Writes GPX track points to GPXTrack. The instance of the class should be added as a listener to the LocationEngine for GPX track recording. Appends the new location to the back segment of the track whenever the listener is called. The following data (if provided) can be recorded and inserted into the resulting GPXTrack: latitude, longitude, altitude, time, bearingInDegrees, pitchInDegrees, speedInMetersPerSecond, horizontalAccuracyInMeters, verticalAccuracyInMeters, bearingAccuracyInDegrees, speedAccuracyInMetersPerSecond and locationTechnology.

Use case examples:

A user wants to create and save a new GPXDocument with one GPXTrack: - create GPXTrackWriter and add it as a location listener to LocationEngine. - set user parameters to getTrack() (e.g. GPXTrack.getName() or GPXTrack.getDescription()). - when writing is completed, create a new GPXDocument with a list of one GPXTrack and save the document via GPXDocument.save(java.lang.String).

A user wants to modify and save GPXTrack in the existing GPXDocument: - load GPXDocument from a file by the relevant constructor. - create GPXTrackWriter with the required track in the list GPXDocument.getTracks(), add the created instance as a location listener to LocationEngine. - when writing is completed, save the document via GPXDocument.save(java.lang.String).

The GPXDocument including all tracks is saved in the GPX file format. Hence, once saved, it can be easily shared with other applications that understand the GPX file format.