Application: gvSIG desktop » gvSIG tools: Vector editing

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright ? 2007-2014 gvSIG Association

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.vectorediting.lib.prov.split.operation;

import org.gvsig.fmap.geom.Geometry;

import org.gvsig.fmap.geom.GeometryLocator;

import org.gvsig.fmap.geom.aggregate.MultiCurve;

import org.gvsig.fmap.geom.aggregate.MultiPoint;

import org.gvsig.fmap.geom.exception.CreateGeometryException;

import org.gvsig.fmap.geom.operation.GeometryOperationException;

import org.gvsig.fmap.geom.operation.GeometryOperationNotSupportedException;

import org.gvsig.fmap.geom.primitive.Curve;

import org.gvsig.fmap.geom.primitive.Point;

/**

 * @author llmarques

 *

 */

public class CurveSplitOperation implements SplitOperation {

    /*

     * Strategy:

     * 

     * 1. Get intersection points.

     * 2. Get difference between geometry and splitter. If splitter does not

     * touch geometry return original geometry.

     * 3. If any intersection points are not equal to first or last vertex of

     * original geometry, join last and first curve splitted. It's necessary do

     * it because the difference between geometry and splitter returns a

     * multicurve that its first curve starts at first vertex of ORGINAL and

     * ends at first intersection point and its last curve starts at

     * last intersection point and ends at last vertex of ORIGINAL geometry, so

     * we have to join them. If any intersection points are equal to first or

     * last vertex do nothing.

     */

    public Geometry split(Geometry geometryToBeSplitted, Geometry splitter)

        throws GeometryOperationNotSupportedException,

        GeometryOperationException, CreateGeometryException {

        Curve curveToBeSplitted = (Curve) geometryToBeSplitted;

        Geometry intersection = geometryToBeSplitted.intersection(splitter);

        MultiCurve multicurveSplitted = null;

        if (intersection instanceof MultiPoint) {

            MultiPoint intersectionMultiPoint = (MultiPoint) intersection;

            Point firstVertex = intersectionMultiPoint.getPointAt(0);

            Point lastVertex =

                intersectionMultiPoint.getPointAt(intersectionMultiPoint

                    .getPrimitivesNumber() - 1);

            MultiCurve difference =

                (MultiCurve) geometryToBeSplitted.difference(splitter);

            if (difference == null) {

                return geometryToBeSplitted;

            }

            if ((!firstVertex.equals(curveToBeSplitted.getVertex(0)) && !lastVertex

                .equals(curveToBeSplitted.getVertex(0)))

                && isClosed(curveToBeSplitted)) {

                Curve firstCurve = difference.getCurveAt(0);

                Curve lastCurve =

                    difference.getCurveAt(difference.getPrimitivesNumber() - 1);

                Curve union =

                    GeometryLocator.getGeometryManager().createLine(

                        geometryToBeSplitted.getGeometryType().getSubType());

                for (int i = 0; i < lastCurve.getNumVertices(); i++) {

                    union.addVertex(lastCurve.getVertex(i));

                }

                for (int i = 0; i < firstCurve.getNumVertices(); i++) {

                    union.addVertex(firstCurve.getVertex(i));

                }

                multicurveSplitted =

                    GeometryLocator.getGeometryManager().createMultiCurve(

                        geometryToBeSplitted.getGeometryType().getSubType());

                multicurveSplitted.addCurve(union);

                for (int i = 1; i < difference.getPrimitivesNumber() - 1; i++) {

                    multicurveSplitted.addCurve(difference.getCurveAt(i));

                }

            }

        }

        if(multicurveSplitted == null){

            return geometryToBeSplitted.difference(splitter);

        }

        return multicurveSplitted;

    }

    private boolean isClosed(Curve curveToBeSplitted) {

        Point firstPoint = curveToBeSplitted.getVertex(0);

        Point lastPoint =

            curveToBeSplitted.getVertex(curveToBeSplitted.getNumVertices()-1);

        if (firstPoint.equals(lastPoint)) {

            return true;

        }

        return false;

    }

}