/**
* Copyright (c) 2005, www.pdfbox.org
* All rights reserved.
*
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* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of pdfbox; 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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
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*/
package org.pdfbox.pdmodel.graphics.predictor;
/**
* The sub algorithm.
*
* Sub(i,j) = Raw(i,j) - Raw(i-1,j)
*
* Raw(i,j) = Sub(i,j) + Raw(i-1,j)
*
* @author xylifyx@yahoo.co.uk
* @version $Revision: 1.2 $
*/
public class Sub extends PredictorAlgorithm
{
/**
* @see org.pdfbox.pdmodel.graphics.predictor.PredictorAlgorithm#encodeLine(byte[], byte[], int, int, int, int)
*/
public void encodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset,
int destDy, int destOffset)
{
int bpl = getWidth()*getBpp();
int bpp = getBpp();
// case: x < bpp
for (int x = 0; x < bpl && x < bpp; x++)
{
dest[x + destOffset] = src[x + srcOffset];
}
// otherwise
for (int x = getBpp(); x < bpl; x++)
{
dest[x + destOffset] = (byte) (src[x + srcOffset] - src[x
+ srcOffset - bpp]);
}
}
/**
* @see org.pdfbox.pdmodel.graphics.predictor.PredictorAlgorithm#decodeLine(byte[], byte[], int, int, int, int)
*/
public void decodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset,
int destDy, int destOffset)
{
int bpl = getWidth()*getBpp();
int bpp = getBpp();
// case: x < bpp
for (int x = 0; x < bpl && x < bpp; x++)
{
dest[x + destOffset] = src[x + srcOffset];
}
// otherwise
for (int x = getBpp(); x < bpl; x++)
{
dest[x + destOffset] = (byte) (src[x + srcOffset] + dest[x
+ destOffset - bpp]);
}
}
}