安卓方向传感器

Question

在查看相机预览时，是否可能知道手机指向的方向，或者必须像使用指南针一样将手机放平？

谢谢。

- izeko

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你可以获取手机指向的方向和沿着三轴传感器旋转的角度。因此，你可以做任何你想做的事情。 - Falmarri

Answer 1

是的 - 下面的代码应该可以完成任务。

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);
    }
}

- SimpleSi

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我怎样才能在日志中打印方向？？？？你是从哪个变量中获取方向的？？？ - Mitesh Shah

@Mitesh 你应该打印方位角值。Log.d("direction", String.valueOf(azimuth)) 可以完成这个任务。 - Dick Lucas

@Richard：谢谢.. :) - Mitesh Shah

@Richard 我认为如果用户正在使用相机并且需要计算方向，则此时方位角值将与原始值不同，因为在使用相机时设备不平行于地面，因此我们还必须考虑其他值以获取设备的实际方向。 - Shrijit Basak