mapping.java

//...
// java code
//...
/**
* https://stackoverflow.com/a/38675842
*/
protected boolean isInside(Point p, Polygon polygon) {
  if (polygon == null) {
    return false;
  }
  int intersections = 0;
  Point prev = polygon.getPoints().get(polygon.getPoints().size() - 1);
  for (Point next : polygon.getPoints()) {
    if ((prev.getY() <= p.getY() && p.getY() < next.getY()) || (prev.getY() >= p.getY() && p.getY() > next.getY())) {
      double dy = next.getY() - prev.getY();
      double dx = next.getX() - prev.getX();
      double x = (p.getY() - prev.getY()) / dy * dx + prev.getX();
      if (x > p.getX()) {
        intersections++;
      }
    }
    prev = next;
  }
  return intersections % 2 == 1;
}