1 files changed, 97 insertions, 0 deletions
diff --git a/main/src/cgeo/geocaching/sensors/RotationProvider.java b/main/src/cgeo/geocaching/sensors/RotationProvider.java
new file mode 100644
index 0000000..c63e39f
--- /dev/null
+++ b/main/src/cgeo/geocaching/sensors/RotationProvider.java
@@ -0,0 +1,97 @@
+package cgeo.geocaching.sensors;
+
+import cgeo.geocaching.utils.Log;
+import cgeo.geocaching.utils.RxUtils.LooperCallbacks;
+
+import rx.Observable;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.hardware.Sensor;
+import android.hardware.SensorEvent;
+import android.hardware.SensorEventListener;
+import android.hardware.SensorManager;
+
+public class RotationProvider extends LooperCallbacks<Float> implements SensorEventListener {
+
+    private final SensorManager sensorManager;
+    private final Sensor rotationSensor;
+    private final float[] rotationMatrix = new float[16];
+    private final float[] orientation = new float[4];
+    private final float[] values = new float[4];
+
+    @TargetApi(19)
+    protected RotationProvider(final Context context, final boolean lowPower) {
+        sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
+        // The geomagnetic rotation vector introduced in Android 4.4 (API 19) requires less power. Favour it
+        // even if it is more sensible to noise in low-power settings.
+        final Sensor sensor = lowPower ? sensorManager.getDefaultSensor(Sensor.TYPE_GEOMAGNETIC_ROTATION_VECTOR) : null;
+        if (sensor != null) {
+            rotationSensor = sensor;
+            Log.d("RotationProvider: geomagnetic (low-power) sensor found");
+        } else {
+            rotationSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR);
+            if (rotationSensor != null) {
+                Log.d("RotationProvider: sensor found");
+            } else {
+                Log.w("RotationProvider: no rotation sensor on this device");
+            }
+        }
+    }
+
+    public static boolean hasRotationSensor(final Context context) {
+        return ((SensorManager) context.getSystemService(Context.SENSOR_SERVICE)).getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR) != null;
+    }
+
+    @TargetApi(19)
+    public static boolean hasGeomagneticRotationSensor(final Context context) {
+        return ((SensorManager) context.getSystemService(Context.SENSOR_SERVICE)).getDefaultSensor(Sensor.TYPE_GEOMAGNETIC_ROTATION_VECTOR) != null;
+    }
+
+    @Override
+    public void onSensorChanged(final SensorEvent event) {
+        // On some Samsung devices, SensorManager#getRotationMatrixFromVector throws an exception if the rotation
+        // vector has more than 4 elements. Since only the four first elements are used, we can truncate the vector
+        // without losing precision.
+        if (event.values.length > 4) {
+            System.arraycopy(event.values, 0, values, 0, 4);
+            SensorManager.getRotationMatrixFromVector(rotationMatrix, values);
+        } else {
+            SensorManager.getRotationMatrixFromVector(rotationMatrix, event.values);
+        }
+        SensorManager.getOrientation(rotationMatrix, orientation);
+        subject.onNext((float) (orientation[0] * 180 / Math.PI));
+    }
+
+    @Override
+    public void onAccuracyChanged(final Sensor sensor, final int accuracy) {
+    }
+
+    @Override
+    public void onStart() {
+        if (rotationSensor != null) {
+            Log.d("RotationProvider: starting the rotation provider");
+            try {
+                sensorManager.registerListener(this, rotationSensor, SensorManager.SENSOR_DELAY_NORMAL);
+            } catch (final Exception e) {
+                Log.w("RotationProvider: unable to register listener", e);
+                subject.onError(e);
+            }
+        } else {
+            subject.onError(new RuntimeException("rotation sensor is absent on this device"));
+        }
+    }
+
+    @Override
+    public void onStop() {
+        if (rotationSensor != null) {
+            Log.d("RotationProvider: stopping the rotation provider");
+            sensorManager.unregisterListener(this);
+        }
+    }
+
+    public static Observable<Float> create(final Context context, final boolean lowPower) {
+        return Observable.create(new RotationProvider(context, lowPower)).onBackpressureDrop();
+    }
+
+}