001 /* JPEGImageWriteParam.java -- 002 Copyright (C) 2006 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package javax.imageio.plugins.jpeg; 040 041 import java.util.Locale; 042 import java.util.PropertyResourceBundle; 043 import java.util.ResourceBundle; 044 import javax.imageio.ImageWriteParam; 045 046 /** 047 * The JPEGImageWriteParam class can be used to specify tables and 048 * settings used in the JPEG encoding process. Encoding tables are 049 * taken from the metadata associated with the output stream, and 050 * failing that (if the metadata tables are null) from an instance of 051 * JPEGImageWriteParam. The default metadata uses the standard JPEG 052 * tables from the JPEGQTable and JPEGHuffmanTable classes. Non-null 053 * metadata tables override JPEGImageWriteParam tables. Compression 054 * settings range from 1.0, best compression, through 0.75, default 055 * compression, to 0.0, worst compression. 056 * 057 * A JPEGImageWriteParam instance is retrieved from the built-in JPEG 058 * ImageWriter using the getDefaultImageWriteParam method. 059 */ 060 public class JPEGImageWriteParam 061 extends ImageWriteParam 062 { 063 private JPEGQTable[] qTables; 064 private JPEGHuffmanTable[] DCHuffmanTables; 065 private JPEGHuffmanTable[] ACHuffmanTables; 066 private boolean optimize; 067 private String[] compressionQualityDescriptions; 068 private float[] compressionQualityValues; 069 070 /** 071 * Localized messages are stored in separate files. 072 */ 073 private ResourceBundle messages; 074 075 /** 076 * Construct a JPEGImageWriteParam with the following state: tiling 077 * is not supported, progressive mode is supported, initial 078 * progressive mode is MODE_DISABLED, compression is supported, one 079 * compression type named "JPEG" is supported and the default 080 * compression quality is 0.75f. Compression type names and 081 * compression quality descriptions are localized to the given 082 * locale. 083 * 084 * @param locale the locale used for message localization 085 */ 086 public JPEGImageWriteParam(Locale locale) 087 { 088 super(locale); 089 090 // Get localized compression type and compression quality 091 // description strings for the given locale. 092 messages = PropertyResourceBundle.getBundle 093 ("javax/imageio/plugins/jpeg/MessagesBundle", locale); 094 095 // Initialize inherited ImageWriter fields. 096 canWriteTiles = false; 097 canWriteProgressive = true; 098 progressiveMode = MODE_DISABLED; 099 canWriteCompressed = true; 100 compressionTypes = new String[] 101 { 102 messages.getString("compression.types.jpeg") 103 }; 104 compressionType = compressionTypes[0]; 105 compressionQuality = 0.75f; 106 } 107 108 /** 109 * Reset the compression quality to 0.75f. 110 */ 111 public void unsetCompression() 112 { 113 compressionQuality = 0.75f; 114 } 115 116 /** 117 * Check if compression algorithm is lossless. JPEGImageWriteParam 118 * overrides this ImageWriteParam method to always return false 119 * since JPEG compression is inherently lossy. 120 * 121 * @return false 122 */ 123 public boolean isCompressionLossless() 124 { 125 return false; 126 } 127 128 /** 129 * Retrieve an array of compression quality descriptions. These 130 * messages are localized using the locale provided upon 131 * construction. Each compression quality description in the 132 * returned array corresponds to the compression quality value at 133 * the same index in the array returned by 134 * getCompressionQualityValues. 135 * 136 * @return an array of strings each of which describes a compression 137 * quality value 138 */ 139 public String[] getCompressionQualityDescriptions() 140 { 141 // Make sure exceptions are thrown when this image write param is 142 // in the wrong state. 143 super.getCompressionQualityDescriptions(); 144 145 if (compressionQualityDescriptions == null) 146 { 147 compressionQualityDescriptions = new String[] 148 { 149 messages.getString("compression.minimum"), 150 messages.getString("compression.default"), 151 messages.getString("compression.maximum") 152 }; 153 } 154 155 return compressionQualityDescriptions; 156 } 157 158 /** 159 * Retrieve an array of compression quality values, ordered from 160 * lowest quality to highest quality. 161 * 162 * @return an array of compressions quality values 163 */ 164 public float[] getCompressionQualityValues() 165 { 166 // Make sure exceptions are thrown when this image write param is 167 // in the wrong state. 168 super.getCompressionQualityValues(); 169 170 if (compressionQualityValues == null) 171 compressionQualityValues = new float[] { 0.05f, 0.75f, 0.95f }; 172 173 return compressionQualityValues; 174 } 175 176 /** 177 * Check if the encoding tables are set. 178 * 179 * @return true if the encoding tables are set, false otherwise 180 */ 181 public boolean areTablesSet() 182 { 183 // If qTables is not null then all tables are set. 184 return (qTables != null); 185 } 186 187 /** 188 * Set the quantization and Huffman tables that will be used to 189 * encode the stream. Copies are created of the array arguments. 190 * The number of Huffman tables must be the same in both Huffman 191 * table arrays. No argument may be null and no array may be longer 192 * than four elements. 193 * 194 * @param qTables JPEG quantization tables 195 * @param DCHuffmanTables JPEG DC Huffman tables 196 * @param ACHuffmanTables JPEG AC Huffman tables 197 * 198 * @throws IllegalArgumentException if any argument is null, if any 199 * of the arrays are longer than four elements, or if the Huffman 200 * table arrays do not have the same number of elements 201 */ 202 public void setEncodeTables(JPEGQTable[] qTables, 203 JPEGHuffmanTable[] DCHuffmanTables, 204 JPEGHuffmanTable[] ACHuffmanTables) 205 { 206 if (qTables == null || DCHuffmanTables == null || ACHuffmanTables == null) 207 throw new IllegalArgumentException("null argument"); 208 209 if (qTables.length > 4 || DCHuffmanTables.length > 4 210 || ACHuffmanTables.length > 4) 211 throw new IllegalArgumentException("argument has too many elements"); 212 213 if (DCHuffmanTables.length != ACHuffmanTables.length) 214 throw new IllegalArgumentException("Huffman table arrays differ in length"); 215 216 // Do a shallow copy. JPEGQTable's data is not directly 217 // modifyable since JPEGQTable.getTable returns a copy. Therefore 218 // it is safe to have multiple references to a single JPEGQTable. 219 // Likewise for JPEGHuffmanTable. 220 this.qTables = (JPEGQTable[]) qTables.clone(); 221 this.DCHuffmanTables = (JPEGHuffmanTable[]) DCHuffmanTables.clone(); 222 this.ACHuffmanTables = (JPEGHuffmanTable[]) ACHuffmanTables.clone(); 223 } 224 225 /** 226 * Clear the quantization and Huffman encoding tables. 227 */ 228 public void unsetEncodeTables() 229 { 230 qTables = null; 231 DCHuffmanTables = null; 232 ACHuffmanTables = null; 233 } 234 235 /** 236 * Retrieve the quantization tables. 237 * 238 * @returns an array of JPEG quantization tables 239 */ 240 public JPEGQTable[] getQTables() 241 { 242 return qTables == null ? qTables : (JPEGQTable[]) qTables.clone(); 243 } 244 245 /** 246 * Retrieve the DC Huffman tables. 247 * 248 * @return an array of JPEG DC Huffman tables 249 */ 250 public JPEGHuffmanTable[] getDCHuffmanTables() 251 { 252 return DCHuffmanTables == null ? DCHuffmanTables 253 : (JPEGHuffmanTable[]) DCHuffmanTables.clone(); 254 } 255 256 /** 257 * Retrieve the AC Huffman tables. 258 * 259 * @return an array of JPEG AC Huffman tables 260 */ 261 public JPEGHuffmanTable[] getACHuffmanTables() 262 { 263 return ACHuffmanTables == null ? ACHuffmanTables 264 : (JPEGHuffmanTable[]) ACHuffmanTables.clone(); 265 } 266 267 /** 268 * Specify whether or not Huffman tables written to the output 269 * stream should be optimized. Every image encoded with this flag 270 * set will contain a Huffman table, and the generated Huffman 271 * tables will override those specified in the metadata. 272 * 273 * @param optimize true to generate optimized Huffman tables, false 274 * otherwise 275 */ 276 public void setOptimizeHuffmanTables(boolean optimize) 277 { 278 this.optimize = optimize; 279 } 280 281 /** 282 * Check whether or not Huffman tables written to the output stream 283 * will be optimized. Unless otherwise set using 284 * setOptimizeHuffmanTables, this returns false. 285 * 286 * @return true Huffman tables written to the output stream will be 287 * optimized, false otherwise 288 */ 289 public boolean getOptimizeHuffmanTables() 290 { 291 return optimize; 292 } 293 }