lowenergyscanner: use permissions API

To explicitly handle Bluetooth permissions, not relying on QtBluetooth
silently doing this under the hood.

Task-number: QTBUG-109964
Change-Id: If8851e764bd0d06bddac815e8c8d1a88eb749438
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

2 files changed, 26 insertions, 0 deletions

diff --git a/examples/bluetooth/lowenergyscanner/device.cpp b/examples/bluetooth/lowenergyscanner/device.cpp
index d645931c..f6c346c3 100644
--- a/examples/bluetooth/lowenergyscanner/device.cpp
+++ b/examples/bluetooth/lowenergyscanner/device.cpp
@@ -9,6 +9,12 @@
 #include <qbluetoothlocaldevice.h>
 #include <qbluetoothdeviceinfo.h>
 #include <qbluetoothservicediscoveryagent.h>
+
+#if QT_CONFIG(permissions)
+#include <QGuiApplication>
+#include <QPermission>
+#endif
+
 #include <QDebug>
 #include <QList>
 #include <QMetaEnum>
@@ -43,6 +49,20 @@ Device::~Device()
 
 void Device::startDeviceDiscovery()
 {
+#if QT_CONFIG(permissions)
+    //! [les-bluetooth-permission]
+    const auto permissionStatus = qApp->checkPermission(QBluetoothPermission{});
+    if (permissionStatus == Qt::PermissionStatus::Undetermined) {
+        qApp->requestPermission(QBluetoothPermission{}, this, &Device::startDeviceDiscovery);
+        return;
+    }
+    if (permissionStatus == Qt::PermissionStatus::Denied) {
+        setUpdate("Bluetooth permission required.");
+        return;
+    }
+    //! [les-bluetooth-permission]
+#endif // QT_CONFIG(permissions)
+
     qDeleteAll(devices);
     devices.clear();
     emit devicesUpdated();
diff --git a/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc b/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc
index bba28796..9d013203 100644
--- a/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc
+++ b/examples/bluetooth/lowenergyscanner/doc/src/lowenergyscanner.qdoc
@@ -32,6 +32,12 @@
 
     \include examples-run.qdocinc
 
+    \section1 Requesting Permission to use Bluetooth
+    Before the application can start using Bluetooth, we have to check Bluetooth
+    permission, and if its status is not determined yet, request this permission:
+
+    \snippet lowenergyscanner/device.cpp les-bluetooth-permission
+
     \section1 Scanning for Devices
 
     The first step is to find all peripheral devices. The devices can be found using