001    /* BandCombineOp.java - perform a combination on the bands of a raster
002       Copyright (C) 2004, 2006  Free Software Foundation
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    package java.awt.image;
039    
040    import java.awt.RenderingHints;
041    import java.awt.geom.Point2D;
042    import java.awt.geom.Rectangle2D;
043    import 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     */
062    public 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    }