PieLabelDistributor


1   /* ===========================================================
2    * JFreeChart : a free chart library for the Java(tm) platform
3    * ===========================================================
4    *
5    * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6    *
7    * Project Info:  http://www.jfree.org/jfreechart/index.html
8    *
9    * This library is free software; you can redistribute it and/or modify it 
10   * under the terms of the GNU Lesser General Public License as published by 
11   * the Free Software Foundation; either version 2.1 of the License, or 
12   * (at your option) any later version.
13   *
14   * This library is distributed in the hope that it will be useful, but 
15   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
16   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
17   * License for more details.
18   *
19   * You should have received a copy of the GNU Lesser General Public
20   * License along with this library; if not, write to the Free Software
21   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
22   * USA.  
23   *
24   * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
25   * in the United States and other countries.]
26   *
27   * ------------------------
28   * PieLabelDistributor.java
29   * ------------------------
30   * (C) Copyright 2004, 2005, by Object Refinery Limited and Contributors.
31   *
32   * Original Author:  David Gilbert (for Object Refinery Limited);
33   * Contributor(s):   -;
34   *
35   * $Id: PieLabelDistributor.java,v 1.5.2.1 2005/10/25 20:52:08 mungady Exp $
36   *
37   * Changes
38   * -------
39   * 08-Mar-2004 : Version 1 (DG);
40   * 18-Apr-2005 : Use StringBuffer (DG);
41   *
42   */
43  
44  package org.jfree.chart.plot;
45  
46  import java.util.ArrayList  ;
47  import java.util.Collections  ;
48  import java.util.List  ;
49  
50  /**
51   * This class distributes the section labels for one side of a pie chart so 
52   * that they do not overlap.
53   */
54  public class PieLabelDistributor {
55      
56      /** The label records. */
57      private List   labels;
58      
59      /** The minimum gap. */
60      private double minGap = 4.0;
61      
62      /**
63       * Creates a new distributor.
64       * 
65       * @param labelCount  the number of labels.
66       */
67      public PieLabelDistributor(int labelCount) {
68          this.labels = new ArrayList  (labelCount);
69      }
70      
71      /**
72       * Returns a label record from the list.
73       * 
74       * @param index  the index.
75       * 
76       * @return The label record.
77       */
78      public PieLabelRecord getPieLabelRecord(int index) {
79          return (PieLabelRecord) this.labels.get(index);   
80      }
81      
82      /**
83       * Adds a label record.
84       * 
85       * @param record  the label record.
86       */
87      public void addPieLabelRecord(PieLabelRecord record) {
88          this.labels.add(record);
89      }
90      
91      /**
92       * Returns the number of items in the list.
93       * 
94       * @return The item count.
95       */
96      public int getItemCount() {
97          return this.labels.size();   
98      }
99      
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 }
266
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