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}