001/* Kernel.java -- Java class for an image processing kernel 002 Copyright (C) 2004, 2005, 2006, 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 * Kernel represents an image processing kernel. It gets used to hold 043 * convolution filters among other purposes. It stores an array of float 044 * values representing a 2-dimensional array in row-major order. 045 * 046 * @author Jerry Quinn (jlquinn@optonline.net) 047 */ 048public class Kernel implements Cloneable 049{ 050 /** The kernel width. */ 051 private final int width; 052 053 /** The kernel height. */ 054 private final int height; 055 056 /** Internal storage for the kernel's values. */ 057 private final float[] data; 058 059 /** 060 * Creates a new <code>Kernel</code> instance with the specified dimensions 061 * and values. The first <code>width * height</code> values in the specified 062 * <code>data</code> array are copied to internal storage. 063 * 064 * @param width the kernel width. 065 * @param height the kernel height. 066 * @param data the source data array (<code>null</code> not permitted). 067 * 068 * @throws IllegalArgumentException if <code>data.length</code> is less than 069 * <code>width * height</code>. 070 * @throws IllegalArgumentException if <code>width</code> or 071 * <code>height</code> is less than zero. 072 * @throws NullPointerException if <code>data</code> is <code>null</code>. 073 */ 074 public Kernel(int width, int height, float[] data) 075 throws IllegalArgumentException 076 { 077 this.width = width; 078 this.height = height; 079 if (data.length < width * height || width < 0 || height < 0) 080 throw new IllegalArgumentException(); 081 this.data = new float[width * height]; 082 System.arraycopy(data, 0, this.data, 0, width * height); 083 } 084 085 /** 086 * Returns the x-origin for the kernel, which is calculated as 087 * <code>(width - 1) / 2</code>. 088 * 089 * @return The x-origin for the kernel. 090 */ 091 public final int getXOrigin() 092 { 093 return (width - 1) / 2; 094 } 095 096 /** 097 * Returns the y-origin for the kernel, which is calculated as 098 * <code>(height - 1) / 2</code>. 099 * 100 * @return The y-origin for the kernel. 101 */ 102 public final int getYOrigin() 103 { 104 return (height - 1) / 2; 105 } 106 107 /** 108 * Returns the kernel width (as supplied to the constructor). 109 * 110 * @return The kernel width. 111 */ 112 public final int getWidth() 113 { 114 return width; 115 } 116 117 /** 118 * Returns the kernel height (as supplied to the constructor). 119 * 120 * @return The kernel height. 121 */ 122 public final int getHeight() 123 { 124 return height; 125 } 126 127 /** 128 * Returns an array containing a copy of the kernel data. If the 129 * <code>data</code> argument is non-<code>null</code>, the kernel values 130 * are copied into it and then <code>data</code> is returned as the result. 131 * If the <code>data</code> argument is <code>null</code>, this method 132 * allocates a new array then populates and returns it. 133 * 134 * @param data an array to copy the return values into (if 135 * <code>null</code>, a new array is allocated). 136 * 137 * @return The array with copied values. 138 * 139 * @throws IllegalArgumentException if <code>data.length</code> is less than 140 * the kernel's <code>width * height</code>. 141 */ 142 public final float[] getKernelData(float[] data) 143 throws IllegalArgumentException 144 { 145 if (data == null) 146 return (float[]) this.data.clone(); 147 148 if (data.length < this.data.length) 149 throw new IllegalArgumentException(); 150 151 System.arraycopy(this.data, 0, data, 0, this.data.length); 152 return data; 153 } 154 155 /** 156 * Returns a clone of this kernel. 157 * 158 * @return a clone of this Kernel. 159 */ 160 public Object clone() 161 { 162 try 163 { 164 return super.clone(); 165 } 166 catch (CloneNotSupportedException e) 167 { 168 throw (Error) new InternalError().initCause(e); // Impossible 169 } 170 } 171}