QtMobility Reference Documentation

QBluetoothDeviceDiscoveryAgent Class Reference

The QBluetoothDeviceDiscoveryAgent class provides an API for discovering nearby Bluetooth devices. More...

 #include <QBluetoothDeviceDiscoveryAgent>

Inherits: QObject.

This class was introduced in Qt Mobility 1.2.

Public Types

enum Error { NoError, PoweredOff, IOFailure, UnknownError }
enum InquiryType { GeneralUnlimitedInquiry, LimitedInquiry }


  • inquiryType : QBluetoothDeviceDiscoveryAgent::InquiryType
  • 1 property inherited from QObject

Public Functions

QBluetoothDeviceDiscoveryAgent ( QObject * parent = 0 )
~QBluetoothDeviceDiscoveryAgent ()
QList<QBluetoothDeviceInfo> discoveredDevices () const
Error error () const
QString errorString () const
QBluetoothDeviceDiscoveryAgent::InquiryType inquiryType () const
bool isActive () const
void setInquiryType ( QBluetoothDeviceDiscoveryAgent::InquiryType type )
  • 29 public functions inherited from QObject

Public Slots

void start ()
void stop ()
  • 1 public slot inherited from QObject


void canceled ()
void deviceDiscovered ( const QBluetoothDeviceInfo & info )
void error ( QBluetoothDeviceDiscoveryAgent::Error error )
void finished ()

Additional Inherited Members

  • 1 public variable inherited from QObject
  • 4 static public members inherited from QObject
  • 7 protected functions inherited from QObject
  • 2 protected variables inherited from QObject

Detailed Description

The QBluetoothDeviceDiscoveryAgent class provides an API for discovering nearby Bluetooth devices.

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

     QBluetoothDeviceDiscoveryAgent *discoveryAgent = new QBluetoothDeviceDiscoveryAgent(this);

     connect(discoveryAgent, SIGNAL(deviceDiscovered(const QBluetoothDeviceInfo&)),
             this, SLOT(deviceDiscovered(const QBluetoothDeviceInfo&)));

     // Automatically delete agent when device discovery finishes.
     connect(discoveryAgent, SIGNAL(finished()), this, SLOT(deleteLater()));


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

Member Type Documentation

enum QBluetoothDeviceDiscoveryAgent::Error

Indicates all possible error conditions found during Bluetooth device discovery.

QBluetoothDeviceDiscoveryAgent::NoError0No error has occurred.
QBluetoothDeviceDiscoveryAgent::PoweredOff2Bluetooth adaptor is powered off, power it on before doing discovery.
QBluetoothDeviceDiscoveryAgent::IOFailure1Writing or reading from device resulted in an error.
QBluetoothDeviceDiscoveryAgent::UnknownError100An unknown error has occurred.

enum QBluetoothDeviceDiscoveryAgent::InquiryType

This enum describes the inquiry type used when discovering Bluetooth devices.

QBluetoothDeviceDiscoveryAgent::GeneralUnlimitedInquiry0A general unlimited inquiry. Discovers all visible Bluetooth devices in the local vicinity.
QBluetoothDeviceDiscoveryAgent::LimitedInquiry1A limited inquiry. Only discovers devices that are in limited inquiry mode. Not all platforms support limited inquiry. If limited inquiry is requested on a platform that does not support it general unlimited inquiry we be used instead. Setting LimitedInquiry is useful for 2 games that wish to find each other quickly. The phone scans for devices in LimitedInquiry and Service Discovery is only done on one or two devices speeding up the service scan. After the game has connected the device returns to GeneralUnilimitedInquiry

Property Documentation

inquiryType : QBluetoothDeviceDiscoveryAgent::InquiryType

This property holds type of inquiry scan to use when discovering devices.

This property affects the type of inquiry scan which is performed when discovering devices.

By default, this property is set to GeneralUnlimitedInquiry.

Not all platforms support LimitedInquiry.

Access functions:

QBluetoothDeviceDiscoveryAgent::InquiryType inquiryType () const
void setInquiryType ( QBluetoothDeviceDiscoveryAgent::InquiryType type )

See also InquiryType.

Member Function Documentation

QBluetoothDeviceDiscoveryAgent::QBluetoothDeviceDiscoveryAgent ( QObject * parent = 0 )

Constructs a new Bluetooth device discovery agent with parent parent.

QBluetoothDeviceDiscoveryAgent::~QBluetoothDeviceDiscoveryAgent ()

Destructor for ~QBluetoothDeviceDiscoveryAgent()

void QBluetoothDeviceDiscoveryAgent::canceled () [signal]

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

void QBluetoothDeviceDiscoveryAgent::deviceDiscovered ( const QBluetoothDeviceInfo & info ) [signal]

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

QList<QBluetoothDeviceInfo> QBluetoothDeviceDiscoveryAgent::discoveredDevices () const

Returns a list of all discovered Bluetooth devices.

Error QBluetoothDeviceDiscoveryAgent::error () const

Returns the last error which has occurred.

void QBluetoothDeviceDiscoveryAgent::error ( QBluetoothDeviceDiscoveryAgent::Error error ) [signal]

This signal is emitted when an error occurs during Bluetooth device discovery.

See also error() and errorString().

QString QBluetoothDeviceDiscoveryAgent::errorString () const

Returns a human-readable description of the last error that occurred.

void QBluetoothDeviceDiscoveryAgent::finished () [signal]

This signal is emitted when Bluetooth device discovery completes.

bool QBluetoothDeviceDiscoveryAgent::isActive () const

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

void QBluetoothDeviceDiscoveryAgent::start () [slot]

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.

void QBluetoothDeviceDiscoveryAgent::stop () [slot]

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 silently discarded.


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