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jeremybenn |
/* JPEGImageReadParam.java --
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Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package javax.imageio.plugins.jpeg;
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import javax.imageio.ImageReadParam;
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/**
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* The JPEGImageReadParam class is only used to set JPEG decoding
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* tables for streams that do not provide their own tables. If a
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* stream does not provide tables and a custom JPEGImageReadParam is
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* not provided, then the standard JPEG tables are used from the
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* JPEGQTable and JPEGHuffmanTable classes. If a stream does provide
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* decoding tables then JPEGImageReadParam will be ignored.
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* JPEGImageReadParam cannot be used to retrieve the tables from a
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* stream. Instead, use IIOMetadata for this purpose.
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*
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* A JPEGImageReadParam instance is retrieved from the built-in JPEG
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* ImageReader using the getDefaultImageReadParam method.
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*/
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public class JPEGImageReadParam
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extends ImageReadParam
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{
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private JPEGQTable[] qTables;
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private JPEGHuffmanTable[] DCHuffmanTables;
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private JPEGHuffmanTable[] ACHuffmanTables;
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/**
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* Construct a JPEGImageReadParam.
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*/
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public JPEGImageReadParam()
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{
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super();
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}
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/**
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* Check if the decoding tables are set.
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*
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* @return true if the decoding tables are set, false otherwise
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*/
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public boolean areTablesSet()
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{
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// If qTables is not null then all tables are set.
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return (qTables != null);
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}
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/**
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* Set the quantization and Huffman tables that will be used to
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* decode the stream. Copies are created of the array arguments.
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* The number of Huffman tables must be the same in both Huffman
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* table arrays. No argument may be null and no array may be longer
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* than four elements.
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*
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* @param qTables JPEG quantization tables
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* @param DCHuffmanTables JPEG DC Huffman tables
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* @param ACHuffmanTables JPEG AC Huffman tables
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*
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* @throws IllegalArgumentException if any argument is null, if any
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* of the arrays are longer than four elements, or if the Huffman
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* table arrays do not have the same number of elements
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*/
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public void setDecodeTables(JPEGQTable[] qTables,
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JPEGHuffmanTable[] DCHuffmanTables,
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JPEGHuffmanTable[] ACHuffmanTables)
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{
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if (qTables == null || DCHuffmanTables == null || ACHuffmanTables == null)
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throw new IllegalArgumentException("null argument");
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if (qTables.length > 4 || DCHuffmanTables.length > 4
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|| ACHuffmanTables.length > 4)
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throw new IllegalArgumentException("argument has too many elements");
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if (DCHuffmanTables.length != ACHuffmanTables.length)
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throw new IllegalArgumentException("Huffman table arrays differ in length");
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// Do a shallow copy. JPEGQTable's data is not directly
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// modifyable since JPEGQTable.getTable returns a copy. Therefore
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// it is safe to have multiple references to a single JPEGQTable.
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// Likewise for JPEGHuffmanTable.
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this.qTables = (JPEGQTable[]) qTables.clone();
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this.DCHuffmanTables = (JPEGHuffmanTable[]) DCHuffmanTables.clone();
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this.ACHuffmanTables = (JPEGHuffmanTable[]) ACHuffmanTables.clone();
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}
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/**
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* Clear the quantization and Huffman decoding tables.
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*/
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public void unsetDecodeTables()
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{
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qTables = null;
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DCHuffmanTables = null;
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ACHuffmanTables = null;
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}
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/**
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* Retrieve the quantization tables.
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*
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* @returns an array of JPEG quantization tables
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*/
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public JPEGQTable[] getQTables()
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{
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return qTables == null ? qTables : (JPEGQTable[]) qTables.clone();
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}
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/**
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* Retrieve the DC Huffman tables.
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*
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* @return an array of JPEG DC Huffman tables
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*/
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public JPEGHuffmanTable[] getDCHuffmanTables()
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{
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return DCHuffmanTables == null ? DCHuffmanTables
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: (JPEGHuffmanTable[]) DCHuffmanTables.clone();
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}
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/**
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* Retrieve the AC Huffman tables.
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*
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* @return an array of JPEG AC Huffman tables
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*/
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public JPEGHuffmanTable[] getACHuffmanTables()
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{
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return ACHuffmanTables == null ? ACHuffmanTables
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: (JPEGHuffmanTable[]) ACHuffmanTables.clone();
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}
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}
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