Qt Location Module

Concepts (in a QML Context)

What follows assumes that we are using the Qt Location QML API.

Position information can come from a variety of sources including satellites, wifi, text files and so on.

The position is described by the usual latitude, longitude, and the altitude in meters. For more information see Geographic Coordinate.

The QML position is stored in a Coordinate which contains the latitude, longitude and altitude of the device. The Location contains this Coordinate and adds an address, and a bounding box thus making the location a region and not just a point.

Now that the device has a position, with regular updates the API can determine the speed and heading of the device. It can define a box or a circle that can produce a notification when the device either leaves or enters that region.

If we introduce the idea of a Map with positions of interest, Places, then the device can be made aware of nearby features and related information, displayed graphically. Features on the Map may be places of business, entertainment and so on. They may include paths, roads, or forms of transport leading to the idea that navigation optimization and assistance are possible.

To enable navigation we need Routes from start to destination. These routes are made up of segments. Each RouteSegment can be considered a navigation sub-task: drive 100 meters, turn left. The beginning and end of each segment is a waypoint, that is, one part of our journey.

A typical use case for the API is a user looking for a particular type of place, say a restaurant. The user could enter a search string into the map application and respond to a list or display of results for restaurants "near" the device. The application could then be used to navigate to the restaurant using an optimized route that is aware of features in the environment that can help or hinder the journey. The navigation then proceeds with the user's progress monitored by means of the current Location. In the context of this API the map application would be aware of the location and size of various places and the location of the user. Plugins would supply the data used by the application to determine routes and navigation instructions. The Place types would hold information about the destination and surrounding objects including displayable representations. The Map type would enable this information to be displayed, panned, zoomed and so on. The Route would be determined by a plugin with each RouteSegment holding the navigation instructions guided by the updated current Location.

Plugins are a means of specifying which Location based service to use. For example, a plugin may allow connection to a provider's service that handles geocoding and routing that the API and application can use. There may be various GeoServices plugins for various tasks with some plugins providing more than one service. One QML Plugin should be created for each required GeoService plugin. Plugins are required for maps, routing and geocoding, however the default plugin handles all three of these services. A plugin may require online access or may support on-board maps and data. The default "nokia" plugin only supports online use which would be managed by QNetworkInfo and QNetworkConfigurationManager.

Note: : Plugins may not provide various features such as paging or relevance hints. Since plugins may be supplied by other providers, support for these aspects is dependent on the provider's implementation.