Qt Positioning 插件

Qt Positioning provides the majority of its functionality through plugins. This document outlines how to develop a new position plugin.

Default plugins

Some plugins already ship with Qt. These are:

android	Wraps Android positioning subsystem. Available only on Android.
corelocation	A Core Location backend wraps iOS and macOS positioning subsystems. Available only on Apple platforms supporting corelocation.
geoclue	Interfaces with GeoClue v0.12. Requires GeoClue 0.12 to be present to function.
geoclue2	Interfaces with GeoClue v2. Requires GeoClue v2 to be present to function.
gypsy	Interfaces with Gypsy daemon. Requires Gypsy to be present to function.
winrt	Wraps WinRT positioning subsystem. Available only on WinRT and Windows10.
serialnmea	A Serial NMEA backend that parses NMEA streams from a GPS receiver over a serial link to provide position updates.
positionpoll	A backend providing only area monitoring functionalities via polling on position updates.

Plugin Description

Each plugin is described by a json file. The json describes the plugins capabilities and version. Below is an example of a json file used by the postionpoll plugin:

{
    "Keys": ["positionpoll"],
    "Provider": "positionpoll",
    "Position": false,
    "Satellite": false,
    "Monitor": true,
    "Priority": 1000,
    "Testable": true
}

The entries have the following meaning:

Key	描述
键	The unique name/key of the plugin. Each position plugin must have a unique name.
Provider	The provider name of the services. Multiple plugins may have the same name. In such cases the Version string will be used to further distinguish the plugins.
Position	Set to `true` if the plugin implements a QGeoPositionInfoSource .
Satellite	Set to `true` if the plugin implements a QGeoSatelliteInfoSource .
Monitor	Set to `true` if the plugin implements a QGeoAreaMonitorSource .
优先级	The plugin priority. If multiple plugins have the same provider name, the plugin with the higest priority will be used.

Implementing Plugins

A plugin implementer needs to subclass QGeoPositionInfoSourceFactory and override one or more of its functions. If a plugin does not support a specific feature the function should return 0 or utilize the default implementation.