src/java.desktop/share/classes/com/sun/imageio/plugins/tiff/TIFFPackBitsDecompressor.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
 * questions.
 */
package com.sun.imageio.plugins.tiff;

import java.io.IOException;

public class TIFFPackBitsDecompressor extends TIFFDecompressor {

    public TIFFPackBitsDecompressor() {
    }

    public int decode(byte[] srcData, int srcOffset,
                      byte[] dstData, int dstOffset)
        throws IOException {

        int srcIndex = srcOffset;
        int dstIndex = dstOffset;

        int dstArraySize = dstData.length;
        int srcArraySize = srcData.length;
        try {
            while (dstIndex < dstArraySize && srcIndex < srcArraySize) {
                byte b = srcData[srcIndex++];

                if (b >= 0 && b <= 127) {
                    // Literal run packet

                    for (int i = 0; i < b + 1; i++) {
                        dstData[dstIndex++] = srcData[srcIndex++];
                    }
                } else if (b <= -1 && b >= -127) {
                    // 2-byte encoded run packet
                    byte repeat = srcData[srcIndex++];
                    for (int i = 0; i < (-b + 1); i++) {
                        dstData[dstIndex++] = repeat;
                    }
                } else {
                    // No-op packet, do nothing
                    ++srcIndex;
                }
            }
        } catch(ArrayIndexOutOfBoundsException e) {
            if(reader instanceof TIFFImageReader) {
                ((TIFFImageReader)reader).forwardWarningMessage
                    ("ArrayIndexOutOfBoundsException ignored in TIFFPackBitsDecompressor.decode()");
            }
        }

        return dstIndex - dstOffset;
    }

    public void decodeRaw(byte[] b,
                          int dstOffset,
                          int bitsPerPixel,
                          int scanlineStride) throws IOException {
        stream.seek(offset);

        byte[] srcData = new byte[byteCount];
        stream.readFully(srcData);

        int bytesPerRow = (srcWidth*bitsPerPixel + 7)/8;
        byte[] buf;
        int bufOffset;
        if(bytesPerRow == scanlineStride) {
            buf = b;
            bufOffset = dstOffset;
        } else {
            buf = new byte[bytesPerRow*srcHeight];
            bufOffset = 0;
        }

        decode(srcData, 0, buf, bufOffset);

        if(bytesPerRow != scanlineStride) {
            int off = 0;
            for (int y = 0; y < srcHeight; y++) {
                System.arraycopy(buf, off, b, dstOffset, bytesPerRow);
                off += bytesPerRow;
                dstOffset += scanlineStride;
            }
        }
    }
}