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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();
}
}
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