001/*
002 * $RCSfile: TIFFLZWCompressor.java,v $
003 *
004 * 
005 * Copyright (c) 2005 Sun Microsystems, Inc. All  Rights Reserved.
006 * 
007 * Redistribution and use in source and binary forms, with or without
008 * modification, are permitted provided that the following conditions
009 * are met: 
010 * 
011 * - Redistribution of source code must retain the above copyright 
012 *   notice, this  list of conditions and the following disclaimer.
013 * 
014 * - Redistribution in binary form must reproduce the above copyright
015 *   notice, this list of conditions and the following disclaimer in 
016 *   the documentation and/or other materials provided with the
017 *   distribution.
018 * 
019 * Neither the name of Sun Microsystems, Inc. or the names of 
020 * contributors may be used to endorse or promote products derived 
021 * from this software without specific prior written permission.
022 * 
023 * This software is provided "AS IS," without a warranty of any 
024 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
025 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
026 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
027 * EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL 
028 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF 
029 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
030 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR 
031 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
032 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
033 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
034 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
035 * POSSIBILITY OF SUCH DAMAGES. 
036 * 
037 * You acknowledge that this software is not designed or intended for 
038 * use in the design, construction, operation or maintenance of any 
039 * nuclear facility. 
040 *
041 * $Revision: 1.1 $
042 * $Date: 2005/02/11 05:01:48 $
043 * $State: Exp $
044 */
045package com.github.jaiimageio.impl.plugins.tiff;
046
047import java.io.IOException;
048
049import javax.imageio.stream.ImageOutputStream;
050
051import com.github.jaiimageio.impl.common.LZWCompressor;
052import com.github.jaiimageio.plugins.tiff.BaselineTIFFTagSet;
053import com.github.jaiimageio.plugins.tiff.TIFFCompressor;
054
055/**
056 * LZW Compressor.
057 */
058public class TIFFLZWCompressor extends TIFFCompressor {
059
060    int predictor;
061
062    public TIFFLZWCompressor(int predictorValue) {
063        super("LZW", BaselineTIFFTagSet.COMPRESSION_LZW, true);
064        this.predictor = predictorValue;
065    }
066
067    public void setStream(ImageOutputStream stream) {
068        super.setStream(stream);
069    }
070
071    public int encode(byte[] b, int off,
072                      int width, int height,
073                      int[] bitsPerSample,
074                      int scanlineStride) throws IOException {
075
076        LZWCompressor lzwCompressor = new LZWCompressor(stream, 8, true);
077
078        int samplesPerPixel = bitsPerSample.length;
079        int bitsPerPixel = 0;
080        for (int i = 0; i < samplesPerPixel; i++) {
081            bitsPerPixel += bitsPerSample[i];
082        }
083        int bytesPerRow = (bitsPerPixel*width + 7)/8;
084
085        long initialStreamPosition = stream.getStreamPosition();
086
087        boolean usePredictor =
088            predictor == BaselineTIFFTagSet.PREDICTOR_HORIZONTAL_DIFFERENCING;
089
090        if(bytesPerRow == scanlineStride && !usePredictor) {
091            lzwCompressor.compress(b, off, bytesPerRow*height);
092        } else {
093            byte[] rowBuf = usePredictor ? new byte[bytesPerRow] : null;
094            for(int i = 0; i < height; i++) {
095                if(usePredictor) {
096                    // Cannot modify b[] in place as it might be a data
097                    // array from the image being written so make a copy.
098                    System.arraycopy(b, off, rowBuf, 0, bytesPerRow);
099                    for(int j = bytesPerRow - 1; j >= samplesPerPixel; j--) {
100                        rowBuf[j] -= rowBuf[j - samplesPerPixel];
101                    }
102                    lzwCompressor.compress(rowBuf, 0, bytesPerRow);
103                } else {
104                    lzwCompressor.compress(b, off, bytesPerRow);
105                }
106                off += scanlineStride;
107            }
108        }
109
110        lzwCompressor.flush();
111
112        int bytesWritten =
113            (int)(stream.getStreamPosition() - initialStreamPosition);
114
115        return bytesWritten;
116    }
117}