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Java > Open Source Codes > org > pdfbox > pdmodel > graphics > predictor > Up


1 /**
2  * Copyright (c) 2005, www.pdfbox.org
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright notice,
9  * this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright notice,
11  * this list of conditions and the following disclaimer in the documentation
12  * and/or other materials provided with the distribution.
13  * 3. Neither the name of pdfbox; nor the names of its
14  * contributors may be used to endorse or promote products derived from this
15  * software without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20  * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
24  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
26  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  *
28  * http://www.pdfbox.org
29  *
30  */
31 package org.pdfbox.pdmodel.graphics.predictor;
32
33 /**
34  * The up algorithm.
35  *
36  * <code>Up(i,j) = Raw(i,j) - Raw(i,j-1)</code>
37  *
38  * <code>Raw(i,j) = Up(i,j) + Raw(i,j-1)</code>
39  *
40  * @author xylifyx@yahoo.co.uk
41  * @version $Revision: 1.3 $
42  */
43 public class Up extends PredictorAlgorithm
44 {
45     /**
46      * {@inheritDoc}
47      */
48     public void encodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset,
49             int destDy, int destOffset)
50     {
51         int bpl = getWidth()*getBpp();
52         // case: y = 0;
53 if (srcOffset - srcDy < 0)
54         {
55             if (0 < getHeight())
56             {
57                 for (int x = 0; x < bpl; x++)
58                 {
59                     dest[destOffset + x] = src[srcOffset + x];
60                 }
61             }
62         }
63         else
64         {
65             for (int x = 0; x < bpl; x++)
66             {
67                 dest[destOffset + x] = (byte) (src[srcOffset + x] - src[srcOffset
68                         + x - srcDy]);
69             }
70         }
71     }
72
73     /**
74      * {@inheritDoc}
75      */
76     public void decodeLine(byte[] src, byte[] dest, int srcDy, int srcOffset,
77             int destDy, int destOffset)
78     {
79         // case: y = 0;
80 int bpl = getWidth()*getBpp();
81         if (destOffset - destDy < 0)
82         {
83             if (0 < getHeight())
84             {
85                 for (int x = 0; x < bpl; x++)
86                 {
87                     dest[destOffset + x] = src[srcOffset + x];
88                 }
89             }
90         }
91         else
92         {
93             for (int x = 0; x < bpl; x++)
94             {
95                 dest[destOffset + x] = (byte) (src[srcOffset + x] + dest[destOffset
96                         + x - destDy]);
97             }
98         }
99     }
100 }
101
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