code: public boolean isVisibleAtViewPortResolution(ViewPort viewPort) {
  		if (viewPort.getResolution() > getMinResolution()
  				&& viewPort.getResolution() <= getMaxResolution()) {
  			return true;
  		}
  		return false;
  	}
docs: Check if current viewPort resolution is between the minimum (inclusive) and
  the maximum scale (exclusive) of the layer.
  Inclusive/exclusive follows SLD convention: exclusive minResolution, inclusive maxResolution.
  
  @param viewPort the viewPort
  @return whether the layer is visible in the provided viewPort resolution