ST_NumInteriorRings.java

/**
 * H2GIS is a library that brings spatial support to the H2 Database Engine
 * <http://www.h2database.com>. H2GIS is developed by CNRS
 * <http://www.cnrs.fr/>.
 *
 * This code is part of the H2GIS project. H2GIS is free software; 
 * you can redistribute it and/or modify it under the terms of the GNU
 * Lesser General Public License as published by the Free Software Foundation;
 * version 3.0 of the License.
 *
 * H2GIS is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details <http://www.gnu.org/licenses/>.
 *
 *
 * For more information, please consult: <http://www.h2gis.org/>
 * or contact directly: info_at_h2gis.org
 */

package org.h2gis.functions.spatial.properties;

import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryCollection;
import com.vividsolutions.jts.geom.MultiPolygon;
import com.vividsolutions.jts.geom.Polygon;
import org.h2gis.api.DeterministicScalarFunction;

/**
 * Return the number of holes in a geometry
 * @author Nicolas Fortin
 */
public class ST_NumInteriorRings extends DeterministicScalarFunction {

    /**
     * Default constructor
     */
    public ST_NumInteriorRings() {
        addProperty(PROP_REMARKS, "Return the number of interior rings of the first polygon in the geometry. \nThis will work with both POLYGON and MULTIPOLYGON.\n Return NULL if there is no polygon in the geometry.");
    }

    @Override
    public String getJavaStaticMethod() {
        return "getHoles";
    }

    /**
     * Return the number of holes in a Polygon or MultiPolygon
     * @param g Geometry instance
     * @return Number of holes or null if geometry is null
     */
    public static Integer getHoles(Geometry g) {
        if(g == null) {
            return null;
        }
        if (g instanceof MultiPolygon) {            
            Polygon p = (Polygon) g.getGeometryN(0);
            if(p!=null){
                return p.getNumInteriorRing();
            }            
        } else if (g instanceof Polygon) {
            return ((Polygon) g).getNumInteriorRing();
        }
        return null;
    }
}