Log File Position Source (C++)

Logfile Position Source shows how to create and work with a custom NMEA position source, for platforms without GPS

clientapplication.cpp Example File

clientapplication.h Example File

logfilepositionsource.cpp Example File

logfilepositionsource.h Example File

main.cpp Example File

logfile.qrc Example File

logfilepositionsource.pro Example File

The Logfile Position Source shows how to create and work with a custom NMEA position source, for platforms without GPS.

The data is read from a file which has positional data in NMEA format. The resulting time and position information is then displayed to the screen as simple text in date/time and latitude/longitude format.

This example class reads position data from a text file, log.txt . The file specifies position data using a simple text format: it contains one position update per line, where each line contains a date/time, a latitude and a longitude, separated by spaces. The date/time is in ISO 8601 format and the latitude and longitude are in degrees decimal format. Here is an excerpt from log.txt :

2009-08-24T22:25:01 -27.576082 153.092415
2009-08-24T22:25:02 -27.576223 153.092530
2009-08-24T22:25:03 -27.576364 153.092648

The class reads this data and distributes it via the positionUpdated() signal.

Here is the definition of the LogFilePositionSource class:

The main methods overrided by the subclass are:

  • startUpdates(): called by client applications to start regular position updates.

  • stopUpdates(): called by client applications to stop regular position updates.

  • requestUpdate(): called by client applications to request a single update, with a specified timeout.

When a position update is available, the subclass emits the positionUpdated() signal.

Here are the key methods in the class implementation: