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jfreechart example source code file (MouseWheelHandler.java)

This example jfreechart source code file (MouseWheelHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

awt, chartrenderinginfo, event, geometry, io, jfreechart, mousewheelevent, mousewheelhandler, mousewheelhandler, mousewheellistener, plot, plot, plotrenderinginfo, point2d, point2d, serializable, zoomable, zoomable

The jfreechart MouseWheelHandler.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ----------------------
 * MouseWheelHandler.java
 * ----------------------
 * (C) Copyright 2009, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   Ulrich Voigt - patch 2686040;
 *
 * Changes
 * -------
 * 18-Mar-2009 : Version 1, based on ideas by UV in patch 2686040 (DG);
 * 26-Mar-2009 : Implemented Serializable (DG);
 * 
 */

package org.jfree.chart;

import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.geom.Point2D;

import java.io.Serializable;
import org.jfree.chart.plot.Plot;
import org.jfree.chart.plot.PlotRenderingInfo;
import org.jfree.chart.plot.Zoomable;

/**
 * A class that handles mouse wheel events for the {@link ChartPanel} class.
 * Mouse wheel event support was added in JDK 1.4, so this class will be omitted
 * from JFreeChart if you build it using JDK 1.3.
 *
 * @since 1.0.13
 */
class MouseWheelHandler implements MouseWheelListener, Serializable {

    /** The chart panel. */
    private ChartPanel chartPanel;

    /** The zoom factor. */
    double zoomFactor;

    /**
     * Creates a new instance.
     *
     * @param chartPanel  the chart panel (<code>null not permitted).
     */
    public MouseWheelHandler(ChartPanel chartPanel) {
        this.chartPanel = chartPanel;
        this.zoomFactor = 0.10;
        this.chartPanel.addMouseWheelListener(this);
    }

    /**
     * Returns the current zoom factor.  The default value is 0.10 (ten
     * percent).
     *
     * @return The zoom factor.
     *
     * @see #setZoomFactor(double)
     */
    public double getZoomFactor() {
        return this.zoomFactor;
    }

    /**
     * Sets the zoom factor.
     *
     * @param zoomFactor  the zoom factor.
     *
     * @see #getZoomFactor()
     */
    public void setZoomFactor(double zoomFactor) {
        this.zoomFactor = zoomFactor;
    }

    /**
     * Handles a mouse wheel event from the underlying chart panel.
     *
     * @param e  the event.
     */
    public void mouseWheelMoved(MouseWheelEvent e) {
        JFreeChart chart = this.chartPanel.getChart();
        if (chart == null) {
            return;
        }
        Plot plot = chart.getPlot();
        if (plot instanceof Zoomable) {
            Zoomable zoomable = (Zoomable) plot;
            handleZoomable(zoomable, e);
        }
        // TODO:  here we could handle non-zoomable plots in interesting
        // ways (for example, the wheel could rotate a PiePlot or just zoom
        // in on the whole panel).
    }

    /**
     * Handle the case where a plot implements the {@link Zoomable} interface.
     *
     * @param zoomable  the zoomable plot.
     * @param e  the mouse wheel event.
     */
    private void handleZoomable(Zoomable zoomable, MouseWheelEvent e) {
        Plot plot = (Plot) zoomable;
        ChartRenderingInfo info = this.chartPanel.getChartRenderingInfo();
        PlotRenderingInfo pinfo = info.getPlotInfo();
        Point2D p = this.chartPanel.translateScreenToJava2D(e.getPoint());
        if (!pinfo.getDataArea().contains(p)) {
            return;
        }
        int clicks = e.getWheelRotation();
        int direction = 0;
        if (clicks < 0) {
            direction = -1;
        }
        else if (clicks > 0) {
            direction = 1;
        }

        boolean old = plot.isNotify();

        // do not notify while zooming each axis
        plot.setNotify(false);
        double increment = 1.0 + this.zoomFactor;
        if (direction > 0) {
            zoomable.zoomDomainAxes(increment, pinfo, p, true);
            zoomable.zoomRangeAxes(increment, pinfo, p, true);
        }
        else if (direction < 0) {
            zoomable.zoomDomainAxes(1.0 / increment, pinfo, p, true);
            zoomable.zoomRangeAxes(1.0 / increment, pinfo, p, true);
        }
        // set the old notify status
        plot.setNotify(old);

    }

}

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