Source for org.jfree.chart.plot.PieLabelDistributor

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2007, 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 2004-2007, by Object Refinery Limited and Contributors.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes
  36:  * -------
  37:  * 08-Mar-2004 : Version 1 (DG);
  38:  * 18-Apr-2005 : Use StringBuffer (DG);
  39:  * 14-Jun-2007 : Now extends AbstractPieLabelDistributor (DG);
  40:  *
  41:  */
  42: 
  43: package org.jfree.chart.plot;
  44: 
  45: import java.util.Collections;
  46: 
  47: /**
  48:  * This class distributes the section labels for one side of a pie chart so 
  49:  * that they do not overlap.
  50:  */
  51: public class PieLabelDistributor extends AbstractPieLabelDistributor {
  52:         
  53:     /** The minimum gap. */
  54:     private double minGap = 4.0;
  55:     
  56:     /**
  57:      * Creates a new distributor.
  58:      * 
  59:      * @param labelCount  the number of labels (ignored).
  60:      */
  61:     public PieLabelDistributor(int labelCount) {
  62:         super();
  63:     }
  64:     
  65:     /**
  66:      * Distributes the labels.
  67:      * 
  68:      * @param minY  the minimum y-coordinate in Java2D-space.
  69:      * @param height  the available height (in Java2D units).
  70:      */
  71:     public void distributeLabels(double minY, double height) {
  72:         sort();  // sorts the label records into ascending order by baseY
  73:         if (isOverlap()) {
  74:             adjustInwards();
  75:         }
  76:         
  77:         // if still overlapping, do something else...
  78:         if (isOverlap()) {
  79:             adjustDownwards(minY, height);
  80:         }
  81:         
  82:         if (isOverlap()) { 
  83:             adjustUpwards(minY, height);
  84:         }
  85:         
  86:         if (isOverlap()) {  
  87:             spreadEvenly(minY, height);
  88:         }
  89: 
  90:     }
  91:     
  92:     /**
  93:      * Returns <code>true</code> if there are overlapping labels in the list, 
  94:      * and <code>false</code> otherwise.
  95:      * 
  96:      * @return A boolean.
  97:      */
  98:     private boolean isOverlap() {
  99:         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: }