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Location QML PluginOverviewThe Location API gives users of the Qt Mobility Project the capability to write applications that understand a geographical location and movement of the position coordinates. Backend services can be called by the API to detect landmarks and display appropriate information. The QML Location Plugin delivers these capabilities in an easy to use form. PositioningCoordinateThe Coordinate is a basic unit of geographical information. The Coordinate element includes properties to hold the coordinate values for latitude, longitude and altitude. PositionThe three dimensional position of an object such as a mobile device can be specified by giving the latitude, longitude and altitude. That is the values held in the Coordinate element. Additionally for computation of future positions we would like to know if the object is moving, what speed it is doing and what is the timestamp of the last position data. Position therefore includes values for latitude, longitude, altitude, speed and a timestamp. Position also takes responsibility for validation of sensible values for these properties: just as there is a latitude there is a property latitudeValid. Similarly for the other properties with the exception of the timestamp. PositionSourceWe have a Position element, a Coordinate element but where do we get the data from? It is a good idea to be able to indicate alternative sources. Perhaps instead of directly picking up GPS satellites you want to do some testing using a datafile. We may also need to manage our interaction with the source. The PositionSource element provides the developer with control, within the limits allowed by the platform, of the source of the geographical data. The positional data can be sourced from a logfile which is in NMEA format. NMEA is a common text-based protocol for specifying navigational data. For convenience, the nmeaSource property is provided to enable QML applications to read NMEA data from a log file, the source will emit updates according to the time stamp of each NMEA sentence to produce a "replay" of the recorded data. Positioning Elements
MapsThe Map element can be used be used to display a map of the world. The bulk of the functionality is provided by a mapping plugin described by the Plugin element associated with the Map. Various map objects can be added to the map. These map objects are specified in terms of coordinates and metres. Note: At the time of the Qt Mobility 1.1 release the QML support for the Maps and Navigation API is incomplete and likely to be refined and improved in the next patch release. Map Elements
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