Application: gvSIG desktop

/* gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana

 *

 * Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.

 *

 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307,USA.

 *

 * For more information, contact:

 *

 *  Generalitat Valenciana

 *   Conselleria d'Infraestructures i Transport

 *   Av. Blasco Ib??ez, 50

 *   46010 VALENCIA

 *   SPAIN

 *

 *      +34 963862235

 *   gvsig@gva.es

 *      www.gvsig.gva.es

 *

 *    or

 *

 *   IVER T.I. S.A

 *   Salamanca 50

 *   46005 Valencia

 *   Spain

 *

 *   +34 963163400

 *   dac@iver.es

 */

package com.iver.cit.gvsig.fmap.tools;

import java.awt.Cursor;

import java.awt.Image;

import java.awt.Point;

import java.awt.Toolkit;

import java.awt.geom.Point2D;

import javax.swing.ImageIcon;

import com.iver.cit.gvsig.fmap.MapControl;

import com.iver.cit.gvsig.fmap.ViewPort;

import com.iver.cit.gvsig.fmap.tools.Events.MeasureEvent;

import com.iver.cit.gvsig.fmap.tools.Listeners.PolylineListener;

/**

 * Implementaci?n de la interfaz MeasureListener como herramienta para medir el

 * ?rea.

 *

 * @author Vicente Caballero Navarro

 */

public class AreaListenerImpl implements PolylineListener {

        private final Image iarea = new ImageIcon(MapControl.class.getResource(

                                "images/AreaCursor.gif")).getImage();

        private Cursor cur = Toolkit.getDefaultToolkit().createCustomCursor(iarea,

                        new Point(16, 16), "");

        protected MapControl mapCtrl;

        protected MeasureEvent event;

        /**

         * Crea un nuevo AreaListenerImpl.

         *

         * @param mc MapControl.

         */

        public AreaListenerImpl(MapControl mc) {

                this.mapCtrl = mc;

        }

        /**

         * @see com.iver.cit.gvsig.fmap.tools.Listeners.PolylineListener#points(com.iver.cit.gvsig.fmap.tools.Events.MeasureEvent)

         */

        public void points(MeasureEvent event) {

                this.event = event;

                double dist = 0;

                double distAll = 0;

                ViewPort vp = mapCtrl.getMapContext().getViewPort();

                for (int i = 0; i < (event.getXs().length - 1); i++) {

                        dist = 0;

                        Point p = new Point(event.getXs()[i].intValue(),

                                        event.getXs()[i].intValue());

                        Point p2 = new Point(event.getXs()[i + 1].intValue(),

                                        event.getXs()[i + 1].intValue());

                        ///dist = vp.toMapDistance((int) p.distance(p2));

                        dist = vp.distanceWorld(p, p2);

                        distAll += dist;

                }

                System.out.println("Per?metro = " + distAll + " ?rea = " +

                        (returnArea(vp.toMapPoint(

                                        new Point2D.Double(

                                                event.getXs()[event.getXs().length - 2].doubleValue(),

                                                event.getYs()[event.getYs().length - 2].doubleValue())))));

        }

        /**

         * <p>

         * Computes the area using the trapezoid method. This is, we decompose a polygon in a set of

         * trapezoids defined each two points of the polygon starting and ending in the first user's 

         * entered point. For each trapezoid by these each two points and the points over the y-axis (when y equals 0)

         * that have the same x value than the points defined by the user and then we obtain

         * the area of this trapezoid with this formula.

         * </p>

         * <p>

         * The four points that define the trapezoid we are considering are

         * p1 = (x1, y1) -> the first user point

         * p2 = (x2, y2) -> the second user point

         * p3 = (x3, y3) -> the image over the y-axis of p1

         * p4 = (x4, y4) -> the image over the y-axis

         * </p>

         * <pre>

         *                   (y1 - y2) * (x2 - x1)

         *  A = | ----------------------------| + |((x2 - x1) * (y2 - y1)| (of course, simplify this)

         *                 2 

         * <pre>

         * 

         * Calculated the area of every trapezoid generated at the descomposition, only rests

         * to acumulate it to the total amout when (x2 - x1)>0 and substract it when (x2 - x1)< 0

         * 

         * @param aux, the last point.

         *

         * @return area.

         */

        protected double returnArea(Point2D aux) {

                double elArea;

                int pos;

                Point2D p = new Point2D.Double();

                Point2D.Double pAnt = new Point2D.Double();

                Double[] x = event.getXs();

                Double[] y = event.getYs();

                System.out.println("[equis]");

                for (int j = 0; j < x.length; j++) {

                        System.out.print(x[j].doubleValue()+", ");

                }

                // double baseMayor, baseMenor, altura; // De cada trapezoide

                // El area de cada pareja de puntos ser?a (x2-x1) * baseMenor + (baseMayor-baseMenor)*(x2-x1)

                // Simplificando la ecuaci?n queda: (x2-x1)*((baseMayor+baseMenor)/2). Es decir, que da igual

                // quien es la base mayor y quien la manor.

                // si la coordenada X del punto i+1 es mayor que la del punto i => Area negativa

                // si no => Area positiva

                if (x.length < 2) {

                        return 0.0;

                }

                elArea = 0.0;

                for (pos = 0; pos < x.length; pos++) {

                        p = new Point2D.Double(x[pos].doubleValue(), y[pos].doubleValue());

                        if (pos == 0) {

                                pAnt.x = aux.getX();

                                pAnt.y = aux.getY();

                        }

                        elArea = elArea + ((pAnt.x - p.getX()) * (pAnt.y + p.getY()));

                        pAnt.setLocation(p);

                }

                elArea = elArea + ((pAnt.x - aux.getX()) * (pAnt.y + aux.getY()));

                elArea = Math.abs(elArea / 2.0);

                return elArea;

        }

        /**

         * @see com.iver.cit.gvsig.fmap.tools.Listeners.ToolListener#getCursor()

         */

        public Cursor getCursor() {

                return cur;

        }

        /**

         * @see com.iver.cit.gvsig.fmap.tools.Listeners.PolylineListener#pointFixed(com.iver.cit.gvsig.fmap.tools.Events.MeasureEvent)

         */

        public void pointFixed(MeasureEvent event) {

        }

        /**

         * @see com.iver.cit.gvsig.fmap.tools.Listeners.PolylineListener#polylineFinished(com.iver.cit.gvsig.fmap.tools.Events.MeasureEvent)

         */

        public void polylineFinished(MeasureEvent event) {

        }

        /**

         * @see com.iver.cit.gvsig.fmap.tools.Listeners.ToolListener#cancelDrawing()

         */

        public boolean cancelDrawing() {

                return false;

        }

}