code: public void queryEnvelope(double x, double y, Envelope envelope) {
  		double down = (extentMax - y) / binSize;
  		double over = (x - extentMin) / binSize;
  		
  		double xmin = extentMin + (over * binSize);
  		double xmax = xmin + binSize;
  		double ymax = extentMax - (down * binSize);
  		double ymin = ymax - binSize;
  		
  		envelope.setCoords(xmin, ymin, xmax, ymax);
  	}
docs: Gets the envelope for the bin that contains the x,y coords.
  
  @param x
  @param y
  @param envelope