Android如何在地图上画圆

Question

我正在使用谷歌地图 v2。我想从地图中选择一些区域。当用户在屏幕上移动手指并且我想画一个圆圈以从地图中选择区域时，我想提供该功能。该怎么做？

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_free_draw);

    fram_map = (FrameLayout) findViewById(R.id.fram_map);
    fram_map.addView(new DrawView(FreeDrawActivity.this));

    map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
            .getMap();
    Marker hamburg = map.addMarker(new MarkerOptions().position(HAMBURG)
            .title("Hamburg"));
    Marker kiel = map.addMarker(new MarkerOptions()
            .position(KIEL)
            .title("Kiel")
            .snippet("Kiel is cool")
            .icon(BitmapDescriptorFactory
                    .fromResource(R.drawable.ic_launcher)));

    map.getUiSettings().setScrollGesturesEnabled(false);

    cameraPosition = getIntent().getExtras().getParcelable("position");
    // Move the camera instantly to hamburg with a zoom of 15.
    map.moveCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

    // Zoom in, animating the camera.
    // map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);

    val = new ArrayList<LatLng>();
    fram_map.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            float x = event.getX();
            float y = event.getY();

            int x_co = Math.round(x);
            int y_co = Math.round(y);

            projection = map.getProjection();
            Point x_y_points = new Point(x_co, y_co);

            LatLng latLng = map.getProjection().fromScreenLocation(
                    x_y_points);
            latitude = latLng.latitude;

            longitude = latLng.longitude;

            int eventaction = event.getAction();
            switch (eventaction) {
            case MotionEvent.ACTION_DOWN:
                // finger touches the screen
                val.add(new LatLng(latitude, longitude));

            case MotionEvent.ACTION_MOVE:
                // finger moves on the screen
                val.add(new LatLng(latitude, longitude));

            case MotionEvent.ACTION_UP:
                // finger leaves the screen
                Draw_Map();
                break;
            }

            if (Is_MAP_Moveable == true) {
                return true;

            } else {
                return false;
            }
        }
    });
}

public void Draw_Map() {
    PolygonOptions rectOptions = new PolygonOptions();
    rectOptions.addAll(val);
    rectOptions.strokeColor(Color.BLUE);
    rectOptions.strokeWidth(7);
    rectOptions.fillColor(Color.CYAN);
    Polygon polygon = map.addPolygon(rectOptions);
}

这段代码用手指移动绘制一个多边形。但我想画圆。

Answer 1

试试这样，

 public void Draw_Map(LatLng point) {
      CircleOptions circleOptions = new CircleOptions()
  .center(point)   //set center
  .radius(500)   //set radius in meters
  .fillColor(Color.TRANSPARENT)  //default
  .strokeColor(Color.BLUE)
  .strokeWidth(5);

  Circle myCircle = myMap.addCircle(circleOptions);
    }