bluetooth-overview.qdoc

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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
\ingroup technology-apis
\title Qt Bluetooth Overview
\page qtbluetooth-overview.html
\brief The Qt Bluetooth API enables connectivity with other regular Bluetooth
       and Bluetooth Low Energy enabled devices.
 
    With the Qt Bluetooth API typical use cases are:
 
        \list
        \li Retrieve information about the local Bluetooth device.
        \li Scan for other Bluetooth devices in range and retrieve information about them.
        \li Push files to remote devices using the OBEX Object Push Profile (OPP)
        \li Connect to remote devices through a RFCOMM channel using the Serial Port Profile (SPP).
        \li Create a RFCOMM server that allows incoming connections using SPP.
        \li Retrieve specification about Bluetooth Low Energy device.
        \li Connect to Bluetooth Low Energy device.
        \li Receive advertisement from Bluetooth Low Energy device.
        \endlist
 
    Note that the Object Push Profile is not supported on Android and Windows.
 
    \note Parts of RFCOMM functionality cannot be configured by Qt on
    Windows. A service's \l {QBluetoothServiceInfo::}{ServiceClassIds} and
    \l {QBluetoothServiceInfo::}{ProtocolDescriptorList} are filled
    automatically. Therefore, registering a service with custom values for
    these fields might not yield the expected result on Windows.
 
    \note The Received Signal Strength Indicator (RSSI), as well as
    the Manufacturer Specific Data advertised by Bluetooth LE devices are
    not supported by the Win32 backend. Also, it is only possible to find
    devices that have been previously paired through Windows Settings.
 
    The following sections describe how to use the Qt Bluetooth C++ API classes
    for the above use cases.
 
    \section1 Retrieving Local Device Information
 
    The Qt Bluetooth API has three main purposes. The first one is to
    obtain local and remote device information. The first steps in retrieving device information are
    to check if Bluetooth is available on the device and read the local device address and name.
    QBluetoothLocalDevice is the class that provides all of this information. Additionally you can use it
    to turn Bluetooth on/off, set the visibility of the device and determine the current connections.
 
    \snippet doc_src_qtbluetooth.cpp turningon
 
    \section1 Scanning for Bluetooth Devices
 
    Similar to the QBluetoothLocalDevice, the API offers QBluetoothDeviceInfo which provides
    similar information for remote devices. Although you can just create QBluetoothDeviceInfo objects on
    your own and fill them with data, the easier way is to use the QBluetoothDeviceDiscoveryAgent to
    start an automated search for visible Bluetooth devices within the connectable range.
 
    \snippet doc_src_qtbluetooth.cpp device_discovery
 
    \section1 Exchanging Data Between Devices
 
    The more flexible approach for communication between two Bluetooth enabled devices, is to
    create a virtual serial port connection and freely exchange data over that connection. This can
    be done by the Serial Port Profile (SPP). The Serial Port Profile emulates a serial connection
    over the Bluetooth transport protocol RFCOMM.
 
    To be able to receive incoming SPP connections, you need to listen to incoming connections using
    \l QBluetoothServer.
 
    \snippet btchat/chatserver.cpp Create the server
 
    Connect to this server from another device playing the client role by using a
    QBluetoothSocket:
 
    \snippet btchat/chatclient.cpp startClient
 
    Using such a connection allows to exchange any form of data in both directions.
    It is perfectly suited for gaming or for syncing the state between two instances of
    an application on two devices. For more detailed descriptions on how to configure the server
    and client, please refer to the detailed description sections in the \l QBluetoothServer and
    \l QBluetoothSocket classes. A good example to start with SPP is the \l{btchat}{Bluetooth Chat}
    example.
 
    \section1 Bluetooth Low Energy
 
    Bluetooth Low Energy, also known as Bluetooth Smart, is a new technology enabling
    devices with low energy consumption to communicate with each other. More details about
    this technology and the related Qt APIs can be found in the \l {Bluetooth Low Energy Overview}.
*/