mirror of git://gcc.gnu.org/git/gcc.git
294 lines
9.7 KiB
Java
294 lines
9.7 KiB
Java
/* JPEGImageWriteParam.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 java.util.Locale;
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import java.util.PropertyResourceBundle;
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import java.util.ResourceBundle;
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import javax.imageio.ImageWriteParam;
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/**
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* The JPEGImageWriteParam class can be used to specify tables and
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* settings used in the JPEG encoding process. Encoding tables are
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* taken from the metadata associated with the output stream, and
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* failing that (if the metadata tables are null) from an instance of
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* JPEGImageWriteParam. The default metadata uses the standard JPEG
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* tables from the JPEGQTable and JPEGHuffmanTable classes. Non-null
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* metadata tables override JPEGImageWriteParam tables. Compression
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* settings range from 1.0, best compression, through 0.75, default
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* compression, to 0.0, worst compression.
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*
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* A JPEGImageWriteParam instance is retrieved from the built-in JPEG
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* ImageWriter using the getDefaultImageWriteParam method.
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*/
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public class JPEGImageWriteParam
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extends ImageWriteParam
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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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private boolean optimize;
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private String[] compressionQualityDescriptions;
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private float[] compressionQualityValues;
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/**
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* Localized messages are stored in separate files.
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*/
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private ResourceBundle messages;
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/**
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* Construct a JPEGImageWriteParam with the following state: tiling
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* is not supported, progressive mode is supported, initial
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* progressive mode is MODE_DISABLED, compression is supported, one
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* compression type named "JPEG" is supported and the default
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* compression quality is 0.75f. Compression type names and
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* compression quality descriptions are localized to the given
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* locale.
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*
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* @param locale the locale used for message localization
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*/
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public JPEGImageWriteParam(Locale locale)
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{
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super(locale);
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// Get localized compression type and compression quality
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// description strings for the given locale.
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messages = PropertyResourceBundle.getBundle
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("javax/imageio/plugins/jpeg/MessagesBundle", locale);
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// Initialize inherited ImageWriter fields.
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canWriteTiles = false;
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canWriteProgressive = true;
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progressiveMode = MODE_DISABLED;
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canWriteCompressed = true;
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compressionTypes = new String[]
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{
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messages.getString("compression.types.jpeg")
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};
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compressionType = compressionTypes[0];
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compressionQuality = 0.75f;
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}
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/**
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* Reset the compression quality to 0.75f.
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*/
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public void unsetCompression()
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{
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compressionQuality = 0.75f;
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}
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/**
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* Check if compression algorithm is lossless. JPEGImageWriteParam
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* overrides this ImageWriteParam method to always return false
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* since JPEG compression is inherently lossy.
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*
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* @return false
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*/
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public boolean isCompressionLossless()
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{
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return false;
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}
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/**
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* Retrieve an array of compression quality descriptions. These
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* messages are localized using the locale provided upon
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* construction. Each compression quality description in the
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* returned array corresponds to the compression quality value at
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* the same index in the array returned by
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* getCompressionQualityValues.
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*
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* @return an array of strings each of which describes a compression
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* quality value
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*/
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public String[] getCompressionQualityDescriptions()
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{
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// Make sure exceptions are thrown when this image write param is
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// in the wrong state.
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super.getCompressionQualityDescriptions();
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if (compressionQualityDescriptions == null)
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{
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compressionQualityDescriptions = new String[]
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{
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messages.getString("compression.minimum"),
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messages.getString("compression.default"),
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messages.getString("compression.maximum")
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};
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}
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return compressionQualityDescriptions;
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}
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/**
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* Retrieve an array of compression quality values, ordered from
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* lowest quality to highest quality.
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*
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* @return an array of compressions quality values
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*/
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public float[] getCompressionQualityValues()
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{
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// Make sure exceptions are thrown when this image write param is
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// in the wrong state.
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super.getCompressionQualityValues();
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if (compressionQualityValues == null)
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compressionQualityValues = new float[] { 0.05f, 0.75f, 0.95f };
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return compressionQualityValues;
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}
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/**
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* Check if the encoding tables are set.
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*
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* @return true if the encoding 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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* encode 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 setEncodeTables(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 encoding tables.
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*/
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public void unsetEncodeTables()
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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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* Specify whether or not Huffman tables written to the output
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* stream should be optimized. Every image encoded with this flag
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* set will contain a Huffman table, and the generated Huffman
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* tables will override those specified in the metadata.
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*
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* @param optimize true to generate optimized Huffman tables, false
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* otherwise
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*/
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public void setOptimizeHuffmanTables(boolean optimize)
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{
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this.optimize = optimize;
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}
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/**
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* Check whether or not Huffman tables written to the output stream
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* will be optimized. Unless otherwise set using
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* setOptimizeHuffmanTables, this returns false.
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*
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* @return true Huffman tables written to the output stream will be
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* optimized, false otherwise
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*/
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public boolean getOptimizeHuffmanTables()
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{
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return optimize;
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}
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}
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