src/java.desktop/share/classes/com/sun/imageio/plugins/tiff/TIFFDeflater.java

/*
 * Copyright (c) 2005, 2015, 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
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package com.sun.imageio.plugins.tiff;

import javax.imageio.plugins.tiff.BaselineTIFFTagSet;
import java.io.IOException;
import java.util.zip.Deflater;
import javax.imageio.ImageWriteParam;

/**
 * Compressor superclass for Deflate and ZLib compression.
 */
public class TIFFDeflater extends TIFFCompressor {

    Deflater deflater;
    int predictor;

    public TIFFDeflater(String compressionType,
                        int compressionTagValue,
                        ImageWriteParam param,
                        int predictorValue) {
        super(compressionType, compressionTagValue, true);

        this.predictor = predictorValue;

        // Set the deflate level.
        int deflateLevel;
        if(param != null &&
           param.getCompressionMode() == ImageWriteParam.MODE_EXPLICIT) {
            float quality = param.getCompressionQuality();
            deflateLevel = (int)(1 + 8*quality);
        } else {
            deflateLevel = Deflater.DEFAULT_COMPRESSION;
        }

        this.deflater = new Deflater(deflateLevel);
    }

    public int encode(byte[] b, int off,
                      int width, int height,
                      int[] bitsPerSample,
                      int scanlineStride) throws IOException {

        int inputSize = height*scanlineStride;
        int blocks = (inputSize + 32767)/32768;

        // Worst case for Zlib deflate is input size + 5 bytes per 32k
        // block, plus 6 header bytes
        byte[] compData = new byte[inputSize + 5*blocks + 6];

        int numCompressedBytes = 0;
        if(predictor == BaselineTIFFTagSet.PREDICTOR_HORIZONTAL_DIFFERENCING) {
            int samplesPerPixel = bitsPerSample.length;
            int bitsPerPixel = 0;
            for (int i = 0; i < samplesPerPixel; i++) {
                bitsPerPixel += bitsPerSample[i];
            }
            int bytesPerRow = (bitsPerPixel*width + 7)/8;
            byte[] rowBuf = new byte[bytesPerRow];

            int maxRow = height - 1;
            for(int i = 0; i < height; i++) {
                // Cannot modify b[] in place as it might be a data
                // array from the image being written so make a copy.
                System.arraycopy(b, off, rowBuf, 0, bytesPerRow);
                for(int j = bytesPerRow - 1; j >= samplesPerPixel; j--) {
                    rowBuf[j] -= rowBuf[j - samplesPerPixel];
                }

                deflater.setInput(rowBuf);
                if(i == maxRow) {
                    deflater.finish();
                }

                int numBytes = 0;
                while((numBytes = deflater.deflate(compData,
                                                   numCompressedBytes,
                                                   compData.length -
                                                   numCompressedBytes)) != 0) {
                    numCompressedBytes += numBytes;
                }

                off += scanlineStride;
            }
        } else {
            deflater.setInput(b, off, height*scanlineStride);
            deflater.finish();

            numCompressedBytes = deflater.deflate(compData);
        }

        deflater.reset();

        stream.write(compData, 0, numCompressedBytes);

        return numCompressedBytes;
    }
}