Add BTLE device discovery timeout API

This timeout adjusts the BTLE device discovery. Some BTLE devices
require some time to show up in such a search. In general the platforms
use open ended search methodologies as their own usage pattern for
BTLE device discovery too. So far Qt Bluetooth limited the time
through a hardcoded value which the API user could not adjust.

Task-number: QTBUG-53012
Change-Id: Ia37cebd4015b438db998c6b4a265f563c1a2f89f
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@theqtcompany.com>
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

1 files changed, 43 insertions, 0 deletions

diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent.cpp b/src/bluetooth/qbluetoothdevicediscoveryagent.cpp
index b6faee75..b90f6b01 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent.cpp
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent.cpp
@@ -232,6 +232,49 @@ QList<QBluetoothDeviceInfo> QBluetoothDeviceDiscoveryAgent::discoveredDevices()
 }
 
 /*!
+    Sets the maximum search time for Bluetooth Low Energy device search to
+    \a timeout in milliseconds. If \a timeout is \c 0 the discovery runs
+    until \l stop() is called.
+
+    This reflects the fact that the discovery process for Bluetooth Low Energy devices
+    is mostly open ended. The platform continues to look for more devices until the search is
+    manually stopped. The timeout ensures that the search is aborted after \a timeout milliseconds.
+    Of course, it is still possible to manually abort the discovery by calling \l stop().
+
+    The new timeout value does not take effect until the device search is restarted.
+    In addition the timeout does not affect the classic Bluetooth device search. Depending on
+    the platform it may add more time to the total discovery process beyond \a timeout.
+
+    \a lowEnergyDiscoveryTimeout()
+    \since 5.8
+ */
+void QBluetoothDeviceDiscoveryAgent::setLowEnergyDiscoveryTimeout(int timeout)
+{
+    Q_D(QBluetoothDeviceDiscoveryAgent);
+
+    // cannot deliberately turn it off
+    if (d->lowEnergySearchTimeout < 0 || timeout < 0)
+        return;
+
+    d->lowEnergySearchTimeout = timeout;
+}
+
+/*!
+    Returns a timeout in milliseconds that is applied to the Bluetooth Low Energy device search.
+    A value of \c -1 implies that the platform does not support this property and the timeout for
+    the device search cannot be adjusted. A return value of \c 0
+    implies a never-ending search which must be manually stopped via \l stop().
+
+    \sa setLowEnergyDiscoveryTimeout()
+    \since 5.8
+ */
+int QBluetoothDeviceDiscoveryAgent::lowEnergyDiscoveryTimeout() const
+{
+    Q_D(const QBluetoothDeviceDiscoveryAgent);
+    return d->lowEnergySearchTimeout;
+}
+
+/*!
     Starts Bluetooth device discovery, if it is not already started.
 
     The deviceDiscovered() signal is emitted as each device is discovered. The finished() signal