安卓谷歌地图当前位置方位

Question

我目前在Android上使用谷歌地图，但我不确定如何旋转地图以显示用户当前面对的方向。

当我设置

mMap.setMyLocationEnabled(true);

我注意到当前标记有一个小的方向箭头(当手机倾斜时，等等)。

@Override
public void onLocationChanged(Location location) {
    handleNewLocation(location);
}
private void handleNewLocation(Location location) {
    Log.d(TAG, location.toString());
    double currentLatitude = location.getLatitude();
    double currentLongitude = location.getLongitude();
    LatLng latLng = new LatLng(currentLatitude, currentLongitude);
    CameraPosition camPos = new CameraPosition.Builder()
            .target(latLng)
            .zoom(16.0f)
            .bearing(location.getBearing())
            .build();
    mMap.animateCamera(CameraUpdateFactory.newCameraPosition(camPos));
}

这成功地根据位置更新了地图上的标记位置。但是，如何根据手机的偏航倾斜，通过旋转地图来改变标记的面向方向呢?

Answer 1

试试下面的代码:

private SensorManager mSensorManager;
private SensorEventListener sensorEventListener;
private Sensor accelerometer;
private Sensor magnetometer;
private float[] mGravity;
private float[] mGeomagnetic;
private Float azimut;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_activity);
    mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
    accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
    sensorEventListener= new SensorEventListener() {
        @Override
        public void onSensorChanged(SensorEvent event) {
            if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
                mGravity = event.values;
            if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
                mGeomagnetic = event.values;
            if (mGravity != null && mGeomagnetic != null) {
                float R[] = new float[9];
                float I[] = new float[9];
                boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic);
                if (success) {
                    float orientation[] = new float[3];
                    SensorManager.getOrientation(R, orientation);
                    azimut = orientation[0]; // orientation contains: azimut, pitch and roll
                    float degrees = (float) Math.toDegrees(azimut);
                    /**
                     * TRY THIS TO UPDATE YOUR CAMERA
                     * degrees you can use as bearing
                     * CameraPosition cameraPosition = new CameraPosition( myLatLng, 15, 0, degrees);
                     * map.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition),200, null);
                     **/
                }
            }
        }
        @Override
        public void onAccuracyChanged(Sensor sensor, int accuracy) {
        }
    };
}
@Override
protected void onPause() {
    super.onPause();
    mSensorManager.unregisterListener(sensorEventListener);
}
@Override
protected void onResume() {
    super.onResume();
    mSensorManager.registerListener(sensorEventListener, accelerometer, SensorManager.SENSOR_DELAY_UI);
    mSensorManager.registerListener(sensorEventListener, magnetometer, SensorManager.SENSOR_DELAY_UI);
}