Java tutorial
/* * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt.image; /** * This class defines a lookup table object. The output of a * lookup operation using an object of this class is interpreted * as an unsigned byte quantity. The lookup table contains byte * data arrays for one or more bands (or components) of an image, * and it contains an offset which will be subtracted from the * input values before indexing the arrays. This allows an array * smaller than the native data size to be provided for a * constrained input. If there is only one array in the lookup * table, it will be applied to all bands. * * @see ShortLookupTable * @see LookupOp */ public class ByteLookupTable extends LookupTable { /** * Constants */ byte[][] data; /** * Constructs a ByteLookupTable object from an array of byte * arrays representing a lookup table for each * band. The offset will be subtracted from input * values before indexing into the arrays. The number of * bands is the length of the data argument. The * data array for each band is stored as a reference. * @param offset the value subtracted from the input values * before indexing into the arrays * @param data an array of byte arrays representing a lookup * table for each band * @throws IllegalArgumentException if {@code offset} is * is less than 0 or if the length of {@code data} * is less than 1 */ public ByteLookupTable(int offset, byte[][] data) { super(offset, data.length); numComponents = data.length; numEntries = data[0].length; this.data = new byte[numComponents][]; // Allocate the array and copy the data reference for (int i = 0; i < numComponents; i++) { this.data[i] = data[i]; } } /** * Constructs a ByteLookupTable object from an array * of bytes representing a lookup table to be applied to all * bands. The offset will be subtracted from input * values before indexing into the array. * The data array is stored as a reference. * @param offset the value subtracted from the input values * before indexing into the array * @param data an array of bytes * @throws IllegalArgumentException if {@code offset} is * is less than 0 or if the length of {@code data} * is less than 1 */ public ByteLookupTable(int offset, byte[] data) { super(offset, data.length); numComponents = 1; numEntries = data.length; this.data = new byte[1][]; this.data[0] = data; } /** * Returns the lookup table data by reference. If this ByteLookupTable * was constructed using a single byte array, the length of the returned * array is one. * @return the data array of this {@code ByteLookupTable}. */ public final byte[][] getTable() { return data; } /** * Returns an array of samples of a pixel, translated with the lookup * table. The source and destination array can be the same array. * Array {@code dst} is returned. * * @param src the source array. * @param dst the destination array. This array must be at least as * long as {@code src}. If {@code dst} is * {@code null}, a new array will be allocated having the * same length as {@code src}. * @return the array {@code dst}, an {@code int} array of * samples. * @exception ArrayIndexOutOfBoundsException if {@code src} is * longer than {@code dst} or if for any element * {@code i} of {@code src}, * {@code src[i]-offset} is either less than zero or * greater than or equal to the length of the lookup table * for any band. */ public int[] lookupPixel(int[] src, int[] dst) { if (dst == null) { // Need to alloc a new destination array dst = new int[src.length]; } if (numComponents == 1) { // Apply one LUT to all bands for (int i = 0; i < src.length; i++) { int s = src[i] - offset; if (s < 0) { throw new ArrayIndexOutOfBoundsException("src[" + i + "]-offset is " + "less than zero"); } dst[i] = (int) data[0][s]; } } else { for (int i = 0; i < src.length; i++) { int s = src[i] - offset; if (s < 0) { throw new ArrayIndexOutOfBoundsException("src[" + i + "]-offset is " + "less than zero"); } dst[i] = (int) data[i][s]; } } return dst; } /** * Returns an array of samples of a pixel, translated with the lookup * table. The source and destination array can be the same array. * Array {@code dst} is returned. * * @param src the source array. * @param dst the destination array. This array must be at least as * long as {@code src}. If {@code dst} is * {@code null}, a new array will be allocated having the * same length as {@code src}. * @return the array {@code dst}, an {@code int} array of * samples. * @exception ArrayIndexOutOfBoundsException if {@code src} is * longer than {@code dst} or if for any element * {@code i} of {@code src}, * {@code (src[i]&0xff)-offset} is either less than * zero or greater than or equal to the length of the * lookup table for any band. */ public byte[] lookupPixel(byte[] src, byte[] dst) { if (dst == null) { // Need to alloc a new destination array dst = new byte[src.length]; } if (numComponents == 1) { // Apply one LUT to all bands for (int i = 0; i < src.length; i++) { int s = (src[i] & 0xff) - offset; if (s < 0) { throw new ArrayIndexOutOfBoundsException("src[" + i + "]-offset is " + "less than zero"); } dst[i] = data[0][s]; } } else { for (int i = 0; i < src.length; i++) { int s = (src[i] & 0xff) - offset; if (s < 0) { throw new ArrayIndexOutOfBoundsException("src[" + i + "]-offset is " + "less than zero"); } dst[i] = data[i][s]; } } return dst; } }