Keep Android screen on while a vehicle is connected.

android/AndroidManifest.xml

 <?xml version="1.0"?>
 <manifest package="org.mavlink.qgroundcontrol" xmlns:android="http://schemas.android.com/apk/res/android" android:versionName="2.8.0" android:versionCode="2152" android:installLocation="auto">
     <application android:hardwareAccelerated="true" android:name="org.qtproject.qt5.android.bindings.QtApplication" android:label="-- %%INSERT_APP_NAME%% --" android:icon="@drawable/icon">
-        <activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|locale|fontScale|keyboard|keyboardHidden|navigation" android:name="org.qgroundcontrol.qgchelper.UsbDeviceJNI" android:label="-- %%INSERT_APP_NAME%% --" android:screenOrientation="sensorLandscape" android:launchMode="singleTask">
+        <activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|locale|fontScale|keyboard|keyboardHidden|navigation" android:name="org.qgroundcontrol.qgchelper.UsbDeviceJNI" android:label="-- %%INSERT_APP_NAME%% --" android:screenOrientation="sensorLandscape" android:launchMode="singleTask" android:keepScreenOn="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.LAUNCHER"/>

android/src/org/qgroundcontrol/qgchelper/UsbDeviceJNI.java

@@ -43,6 +43,7 @@ import android.content.IntentFilter;
 import android.hardware.usb.*;
 import android.widget.Toast;
 import android.util.Log;
+import android.os.PowerManager;
 //-- Text To Speech
 import android.os.Bundle;
 import android.speech.tts.TextToSpeech;
@@ -53,7 +54,7 @@ import org.qtproject.qt5.android.bindings.QtApplication;
 
 public class UsbDeviceJNI extends QtActivity implements TextToSpeech.OnInitListener
 {
-    public static int BAD_PORT = 0;
+    public  static int BAD_PORT = 0;
     private static UsbDeviceJNI m_instance;
     private static UsbManager m_manager;    //  ANDROID USB HOST CLASS
     private static List<UsbSerialDriver> m_devices; //  LIST OF CURRENT DEVICES
@@ -65,6 +66,7 @@ public class UsbDeviceJNI extends QtActivity implements TextToSpeech.OnInitListe
     private final static ExecutorService m_Executor = Executors.newSingleThreadExecutor();
     private static final String TAG = "QGC_UsbDeviceJNI";
     private static TextToSpeech  m_tts;
+    private static PowerManager.WakeLock m_wl;
 
     private final static UsbIoManager.Listener m_Listener =
             new UsbIoManager.Listener()
@@ -113,6 +115,8 @@ public class UsbDeviceJNI extends QtActivity implements TextToSpeech.OnInitListe
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         m_tts = new TextToSpeech(this,this);
+        PowerManager pm = (PowerManager)m_instance.getSystemService(Context.POWER_SERVICE);
+        m_wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, "QGroundControl");
     }
 
     @Override
@@ -130,6 +134,24 @@ public class UsbDeviceJNI extends QtActivity implements TextToSpeech.OnInitListe
         m_tts.speak(msg, TextToSpeech.QUEUE_FLUSH, null);
     }
 
+    public static void keepScreenOn()
+    {
+        if(m_wl != null) {
+            m_wl.acquire();
+            Log.i(TAG, "SCREEN_BRIGHT_WAKE_LOCK acquired.");
+        } else {
+            Log.i(TAG, "SCREEN_BRIGHT_WAKE_LOCK not acquired!!!");
+        }
+    }
+
+    public static void restoreScreenOn()
+    {
+        if(m_wl != null) {
+            m_wl.release();
+            Log.i(TAG, "SCREEN_BRIGHT_WAKE_LOCK released.");
+        }
+    }
+
     /////////////////////////////////////////////////////////////////////////////////////////////////////////
     //
     //  Find all current devices that match the device filter described in the androidmanifest.xml and the

src/Vehicle/MultiVehicleManager.cc

@@ -30,9 +30,15 @@
 #include "UAS.h"
 #include "QGCApplication.h"
 
+#if defined __android__
+#include <QtAndroidExtras/QtAndroidExtras>
+#include <QtAndroidExtras/QAndroidJniObject>
+#endif
+
 QGC_LOGGING_CATEGORY(MultiVehicleManagerLog, "MultiVehicleManagerLog")
 
 const char* MultiVehicleManager::_gcsHeartbeatEnabledKey = "gcsHeartbeatEnabled";
+static const char* kJniClassName = "org/qgroundcontrol/qgchelper/UsbDeviceJNI";
 
 MultiVehicleManager::MultiVehicleManager(QGCApplication* app)
     : QGCTool(app)
@@ -108,6 +114,15 @@ void MultiVehicleManager::_vehicleHeartbeatInfo(LinkInterface* link, int vehicle
     emit vehicleAdded(vehicle);
 
     setActiveVehicle(vehicle);
+
+#if defined __android__
+    if(_vehicles.count() == 1) {
+        //-- Once a vehicle is connected, keep Android screen from going off
+        qCDebug(MultiVehicleManagerLog) << "QAndroidJniObject::keepScreenOn";
+        QAndroidJniObject::callStaticMethod<void>(kJniClassName, "keepScreenOn", "()V");
+    }
+#endif
+
 }
 
 /// This slot is connected to the Vehicle::allLinksDestroyed signal such that the Vehicle is deleted
@@ -141,6 +156,14 @@ void MultiVehicleManager::_deleteVehiclePhase1(Vehicle* vehicle)
     emit parameterReadyVehicleAvailableChanged(false);
     emit vehicleRemoved(vehicle);
 
+#if defined __android__
+    if(_vehicles.count() == 0) {
+        //-- Once no vehicles are connected, we no longer need to keep Android screen from going off
+        qCDebug(MultiVehicleManagerLog) << "QAndroidJniObject::restoreScreenOn";
+        QAndroidJniObject::callStaticMethod<void>(kJniClassName, "restoreScreenOn", "()V");
+    }
+#endif
+
     // We must let the above signals flow through the system as well as get back to the main loop event queue
     // before we can actually delete the Vehicle. The reason is that Qml may be holding on the references to it.
     // Even though the above signals should unload any Qml which has references, that Qml will not be destroyed