[android] register compass sensor listener only if provided data is consumed by the location layer or location camera

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/location/CompassEngine.java

@@ -55,11 +55,17 @@ public interface CompassEngine {
 
   /**
    * Lifecycle method that can be used for adding or releasing resources.
+   *
+   * @deprecated Use {@link #addCompassListener(CompassListener)}
    */
+  @Deprecated
   void onStart();
 
   /**
    * Lifecycle method that can be used for adding or releasing resources.
+   *
+   * @deprecated Use {@link #removeCompassListener(CompassListener)}
    */
+  @Deprecated
   void onStop();
 }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/location/CompassListener.java

@@ -7,7 +7,7 @@ public interface CompassListener {
 
   /**
    * Callback's invoked when a new compass update occurs. You can listen into the compass updates
-   * using {@link LocationComponent#addCompassListener(CompassListener)} and implementing these
+   * using {@link CompassEngine#addCompassListener(CompassListener)} and implementing these
    * callbacks. Note that this interface is also used internally to to update the UI chevron/arrow.
    *
    * @param userHeading the new compass heading

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/location/LocationCameraController.java

@@ -7,6 +7,7 @@ import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.annotation.VisibleForTesting;
 import android.view.MotionEvent;
+
 import com.mapbox.android.gestures.AndroidGesturesManager;
 import com.mapbox.android.gestures.MoveGestureDetector;
 import com.mapbox.android.gestures.RotateGestureDetector;
@@ -246,6 +247,11 @@ final class LocationCameraController implements MapboxAnimator.OnCameraAnimation
     }
   }
 
+  boolean isConsumingCompass() {
+    return cameraMode == CameraMode.TRACKING_COMPASS
+      || cameraMode == CameraMode.NONE_COMPASS;
+  }
+
   private boolean isLocationTracking() {
     return cameraMode == CameraMode.TRACKING
       || cameraMode == CameraMode.TRACKING_COMPASS

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/location/LocationComponent.java

@@ -107,6 +107,7 @@ public final class LocationComponent {
   private LocationEngineCallback<LocationEngineResult> lastLocationEngineListener
     = new LastLocationEngineCallback(this);
 
+  @Nullable
   private CompassEngine compassEngine;
 
   private LocationLayerController locationLayerController;
@@ -146,6 +147,11 @@ public final class LocationComponent {
    */
   private boolean isLayerReady;
 
+  /**
+   * Indicates whether we are listening for compass updates.
+   */
+  private boolean isListeningToCompass;
+
   private StaleStateManager staleStateManager;
   private final CopyOnWriteArrayList<OnLocationStaleListener> onLocationStaleListeners
     = new CopyOnWriteArrayList<>();
@@ -439,6 +445,7 @@ public final class LocationComponent {
   public void setCameraMode(@CameraMode.Mode int cameraMode,
                             @Nullable OnLocationCameraTransitionListener transitionListener) {
     locationCameraController.setCameraMode(cameraMode, lastLocation, new CameraTransitionListener(transitionListener));
+    updateCompassListenerState(true);
   }
 
   /**
@@ -498,6 +505,7 @@ public final class LocationComponent {
   public void setRenderMode(@RenderMode.Mode int renderMode) {
     locationLayerController.setRenderMode(renderMode);
     updateLayerOffsets(true);
+    updateCompassListenerState(true);
   }
 
   /**
@@ -734,10 +742,12 @@ public final class LocationComponent {
    *
    * @param compassEngine to be used
    */
-  public void setCompassEngine(@NonNull CompassEngine compassEngine) {
-    this.compassEngine.removeCompassListener(compassListener);
+  public void setCompassEngine(@Nullable CompassEngine compassEngine) {
+    if (this.compassEngine != null) {
+      updateCompassListenerState(false);
+    }
     this.compassEngine = compassEngine;
-    compassEngine.addCompassListener(compassListener);
+    updateCompassListenerState(true);
   }
 
   /**
@@ -745,7 +755,7 @@ public final class LocationComponent {
    *
    * @return compass engine currently being used
    */
-  @NonNull
+  @Nullable
   public CompassEngine getCompassEngine() {
     return compassEngine;
   }
@@ -767,9 +777,11 @@ public final class LocationComponent {
    * The last known accuracy of the compass sensor, one of SensorManager.SENSOR_STATUS_*
    *
    * @return the last know compass accuracy bearing
+   * @deprecated Use {@link #getCompassEngine()}
    */
+  @Deprecated
   public float getLastKnownCompassAccuracyStatus() {
-    return compassEngine.getLastAccuracySensorStatus();
+    return compassEngine != null ? compassEngine.getLastAccuracySensorStatus() : 0;
   }
 
   /**
@@ -778,9 +790,13 @@ public final class LocationComponent {
    *
    * @param compassListener a {@link CompassListener} for listening into compass heading and
    *                        accuracy changes
+   * @deprecated Use {@link #getCompassEngine()}
    */
+  @Deprecated
   public void addCompassListener(@NonNull CompassListener compassListener) {
-    compassEngine.addCompassListener(compassListener);
+    if (compassEngine != null) {
+      compassEngine.addCompassListener(compassListener);
+    }
   }
 
   /**
@@ -788,9 +804,13 @@ public final class LocationComponent {
    *
    * @param compassListener the {@link CompassListener} which you'd like to remove from the listener
    *                        list.
+   * @deprecated Use {@link #getCompassEngine()}
    */
+  @Deprecated
   public void removeCompassListener(@NonNull CompassListener compassListener) {
-    compassEngine.removeCompassListener(compassListener);
+    if (compassEngine != null) {
+      compassEngine.removeCompassListener(compassListener);
+    }
   }
 
   /**
@@ -934,7 +954,6 @@ public final class LocationComponent {
       if (options.enableStaleState()) {
         staleStateManager.onStart();
       }
-      compassEngine.onStart();
     }
 
     if (isEnabled) {
@@ -948,6 +967,7 @@ public final class LocationComponent {
       }
       setCameraMode(locationCameraController.getCameraMode());
       setLastLocation();
+      updateCompassListenerState(true);
       setLastCompassHeading();
     }
   }
@@ -960,7 +980,9 @@ public final class LocationComponent {
     isLayerReady = false;
     locationLayerController.hide();
     staleStateManager.onStop();
-    compassEngine.onStop();
+    if (compassEngine != null) {
+      updateCompassListenerState(false);
+    }
     locationAnimatorCoordinator.cancelAllAnimations();
     if (locationEngine != null) {
       locationEngine.removeLocationUpdates(currentLocationEngineListener);
@@ -1001,8 +1023,9 @@ public final class LocationComponent {
 
     WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
     SensorManager sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
-    compassEngine = new LocationComponentCompassEngine(windowManager, sensorManager);
-    compassEngine.addCompassListener(compassListener);
+    if (windowManager != null && sensorManager != null) {
+      compassEngine = new LocationComponentCompassEngine(windowManager, sensorManager);
+    }
     staleStateManager = new StaleStateManager(onLocationStaleListener, options);
 
     updateMapWithOptions(options);
@@ -1022,6 +1045,38 @@ public final class LocationComponent {
     locationEngine = internalLocationEngineProvider.getBestLocationEngine(context, false);
   }
 
+  private void updateCompassListenerState(boolean canListen) {
+    if (compassEngine != null) {
+      if (!canListen) {
+        // We shouldn't listen, simply unregistering
+        removeCompassListener(compassEngine);
+        return;
+      }
+
+      if (!isComponentInitialized || !isComponentStarted || !isEnabled) {
+        return;
+      }
+
+      if (locationCameraController.isConsumingCompass() || locationLayerController.isConsumingCompass()) {
+        // If we have a consumer, and not yet listening, then start listening
+        if (!isListeningToCompass) {
+          isListeningToCompass = true;
+          compassEngine.addCompassListener(compassListener);
+        }
+      } else {
+        // If we have no consumers, stop listening
+        removeCompassListener(compassEngine);
+      }
+    }
+  }
+
+  private void removeCompassListener(@NonNull CompassEngine engine) {
+    if (isListeningToCompass) {
+      isListeningToCompass = false;
+      engine.removeCompassListener(compassListener);
+    }
+  }
+
   private void enableLocationComponent() {
     isEnabled = true;
     onLocationLayerStart();
@@ -1091,7 +1146,7 @@ public final class LocationComponent {
   }
 
   private void setLastCompassHeading() {
-    updateCompassHeading(compassEngine.getLastHeading());
+    updateCompassHeading(compassEngine != null ? compassEngine.getLastHeading() : 0);
   }
 
   @SuppressLint("MissingPermission")

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/location/LocationComponentCompassEngine.java

@@ -10,6 +10,8 @@ import android.support.annotation.Nullable;
 import android.view.Surface;
 import android.view.WindowManager;
 
+import com.mapbox.mapboxsdk.log.Logger;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -21,15 +23,18 @@ import timber.log.Timber;
  */
 class LocationComponentCompassEngine implements CompassEngine, SensorEventListener {
 
+  private static final String TAG = "Mbgl-LocationComponentCompassEngine";
+
   // The rate sensor events will be delivered at. As the Android documentation states, this is only
   // a hint to the system and the events might actually be received faster or slower then this
   // specified rate. Since the minimum Android API levels about 9, we are able to set this value
   // ourselves rather than using one of the provided constants which deliver updates too quickly for
   // our use case. The default is set to 100ms
-  private static final int SENSOR_DELAY_MICROS = 100 * 1000;
+  static final int SENSOR_DELAY_MICROS = 100 * 1000;
   // Filtering coefficient 0 < ALPHA < 1
   private static final float ALPHA = 0.45f;
 
+  @NonNull
   private final WindowManager windowManager;
   @NonNull
   private final SensorManager sensorManager;
@@ -61,7 +66,7 @@ class LocationComponentCompassEngine implements CompassEngine, SensorEventListen
    * Construct a new instance of the this class. A internal compass listeners needed to separate it
    * from the cleared list of public listeners.
    */
-  LocationComponentCompassEngine(WindowManager windowManager, SensorManager sensorManager) {
+  LocationComponentCompassEngine(@NonNull WindowManager windowManager, @NonNull SensorManager sensorManager) {
     this.windowManager = windowManager;
     this.sensorManager = sensorManager;
     compassSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR);
@@ -80,7 +85,7 @@ class LocationComponentCompassEngine implements CompassEngine, SensorEventListen
   @Override
   public void addCompassListener(@NonNull CompassListener compassListener) {
     if (compassListeners.isEmpty()) {
-      onStart();
+      registerSensorListeners();
     }
     compassListeners.add(compassListener);
   }
@@ -89,7 +94,7 @@ class LocationComponentCompassEngine implements CompassEngine, SensorEventListen
   public void removeCompassListener(@NonNull CompassListener compassListener) {
     compassListeners.remove(compassListener);
     if (compassListeners.isEmpty()) {
-      onStop();
+      unregisterSensorListeners();
     }
   }
 
@@ -105,12 +110,16 @@ class LocationComponentCompassEngine implements CompassEngine, SensorEventListen
 
   @Override
   public void onStart() {
-    registerSensorListeners();
+    if (!compassListeners.isEmpty()) {
+      registerSensorListeners();
+    }
   }
 
   @Override
   public void onStop() {
-    unregisterSensorListeners();
+    if (!compassListeners.isEmpty()) {
+      unregisterSensorListeners();
+    }
   }
 
   @Override
@@ -121,7 +130,7 @@ class LocationComponentCompassEngine implements CompassEngine, SensorEventListen
       return;
     }
     if (lastAccuracySensorStatus == SensorManager.SENSOR_STATUS_UNRELIABLE) {
-      Timber.d("Compass sensor is unreliable, device calibration is needed.");
+      Logger.d(TAG, "Compass sensor is unreliable, device calibration is needed.");
       return;
     }
     if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR) {
@@ -238,7 +247,7 @@ class LocationComponentCompassEngine implements CompassEngine, SensorEventListen
    * @param smoothedValues array of float, that contains previous state
    * @return float filtered array of float
    */
-  @Nullable
+  @NonNull
   private float[] lowPassFilter(@NonNull float[] newValues, @Nullable float[] smoothedValues) {
     if (smoothedValues == null) {
       return newValues;

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/location/LocationLayerController.java

@@ -11,8 +11,8 @@ import com.google.gson.JsonObject;
 import com.mapbox.geojson.Feature;
 import com.mapbox.geojson.Point;
 import com.mapbox.mapboxsdk.geometry.LatLng;
-import com.mapbox.mapboxsdk.maps.MapboxMap;
 import com.mapbox.mapboxsdk.location.modes.RenderMode;
+import com.mapbox.mapboxsdk.maps.MapboxMap;
 import com.mapbox.mapboxsdk.maps.Style;
 import com.mapbox.mapboxsdk.style.layers.Layer;
 import com.mapbox.mapboxsdk.style.layers.SymbolLayer;
@@ -196,6 +196,10 @@ final class LocationLayerController implements MapboxAnimator.OnLayerAnimationsV
     return isHidden;
   }
 
+  boolean isConsumingCompass() {
+    return renderMode == RenderMode.COMPASS;
+  }
+
   private void setLayerVisibility(@NonNull String layerId, boolean visible) {
     Layer layer = style.getLayer(layerId);
     if (layer != null) {