Android: Add access to BTLE connection parameters

Unfortunately, Android only provides access to a very generic connection
priority. The patch uses the minimalInterval() to determine the desired
priority. Everything below 30ms is high priority and everything above
100ms is low priority. Every other value is balanced priority.

QLowEnergyController::requestConnectionUpdate() was modified
to permit access when the controller is connected, discovered or
in the process of being discovered. The limiting factor is an
existing physical connection.

The documentation was updated to reflect Android's API limitations.

[ChangeLog][QtBluetooth][Android] Added access to BTLE connection
parameter settings.

Task-number: QTBUG-53476
Change-Id: I3e22c65bd9598296a9219463dd05f0d9fc73599d
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

1 files changed, 28 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 3348e4de..53c7305f 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
@@ -52,6 +52,7 @@ import android.os.Handler;
 import android.os.Looper;
 import android.util.Log;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.lang.reflect.Method;
 
 import java.util.ArrayList;
 import java.util.Hashtable;
@@ -60,6 +61,7 @@ import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.UUID;
 
+
 public class QtBluetoothLE {
     private static final String TAG = "QtBluetoothGatt";
     private final BluetoothAdapter mBluetoothAdapter;
@@ -1282,6 +1284,32 @@ public class QtBluetoothLE {
         return modifiedHandle;
     }
 
+    // Directly called from public Qt API
+    public boolean requestConnectionUpdatePriority(double minimalInterval)
+    {
+        if (mBluetoothGatt == null)
+            return false;
+
+        try {
+            //Android API v21
+            Method connectionUpdateMethod = mBluetoothGatt.getClass().getDeclaredMethod(
+                                                "requestConnectionPriority", int.class);
+            if (connectionUpdateMethod == null)
+                return false;
+
+            int requestPriority = 0; // BluetoothGatt.CONNECTION_PRIORITY_BALANCED
+            if (minimalInterval < 30)
+                requestPriority = 1; // BluetoothGatt.CONNECTION_PRIORITY_HIGH
+            else if (minimalInterval > 100)
+                requestPriority = 2; //BluetoothGatt/CONNECTION_PRIORITY_LOW_POWER
+
+            Object result = connectionUpdateMethod.invoke(mBluetoothGatt, requestPriority);
+            return (Boolean) result;
+        } catch (Exception ex) {
+            return false;
+        }
+    }
+
     public native void leConnectionStateChange(long qtObject, int wasErrorTransition, int newState);
     public native void leServicesDiscovered(long qtObject, int errorCode, String uuidList);
     public native void leServiceDetailDiscoveryFinished(long qtObject, final String serviceUuid,