Hi,
i've hacked together a slightly incomplete GpsdPositionInfoSource. This allows
to use qt mobility location
on a gpsd based system (e.g. ordinary linux desktops).
It's slightly incomplete as it doesn't support changing the update interval
nor the timeout on requestUpdate.
Both are things i don't need/use in the app i wrote this for (cacheme).
The code is public domain and uses the json parser from
http://nilier.blogspot.com/2010/08/json-parser-class-for-qt.html
Have fun,
Till
/****************************************************************************
** GpsdPositionInfoSource
** (c) 2011 by Till Harbaum <t...@harbaum.org>
** This code is public domain, do what you want with it
****************************************************************************/
// Based infos from:
// http://gpsd.berlios.de/client-howto.html
// http://doc.qt.nokia.com/qtmobility-1.0-tp/qgeopositioninfosource.html
#include <QDebug>
#include <QByteArray>
#include <QStringList>
#include <math.h>
#include "gpsdpositioninfosource.h"
#include "json.h"
#ifndef NAN
#define NAN (0.0/0.0)
#endif
qreal GpsdPositionInfoSource::getReal(const QMap<QString, QVariant> &map, const QString &name) {
// make sure that key exists
if(!map.contains(name)) return NAN;
QVariant variant = map.value(name);
// make sure value is variant of correkt type
if(QVariant::String != variant.type())
return NAN;
// extract string and convert to float
return variant.toString().toFloat();
}
void GpsdPositionInfoSource::setAttribute(QGeoPositionInfo &info,
QGeoPositionInfo::Attribute attr, const QMap<QString, QVariant> &map, const QString &name) {
qreal value = getReal(map, name);
if(!isnan(value)) info.setAttribute(attr, value);
}
void GpsdPositionInfoSource::parse(const QString &str) {
bool ok;
// feed reply into json parser
// json is a QString containing the data to convert
QVariant result = Json::parse(str, ok);
if(!ok) {
qDebug() << __FUNCTION__ << "Json deconding failed.";
return;
}
// we expect a qvariantmap
if(QVariant::Map != result.type()) {
qDebug() << __FUNCTION__ << "Unexpected result type:" << result.type();
return;
}
QMap<QString, QVariant> map = result.toMap();
// extract reply class
QString classStr = map.value("class").toString();
if(!classStr.compare("VERSION")) {
qDebug() << "Connected to GPSD:";
qDebug() << "Release:" << map.value("release").toString();
qDebug() << "Revision:" << map.value("rev").toString();
qDebug() << "Protocol version:" <<
map.value("proto_major").toString() + "." +
map.value("proto_minor").toString();
} else if(!classStr.compare("TPV")) {
// TPV is the most interesting string for us
m_lastKnown = QGeoPositionInfo();
int mode = map.value("mode").toInt();
if(mode > 0) {
QGeoCoordinate coo(getReal(map, "lat"), getReal(map, "lon"));
if(mode == 3)
coo.setAltitude(getReal(map, "alt"));
m_lastKnown.setCoordinate(coo);
}
setAttribute(m_lastKnown, QGeoPositionInfo::Direction, map, "track");
setAttribute(m_lastKnown, QGeoPositionInfo::VerticalSpeed, map, "climb");
setAttribute(m_lastKnown, QGeoPositionInfo::GroundSpeed, map, "speed");
setAttribute(m_lastKnown, QGeoPositionInfo::VerticalAccuracy, map, "epv");
setAttribute(m_lastKnown, QGeoPositionInfo::HorizontalAccuracy, map, "epv");
// horizontal error in lat or long
qreal epx = getReal(map, "epx");
qreal epy = getReal(map, "epy");
if(!isnan(epx) && !isnan(epy))
m_lastKnown.setAttribute(QGeoPositionInfo::HorizontalAccuracy, epx>epy?epx:epy);
QDateTime time;
time.setTime_t(getReal(map, "time"));
m_lastKnown.setTimestamp(time);
emit positionUpdated( m_lastKnown );
}
}
void GpsdPositionInfoSource::readData() {
// split reply into seperate strings at newline
QStringList data = QString::fromUtf8(m_tcpSocket->readAll()).split('\n');
for(int i=0;i<data.size();i++)
if(!data[i].trimmed().isEmpty())
parse(data[i].trimmed());
}
void GpsdPositionInfoSource::displayError(QAbstractSocket::SocketError) {
qDebug() << __FUNCTION__ << "Error: " << m_tcpSocket->errorString();
}
GpsdPositionInfoSource::GpsdPositionInfoSource(QObject *parent)
: QGeoPositionInfoSource(parent) {
qDebug() << __FUNCTION__;
// connect to gpsd
m_tcpSocket = new QTcpSocket(this);
connect(m_tcpSocket, SIGNAL(readyRead()), this, SLOT(readData()));
connect(m_tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
this, SLOT(displayError(QAbstractSocket::SocketError)));
m_tcpSocket->connectToHost("localhost", 2947);
}
GpsdPositionInfoSource::~GpsdPositionInfoSource() {
qDebug() << __FUNCTION__;
m_tcpSocket->close();
}
void GpsdPositionInfoSource::setUpdateInterval(int msec) {
int interval = msec;
if (interval != 0)
interval = qMax(msec, minimumUpdateInterval());
QGeoPositionInfoSource::setUpdateInterval(interval);
}
void GpsdPositionInfoSource::startUpdates() {
// request info from gpsd
QString request = "?WATCH={\"enable\":true,\"json\":true}";
m_tcpSocket->write(request.toUtf8());
}
void GpsdPositionInfoSource::stopUpdates() {
// ask gpsd to stop sending data
QString request = "?WATCH={\"enable\":false}";
m_tcpSocket->write(request.toUtf8());
}
void GpsdPositionInfoSource::requestUpdate(int) {
emit positionUpdated( m_lastKnown );
}
QGeoPositionInfo GpsdPositionInfoSource::lastKnownPosition(bool) const {
// the bool value does not matter since we only use satellite positioning
return m_lastKnown;
}
QGeoPositionInfoSource::PositioningMethods GpsdPositionInfoSource::supportedPositioningMethods() const {
return SatellitePositioningMethods;
}
int GpsdPositionInfoSource::minimumUpdateInterval() const {
return 1000;
}
/****************************************************************************
** GpsdPositionInfoSource
** (c) 2011 by Till Harbaum <t...@harbaum.org>
** This code is public domain, do what you want with it
****************************************************************************/
#ifndef GPSDPOSITIONINFOSOURCE_H
#define GPSDPOSITIONINFOSOURCE_H
#include <QObject>
#include <QTcpSocket>
#include <QGeoPositionInfoSource>
QTM_USE_NAMESPACE
class GpsdPositionInfoSource : public QGeoPositionInfoSource {
Q_OBJECT
public:
GpsdPositionInfoSource(QObject *parent = 0);
~GpsdPositionInfoSource();
void setUpdateInterval(int msec);
QGeoPositionInfo lastKnownPosition(bool fromSatellitePositioningMethodsOnly = false) const;
PositioningMethods supportedPositioningMethods() const;
int minimumUpdateInterval() const;
public slots:
void startUpdates();
void stopUpdates();
void requestUpdate(int timeout = 0);
private slots:
void readData();
void displayError(QAbstractSocket::SocketError);
private:
qreal getReal(const QMap<QString, QVariant> &, const QString &);
void setAttribute(QGeoPositionInfo &, QGeoPositionInfo::Attribute, const QMap<QString, QVariant> &, const QString &);
void parse(const QString &);
QTcpSocket *m_tcpSocket;
QGeoPositionInfo m_lastKnown;
};
#endif
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