001/* LookupTable.java -- Java class for a pixel translation table. 002 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package 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 */ 053public 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}