| /* |
| * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package javax.imageio.plugins.jpeg; |
| |
| import javax.imageio.ImageReadParam; |
| |
| /** |
| * This class adds the ability to set JPEG quantization and Huffman |
| * tables when using the built-in JPEG reader plug-in. An instance of |
| * this class will be returned from the |
| * {@code getDefaultImageReadParam} methods of the built-in JPEG |
| * {@code ImageReader}. |
| * |
| * <p> The sole purpose of these additions is to allow the |
| * specification of tables for use in decoding abbreviated streams. |
| * The built-in JPEG reader will also accept an ordinary |
| * {@code ImageReadParam}, which is sufficient for decoding |
| * non-abbreviated streams. |
| * |
| * <p> While tables for abbreviated streams are often obtained by |
| * first reading another abbreviated stream containing only the |
| * tables, in some applications the tables are fixed ahead of time. |
| * This class allows the tables to be specified directly from client |
| * code. If no tables are specified either in the stream or in a |
| * {@code JPEGImageReadParam}, then the stream is presumed to use |
| * the "standard" visually lossless tables. See {@link JPEGQTable JPEGQTable} |
| * and {@link JPEGHuffmanTable JPEGHuffmanTable} for more information |
| * on the default tables. |
| * |
| * <p> The default {@code JPEGImageReadParam} returned by the |
| * {@code getDefaultReadParam} method of the builtin JPEG reader |
| * contains no tables. Default tables may be obtained from the table |
| * classes {@link JPEGQTable JPEGQTable} and |
| * {@link JPEGHuffmanTable JPEGHuffmanTable}. |
| * |
| * <p> If a stream does contain tables, the tables given in a |
| * {@code JPEGImageReadParam} are ignored. Furthermore, if the |
| * first image in a stream does contain tables and subsequent ones do |
| * not, then the tables given in the first image are used for all the |
| * abbreviated images. Once tables have been read from a stream, they |
| * can be overridden only by tables subsequently read from the same |
| * stream. In order to specify new tables, the {@link |
| * javax.imageio.ImageReader#setInput setInput} method of |
| * the reader must be called to change the stream. |
| * |
| * <p> Note that this class does not provide a means for obtaining the |
| * tables found in a stream. These may be extracted from a stream by |
| * consulting the IIOMetadata object returned by the reader. |
| * |
| * <p> |
| * For more information about the operation of the built-in JPEG plug-ins, |
| * see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG |
| * metadata format specification and usage notes</A>. |
| * |
| */ |
| public class JPEGImageReadParam extends ImageReadParam { |
| |
| private JPEGQTable[] qTables = null; |
| private JPEGHuffmanTable[] DCHuffmanTables = null; |
| private JPEGHuffmanTable[] ACHuffmanTables = null; |
| |
| /** |
| * Constructs a {@code JPEGImageReadParam}. |
| */ |
| public JPEGImageReadParam() { |
| super(); |
| } |
| |
| /** |
| * Returns {@code true} if tables are currently set. |
| * |
| * @return {@code true} if tables are present. |
| */ |
| public boolean areTablesSet() { |
| return (qTables != null); |
| } |
| |
| /** |
| * Sets the quantization and Huffman tables to use in decoding |
| * abbreviated streams. There may be a maximum of 4 tables of |
| * each type. These tables are ignored once tables are |
| * encountered in the stream. All arguments must be |
| * non-{@code null}. The two arrays of Huffman tables must |
| * have the same number of elements. The table specifiers in the |
| * frame and scan headers in the stream are assumed to be |
| * equivalent to indices into these arrays. The argument arrays |
| * are copied by this method. |
| * |
| * @param qTables an array of quantization table objects. |
| * @param DCHuffmanTables an array of Huffman table objects. |
| * @param ACHuffmanTables an array of Huffman table objects. |
| * |
| * @exception IllegalArgumentException if any of the arguments |
| * is {@code null}, has more than 4 elements, or if the |
| * numbers of DC and AC tables differ. |
| * |
| * @see #unsetDecodeTables |
| */ |
| public void setDecodeTables(JPEGQTable[] qTables, |
| JPEGHuffmanTable[] DCHuffmanTables, |
| JPEGHuffmanTable[] ACHuffmanTables) { |
| if ((qTables == null) || |
| (DCHuffmanTables == null) || |
| (ACHuffmanTables == null) || |
| (qTables.length > 4) || |
| (DCHuffmanTables.length > 4) || |
| (ACHuffmanTables.length > 4) || |
| (DCHuffmanTables.length != ACHuffmanTables.length)) { |
| throw new IllegalArgumentException |
| ("Invalid JPEG table arrays"); |
| } |
| this.qTables = qTables.clone(); |
| this.DCHuffmanTables = DCHuffmanTables.clone(); |
| this.ACHuffmanTables = ACHuffmanTables.clone(); |
| } |
| |
| /** |
| * Removes any quantization and Huffman tables that are currently |
| * set. |
| * |
| * @see #setDecodeTables |
| */ |
| public void unsetDecodeTables() { |
| this.qTables = null; |
| this.DCHuffmanTables = null; |
| this.ACHuffmanTables = null; |
| } |
| |
| /** |
| * Returns a copy of the array of quantization tables set on the |
| * most recent call to {@code setDecodeTables}, or |
| * {@code null} if tables are not currently set. |
| * |
| * @return an array of {@code JPEGQTable} objects, or |
| * {@code null}. |
| * |
| * @see #setDecodeTables |
| */ |
| public JPEGQTable[] getQTables() { |
| return (qTables != null) ? qTables.clone() : null; |
| } |
| |
| /** |
| * Returns a copy of the array of DC Huffman tables set on the |
| * most recent call to {@code setDecodeTables}, or |
| * {@code null} if tables are not currently set. |
| * |
| * @return an array of {@code JPEGHuffmanTable} objects, or |
| * {@code null}. |
| * |
| * @see #setDecodeTables |
| */ |
| public JPEGHuffmanTable[] getDCHuffmanTables() { |
| return (DCHuffmanTables != null) |
| ? DCHuffmanTables.clone() |
| : null; |
| } |
| |
| /** |
| * Returns a copy of the array of AC Huffman tables set on the |
| * most recent call to {@code setDecodeTables}, or |
| * {@code null} if tables are not currently set. |
| * |
| * @return an array of {@code JPEGHuffmanTable} objects, or |
| * {@code null}. |
| * |
| * @see #setDecodeTables |
| */ |
| public JPEGHuffmanTable[] getACHuffmanTables() { |
| return (ACHuffmanTables != null) |
| ? ACHuffmanTables.clone() |
| : null; |
| } |
| } |
