Gyroscopeを使った回転量の計算|Android開発

public class GyroscopeTest implements SensorEventListener {

    private static final float NS2S = 1.0f / 1000000000.0f;
    private float mLastTimestamp;

    private float mRadianLandscape;
    private float mRadianPortrait;

    protected int mCurrentDegreeLandscape;
    protected int mCurrentDegreePortrait;
    protected int mDirection;
    protected boolean isLandscape;

    public static final Object SynchronizedObject = new Object();

    public void start(int rotation, int direction) {
        isLandscape = (rotation == 0 || rotation == 180);
        synchronized (SynchronizedObject) {
            mLastTimestamp = 0;
            mRadianLandscape = 0;
            mRadianPortrait = 0;
            mDirection = direction;
        }
    }

    protected int currentDegree() {
        return isLandscape ? mCurrentDegreeLandscape : mCurrentDegreePortrait;
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() != Sensor.TYPE_GYROSCOPE) {
            return;
        }

        synchronized (SynchronizedObject) {
            if (mLastTimestamp != 0) {
                final float dT = (event.timestamp - mLastTimestamp) * NS2S;
                float axisX = event.values[0];
                float axisY = event.values[1];
                float axisZ = event.values[2];

                mRadianLandscape += (axisX * dT);
                mRadianPortrait += (axisY * dT);
            }

            mLastTimestamp = event.timestamp;
            int degreeLandscape = radianToDegree(mRadianLandscape);
            int degreePortrait = radianToDegree(mRadianPortrait);

            if (degreeLandscape < 0) {
                degreeLandscape += 360;
            }
            if (degreePortrait < 0) {
                degreePortrait += 360;
            }

            mCurrentDegreeLandscape = degreeLandscape;
            mCurrentDegreePortrait = degreePortrait;
            //Log.v("GyroscopeTest", String.format("Gyroscope: %d %d", mCurrentDegreeLandscape, mCurrentDegreePortrait));
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // NOP
    }

    protected static int radianToDegree(float radian) {
        return (int) Math.floor(Math.toDegrees(radian));
    }
}