001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
006     *
007     * Project Info:  http://www.jfree.org/jfreechart/index.html
008     *
009     * This library is free software; you can redistribute it and/or modify it 
010     * under the terms of the GNU Lesser General Public License as published by 
011     * the Free Software Foundation; either version 2.1 of the License, or 
012     * (at your option) any later version.
013     *
014     * This library is distributed in the hope that it will be useful, but 
015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017     * License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this library; if not, write to the Free Software
021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022     * USA.  
023     *
024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025     * in the United States and other countries.]
026     *
027     * ------------------------
028     * PieLabelDistributor.java
029     * ------------------------
030     * (C) Copyright 2004-2007, by Object Refinery Limited and Contributors.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   -;
034     *
035     * Changes
036     * -------
037     * 08-Mar-2004 : Version 1 (DG);
038     * 18-Apr-2005 : Use StringBuffer (DG);
039     * 14-Jun-2007 : Now extends AbstractPieLabelDistributor (DG);
040     *
041     */
042    
043    package org.jfree.chart.plot;
044    
045    import java.util.Collections;
046    
047    /**
048     * This class distributes the section labels for one side of a pie chart so 
049     * that they do not overlap.
050     */
051    public class PieLabelDistributor extends AbstractPieLabelDistributor {
052            
053        /** The minimum gap. */
054        private double minGap = 4.0;
055        
056        /**
057         * Creates a new distributor.
058         * 
059         * @param labelCount  the number of labels (ignored).
060         */
061        public PieLabelDistributor(int labelCount) {
062            super();
063        }
064        
065        /**
066         * Distributes the labels.
067         * 
068         * @param minY  the minimum y-coordinate in Java2D-space.
069         * @param height  the available height (in Java2D units).
070         */
071        public void distributeLabels(double minY, double height) {
072            sort();  // sorts the label records into ascending order by baseY
073            if (isOverlap()) {
074                adjustInwards();
075            }
076            
077            // if still overlapping, do something else...
078            if (isOverlap()) {
079                adjustDownwards(minY, height);
080            }
081            
082            if (isOverlap()) { 
083                adjustUpwards(minY, height);
084            }
085            
086            if (isOverlap()) {  
087                spreadEvenly(minY, height);
088            }
089    
090        }
091        
092        /**
093         * Returns <code>true</code> if there are overlapping labels in the list, 
094         * and <code>false</code> otherwise.
095         * 
096         * @return A boolean.
097         */
098        private boolean isOverlap() {
099            double y = 0.0;
100            for (int i = 0; i < this.labels.size(); i++) {
101                PieLabelRecord plr = getPieLabelRecord(i);
102                if (y > plr.getLowerY()) {
103                    return true;
104                }
105                y = plr.getUpperY();    
106            }
107            return false;
108        }
109        
110        /**
111         * Adjusts the y-coordinate for the labels in towards the center in an 
112         * attempt to fix overlapping.
113         */
114        protected void adjustInwards() {   
115            int lower = 0;
116            int upper = this.labels.size() - 1;
117            while (upper > lower) {
118                if (lower < upper - 1) {
119                    PieLabelRecord r0 = getPieLabelRecord(lower);
120                    PieLabelRecord r1 = getPieLabelRecord(lower + 1); 
121                    if (r1.getLowerY() < r0.getUpperY()) {
122                        double adjust = r0.getUpperY() - r1.getLowerY() 
123                                        + this.minGap;  
124                        r1.setAllocatedY(r1.getAllocatedY() + adjust);   
125                    }
126                }
127                PieLabelRecord r2 = getPieLabelRecord(upper - 1);
128                PieLabelRecord r3 = getPieLabelRecord(upper);  
129                if (r2.getUpperY() > r3.getLowerY()) {
130                    double adjust = (r2.getUpperY() - r3.getLowerY()) + this.minGap;
131                    r3.setAllocatedY(r3.getAllocatedY() + adjust);   
132                }                
133                lower++; 
134                upper--;
135            }
136        }
137        
138        /**
139         * Any labels that are overlapping are moved down in an attempt to 
140         * eliminate the overlaps.
141         * 
142         * @param minY  the minimum y value (in Java2D coordinate space).
143         * @param height  the height available for all labels.
144         */
145        protected void adjustDownwards(double minY, double height) {
146            for (int i = 0; i < this.labels.size() - 1; i++) {
147                PieLabelRecord record0 = getPieLabelRecord(i);
148                PieLabelRecord record1 = getPieLabelRecord(i + 1);
149                if (record1.getLowerY() < record0.getUpperY()) {
150                    record1.setAllocatedY(Math.min(minY + height, 
151                            record0.getUpperY() + this.minGap 
152                            + record1.getLabelHeight() / 2.0));   
153                }
154            }        
155        }
156    
157        /**
158         * Any labels that are overlapping are moved up in an attempt to eliminate 
159         * the overlaps.
160         * 
161         * @param minY  the minimum y value (in Java2D coordinate space).
162         * @param height  the height available for all labels.
163         */
164        protected void adjustUpwards(double minY, double height) {
165            for (int i = this.labels.size() - 1; i > 0; i--) {
166                PieLabelRecord record0 = getPieLabelRecord(i);
167                PieLabelRecord record1 = getPieLabelRecord(i - 1);
168                if (record1.getUpperY() > record0.getLowerY()) {
169                    record1.setAllocatedY(Math.max(minY, record0.getLowerY() 
170                            - this.minGap - record1.getLabelHeight() / 2.0));
171                }
172            }        
173        }
174    
175        /**
176         * Labels are spaced evenly in the available space in an attempt to 
177         * eliminate the overlaps.
178         * 
179         * @param minY  the minimum y value (in Java2D coordinate space).
180         * @param height  the height available for all labels.
181         */
182        protected void spreadEvenly(double minY, double height) {
183            double y = minY;
184            double sumOfLabelHeights = 0.0;
185            for (int i = 0; i < this.labels.size(); i++) {
186                sumOfLabelHeights += getPieLabelRecord(i).getLabelHeight();
187            }
188            double gap = Math.max(0, height - sumOfLabelHeights);
189            if (this.labels.size() > 1) {
190                gap = gap / (this.labels.size() - 1);   
191            }
192            for (int i = 0; i < this.labels.size(); i++) {
193                PieLabelRecord record = getPieLabelRecord(i);
194                y = y + record.getLabelHeight() / 2.0;
195                record.setAllocatedY(y);
196                y = y + record.getLabelHeight() / 2.0 + gap;
197            }        
198        }
199            
200        /**
201         * Sorts the label records into ascending order by y-value.
202         */
203        public void sort() {
204            Collections.sort(this.labels);  
205        }
206        
207        /**
208         * Returns a string containing a description of the object for 
209         * debugging purposes.
210         * 
211         * @return A string.
212         */
213        public String toString() {
214            StringBuffer result = new StringBuffer();
215            for (int i = 0; i < this.labels.size(); i++) {
216                result.append(getPieLabelRecord(i).toString()).append("\n");   
217            }
218            return result.toString();
219        }
220        
221    }