Qt 5.11 | Qt Positioning | C++ Classes | QGeoSatelliteInfoSource

Qt 5.11.3 Reference Documentation

# QGeoSatelliteInfoSource Class

The QGeoSatelliteInfoSource class is an abstract base class for the distribution of satellite information updates. More...

Header: | #include <QGeoSatelliteInfoSource>
qmake: | QT += positioning
Since: | Qt 5.2

- List of all members, including inherited members

## Public Types

enum | Error { AccessError, ClosedError, NoError, UnknownSourceError }

## Properties

- minimumUpdateInterval : const int
- updateInterval : int

## Public Functions

| QGeoSatelliteInfoSource(QObject *parent)
virtual | ~QGeoSatelliteInfoSource()
virtual QGeoSatelliteInfoSource::Error | error() const = 0
virtual int | minimumUpdateInterval() const = 0
virtual void | setUpdateInterval(int msec)
QString | sourceName() const
int | updateInterval() const

## Public Slots

virtual void | requestUpdate(int timeout = ...) = 0
virtual void | startUpdates() = 0
virtual void | stopUpdates() = 0

## Signals

void | error(QGeoSatelliteInfoSource::Error satelliteError)
void | requestTimeout()
void | satellitesInUseUpdated(const QList<QGeoSatelliteInfo> &satellites)
void | satellitesInViewUpdated(const QList<QGeoSatelliteInfo> &satellites)

## Static Public Members

QStringList | availableSources()
QGeoSatelliteInfoSource * | createDefaultSource(QObject *parent)
QGeoSatelliteInfoSource * | createSource(const QString &sourceName, QObject *parent)

## Detailed Description

The QGeoSatelliteInfoSource class is an abstract base class for the distribution of satellite information updates.

The static function QGeoSatelliteInfoSource::createDefaultSource() creates a default satellite data source that is appropriate for the platform, if one is available. Otherwise, available QGeoPositionInfoSourceFactory plugins will be checked for one that has a satellite data source available.

Call startUpdates() and stopUpdates() to start and stop regular updates, or requestUpdate() to request a single update. When an update is available, satellitesInViewUpdated() and/or satellitesInUseUpdated() will be emitted.

If regular satellite updates are required, setUpdateInterval() can be used to specify how often these updates should be emitted. If no interval is specified, updates are simply provided whenever they are available. For example:

      // Emit updates every 10 seconds if available
      QGeoSatelliteInfoSource *source = QGeoSatelliteInfoSource::createDefaultSource(0);
      if (source)
          source->setUpdateInterval(10000);

To remove an update interval that was previously set, call setUpdateInterval() with a value of 0.

Note that the satellite source may have a minimum value requirement for update intervals, as returned by minimumUpdateInterval().

## Member Type Documentation

### enum QGeoSatelliteInfoSource::Error

The Error enumeration represents the errors which can occur.

Constant | Value | Description
--- | --- | ---
`QGeoSatelliteInfoSource::AccessError` | `0` | The connection setup to the satellite backend failed because the application lacked the required privileges.
`QGeoSatelliteInfoSource::ClosedError` | `1` | The satellite backend closed the connection, which happens for example in case the user is switching location services to off. This object becomes invalid and should be deleted. A new satellite source can be created by calling createDefaultSource() later on.
`QGeoSatelliteInfoSource::NoError` | `2` | No error has occurred.
`QGeoSatelliteInfoSource::UnknownSourceError` | `-1` | An unidentified error occurred.

## Property Documentation

### minimumUpdateInterval : const int

This property holds the minimum time (in milliseconds) required to retrieve a satellite update.

This is the minimum value accepted by setUpdateInterval() and requestUpdate().

Access functions:

virtual int | minimumUpdateInterval() const = 0

### updateInterval : int

This property holds the requested interval in milliseconds between each update.

If the update interval is not set (or is set to 0) the source will provide updates as often as necessary.

If the update interval is set, the source will provide updates at an interval as close to the requested interval as possible. If the requested interval is less than the minimumUpdateInterval(), the minimum interval is used instead.

Changes to the update interval will happen as soon as is practical, however the time the change takes may vary between implementations. Whether or not the elapsed time from the previous interval is counted as part of the new interval is also implementation dependent.

The default value for this property is 0.

Note: Subclass implementations must call the base implementation of setUpdateInterval() so that updateInterval() returns the correct value.

Access functions:

int | updateInterval() const
virtual void | setUpdateInterval(int msec)

## Member Function Documentation

### QGeoSatelliteInfoSource::QGeoSatelliteInfoSource(QObject *parent)

Creates a satellite source with the specified parent.

### `[virtual]` QGeoSatelliteInfoSource::~QGeoSatelliteInfoSource()

Destroys the satellite source.

### `[static]` QStringList QGeoSatelliteInfoSource::availableSources()

Returns a list of available source plugins, including the default system backend if one is available.

### `[static]` QGeoSatelliteInfoSource *QGeoSatelliteInfoSource::createDefaultSource(QObject *parent)

Creates and returns a source with the specified parent that reads from the system's default source of satellite update information, or the highest priority available plugin.

Returns 0 if the system has no default satellite source, no valid plugins could be found or the user does not have the permission to access the satellite data.

### `[static]` QGeoSatelliteInfoSource *QGeoSatelliteInfoSource::createSource(const QString &sourceName, QObject *parent)

Creates and returns a source with the given parent, by loading the plugin named sourceName.

Returns 0 if the plugin cannot be found.

### `[pure virtual]` QGeoSatelliteInfoSource::Error QGeoSatelliteInfoSource::error() const

Returns the last error that occurred.

This signal is not emitted when a requestTimeout() has occurred.

### `[signal]` void QGeoSatelliteInfoSource::error(QGeoSatelliteInfoSource::Error satelliteError)

This signal is emitted after an error occurred. The satelliteError parameter describes the type of error that occurred.

Note: Signal error is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

      connect(geoSatelliteInfoSource, QOverload<QGeoSatelliteInfoSource::Error>::of(&QGeoSatelliteInfoSource::error),
          [=](QGeoSatelliteInfoSource::Error satelliteError){ /* ... */ });

### `[signal]` void QGeoSatelliteInfoSource::requestTimeout()

Emitted if requestUpdate() was called and the current satellite information could not be retrieved within the specified timeout.

While the triggering of this signal may be considered an error condition, it does not imply the emission of the `error()` signal. Only the emission of `requestTimeout()` is required to indicate a timeout.

### `[pure virtual slot]` void QGeoSatelliteInfoSource::requestUpdate(int timeout = ...)

Attempts to get the current satellite information and emit satellitesInViewUpdated() and satellitesInUseUpdated() with this information. If the current satellite information cannot be found within the given timeout (in milliseconds) or if timeout is less than the value returned by minimumUpdateInterval(), requestTimeout() is emitted.

If the timeout is zero, the timeout defaults to a reasonable timeout period as appropriate for the source.

This does nothing if another update request is in progress. However it can be called even if startUpdates() has already been called and regular updates are in progress.

### `[signal]` void QGeoSatelliteInfoSource::satellitesInUseUpdated(const QList<QGeoSatelliteInfo> &satellites)

If startUpdates() or requestUpdate() is called, this signal is emitted when an update is available on the number of satellites that are currently in use.

These are the satellites that are used to get a "fix" - that is, those used to determine the current position.

The satellites parameter holds the satellites currently in use.

### `[signal]` void QGeoSatelliteInfoSource::satellitesInViewUpdated(const QList<QGeoSatelliteInfo> &satellites)

If startUpdates() or requestUpdate() is called, this signal is emitted when an update is available on the satellites that are currently in view.

The satellites parameter holds the satellites currently in view.

### QString QGeoSatelliteInfoSource::sourceName() const

Returns the unique name of the satellite source implementation in use.

This is the same name that can be passed to createSource() in order to create a new instance of a particular satellite source implementation.

### `[pure virtual slot]` void QGeoSatelliteInfoSource::startUpdates()

Starts emitting updates at regular intervals. The updates will be provided whenever new satellite information becomes available.

If satellite information cannot be retrieved or some other form of timeout has occurred the satellitesInViewUpdated() and satellitesInUseUpdated() signals may be emitted with empty parameter lists.

See also satellitesInViewUpdated() and satellitesInUseUpdated().

### `[pure virtual slot]` void QGeoSatelliteInfoSource::stopUpdates()

Stops emitting updates at regular intervals.