Android: Fix automatic notification sending when device demands it

Some BTLE devices enable notifications be default. However since
Android's BTLE API requires a call to
BluetoothGatt.setCharacteristicNotification(..) to forward them,
we have to peek at the ClientCharacteristicConfigurations during the
service detail discovery and tell Android to forward the notification
when required.

Change-Id: Ief419404694d70a1373218c1b8275ef868a49ddb
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/android/bluetooth/src/org/qtproject/qt5/android/bluetooth/QtBluetoothLE.java b/src/android/bluetooth/src/org/qtproject/qt5/android/bluetooth/QtBluetoothLE.java
index ea5d6ce6..edeacb82 100644
--- a/src/android/bluetooth/src/org/qtproject/qt5/android/bluetooth/QtBluetoothLE.java
+++ b/src/android/bluetooth/src/org/qtproject/qt5/android/bluetooth/QtBluetoothLE.java
@@ -347,6 +347,24 @@ public class QtBluetoothLE {
             leDescriptorRead(qtObject, descriptor.getCharacteristic().getService().getUuid().toString(),
                     descriptor.getCharacteristic().getUuid().toString(), runningHandle+1,
                     descriptor.getUuid().toString(), descriptor.getValue());
+
+            /* Some devices preset ClientCharacteristicConfiguration descriptors
+             * to enable notifications out of the box. However the additional
+             * BluetoothGatt.setCharacteristicNotification call prevents
+             * automatic notifications from coming through. Hence we manually set them
+             * up here.
+             */
+
+            if (descriptor.getUuid().compareTo(clientCharacteristicUuid) == 0) {
+                final int value = descriptor.getValue()[0];
+                // notification or indication bit set?
+                if ((value & 0x03) > 0) {
+                    Log.d(TAG, "Found descriptor with automatic notifications.");
+                    mBluetoothGatt.setCharacteristicNotification(
+                            descriptor.getCharacteristic(), true);
+                }
+            }
+
             performServiceDetailDiscoveryForHandle(runningHandle + 1, false);
         }