001/* BandCombineOp.java - perform a combination on the bands of a raster
002   Copyright (C) 2004, 2006  Free Software Foundation
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
038package java.awt.image;
039
040import java.awt.RenderingHints;
041import java.awt.geom.Point2D;
042import java.awt.geom.Rectangle2D;
043import java.util.Arrays;
044
045/**
046 * Filter Raster pixels by applying a matrix.
047 * 
048 * BandCombineOp applies a matrix to each pixel to produce new pixel values.
049 * The width of the matrix must be the same or one more than the number of
050 * bands in the source Raster.  If one more, the pixels in the source are
051 * assumed to contain an implicit 1.0 at the end.
052 * 
053 * The rows of the matrix are multiplied by the pixel to produce the values
054 * for the destination.  Therefore the destination Raster must contain the
055 * same number of bands as the number of rows in the filter matrix.
056 * 
057 * This Op assumes that samples are integers; floating point sample types will
058 * be rounded to their nearest integer value during filtering.
059 * 
060 * @author Jerry Quinn (jlquinn@optonline.net)
061 */
062public class BandCombineOp implements RasterOp
063{
064  private RenderingHints hints;
065  private float[][] matrix;
066  
067  /**
068   * Construct a BandCombineOp.
069   * 
070   * @param matrix The matrix to filter pixels with.
071   * @param hints Rendering hints to apply.  Ignored.
072   * @throws ArrayIndexOutOfBoundsException if the matrix is invalid
073   */
074  public BandCombineOp(float[][] matrix, RenderingHints hints)
075  {
076    this.matrix = new float[matrix.length][];
077    int width = matrix[0].length;
078    for (int i = 0; i < matrix.length; i++)
079      {
080        this.matrix[i] = new float[width + 1];
081        for (int j = 0; j < width; j++)
082          this.matrix[i][j] = matrix[i][j];
083
084        // The reference implementation pads the array with a trailing zero...
085        this.matrix[i][width] = 0;
086      }
087
088    this.hints = hints;
089  }
090
091  /**
092   * Filter Raster pixels through a matrix. Applies the Op matrix to source
093   * pixes to produce dest pixels. Each row of the matrix is multiplied by the
094   * src pixel components to produce the dest pixel. If matrix is one more than
095   * the number of bands in the src, the last element is implicitly multiplied
096   * by 1, i.e. added to the sum for that dest component. If dest is null, a
097   * suitable Raster is created. This implementation uses
098   * createCompatibleDestRaster.
099   * 
100   * @param src The source Raster.
101   * @param dest The destination Raster, or null.
102   * @throws IllegalArgumentException if the destination raster is incompatible
103   *           with the source raster.
104   * @return The filtered Raster.
105   * @see java.awt.image.RasterOp#filter(java.awt.image.Raster,
106   *      java.awt.image.WritableRaster)
107   */
108  public WritableRaster filter(Raster src, WritableRaster dest) {
109    if (dest == null)
110      dest = createCompatibleDestRaster(src);
111    else if (dest.getNumBands() != src.getNumBands()
112             || dest.getTransferType() != src.getTransferType())
113      throw new IllegalArgumentException("Destination raster is incompatible with source raster");
114
115    // Filter the pixels
116    int[] spix = new int[matrix[0].length - 1];
117    int[] spix2 = new int[matrix[0].length - 1];
118    int[] dpix = new int[matrix.length];
119    for (int y = src.getMinY(); y < src.getHeight() + src.getMinY(); y++)
120      for (int x = src.getMinX(); x < src.getWidth() + src.getMinX(); x++)
121        {
122          // In case matrix rows have implicit translation
123          spix[spix.length - 1] = 1;
124          src.getPixel(x, y, spix);
125          
126          // Do not re-calculate if pixel is identical to the last one
127          // (ie, blocks of the same colour)
128          if (!Arrays.equals(spix, spix2))
129            {
130              System.arraycopy(spix, 0, spix2, 0, spix.length);
131              for (int i = 0; i < matrix.length; i++)
132                {
133                  dpix[i] = 0;
134                  for (int j = 0; j < matrix[0].length - 1; j++)
135                    dpix[i] += spix[j] * (int)matrix[i][j];
136                }
137            }
138          dest.setPixel(x, y, dpix);
139        }
140
141    return dest;
142  }
143
144  /* (non-Javadoc)
145   * @see java.awt.image.RasterOp#getBounds2D(java.awt.image.Raster)
146   */
147  public final Rectangle2D getBounds2D(Raster src)
148  {
149    return src.getBounds();
150  }
151
152  /**
153   * Creates a new WritableRaster that can be used as the destination for this
154   * Op. The number of bands in the source raster must equal the number of rows
155   * in the op matrix, which must also be equal to either the number of columns
156   * or (columns - 1) in the matrix.
157   * 
158   * @param src The source raster.
159   * @return A compatible raster.
160   * @see java.awt.image.RasterOp#createCompatibleDestRaster(java.awt.image.Raster)
161   * @throws IllegalArgumentException if the raster is incompatible with the
162   *           matrix.
163   */
164  public WritableRaster createCompatibleDestRaster(Raster src)
165  {
166    // Destination raster must have same number of bands as source
167    if (src.getNumBands() != matrix.length)
168      throw new IllegalArgumentException("Number of rows in matrix specifies an "
169                                             + "incompatible number of bands");
170
171    // We use -1 and -2 because we previously padded the rows with a trailing 0
172    if (src.getNumBands() != matrix[0].length - 1
173        && src.getNumBands() != matrix[0].length - 2)
174      throw new IllegalArgumentException("Incompatible number of bands: "
175                                             + "the number of bands in the raster must equal the number of "
176                                             + "columns in the matrix, optionally minus one");
177
178    return src.createCompatibleWritableRaster();
179  }
180
181  /**
182   * Return corresponding destination point for source point.  Because this is
183   * not a geometric operation, it simply returns a copy of the source.
184   * 
185   * @param src The source point.
186   * @param dst The destination point.
187   * @return dst The destination point.
188   * @see java.awt.image.RasterOp#getPoint2D(java.awt.geom.Point2D,
189   *java.awt.geom.Point2D) 
190   */
191  public final Point2D getPoint2D(Point2D src, Point2D dst)
192  {
193    if (dst == null)
194      return (Point2D)src.clone();
195    
196    dst.setLocation(src);
197    return dst;
198  }
199
200  /* (non-Javadoc)
201   * @see java.awt.image.RasterOp#getRenderingHints()
202   */
203  public final RenderingHints getRenderingHints()
204  {
205    return hints;
206  }
207  
208  /**
209   * Return the matrix used in this operation.
210   *
211   * @return The matrix used in this operation.
212   */
213  public final float[][] getMatrix()
214  {
215    return matrix;
216  }
217
218}