class QBluetoothDeviceDiscoveryAgent¶

The QBluetoothDeviceDiscoveryAgent class discovers the Bluetooth devices nearby. More…

Synopsis¶

Methods¶

def __init__()
def discoveredDevices()
def error()
def errorString()
def isActive()
def lowEnergyDiscoveryTimeout()
def setLowEnergyDiscoveryTimeout()

Slots¶

def start()
def stop()

Static functions¶

def supportedDiscoveryMethods()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description¶

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

To discover the nearby Bluetooth devices:

create an instance of QBluetoothDeviceDiscoveryAgent ,
connect to either the deviceDiscovered() or finished() signals,
and call start() .

def startDeviceDiscovery(self):

    # Create a discovery agent and connect to its signals
    discoveryAgent = QBluetoothDeviceDiscoveryAgent(self)
    connect(discoveryAgent, SIGNAL(deviceDiscovered(QBluetoothDeviceInfo)),
            self, SLOT(deviceDiscovered(QBluetoothDeviceInfo)))
    # Start a discovery
    discoveryAgent.start()
    #...

# In your local slot, read information about the found devices
def deviceDiscovered(self, device):

    print("Found device():", device.name(), '(', device.address().toString(), ')')

To retrieve results asynchronously, connect to the deviceDiscovered() signal. To get a list of all discovered devices, call discoveredDevices() after the finished() signal.

This class can be used to discover Classic and Low Energy Bluetooth devices. The individual device type can be determined via the coreConfigurations() attribute. In most cases the list returned by discoveredDevices() contains both types of devices. However not every platform can detect both types of devices. On platforms with this limitation (for example iOS only suports Low Energy discovery), the discovery process will limit the search to the type which is supported.

Note

Since Android 6.0 the ability to detect devices requires ACCESS_COARSE_LOCATION.

Note

The Win32 backend currently does not support the Received Signal Strength Indicator (RSSI), as well as the Manufacturer Specific Data, or other data updates advertised by Bluetooth LE devices after discovery.

class Error¶

Indicates all possible error conditions found during Bluetooth device discovery.

Constant

Description

QBluetoothDeviceDiscoveryAgent.NoError

No error has occurred.

QBluetoothDeviceDiscoveryAgent.PoweredOffError

The Bluetooth adaptor is powered off, power it on before doing discovery.

QBluetoothDeviceDiscoveryAgent.InputOutputError

Writing or reading from the device resulted in an error.

QBluetoothDeviceDiscoveryAgent.InvalidBluetoothAdapterError

The passed local adapter address does not match the physical adapter address of any local Bluetooth device.

QBluetoothDeviceDiscoveryAgent.UnsupportedPlatformError

Device discovery is not possible or implemented on the current platform. The error is set in response to a call to start() . An example for such cases are iOS versions below 5.0 which do not support Bluetooth device search at all.

QBluetoothDeviceDiscoveryAgent.UnsupportedDiscoveryMethod

One of the requested discovery methods is not supported by the current platform.

QBluetoothDeviceDiscoveryAgent.LocationServiceTurnedOffError

The location service is turned off. Usage of Bluetooth APIs is not possible when location service is turned off.

QBluetoothDeviceDiscoveryAgent.MissingPermissionsError

The operating system requests permissions which were not granted by the user.

QBluetoothDeviceDiscoveryAgent.UnknownError

An unknown error has occurred.

Constant	Description
QBluetoothDeviceDiscoveryAgent.NoError	No error has occurred.
QBluetoothDeviceDiscoveryAgent.PoweredOffError	The Bluetooth adaptor is powered off, power it on before doing discovery.
QBluetoothDeviceDiscoveryAgent.InputOutputError	Writing or reading from the device resulted in an error.
QBluetoothDeviceDiscoveryAgent.InvalidBluetoothAdapterError	The passed local adapter address does not match the physical adapter address of any local Bluetooth device.
QBluetoothDeviceDiscoveryAgent.UnsupportedPlatformError	Device discovery is not possible or implemented on the current platform. The error is set in response to a call to `start()` . An example for such cases are iOS versions below 5.0 which do not support Bluetooth device search at all.
QBluetoothDeviceDiscoveryAgent.UnsupportedDiscoveryMethod	One of the requested discovery methods is not supported by the current platform.
QBluetoothDeviceDiscoveryAgent.LocationServiceTurnedOffError	The location service is turned off. Usage of Bluetooth APIs is not possible when location service is turned off.
QBluetoothDeviceDiscoveryAgent.MissingPermissionsError	The operating system requests permissions which were not granted by the user.
QBluetoothDeviceDiscoveryAgent.UnknownError	An unknown error has occurred.

class DiscoveryMethod¶

(inherits enum.Flag) This enum descibes the type of discovery method employed by the QBluetoothDeviceDiscoveryAgent .

Constant

Description

QBluetoothDeviceDiscoveryAgent.NoMethod

The discovery is not possible. None of the available methods are supported.

QBluetoothDeviceDiscoveryAgent.ClassicMethod

The discovery process searches for Bluetooth Classic (BaseRate) devices.

QBluetoothDeviceDiscoveryAgent.LowEnergyMethod

The discovery process searches for Bluetooth Low Energy devices.

See also

supportedDiscoveryMethods()

Constant	Description
QBluetoothDeviceDiscoveryAgent.NoMethod	The discovery is not possible. None of the available methods are supported.
QBluetoothDeviceDiscoveryAgent.ClassicMethod	The discovery process searches for Bluetooth Classic (BaseRate) devices.
QBluetoothDeviceDiscoveryAgent.LowEnergyMethod	The discovery process searches for Bluetooth Low Energy devices.

__init__([parent=None])¶

Parameters:: parent – QObject

Constructs a new Bluetooth device discovery agent with parent parent.

__init__(deviceAdapter[, parent=None])

Parameters:

deviceAdapter – QBluetoothAddress
parent – QObject

Constructs a new Bluetooth device discovery agent with parent.

It uses deviceAdapter for the device search. If deviceAdapter is default constructed the resulting QBluetoothDeviceDiscoveryAgent object will use the local default Bluetooth adapter.

If a deviceAdapter is specified that is not a local adapter error() will be set to InvalidBluetoothAdapterError . Therefore it is recommended to test the error flag immediately after using this constructor.

See also

error()

canceled()¶

This signal is emitted when device discovery is aborted by a call to stop() .

deviceDiscovered(info)¶

Parameters:: info – QBluetoothDeviceInfo

This signal is emitted when the Bluetooth device described by info is discovered.

The signal is emitted as soon as the most important device information has been collected. However, as long as the finished() signal has not been emitted the information collection continues even for already discovered devices. This is particularly true for signal strength information (RSSI) and manufacturer data updates. If the use case requires continuous manufacturer data or RSSI updates it is advisable to retrieve the device information via discoveredDevices() once the discovery has finished or listen to the deviceUpdated() signal.

If lowEnergyDiscoveryTimeout() is larger than 0 the signal is only ever emitted when at least one attribute of info changes. This reflects the desire to receive updates as more precise information becomes available. The exception to this behavior is the case when lowEnergyDiscoveryTimeout is set to 0. A timeout of 0 expresses the desire to monitor the appearance and disappearance of Low Energy devices over time. Under this condition the deviceDiscovered() signal is emitted even if info has not changed since the last signal emission.

See also

rssi() lowEnergyDiscoveryTimeout()

deviceUpdated(info, updatedFields)¶

Parameters:

info – QBluetoothDeviceInfo
updatedFields – Combination of Field

This signal is emitted when the agent receives additional information about the Bluetooth device described by info. The updatedFields flags tell which information has been updated.

During discovery, some information can change dynamically, such as signal strength and manufacturerData . This signal informs you that if your application is displaying this data, it can be updated, rather than waiting until the discovery has finished.

See also

rssi() lowEnergyDiscoveryTimeout()

discoveredDevices()¶

Return type:: .list of QBluetoothDeviceInfo

Returns a list of all discovered Bluetooth devices.

error()¶

Return type:: Error

Returns the last error.

Any possible previous errors are cleared upon restarting the discovery.

errorOccurred(error)¶

Parameters:: error – Error

This signal is emitted when an error occurs during Bluetooth device discovery. The error parameter describes the error that occurred.

See also

error() errorString()

errorString()¶

Return type:: str

Returns a human-readable description of the last error.

See also

error() errorOccurred()

finished()¶

This signal is emitted when Bluetooth device discovery completes. The signal is not going to be emitted if the device discovery finishes with an error.

isActive()¶

Return type:: bool

Returns true if the agent is currently discovering Bluetooth devices, otherwise returns false.

lowEnergyDiscoveryTimeout()¶

Return type:: int

Returns a timeout in milliseconds that is applied to the Bluetooth Low Energy device search. A value of -1 implies that the platform does not support this property and the timeout for the device search cannot be adjusted. A return value of 0 implies a never-ending search which must be manually stopped via stop() .

See also

setLowEnergyDiscoveryTimeout()

setLowEnergyDiscoveryTimeout(msTimeout)¶

Parameters:: msTimeout – int

Sets the maximum search time for Bluetooth Low Energy device search to timeout in milliseconds. If timeout is 0 the discovery runs until stop() is called.

This reflects the fact that the discovery process for Bluetooth Low Energy devices is mostly open ended. The platform continues to look for more devices until the search is manually stopped. The timeout ensures that the search is aborted after timeout milliseconds. Of course, it is still possible to manually abort the discovery by calling stop() .

The new timeout value does not take effect until the device search is restarted. In addition the timeout does not affect the classic Bluetooth device search. Depending on the platform the classic search may add more time to the total discovery process beyond timeout.

For a reliable Bluetooth Low Energy discovery, use at least 40000 milliseconds.

See also

lowEnergyDiscoveryTimeout()

start()¶

Starts Bluetooth device discovery, if it is not already started.

The deviceDiscovered() signal is emitted as each device is discovered. The finished() signal is emitted once device discovery is complete. The discovery utilizes the maximum set of supported discovery methods on the platform.

See also

supportedDiscoveryMethods()

start(method)

Parameters:: method – Combination of DiscoveryMethod

Starts Bluetooth device discovery, if it is not already started and the provided methods are supported. The discovery methods limit the scope of the device search. For example, if the target service or device is a Bluetooth Low Energy device, this function could be used to limit the search to Bluetooth Low Energy devices and thereby reduces the discovery time significantly.

Note

methods only determines the type of discovery and does not imply the filtering of the results. For example, the search may still contain classic bluetooth devices despite methods being set to LowEnergyMethod only. This may happen due to previously cached search results which may be incorporated into the search results.

stop()¶

Stops Bluetooth device discovery. The cancel() signal is emitted once the device discovery is canceled. start() maybe called before the cancel signal is received. Once start() has been called the cancel signal from the prior discovery will be discarded.

static supportedDiscoveryMethods()¶

Return type:: Combination of DiscoveryMethod

This function returns the discovery methods supported by the current platform. It can be used to limit the scope of the device discovery.