android - 安卓方向传感器

Question

在查看相机预览时是否可以知道手机指向哪个方向，或者您是否必须像指南针一样将手机放平。

谢谢

Answer 1

Yes - The following code should do the job

public class Test extends Activity  implements SensorEventListener{

    public static float swRoll;
    public static float swPitch;
    public static float swAzimuth;


    public static SensorManager mSensorManager;
    public static Sensor accelerometer;
    public static Sensor magnetometer;

    public static float[] mAccelerometer = null;
    public static float[] mGeomagnetic = null;


    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // onSensorChanged gets called for each sensor so we have to remember the values
        if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
            mAccelerometer = event.values;
        }

        if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
            mGeomagnetic = event.values;
        }

        if (mAccelerometer != null && mGeomagnetic != null) {
            float R[] = new float[9];
            float I[] = new float[9];
            boolean success = SensorManager.getRotationMatrix(R, I, mAccelerometer, mGeomagnetic);

            if (success) {
                float orientation[] = new float[3];
                SensorManager.getOrientation(R, orientation);
                // at this point, orientation contains the azimuth(direction), pitch and roll values.
                  double azimuth = 180 * orientation[0] / Math.PI;
                  double pitch = 180 * orientation[1] / Math.PI;
                  double roll = 180 * orientation[2] / Math.PI;
            }
        }
    }



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
        accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
    }

    @Override
    protected void onResume() {
        super.onResume();

        mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_GAME);
        mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_GAME);
    }

    @Override
    protected void onPause() {
        super.onPause();
        mSensorManager.unregisterListener(this, accelerometer);
        mSensorManager.unregisterListener(this, magnetometer);
    }
}