001 /* JPEGImageReadParam.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 javax.imageio.ImageReadParam; 042 043 /** 044 * The JPEGImageReadParam class is only used to set JPEG decoding 045 * tables for streams that do not provide their own tables. If a 046 * stream does not provide tables and a custom JPEGImageReadParam is 047 * not provided, then the standard JPEG tables are used from the 048 * JPEGQTable and JPEGHuffmanTable classes. If a stream does provide 049 * decoding tables then JPEGImageReadParam will be ignored. 050 * JPEGImageReadParam cannot be used to retrieve the tables from a 051 * stream. Instead, use IIOMetadata for this purpose. 052 * 053 * A JPEGImageReadParam instance is retrieved from the built-in JPEG 054 * ImageReader using the getDefaultImageReadParam method. 055 */ 056 public class JPEGImageReadParam 057 extends ImageReadParam 058 { 059 private JPEGQTable[] qTables; 060 private JPEGHuffmanTable[] DCHuffmanTables; 061 private JPEGHuffmanTable[] ACHuffmanTables; 062 063 /** 064 * Construct a JPEGImageReadParam. 065 */ 066 public JPEGImageReadParam() 067 { 068 super(); 069 } 070 071 /** 072 * Check if the decoding tables are set. 073 * 074 * @return true if the decoding tables are set, false otherwise 075 */ 076 public boolean areTablesSet() 077 { 078 // If qTables is not null then all tables are set. 079 return (qTables != null); 080 } 081 082 /** 083 * Set the quantization and Huffman tables that will be used to 084 * decode the stream. Copies are created of the array arguments. 085 * The number of Huffman tables must be the same in both Huffman 086 * table arrays. No argument may be null and no array may be longer 087 * than four elements. 088 * 089 * @param qTables JPEG quantization tables 090 * @param DCHuffmanTables JPEG DC Huffman tables 091 * @param ACHuffmanTables JPEG AC Huffman tables 092 * 093 * @throws IllegalArgumentException if any argument is null, if any 094 * of the arrays are longer than four elements, or if the Huffman 095 * table arrays do not have the same number of elements 096 */ 097 public void setDecodeTables(JPEGQTable[] qTables, 098 JPEGHuffmanTable[] DCHuffmanTables, 099 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 }