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 }