin", &oslo2berlin);
          engine.rootContext()->setContextProperty("berlin2London", &berlin2london);
          engine.load(QUrl(QStringLiteral("qrc:/planespotter.qml")));

          return app.exec();
      }

      #include "main.moc"