001 /* LookupTable.java -- Java class for a pixel translation table.
002 Copyright (C) 2004, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt.image;
040
041 /**
042 * LookupTable represents translation arrays for pixel values. It wraps one
043 * or more data arrays for each layer (or component) in an image, such as
044 * Alpha, R, G, and B. When doing translation, the offset is subtracted from
045 * the pixel values to allow a subset of an array to be used.
046 *
047 * @see ByteLookupTable
048 * @see ShortLookupTable
049 *
050 * @author Jerry Quinn (jlquinn@optonline.net)
051 * @version 1.0
052 */
053 public abstract class LookupTable
054 {
055 // Not protected since that's part of the public API.
056 int offset;
057 int numComponents;
058
059 /**
060 * Creates a new <code>LookupTable</code> instance.
061 *
062 * If numComponents is 1, the same translation table is used for all pixel
063 * components.
064 *
065 * @param offset Offset to be subtracted.
066 * @param numComponents Number of image components.
067 * @exception IllegalArgumentException if offset < 0 or numComponents < 1.
068 */
069 protected LookupTable(int offset, int numComponents)
070 throws IllegalArgumentException
071 {
072 if (offset < 0 || numComponents < 1)
073 throw new IllegalArgumentException();
074 this.offset = offset;
075 this.numComponents = numComponents;
076 }
077
078 /** Return the number of components. */
079 public int getNumComponents()
080 {
081 return numComponents;
082 }
083
084 /** Return the offset. */
085 public int getOffset()
086 {
087 return offset;
088 }
089
090
091 /**
092 * Return translated values for a pixel.
093 *
094 * For each value in the pixel src, use the value minus offset as an index
095 * in the component array and copy the value there to the output for the
096 * component. If dest is null, the output is a new array, otherwise the
097 * translated values are written to dest. Dest can be the same array as
098 * src.
099 *
100 * For example, if the pixel src is [2, 4, 3], and offset is 1, the output
101 * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the
102 * translation arrays.
103 *
104 * @param src Component values of a pixel.
105 * @param dest Destination array for values, or null.
106 * @return Translated values for the pixel.
107 */
108 public abstract int[] lookupPixel(int[] src, int[] dest);
109 }