Source for javax.imageio.plugins.jpeg.JPEGImageReadParam

   1: /* JPEGImageReadParam.java --
   2:  Copyright (C)  2006  Free Software Foundation, Inc.
   3: 
   4:  This file is part of GNU Classpath.
   5: 
   6:  GNU Classpath is free software; you can redistribute it and/or modify
   7:  it under the terms of the GNU General Public License as published by
   8:  the Free Software Foundation; either version 2, or (at your option)
   9:  any later version.
  10: 
  11:  GNU Classpath is distributed in the hope that it will be useful, but
  12:  WITHOUT ANY WARRANTY; without even the implied warranty of
  13:  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14:  General Public License for more details.
  15: 
  16:  You should have received a copy of the GNU General Public License
  17:  along with GNU Classpath; see the file COPYING.  If not, write to the
  18:  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19:  02110-1301 USA.
  20: 
  21:  Linking this library statically or dynamically with other modules is
  22:  making a combined work based on this library.  Thus, the terms and
  23:  conditions of the GNU General Public License cover the whole
  24:  combination.
  25: 
  26:  As a special exception, the copyright holders of this library give you
  27:  permission to link this library with independent modules to produce an
  28:  executable, regardless of the license terms of these independent
  29:  modules, and to copy and distribute the resulting executable under
  30:  terms of your choice, provided that you also meet, for each linked
  31:  independent module, the terms and conditions of the license of that
  32:  module.  An independent module is a module which is not derived from
  33:  or based on this library.  If you modify this library, you may extend
  34:  this exception to your version of the library, but you are not
  35:  obligated to do so.  If you do not wish to do so, delete this
  36:  exception statement from your version. */
  37: 
  38: 
  39: package javax.imageio.plugins.jpeg;
  40: 
  41: import javax.imageio.ImageReadParam;
  42: 
  43: /**
  44:  * The JPEGImageReadParam class is only used to set JPEG decoding
  45:  * tables for streams that do not provide their own tables.  If a
  46:  * stream does not provide tables and a custom JPEGImageReadParam is
  47:  * not provided, then the standard JPEG tables are used from the
  48:  * JPEGQTable and JPEGHuffmanTable classes.  If a stream does provide
  49:  * decoding tables then JPEGImageReadParam will be ignored.
  50:  * JPEGImageReadParam cannot be used to retrieve the tables from a
  51:  * stream.  Instead, use IIOMetadata for this purpose.
  52:  *
  53:  * A JPEGImageReadParam instance is retrieved from the built-in JPEG
  54:  * ImageReader using the getDefaultImageReadParam method.
  55:  */
  56: public class JPEGImageReadParam
  57:   extends ImageReadParam
  58: {
  59:   private JPEGQTable[] qTables;
  60:   private JPEGHuffmanTable[] DCHuffmanTables;
  61:   private JPEGHuffmanTable[] ACHuffmanTables;
  62: 
  63:   /**
  64:    * Construct a JPEGImageReadParam.
  65:    */
  66:   public JPEGImageReadParam()
  67:   {
  68:     super();
  69:   }
  70: 
  71:   /**
  72:    * Check if the decoding tables are set.
  73:    *
  74:    * @return true if the decoding tables are set, false otherwise
  75:    */
  76:   public boolean areTablesSet()
  77:   {
  78:     // If qTables is not null then all tables are set.
  79:     return (qTables != null);
  80:   }
  81: 
  82:   /**
  83:    * Set the quantization and Huffman tables that will be used to
  84:    * decode the stream.  Copies are created of the array arguments.
  85:    * The number of Huffman tables must be the same in both Huffman
  86:    * table arrays.  No argument may be null and no array may be longer
  87:    * than four elements.
  88:    *
  89:    * @param qTables JPEG quantization tables
  90:    * @param DCHuffmanTables JPEG DC Huffman tables
  91:    * @param ACHuffmanTables JPEG AC Huffman tables
  92:    *
  93:    * @throws IllegalArgumentException if any argument is null, if any
  94:    * of the arrays are longer than four elements, or if the Huffman
  95:    * table arrays do not have the same number of elements
  96:    */
  97:   public void setDecodeTables(JPEGQTable[] qTables,
  98:                               JPEGHuffmanTable[] DCHuffmanTables,
  99:                               JPEGHuffmanTable[] ACHuffmanTables)
 100:   {
 101:     if (qTables == null || DCHuffmanTables == null || ACHuffmanTables == null)
 102:       throw new IllegalArgumentException("null argument");
 103: 
 104:     if (qTables.length > 4 || DCHuffmanTables.length > 4
 105:         || ACHuffmanTables.length > 4)
 106:       throw new IllegalArgumentException("argument has too many elements");
 107: 
 108:     if (DCHuffmanTables.length != ACHuffmanTables.length)
 109:       throw new IllegalArgumentException("Huffman table arrays differ in length");
 110: 
 111:     // Do a shallow copy.  JPEGQTable's data is not directly
 112:     // modifyable since JPEGQTable.getTable returns a copy.  Therefore
 113:     // it is safe to have multiple references to a single JPEGQTable.
 114:     // Likewise for JPEGHuffmanTable.
 115:     this.qTables = (JPEGQTable[]) qTables.clone();
 116:     this.DCHuffmanTables = (JPEGHuffmanTable[]) DCHuffmanTables.clone();
 117:     this.ACHuffmanTables = (JPEGHuffmanTable[]) ACHuffmanTables.clone();
 118:   }
 119: 
 120:   /**
 121:    * Clear the quantization and Huffman decoding tables.
 122:    */
 123:   public void unsetDecodeTables()
 124:   {
 125:     qTables = null;
 126:     DCHuffmanTables = null;
 127:     ACHuffmanTables = null;
 128:   }
 129: 
 130:   /**
 131:    * Retrieve the quantization tables.
 132:    *
 133:    * @returns an array of JPEG quantization tables
 134:    */
 135:   public JPEGQTable[] getQTables()
 136:   {
 137:     return qTables == null ? qTables : (JPEGQTable[]) qTables.clone();
 138:   }
 139: 
 140:   /**
 141:    * Retrieve the DC Huffman tables.
 142:    *
 143:    * @return an array of JPEG DC Huffman tables
 144:    */
 145:   public JPEGHuffmanTable[] getDCHuffmanTables()
 146:   {
 147:     return DCHuffmanTables == null ? DCHuffmanTables
 148:       : (JPEGHuffmanTable[]) DCHuffmanTables.clone();
 149:   }
 150: 
 151:   /**
 152:    * Retrieve the AC Huffman tables.
 153:    *
 154:    * @return an array of JPEG AC Huffman tables
 155:    */
 156:   public JPEGHuffmanTable[] getACHuffmanTables()
 157:   {
 158:     return ACHuffmanTables == null ? ACHuffmanTables
 159:       : (JPEGHuffmanTable[]) ACHuffmanTables.clone();
 160:   }
 161: }