001 /* Kernel.java -- Java class for an image processing kernel
002 Copyright (C) 2004, 2005, 2006, 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 * 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 */
048 public 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 }