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/*
* TIFFDecoderPackbits
*
* Copyright (c) 2002, 2003 Marco Schmidt.
* All rights reserved.
*/
package net.sourceforge.jiu.codecs.tiff;
import java.io.DataInput;
import java.io.IOException;
import net.sourceforge.jiu.codecs.tiff.TIFFDecoder;
import net.sourceforge.jiu.codecs.InvalidFileStructureException;
/**
* A TIFF decoder for files compressed with the <em>Packbits</em> method.
* This compression algorithm has the value <code>32773</code>
* in the compression tag of an image file directory.
* @author Marco Schmidt
* @since 0.9.0
*/
public class TIFFDecoderPackbits extends TIFFDecoder
{
public void decode() throws
InvalidFileStructureException,
IOException
{
DataInput in = getInput();
byte[] row = new byte[getBytesPerRow()];
for (int y = getY1(); y <= getY2(); y++)
{
int index = 0;
do
{
byte value = in.readByte();
if (value >= 0)
{
int numSamples = value + 1;
// copy bytes literally
in.readFully(row, index, numSamples);
index += numSamples;
}
else
if (value != (byte)-128)
{
int numSamples = - value + 1;
// write run
byte sample = in.readByte();
while (numSamples-- != 0)
{
row[index++] = sample;
}
}
}
while (index != row.length);
putBytes(row, 0, row.length);
}
}
public Integer[] getCompressionTypes()
{
return new Integer[] {new Integer(TIFFConstants.COMPRESSION_PACKBITS)};
}
}
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