LowEnergyScanner example: allow stopping device discovery

... and also show the newly-discovered devices as soon as they are
discovered.
This requires a more complex logic for updating the device list,
because the deviceDiscovered() signal can be emitted multiple times for
the same device.

Task-number: QTBUG-111972
Pick-to: 6.5
Change-Id: I8e5f839ffb679516819d8f6063393d5a9b0ec840
Reviewed-by: Juha Vuolle <juha.vuolle@qt.io>

4 files changed, 53 insertions, 27 deletions

diff --git a/examples/bluetooth/lowenergyscanner/Devices.qml b/examples/bluetooth/lowenergyscanner/Devices.qml
index 594e6b7d..40afce7f 100644
--- a/examples/bluetooth/lowenergyscanner/Devices.qml
+++ b/examples/bluetooth/lowenergyscanner/Devices.qml
@@ -22,7 +22,15 @@ Rectangle {
     Header {
         id: header
         anchors.top: parent.top
-        headerText: "Start Discovery"
+        headerText: {
+            if (Device.state)
+                return "Discovering"
+
+            if (Device.devicesList.length > 0)
+                return "Select a device"
+
+            return "Start Discovery"
+        }
     }
 
     Dialog {
@@ -50,11 +58,6 @@ Rectangle {
             border.color: "black"
             radius: 5
 
-            Component.onCompleted: {
-                info.visible = false
-                header.headerText = "Select a device"
-            }
-
             MouseArea {
                 anchors.fill: parent
                 onClicked: {
@@ -103,11 +106,15 @@ Rectangle {
         menuHeight: (parent.height / 6)
         menuText: Device.update
         onButtonClick: {
-            Device.startDeviceDiscovery()
-            // if startDeviceDiscovery() failed Device.state is not set
-            if (Device.state) {
-                info.dialogText = "Searching..."
-                info.visible = true
+            if (!Device.state) {
+                Device.startDeviceDiscovery()
+                // if startDeviceDiscovery() failed Device.state is not set
+                if (Device.state) {
+                    info.dialogText = "Searching..."
+                    info.visible = true
+                }
+            } else {
+                Device.stopDeviceDiscovery()
             }
         }
     }
diff --git a/examples/bluetooth/lowenergyscanner/device.cpp b/examples/bluetooth/lowenergyscanner/device.cpp
index 0d72458b..a3c6e106 100644
--- a/examples/bluetooth/lowenergyscanner/device.cpp
+++ b/examples/bluetooth/lowenergyscanner/device.cpp
@@ -29,6 +29,8 @@ Device::Device()
             this, &Device::deviceScanError);
     connect(discoveryAgent, &QBluetoothDeviceDiscoveryAgent::finished,
             this, &Device::deviceScanFinished);
+    connect(discoveryAgent, &QBluetoothDeviceDiscoveryAgent::canceled,
+            this, &Device::deviceScanFinished);
     //! [les-devicediscovery-1]
 
     setUpdate(u"Search"_s);
@@ -64,33 +66,46 @@ void Device::startDeviceDiscovery()
     devices.clear();
     emit devicesUpdated();
 
-    setUpdate(u"Scanning for devices ..."_s);
     //! [les-devicediscovery-2]
     discoveryAgent->start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod);
     //! [les-devicediscovery-2]
 
     if (discoveryAgent->isActive()) {
+        setUpdate(u"Stop"_s);
         m_deviceScanState = true;
         Q_EMIT stateChanged();
     }
 }
 
+void Device::stopDeviceDiscovery()
+{
+    if (discoveryAgent->isActive())
+        discoveryAgent->stop();
+}
+
 //! [les-devicediscovery-3]
 void Device::addDevice(const QBluetoothDeviceInfo &info)
 {
-    if (info.coreConfigurations() & QBluetoothDeviceInfo::LowEnergyCoreConfiguration)
-        setUpdate(u"Last device added: "_s + info.name());
+    if (info.coreConfigurations() & QBluetoothDeviceInfo::LowEnergyCoreConfiguration) {
+        auto devInfo = new DeviceInfo(info);
+        auto it = std::find_if(devices.begin(), devices.end(),
+                               [devInfo](DeviceInfo *dev) {
+                                   return devInfo->getAddress() == dev->getAddress();
+                               });
+        if (it == devices.end()) {
+            devices.append(devInfo);
+        } else {
+            auto oldDev = *it;
+            *it = devInfo;
+            delete oldDev;
+        }
+        emit devicesUpdated();
+    }
 }
 //! [les-devicediscovery-3]
 
 void Device::deviceScanFinished()
 {
-    const QList<QBluetoothDeviceInfo> foundDevices = discoveryAgent->discoveredDevices();
-    for (auto &nextDevice : foundDevices)
-        if (nextDevice.coreConfigurations() & QBluetoothDeviceInfo::LowEnergyCoreConfiguration)
-            devices.append(new DeviceInfo(nextDevice));
-
-    emit devicesUpdated();
     m_deviceScanState = false;
     emit stateChanged();
     if (devices.isEmpty())
@@ -315,18 +330,17 @@ void Device::serviceDetailsDiscovered(QLowEnergyService::ServiceState newState)
 
 void Device::deviceScanError(QBluetoothDeviceDiscoveryAgent::Error error)
 {
-    if (error == QBluetoothDeviceDiscoveryAgent::PoweredOffError)
+    if (error == QBluetoothDeviceDiscoveryAgent::PoweredOffError) {
         setUpdate(u"The Bluetooth adaptor is powered off, power it on before doing discovery."_s);
-    else if (error == QBluetoothDeviceDiscoveryAgent::InputOutputError)
+    } else if (error == QBluetoothDeviceDiscoveryAgent::InputOutputError) {
         setUpdate(u"Writing or reading from the device resulted in an error."_s);
-    else {
+    } else {
         static QMetaEnum qme = discoveryAgent->metaObject()->enumerator(
                     discoveryAgent->metaObject()->indexOfEnumerator("Error"));
         setUpdate(u"Error: "_s + QLatin1StringView(qme.valueToKey(error)));
     }
 
     m_deviceScanState = false;
-    emit devicesUpdated();
     emit stateChanged();
 }
 
diff --git a/examples/bluetooth/lowenergyscanner/device.h b/examples/bluetooth/lowenergyscanner/device.h
index ea5d6ed6..d15b02dc 100644
--- a/examples/bluetooth/lowenergyscanner/device.h
+++ b/examples/bluetooth/lowenergyscanner/device.h
@@ -53,6 +53,7 @@ public:
 
 public slots:
     void startDeviceDiscovery();
+    void stopDeviceDiscovery();
     void scanServices(const QString &address);
 
     void connectToService(const QString &uuid);
@@ -87,9 +88,9 @@ private:
     void setUpdate(const QString &message);
     QBluetoothDeviceDiscoveryAgent *discoveryAgent;
     DeviceInfo currentDevice;
-    QList<QObject *> devices;
-    QList<QObject *> m_services;
-    QList<QObject *> m_characteristics;
+    QList<DeviceInfo *> devices;
+    QList<ServiceInfo *> m_services;
+    QList<CharacteristicInfo *> m_characteristics;
     QString m_previousAddress;
     QString m_message;
     bool connected = false;
diff --git a/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc b/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc
index 7a55f5e9..4a9bff9e 100644
--- a/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc
+++ b/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc
@@ -53,6 +53,10 @@
     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.
+    The \l {QBluetoothDeviceDiscoveryAgent::}{deviceDiscovered()} signal may be
+    emitted multiple times for the same device as more details are discovered.
+    Here we match these device discoveries so that the user only sees the
+    individual devices:
 
     \snippet lowenergyscanner/device.cpp les-devicediscovery-3