如何计算设备旋转的角度？

Question

我正在开发一个应用程序，我需要检测设备旋转的角度。我尝试过使用OrientationEventListener之类的东西。这种方法很有效，但仅适用于旋转后设备位于同一平面的情况。我感兴趣的是检测设备平面也发生变化的旋转角度。为清晰起见，请参见下图

Answer 1

这是一个示例代码，

取自this网站：

package gyroexample.com.example;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;

public class AccessGyroscope extends Activity implements SensorEventListener
{
    //a TextView
    private TextView tv;
    //the Sensor Manager
    private SensorManager sManager;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        //get the TextView from the layout file
        tv = (TextView) findViewById(R.id.tv);

        //get a hook to the sensor service
        sManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    }

    //when this Activity starts
    @Override
    protected void onResume()
    {
        super.onResume();
        /*register the sensor listener to listen to the gyroscope sensor, use the
        callbacks defined in this class, and gather the sensor information as quick
        as possible*/
        sManager.registerListener(this, sManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),SensorManager.SENSOR_DELAY_FASTEST);
    }

  //When this Activity isn't visible anymore
    @Override
    protected void onStop()
    {
        //unregister the sensor listener
        sManager.unregisterListener(this);
        super.onStop();
    }

    @Override
    public void onAccuracyChanged(Sensor arg0, int arg1)
    {
        //Do nothing.
    }

    @Override
    public void onSensorChanged(SensorEvent event)
    {
        //if sensor is unreliable, return void
        if (event.accuracy == SensorManager.SENSOR_STATUS_UNRELIABLE)
        {
            return;
        }

        //else it will output the Roll, Pitch and Yawn values
        tv.setText("Orientation X (Roll) :"+ Float.toString(event.values[2]) +"\n"+
                   "Orientation Y (Pitch) :"+ Float.toString(event.values[1]) +"\n"+
                   "Orientation Z (Yaw) :"+ Float.toString(event.values[0]));
    }
}