jfreechart example source code file (PieLabelDistributor.java)

This example jfreechart source code file (PieLabelDistributor.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

abstractpielabeldistributor, pielabeldistributor, pielabeldistributor, pielabelrecord, pielabelrecord, string, string, stringbuffer, stringbuffer, util

The jfreechart PieLabelDistributor.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, 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.]
 *
 * ------------------------
 * PieLabelDistributor.java
 * ------------------------
 * (C) Copyright 2004-2008, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes
 * -------
 * 08-Mar-2004 : Version 1 (DG);
 * 18-Apr-2005 : Use StringBuffer (DG);
 * 14-Jun-2007 : Now extends AbstractPieLabelDistributor (DG);
 * 31-Mar-2008 : Fix bugs in label distribution (DG);
 *
 */

package org.jfree.chart.plot;

import java.util.Collections;

/**
 * This class distributes the section labels for one side of a pie chart so
 * that they do not overlap.
 */
public class PieLabelDistributor extends AbstractPieLabelDistributor {

    /** The minimum gap. */
    private double minGap = 4.0;

    /**
     * Creates a new distributor.
     *
     * @param labelCount  the number of labels (ignored).
     */
    public PieLabelDistributor(int labelCount) {
        super();
    }

    /**
     * Distributes the labels.
     *
     * @param minY  the minimum y-coordinate in Java2D-space.
     * @param height  the available height (in Java2D units).
     */
    public void distributeLabels(double minY, double height) {
        sort();  // sorts the label records into ascending order by baseY
//        if (isOverlap()) {
//            adjustInwards();
//        }
        // if still overlapping, do something else...
        if (isOverlap()) {
            adjustDownwards(minY, height);
        }

        if (isOverlap()) {
            adjustUpwards(minY, height);
        }

        if (isOverlap()) {
            spreadEvenly(minY, height);
        }
    }

    /**
     * Returns <code>true if there are overlapping labels in the list,
     * and <code>false otherwise.
     *
     * @return A boolean.
     */
    private boolean isOverlap() {
        double y = 0.0;
        for (int i = 0; i < this.labels.size(); i++) {
            PieLabelRecord plr = getPieLabelRecord(i);
            if (y > plr.getLowerY()) {
                return true;
            }
            y = plr.getUpperY();
        }
        return false;
    }

    /**
     * Adjusts the y-coordinate for the labels in towards the center in an
     * attempt to fix overlapping.
     */
    protected void adjustInwards() {
        int lower = 0;
        int upper = this.labels.size() - 1;
        while (upper > lower) {
            if (lower < upper - 1) {
                PieLabelRecord r0 = getPieLabelRecord(lower);
                PieLabelRecord r1 = getPieLabelRecord(lower + 1);
                if (r1.getLowerY() < r0.getUpperY()) {
                    double adjust = r0.getUpperY() - r1.getLowerY()
                                    + this.minGap;
                    r1.setAllocatedY(r1.getAllocatedY() + adjust);
                }
            }
            PieLabelRecord r2 = getPieLabelRecord(upper - 1);
            PieLabelRecord r3 = getPieLabelRecord(upper);
            if (r2.getUpperY() > r3.getLowerY()) {
                double adjust = (r2.getUpperY() - r3.getLowerY()) + this.minGap;
                r3.setAllocatedY(r3.getAllocatedY() + adjust);
            }
            lower++;
            upper--;
        }
    }

    /**
     * Any labels that are overlapping are moved down in an attempt to
     * eliminate the overlaps.
     *
     * @param minY  the minimum y value (in Java2D coordinate space).
     * @param height  the height available for all labels.
     */
    protected void adjustDownwards(double minY, double height) {
        for (int i = 0; i < this.labels.size() - 1; i++) {
            PieLabelRecord record0 = getPieLabelRecord(i);
            PieLabelRecord record1 = getPieLabelRecord(i + 1);
            if (record1.getLowerY() < record0.getUpperY()) {
                record1.setAllocatedY(Math.min(minY + height
                        - record1.getLabelHeight() / 2.0,
                        record0.getUpperY() + this.minGap
                        + record1.getLabelHeight() / 2.0));
            }
        }
    }

    /**
     * Any labels that are overlapping are moved up in an attempt to eliminate
     * the overlaps.
     *
     * @param minY  the minimum y value (in Java2D coordinate space).
     * @param height  the height available for all labels.
     */
    protected void adjustUpwards(double minY, double height) {
        for (int i = this.labels.size() - 1; i > 0; i--) {
            PieLabelRecord record0 = getPieLabelRecord(i);
            PieLabelRecord record1 = getPieLabelRecord(i - 1);
            if (record1.getUpperY() > record0.getLowerY()) {
                record1.setAllocatedY(Math.max(minY
                        + record1.getLabelHeight() / 2.0, record0.getLowerY()
                        - this.minGap - record1.getLabelHeight() / 2.0));
            }
        }
    }

    /**
     * Labels are spaced evenly in the available space in an attempt to
     * eliminate the overlaps.
     *
     * @param minY  the minimum y value (in Java2D coordinate space).
     * @param height  the height available for all labels.
     */
    protected void spreadEvenly(double minY, double height) {
        double y = minY;
        double sumOfLabelHeights = 0.0;
        for (int i = 0; i < this.labels.size(); i++) {
            sumOfLabelHeights += getPieLabelRecord(i).getLabelHeight();
        }
        double gap = height - sumOfLabelHeights;
        if (this.labels.size() > 1) {
            gap = gap / (this.labels.size() - 1);
        }
        for (int i = 0; i < this.labels.size(); i++) {
            PieLabelRecord record = getPieLabelRecord(i);
            y = y + record.getLabelHeight() / 2.0;
            record.setAllocatedY(y);
            y = y + record.getLabelHeight() / 2.0 + gap;
        }
    }

    /**
     * Sorts the label records into ascending order by y-value.
     */
    public void sort() {
        Collections.sort(this.labels);
    }

    /**
     * Returns a string containing a description of the object for
     * debugging purposes.
     *
     * @return A string.
     */
    public String toString() {
        StringBuffer result = new StringBuffer();
        for (int i = 0; i < this.labels.size(); i++) {
            result.append(getPieLabelRecord(i).toString()).append("\n");
        }
        return result.toString();
    }

}