001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2005, 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, 2005, by Object Refinery Limited and Contributors.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   -;
034     *
035     * $Id: PieLabelDistributor.java,v 1.5.2.1 2005/10/25 20:52:08 mungady Exp $
036     *
037     * Changes
038     * -------
039     * 08-Mar-2004 : Version 1 (DG);
040     * 18-Apr-2005 : Use StringBuffer (DG);
041     *
042     */
043    
044    package org.jfree.chart.plot;
045    
046    import java.util.ArrayList;
047    import java.util.Collections;
048    import java.util.List;
049    
050    /**
051     * This class distributes the section labels for one side of a pie chart so 
052     * that they do not overlap.
053     */
054    public class PieLabelDistributor {
055        
056        /** The label records. */
057        private List labels;
058        
059        /** The minimum gap. */
060        private double minGap = 4.0;
061        
062        /**
063         * Creates a new distributor.
064         * 
065         * @param labelCount  the number of labels.
066         */
067        public PieLabelDistributor(int labelCount) {
068            this.labels = new ArrayList(labelCount);
069        }
070        
071        /**
072         * Returns a label record from the list.
073         * 
074         * @param index  the index.
075         * 
076         * @return The label record.
077         */
078        public PieLabelRecord getPieLabelRecord(int index) {
079            return (PieLabelRecord) this.labels.get(index);   
080        }
081        
082        /**
083         * Adds a label record.
084         * 
085         * @param record  the label record.
086         */
087        public void addPieLabelRecord(PieLabelRecord record) {
088            this.labels.add(record);
089        }
090        
091        /**
092         * Returns the number of items in the list.
093         * 
094         * @return The item count.
095         */
096        public int getItemCount() {
097            return this.labels.size();   
098        }
099        
100        /**
101         * Distributes the labels.
102         * 
103         * @param minY  the minimum y-coordinate in Java2D-space.
104         * @param height  the height.
105         */
106        public void distributeLabels(double minY, double height) {
107            sort();
108            if (isOverlap()) {
109                adjustInwards();
110            }
111            
112            // if still overlapping, do something else...
113            if (isOverlap()) {
114                adjustDownwards(minY, height);
115            }
116            
117            if (isOverlap()) { 
118                adjustUpwards(minY, height);
119            }
120            
121            if (isOverlap()) {  
122                spreadEvenly(minY, height);
123            }
124    
125        }
126        
127        /**
128         * Returns <code>true</code> if there are overlapping labels in the list, 
129         * and <code>false</code> otherwise.
130         * 
131         * @return A boolean.
132         */
133        private boolean isOverlap() {
134            double y = 0.0;
135            for (int i = 0; i < this.labels.size(); i++) {
136                PieLabelRecord plr = getPieLabelRecord(i);
137                if (y > plr.getLowerY()) {
138                    return true;
139                }
140                y = plr.getUpperY();    
141            }
142            return false;
143        }
144        
145        /**
146         * Adjusts the y-coordinate for the labels in towards the center in an 
147         * attempt to fix overlapping.
148         */
149        protected void adjustInwards() {   
150            int lower = 0;
151            int upper = this.labels.size() - 1;
152            while (upper > lower) {
153                if (lower < upper - 1) {
154                    PieLabelRecord r0 = getPieLabelRecord(lower);
155                    PieLabelRecord r1 = getPieLabelRecord(lower + 1); 
156                    if (r1.getLowerY() < r0.getUpperY()) {
157                        double adjust = r0.getUpperY() - r1.getLowerY() 
158                                        + this.minGap;  
159                        r1.setAllocatedY(r1.getAllocatedY() + adjust);   
160                    }
161                }
162                PieLabelRecord r2 = getPieLabelRecord(upper - 1);
163                PieLabelRecord r3 = getPieLabelRecord(upper);  
164                if (r2.getUpperY() > r3.getLowerY()) {
165                    double adjust = (r2.getUpperY() - r3.getLowerY()) + this.minGap;
166                    r2.setAllocatedY(r2.getAllocatedY() - adjust);   
167                }                
168                lower++; 
169                upper--;
170            }
171        }
172        
173        /**
174         * Any labels that are overlapping are moved down in an attempt to 
175         * eliminate the overlaps.
176         * 
177         * @param minY  the minimum y value (in Java2D coordinate space).
178         * @param height  the height available for all labels.
179         */
180        protected void adjustDownwards(double minY, double height) {
181            for (int i = 0; i < this.labels.size() - 1; i++) {
182                PieLabelRecord record0 = getPieLabelRecord(i);
183                PieLabelRecord record1 = getPieLabelRecord(i + 1);
184                if (record1.getLowerY() < record0.getUpperY()) {
185                    record1.setAllocatedY(
186                        Math.min(
187                            minY + height, 
188                            record0.getUpperY() + this.minGap 
189                            + record1.getLabelHeight() / 2.0
190                        )
191                    );   
192                }
193            }        
194        }
195    
196        /**
197         * Any labels that are overlapping are moved up in an attempt to eliminate 
198         * the overlaps.
199         * 
200         * @param minY  the minimum y value (in Java2D coordinate space).
201         * @param height  the height available for all labels.
202         */
203        protected void adjustUpwards(double minY, double height) {
204            for (int i = this.labels.size() - 1; i > 0; i--) {
205                PieLabelRecord record0 = getPieLabelRecord(i);
206                PieLabelRecord record1 = getPieLabelRecord(i - 1);
207                if (record1.getUpperY() > record0.getLowerY()) {
208                    record1.setAllocatedY(
209                        Math.max(
210                            minY, 
211                            record0.getLowerY() - this.minGap 
212                            - record1.getLabelHeight() / 2.0
213                        )
214                    );   
215                }
216            }        
217        }
218    
219        /**
220         * Labels are spaced evenly in the available space in an attempt to 
221         * eliminate the overlaps.
222         * 
223         * @param minY  the minimum y value (in Java2D coordinate space).
224         * @param height  the height available for all labels.
225         */
226        protected void spreadEvenly(double minY, double height) {
227            double y = minY;
228            double sumOfLabelHeights = 0.0;
229            for (int i = 0; i < this.labels.size(); i++) {
230                sumOfLabelHeights += getPieLabelRecord(i).getLabelHeight();
231            }
232            double gap = height - sumOfLabelHeights;
233            if (this.labels.size() > 1) {
234                gap = gap / (this.labels.size() - 1);   
235            }
236            for (int i = 0; i < this.labels.size(); i++) {
237                PieLabelRecord record = getPieLabelRecord(i);
238                y = y + record.getLabelHeight() / 2.0;
239                record.setAllocatedY(y);
240                y = y + record.getLabelHeight() / 2.0 + gap;
241            }        
242        }
243            
244        /**
245         * Sorts the label records into ascending order by y-value.
246         */
247        public void sort() {
248            Collections.sort(this.labels);  
249        }
250        
251        /**
252         * Returns a string containing a description of the object for 
253         * debugging purposes.
254         * 
255         * @return A string.
256         */
257        public String toString() {
258            StringBuffer result = new StringBuffer();
259            for (int i = 0; i < this.labels.size(); i++) {
260                result.append(getPieLabelRecord(i).toString()).append("\n");   
261            }
262            return result.toString();
263        }
264        
265    }