Gravity sensor and fix for orientation

.gitignore

@@ -1,2 +1,3 @@
 android/build
 **/*.swp
+.DS_Store

README.md

@@ -137,6 +137,19 @@ DeviceEventEmitter.addListener('Magnetometer', function (data) {
 SensorManager.stopMagnetometer();
 ```
 
+### Gravity
+```js
+DeviceEventEmitter.addListener('Gravity', function (data) {
+  /**
+  * data.x
+  * data.y
+  * data.z
+  **/
+});
+SensorManager.startGravity(100);
+SensorManager.stopGravity();
+```
+
 ### Orientation
 ```js
 SensorManager.startOrientation(100);

android/src/main/java/com/sensormanager/GravityRecord.java

@@ -0,0 +1,90 @@
+package com.sensormanager;
+
+import android.os.Bundle;
+import android.hardware.Sensor;
+import android.hardware.SensorEvent;
+import android.hardware.SensorEventListener;
+import android.hardware.SensorManager;
+import android.util.Log;
+import android.support.annotation.Nullable;
+
+import java.io.*;
+import java.util.Date;
+import java.util.Timer;
+
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.modules.core.DeviceEventManagerModule;
+import com.facebook.react.bridge.ReactApplicationContext;
+
+public class GravityRecord implements SensorEventListener {
+
+    private SensorManager mSensorManager;
+    private Sensor mGravity;
+    private long lastUpdate = 0;
+    private int i = 0, n = 0;
+	private int delay;
+	private int isRegistered = 0;
+
+	private ReactContext mReactContext;
+	private Arguments mArguments;
+
+
+    public GravityRecord(ReactApplicationContext reactContext) {
+        mSensorManager = (SensorManager)reactContext.getSystemService(reactContext.SENSOR_SERVICE);
+        mGravity = mSensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
+		mReactContext = reactContext;
+    }
+
+	public int start(int delay) {
+		this.delay = delay;
+		if (mGravity != null && isRegistered == 0) {
+			mSensorManager.registerListener(this, mGravity, SensorManager.SENSOR_DELAY_FASTEST);
+			isRegistered = 1;
+			return (1);
+		}
+		return (0);
+	}
+
+    public void stop() {
+		if (isRegistered == 1) {
+			mSensorManager.unregisterListener(this);
+			isRegistered = 0;
+		}
+    }
+
+	private void sendEvent(String eventName, @Nullable WritableMap params)
+	{
+		try {
+			mReactContext 
+				.getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class) 
+				.emit(eventName, params);
+		} catch (RuntimeException e) {
+			Log.e("ERROR", "java.lang.RuntimeException: Trying to invoke JS before CatalystInstance has been set!");
+		}
+	}
+
+    @Override
+    public void onSensorChanged(SensorEvent sensorEvent) {
+        Sensor mySensor = sensorEvent.sensor;
+		WritableMap map = mArguments.createMap();
+
+        if (mySensor.getType() == Sensor.TYPE_GRAVITY) {
+            long curTime = System.currentTimeMillis();
+            i++;
+            if ((curTime - lastUpdate) > delay) {
+                i = 0;
+				map.putDouble("x", sensorEvent.values[0]);
+				map.putDouble("y", sensorEvent.values[1]);
+				map.putDouble("z", sensorEvent.values[2]);
+				sendEvent("Gravity", map);
+                lastUpdate = curTime;
+            }
+        }
+    }
+
+    @Override
+    public void onAccuracyChanged(Sensor sensor, int accuracy) {
+    }
+}

android/src/main/java/com/sensormanager/OrientationRecord.java

@@ -105,11 +105,15 @@ public void onSensorChanged(SensorEvent sensorEvent) {
             roll = 360 - (0 - roll);
           }
 
+          i++;
+          if ((curTime - lastUpdate) > delay) {
+              i = 0;
           map.putDouble("azimuth", heading);
           map.putDouble("pitch", pitch);
           map.putDouble("roll", roll);
           sendEvent("Orientation", map);
           lastUpdate = curTime;
+          }
         }
       }
     }

android/src/main/java/com/sensormanager/SensorManagerModule.java

@@ -10,8 +10,8 @@
 import android.util.Log;
 
 public class SensorManagerModule extends ReactContextBaseJavaModule {
-    private static final String		REACT_CLASS = "SensorManager";
-    private AccelerometerRecord		mAccelerometerRecord = null;
+  private static final String		REACT_CLASS = "SensorManager";
+  private AccelerometerRecord		mAccelerometerRecord = null;
 	private GyroscopeRecord 		mGyroscopeRecord = null;
 	private MagnetometerRecord		mMagnetometerRecord = null;
 	private StepCounterRecord		mStepCounterRecord = null;
@@ -20,6 +20,7 @@ public class SensorManagerModule extends ReactContextBaseJavaModule {
 	private OrientationRecord		mOrientationRecord = null;
 	private ProximityRecord			mProximityRecord = null;
   private LightSensorRecord   mLightSensorRecord = null;
+  private GravityRecord		      mGravityRecord = null;
 
 	private ReactApplicationContext	mReactContext;
 
@@ -150,6 +151,19 @@ public void stopLightSensor() {
         mLightSensorRecord.stop();
     }
 
+    @ReactMethod
+    public int startGravity(int delay) {
+		if (mGravityRecord == null)
+			mGravityRecord = new GravityRecord(mReactContext);
+		return (mGravityRecord.start(delay));
+    }
+
+    @ReactMethod
+    public void stopGravity() {
+		if (mGravityRecord != null)
+			mGravityRecord.stop();
+    }
+
 	/*
     @Override
     public ReactBarcodeScannerView createViewInstance(ThemedReactContext context) {