plumneedle.java

Web图形化的Java库

/* ======================================
 * JFreeChart : a free Java chart library
 * ======================================
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 * Project Lead:  David Gilbert ([e-mail]);
 *
 * (C) Copyright 2000-2003, by Object Refinery Limited and Contributors.
 *
 * This library 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;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * ---------------
 * PlumNeedle.java
 * ---------------
 * (C) Copyright 2002, 2003, by the Australian Antarctic Division and Contributors.
 *
 * Original Author:  Bryan Scott (for the Australian Antarctic Division);
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: PlumNeedle.java,v 1.4 2003/09/11 08:10:13 mungady Exp $
 *
 * Changes:
 * --------
 * 25-Sep-2002 : Version 1, contributed by Bryan Scott (DG);
 * 27-Mar-2003 : Implemented Serializable (DG);
 * 09-Sep-2003 : Added equals(...) method (DG);
 *
 */

package org.jfree.chart.needle;

import java.awt.Graphics2D;
import java.awt.geom.Arc2D;
import java.awt.geom.Area;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.io.Serializable;

/**
 * A needle for use with the {@link org.jfree.chart.plot.CompassPlot} class.
 *
 * @author Bryan Scott
 */
public class PlumNeedle extends MeterNeedle implements Serializable {

    /**
     * Draws the needle.
     *
     * @param g2  the graphics device.
     * @param plotArea  the plot area.
     * @param rotate  the rotation point.
     * @param angle  the angle.
     */
    protected void drawNeedle(Graphics2D g2, Rectangle2D plotArea, Point2D rotate, double angle) {

        Arc2D shape = new Arc2D.Double(Arc2D.PIE);
        double radius = plotArea.getHeight();
        double halfX = plotArea.getWidth() / 2;
        double diameter = 2 * radius;

        shape.setFrame(plotArea.getMinX() + halfX - radius ,
                       plotArea.getMinY() - radius,
                       diameter, diameter);
        radius = Math.toDegrees(Math.asin(halfX / radius));
        shape.setAngleStart(270 - radius);
        shape.setAngleExtent(2 * radius);

        Area s = new Area(shape);

        if ((rotate != null) && (angle != 0)) {
            /// we have rotation houston, please spin me
            getTransform().setToRotation(angle, rotate.getX(), rotate.getY());
            s.transform(getTransform());
        }

        defaultDisplay(g2, s);
    }
    
    /**
     * Tests another object for equality with this object.
     * 
     * @param object  the object to test.
     * 
     * @return A boolean.
     */
    public boolean equals(Object object) {
        if (object == null) {
            return false;
        }
        if (object == this) {
            return true;
        }
        if (super.equals(object) && object instanceof PlumNeedle) {
            return true;
        }
        return false;
    }

}