Android的方向感应器 [英] Android direction sensor

问题描述

有没有可能知道哪个方向手机指向，而在相机看preVIEW，或者你必须有手机平板就像指南针一样。

is it possible to know which direction the phone is pointing while looking at the camera preview, or do you have to have the phone flat like a compass.

感谢

推荐答案

是 - 下code应该做的工作。

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);
}

}

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