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/*!
\example logfilepositionsource
\title Log File Position Source (C++)
\ingroup qtpositioning-examples

\brief Logfile Position Source shows how to create and work with a custom
       position source. It can be useful for simulating GPS data, or when the
       data is received in some custom format.

\include examples-run.qdocinc

\section1 Creating custom Position Source

In this example, the data is read from a text file, \e simplelog.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 \e simplelog.txt:

\code
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
\endcode

We create a custom \c LogFilePositionSource class, which derives from
\l QGeoPositionInfoSource. It reads position data from the file and distributes
it via the \l {QGeoPositionInfoSource::}{positionUpdated()} signal.

The resulting time and position information is then displayed on the screen as
simple text in date/time and latitude/longitude format.

Here is the definition of the \c LogFilePositionSource class:

\quotefromfile logfilepositionsource/logfilepositionsource.h
\skipto class LogFilePositionSource
\printuntil };

The main methods overrided by the subclass are:

\list
    \li \l{QGeoPositionInfoSource::startUpdates()}{startUpdates()}: called by client applications
        to start regular position updates.
    \li \l{QGeoPositionInfoSource::stopUpdates()}{stopUpdates()}: called by client applications to
        stop regular position updates.
    \li \l{QGeoPositionInfoSource::requestUpdate()}{requestUpdate()}: called by client applications
        to request a single update, with a specified timeout.
\endlist

When a position update is available, the subclass emits the
\l{QGeoPositionInfoSource::positionUpdated()}{positionUpdated()} signal.

Here are the key methods in the class implementation:

\quotefromfile logfilepositionsource/logfilepositionsource.cpp
\skipto LogFilePositionSource::LogFilePositionSource
\printuntil /^\}/
\skipto LogFilePositionSource::startUpdates
\printuntil /^\}/
\skipto LogFilePositionSource::stopUpdates
\printuntil /^\}/
\skipto LogFilePositionSource::requestUpdate
\printuntil /^\}/
\printuntil LogFilePositionSource::readNextPosition
\printuntil /^\}/
*/
