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/****************************************************************************
**
** Copyright (C) 2013 BlackBerry Limited all rights reserved
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: http://www.gnu.org/copyleft/fdl.html.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\example lowenergyscanner
\title Bluetooth Low Energy Scanner Example
\brief An application designed to browse the content of Bluetooth Low
Energy peripheral devices. The example demonstrates the use of all Qt Bluetooth
Low Energy classes.
The Bluetooth Low Energy Scanner Example shows how to develop Bluetooth
Low Energy applications using the Qt Bluetooth API. The application covers
scanning for Low Energy devices, scanning their services and reading
the service characteristics and descriptors.
\image lowenergyscanner-services.png
The example introduces the following Qt classes:
\list
\li \l QLowEnergyController
\li \l QLowEnergyService
\li \l QLowEnergyCharacteristic
\li \l QLowEnergyDescriptor
\endlist
The example can be used with any arbitrary Bluetooth Low Energy peripheral
device. It creates a snapshot of all services, characteristics and descriptors
and presents them to the user. Therefore the application provides an easy way of
browsing the content offered by a peripheral device.
\include examples-run.qdocinc
\section1 Scanning for Devices
The first step is to find all peripheral devices. The devices can be found using
the \l QBluetoothDeviceDiscoveryAgent class. The discovery process is started using
\l {QBluetoothDeviceDiscoveryAgent::start()}{start()}. Each new device is advertised via
the \l {QBluetoothDeviceDiscoveryAgent::deviceDiscovered()}{deviceDiscovered()} signal:
\snippet lowenergyscanner/device.cpp les-devicediscovery-1
\snippet lowenergyscanner/device.cpp les-devicediscovery-2
The below \c addDevice() slot is triggered as a reaction to the discovery of a new
device. It filters all found devices which
have the \l QBluetoothDeviceInfo::LowEnergyCoreConfiguration flag and adds them to a
list which is shown to the user.
\snippet lowenergyscanner/device.cpp les-devicediscovery-3
The list of devices may look like in the image below. \note It is a prerequisite
that the remote devices actively advertise their presence.
\image lowenergyscanner-devices.png
\section1 Connecting to Services
After the user has selected a device from the list the application connects to the
device and scans all services. The \l QLowEnergyController class is used to connect
to the device. The \l {QLowEnergyController::connectToDevice()} function triggers the
connection process which lasts until the \l {QLowEnergyController::connected()} signal
is received or an error has occurred:
\snippet lowenergyscanner/device.cpp les-controller-1
The slot triggered by the \l {QLowEnergyController::connected()}{connected()}
signal immediately calls \l {QLowEnergyController::discoverServices()} to start the service
discovery on the connected peripheral device.
\snippet lowenergyscanner/device.cpp les-service-2
The resulting list is presented to the user.The image below displays the results when the SensorTag
device is selected. The view lists the names of the services, whether they are
primary or secondary services and the UUID which determines the service type.
\image lowenergyscanner-services.png
As soon as the service is chosen the related \l QLowEnergyService instance is created to
permit interaction with it:
\snippet lowenergyscanner/device.cpp les-service-1
The service object provides the required signals and functions to discover the service details,
read and write characteristics and descriptors, as well as receive data change notifications.
Change notifications can be triggered as a result of writing a value or due to an on-device
update potentially triggered by the internal logic.
During the initial detail search the service's \l {QLowEnergyService::state()}{state()} transitions
from \l {QLowEnergyService::DiscoveryRequired}{DiscoveryRequired} to
\l {QLowEnergyService::DiscoveringServices}{DiscoveringServices} and eventually ends with
\l {QLowEnergyService::ServiceDiscovered}{ServiceDiscovered}:
\snippet lowenergyscanner/device.cpp les-service-3
\section1 Reading Service Data
Upon selection of a service the service details are shown. Each characteristic
is listed together with its name, UUID, value, handle and properties.
\image lowenergyscanner-chars.png
It is possible to retrieve the service's characteristics via
\l QLowEnergyService::characteristics() and in turn, each descriptor can be obtained
via \l QLowEnergyCharacteristic::descriptors().
\snippet lowenergyscanner/device.cpp les-chars
Although the example application does not display descriptors it uses descriptors to
get the name of an individual characteristic if its name cannot be discerned based on its
UUID. The second way to obtain the name is the existence of a descriptor of the type
\l {QBluetoothUuid::CharacteristicUserDescription}. The code below demonstrates how this
may be achieved:
\snippet lowenergyscanner/characteristicinfo.cpp les-get-descriptors
*/
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