Aplicación gvSIG con fines educativos

    private final String[] distAbrev;

        distAbrev = MapContext.getDistanceAbbr();

        String strUnits = distAbrev[vp.getDistanceUnits()];

            sb.append(" ");

            sb.append(strUnits);

            sb.append(" ");

            sb.append(strUnits);

/* 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 org.gvsig.educa.batovi.mapviewer.tools;

import java.awt.geom.Point2D;

import java.text.NumberFormat;

import org.gvsig.educa.batovi.mapviewer.StatusBar;

import org.gvsig.fmap.mapcontext.MapContext;

import org.gvsig.fmap.mapcontext.ViewPort;

import org.gvsig.fmap.mapcontrol.MapControl;

import org.gvsig.fmap.mapcontrol.tools.AreaListenerImpl;

import org.gvsig.fmap.mapcontrol.tools.Events.MeasureEvent;

/**

 * <p>

 * Listener for calculating the area of a polygon, defined in the associated

 * {@link MapControl MapControl} object.

 * </p>

 * <p>

 * Moves the extent of the associated {@link MapControl MapControl} object

 * according the movement between the initial and final points of the line

 * determined by the movement dragged with the third button of the mouse.

 * </p>

 * 

 * <p>

 * Updates the status bar of the main frame of the application with the current

 * area.

 * </p>

 * 

 * @see AreaListenerImpl

 * 

 * @author Vicente Caballero Navarro

 */

public class AreaListener extends AreaListenerImpl {

    private final StatusBar statusBar;

    private final NumberFormat numberFormat;

    private final double[] trans2Meter;

    private final String[] areaAbrev;

    private final String[] distAbrev;

    /**

     * <p>

     * Creates a new listener for calculating the area of a polygon and

     * displaying it at the status bar of the main frame of the application.

     * </p>

     * 

     * @param mc

     *            the <code>MapControl</code> where is calculated the area

     */

    public AreaListener(MapControl mc, StatusBar statusBar) {

        super(mc);

        this.statusBar = statusBar;

        numberFormat = NumberFormat.getInstance();

        numberFormat.setMaximumFractionDigits(2);

        numberFormat.setMinimumFractionDigits(2);

        trans2Meter = MapContext.getDistanceTrans2Meter();

        distAbrev = MapContext.getDistanceAbbr();

        areaAbrev = MapContext.getAreaAbbr();

    }

    /*

     * (non-Javadoc)

     * 

     * @see

     * com.iver.cit.gvsig.fmap.tools.AreaListenerImpl#points(com.iver.cit.gvsig

     * .fmap.tools.Events.MeasureEvent)

     */

    @Override

    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;

            Point2D p =

                new Point2D.Double(event.getXs()[i].doubleValue(),

                    event.getYs()[i].doubleValue());

            Point2D p2 =

                new Point2D.Double(event.getXs()[i + 1].doubleValue(),

                    event.getYs()[i + 1].doubleValue());

            dist = vp.distanceWorld(p, p2);

            distAll += dist;

        }

        if (statusBar != null) {

            int distanceUnits = vp.getDistanceUnits();

            int distanceArea = vp.getDistanceArea();

            StringBuilder sb = new StringBuilder("P: ");

            sb.append(numberFormat.format(distAll / trans2Meter[distanceUnits]));

            sb.append(distAbrev[distanceUnits]);

            sb.append("  ");

            sb.append("A: ");

            sb.append(numberFormat.format(returnArea(new Point2D.Double(event

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

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

                / Math.pow(trans2Meter[distanceArea], 2)));

            sb.append(" ");

            sb.append(areaAbrev[distanceArea]);

            statusBar.setInfo(sb.toString());

        }

    }

}

import org.gvsig.educa.batovi.mapviewer.tools.AreaListener;

    public static final String TOOL_AREA_ID = "area";

        // area

        mapControl.addBehavior(TOOL_AREA_ID, new PolylineBehavior(

            new AreaListener(mapControl, statusBar)));

    private AbstractAction setAreaToolAction;

        setAreaToolAction = new AbstractAction("Tool area") {

            public void actionPerformed(ActionEvent e) {

                setAreaToolAction();

            }

        };

        setAreaToolAction.setEnabled(false);

        toolBar.add(usabManager.createJButton(setAreaToolAction));

        setAreaToolAction.setEnabled(curViewer != null);

        statusBar.setInfo("");

    public void setAreaToolAction() {

        if (curViewer == null) {

            return;

        }

        curViewer.setTool(MapToolsRegistrant.TOOL_AREA_ID);

        statusBar.setInfo("");

    }