Android Compass point to my location instead of north

I'm developing compass application where I want the compass to point to a particular latitude longitude position instead of the usual north. I found some questions related to my problem but I don't manage to make them worked for me. Here's my code:

public class MainActivity extends AppCompatActivity implements SensorEventListener {     private ImageView image;     private float currentDegree = 0f;     private SensorManager mSensorManager;     private TextView tvHeading;     private Location location = new Location("A");     private Location target = new Location("B");     private LocationManager locationManager;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          image = (ImageView) findViewById(R.id.imageViewCompass);         tvHeading = (TextView) findViewById(R.id.tvHeading);          mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);          location.setLatitude(54.903535);         location.setLongitude(23.979342);          target.setLatitude(54.904618);         target.setLongitude(23.978782);     }      @Override     protected void onResume() {         super.onResume();          mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),                 SensorManager.SENSOR_DELAY_GAME);     }      @Override     protected void onPause() {         super.onPause();         mSensorManager.unregisterListener(this); // to stop the listener and save battery     }      @Override     public void onSensorChanged(SensorEvent event) {         float degree = Math.round(event.values[0]);         tvHeading.setText("Heading: " + Float.toString(degree) + " degrees");         RotateAnimation ra = new RotateAnimation(                 currentDegree,                 -degree,                 Animation.RELATIVE_TO_SELF, 0.5f,                 Animation.RELATIVE_TO_SELF,                 0.5f);         ra.setDuration(210);         ra.setFillAfter(true);          image.startAnimation(ra);         currentDegree = -degree;     }      @Override     public void onAccuracyChanged(Sensor sensor, int accuracy) {         // not in use     } } 

currently my pointer shows only in north instead of my harcoded target location.

1 Answers

Answers 1

I think I found the way to do it: Here's the method I have changed to get expected behaviour (Based on this question and CookieMonster answer)

@Override     public void onSensorChanged(SensorEvent event) {         // get the angle around the z-axis rotated         float degree = Math.round(event.values[0]);         degree += geoField.getDeclination();          float bearing = location.bearingTo(target);         degree = (bearing - degree) * -1;         degree = normalizeDegree(degree);          tvHeading.setText("Heading: " + Float.toString(degree) + " degrees");          // create a rotation animation (reverse turn degree degrees)         RotateAnimation ra = new RotateAnimation(                 currentDegree,                 -degree,                 Animation.RELATIVE_TO_SELF, 0.5f,                 Animation.RELATIVE_TO_SELF,                 0.5f);          // how long the animation will take place         ra.setDuration(210);          // set the animation after the end of the reservation status         ra.setFillAfter(true);          // Start the animation         image.startAnimation(ra);         currentDegree = -degree;     }  private float normalizeDegree(float value) {         if (value >= 0.0f && value <= 180.0f) {             return value;         } else {             return 180 + (180 + value);         }     } 

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