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JBIG2ImageReaderSpi.java

/**
 * ===========================================
 * Java Pdf Extraction Decoding Access Library
 * ===========================================
 *
 * Project Info:  http://www.jpedal.org
 * (C) Copyright 1997-2008, IDRsolutions and Contributors.
 * Main Developer: Simon Barnett
 *
 *    This file is part of JPedal
 *
 * Copyright (c) 2008, IDRsolutions
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the IDRsolutions nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY IDRsolutions ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL IDRsolutions BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Other JBIG2 image decoding implementations include
 * jbig2dec (http://jbig2dec.sourceforge.net/)
 * xpdf (http://www.foolabs.com/xpdf/)
 * 
 * The final draft JBIG2 specification can be found at http://www.jpeg.org/public/fcd14492.pdf
 * 
 * All three of the above resources were used in the writing of this software, with methodologies,
 * processes and inspiration taken from all three.
 *
 * ---------------
 * JBIG2ImageReaderSpi.java
 * ---------------
 */
package org.jpedal.jbig2.jai;

import java.io.IOException;
import java.util.Arrays;

import javax.imageio.ImageReader;
import javax.imageio.spi.ImageReaderSpi;
import javax.imageio.stream.ImageInputStream;

public class JBIG2ImageReaderSpi extends ImageReaderSpi {

      public JBIG2ImageReaderSpi() {
            super("JPedal", // vendorName
                        "1.0", // version
                        new String[] { "JBIG2" }, // names
                        new String[] { "jb2", "jbig2" }, // suffixes
                        new String[] { "image/x-jbig2" }, // MIMETypes
                        "org.jpedal.jbig2.jai.JBIG2ImageReader", // readerClassName
                        STANDARD_INPUT_TYPE, // inputTypes
                        null, // writerSpiNames
                        false, // supportsStandardStreamMetadataFormat
                        null, // nativeStreamMetadataFormatName
                        null, // nativeStreamMetadataFormatClassName
                        null, // extraStreamMetadataFormatNames
                        null, // extraStreamMetadataFormatClassNames
                        false, // supportsStandardImageMetadataFormat
                        null, // nativeImageMetadataFormatName
                        null, // nativeImageMetadataFormatClassName
                        null, // extraImageMetadataFormatNames
                        null); // extraImageMetadataFormatClassNames
            
      }

      public boolean canDecodeInput(Object input) throws IOException {

            // The input source must be an ImageInputStream because the constructor
            // passes STANDARD_INPUT_TYPE (an array consisting of ImageInputStream)
            // as the only type of input source that it will deal with to its
            // superclass.
            
            if (!(input instanceof ImageInputStream))
                  return false;

            ImageInputStream stream = (ImageInputStream) input;

            /** Read and validate the input source's header. */
            byte[] header = new byte[8];
            try {
                  // The input source's current position must be preserved so that
                  // other ImageReaderSpis can determine if they can decode the input
                  // source's format, should this input source be unable to handle the
                  // decoding. Because the input source is an ImageInputStream, its
                  // mark() and reset() methods are called to preserve the current
                  // position.

                  stream.mark();
                  stream.read(header);
                  stream.reset();
            } catch (IOException e) {
                  return false;
            }

            byte[] controlHeader = new byte[] { (byte) 151, 74, 66, 50, 13, 10, 26, 10 };

            return Arrays.equals(controlHeader, header);
      }

      public ImageReader createReaderInstance(Object extension) throws IOException {
            // Inform the JBIG2 image reader that this JBIG2 image reader SPI is the
            // originating provider -- the object that creates the JBIG2 image
            // reader.
            return new JBIG2ImageReader(this);
      }

      public String getDescription(java.util.Locale locale) {
            return "JPedal JBIG2 Image Decoder provided by IDRsolutions.  See http://www.jpedal.org/jbig.php";
      }
}

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