001    /* ConvolveOp.java --
002       Copyright (C) 2004, 2005, 2006, Free Software Foundation -- ConvolveOp
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    import java.awt.RenderingHints;
042    import java.awt.geom.Point2D;
043    import java.awt.geom.Rectangle2D;
044    
045    /**
046     * Convolution filter.
047     * 
048     * ConvolveOp convolves the source image with a Kernel to generate a
049     * destination image.  This involves multiplying each pixel and its neighbors
050     * with elements in the kernel to compute a new pixel.
051     * 
052     * Each band in a Raster is convolved and copied to the destination Raster.
053     * For BufferedImages, convolution is applied to all components.  Color 
054     * conversion will be applied if needed.
055     * 
056     * Note that this filter ignores whether the source or destination is alpha
057     * premultiplied.  The reference spec states that data will be premultiplied
058     * prior to convolving and divided back out afterwards (if needed), but testing
059     * has shown that this is not the case with their implementation.
060     * 
061     * @author jlquinn@optonline.net
062     */
063    public class ConvolveOp implements BufferedImageOp, RasterOp
064    {
065      /** Edge pixels are set to 0. */
066      public static final int EDGE_ZERO_FILL = 0;
067      
068      /** Edge pixels are copied from the source. */
069      public static final int EDGE_NO_OP = 1;
070      
071      private Kernel kernel;
072      private int edge;
073      private RenderingHints hints;
074    
075      /**
076       * Construct a ConvolveOp.
077       * 
078       * The edge condition specifies that pixels outside the area that can be
079       * filtered are either set to 0 or copied from the source image.
080       * 
081       * @param kernel The kernel to convolve with.
082       * @param edgeCondition Either EDGE_ZERO_FILL or EDGE_NO_OP.
083       * @param hints Rendering hints for color conversion, or null.
084       */
085      public ConvolveOp(Kernel kernel,
086                                    int edgeCondition,
087                                    RenderingHints hints)
088      {
089        this.kernel = kernel;
090        edge = edgeCondition;
091        this.hints = hints;
092      }
093      
094      /**
095       * Construct a ConvolveOp.
096       * 
097       * The edge condition defaults to EDGE_ZERO_FILL.
098       * 
099       * @param kernel The kernel to convolve with.
100       */
101      public ConvolveOp(Kernel kernel)
102      {
103        this.kernel = kernel;
104        edge = EDGE_ZERO_FILL;
105        hints = null;
106      }
107    
108      /**
109       * Converts the source image using the kernel specified in the
110       * constructor.  The resulting image is stored in the destination image if one
111       * is provided; otherwise a new BufferedImage is created and returned. 
112       * 
113       * The source and destination BufferedImage (if one is supplied) must have
114       * the same dimensions.
115       *
116       * @param src The source image.
117       * @param dst The destination image.
118       * @throws IllegalArgumentException if the rasters and/or color spaces are
119       *            incompatible.
120       * @return The convolved image.
121       */
122      public final BufferedImage filter(BufferedImage src, BufferedImage dst)
123      {
124        if (src == dst)
125          throw new IllegalArgumentException("Source and destination images " +
126                "cannot be the same.");
127        
128        if (dst == null)
129          dst = createCompatibleDestImage(src, src.getColorModel());
130        
131        // Make sure source image is premultiplied
132        BufferedImage src1 = src;
133        // The spec says we should do this, but mauve testing shows that Sun's
134        // implementation does not check this.
135        /*
136        if (!src.isAlphaPremultiplied())
137        {
138          src1 = createCompatibleDestImage(src, src.getColorModel());
139          src.copyData(src1.getRaster());
140          src1.coerceData(true);
141        }
142        */
143    
144        BufferedImage dst1 = dst;
145        if (src1.getColorModel().getColorSpace().getType() != dst.getColorModel().getColorSpace().getType())
146          dst1 = createCompatibleDestImage(src, src.getColorModel());
147    
148        filter(src1.getRaster(), dst1.getRaster());
149        
150        // Since we don't coerceData above, we don't need to divide it back out.
151        // This is wrong (one mauve test specifically tests converting a non-
152        // premultiplied image to a premultiplied image, and it shows that Sun
153        // simply ignores the premultipled flag, contrary to the spec), but we
154        // mimic it for compatibility.
155        /*
156            if (! dst.isAlphaPremultiplied())
157              dst1.coerceData(false);
158        */
159    
160        // Convert between color models if needed
161        if (dst1 != dst)
162          new ColorConvertOp(hints).filter(dst1, dst);
163    
164        return dst;
165      }
166    
167      /**
168       * Creates an empty BufferedImage with the size equal to the source and the
169       * correct number of bands. The new image is created with the specified 
170       * ColorModel, or if no ColorModel is supplied, an appropriate one is chosen.
171       *
172       * @param src The source image.
173       * @param dstCM A color model for the destination image (may be null).
174       * @return The new compatible destination image.
175       */
176      public BufferedImage createCompatibleDestImage(BufferedImage src,
177                                                     ColorModel dstCM)
178      {
179        if (dstCM != null)
180          return new BufferedImage(dstCM,
181                                   src.getRaster().createCompatibleWritableRaster(),
182                                   src.isAlphaPremultiplied(), null);
183    
184        return new BufferedImage(src.getWidth(), src.getHeight(), src.getType());
185      }
186    
187      /* (non-Javadoc)
188       * @see java.awt.image.RasterOp#getRenderingHints()
189       */
190      public final RenderingHints getRenderingHints()
191      {
192        return hints;
193      }
194      
195      /**
196       * Get the edge condition for this Op.
197       * 
198       * @return The edge condition.
199       */
200      public int getEdgeCondition()
201      {
202        return edge;
203      }
204      
205      /**
206       * Returns (a clone of) the convolution kernel.
207       *
208       * @return The convolution kernel.
209       */
210      public final Kernel getKernel()
211      {
212        return (Kernel) kernel.clone();
213      }
214    
215      /**
216       * Converts the source raster using the kernel specified in the constructor.  
217       * The resulting raster is stored in the destination raster if one is 
218       * provided; otherwise a new WritableRaster is created and returned.
219       * 
220       * If the convolved value for a sample is outside the range of [0-255], it
221       * will be clipped.
222       * 
223       * The source and destination raster (if one is supplied) cannot be the same,
224       * and must also have the same dimensions.
225       *
226       * @param src The source raster.
227       * @param dest The destination raster.
228       * @throws IllegalArgumentException if the rasters identical.
229       * @throws ImagingOpException if the convolution is not possible.
230       * @return The transformed raster.
231       */
232      public final WritableRaster filter(Raster src, WritableRaster dest)
233      {
234        if (src == dest)
235          throw new IllegalArgumentException("src == dest is not allowed.");
236        if (kernel.getWidth() > src.getWidth() 
237            || kernel.getHeight() > src.getHeight())
238          throw new ImagingOpException("The kernel is too large.");
239        if (dest == null)
240          dest = createCompatibleDestRaster(src);
241        else if (src.getNumBands() != dest.getNumBands())
242          throw new ImagingOpException("src and dest have different band counts.");
243    
244        // calculate the borders that the op can't reach...
245        int kWidth = kernel.getWidth();
246        int kHeight = kernel.getHeight();
247        int left = kernel.getXOrigin();
248        int right = Math.max(kWidth - left - 1, 0);
249        int top = kernel.getYOrigin();
250        int bottom = Math.max(kHeight - top - 1, 0);
251        
252        // Calculate max sample values for clipping
253        int[] maxValue = src.getSampleModel().getSampleSize();
254        for (int i = 0; i < maxValue.length; i++)
255          maxValue[i] = (int)Math.pow(2, maxValue[i]) - 1;
256        
257        // process the region that is reachable...
258        int regionW = src.width - left - right;
259        int regionH = src.height - top - bottom;
260        float[] kvals = kernel.getKernelData(null);
261        float[] tmp = new float[kWidth * kHeight];
262    
263        for (int x = 0; x < regionW; x++)
264          {
265            for (int y = 0; y < regionH; y++)
266              {
267                // FIXME: This needs a much more efficient implementation
268                for (int b = 0; b < src.getNumBands(); b++)
269                {
270                  float v = 0;
271                  src.getSamples(x, y, kWidth, kHeight, b, tmp);
272                  for (int i = 0; i < tmp.length; i++)
273                    v += tmp[tmp.length - i - 1] * kvals[i];
274                    // FIXME: in the above line, I've had to reverse the order of 
275                    // the samples array to make the tests pass.  I haven't worked 
276                    // out why this is necessary.
277    
278                  // This clipping is is undocumented, but determined by testing.
279                  if (v > maxValue[b])
280                    v = maxValue[b];
281                  else if (v < 0)
282                    v = 0;
283    
284                  dest.setSample(x + kernel.getXOrigin(), y + kernel.getYOrigin(), 
285                                 b, v);
286                }
287              }
288          }
289        
290        // fill in the top border
291        fillEdge(src, dest, 0, 0, src.width, top, edge);
292        
293        // fill in the bottom border
294        fillEdge(src, dest, 0, src.height - bottom, src.width, bottom, edge);
295        
296        // fill in the left border
297        fillEdge(src, dest, 0, top, left, regionH, edge);
298        
299        // fill in the right border
300        fillEdge(src, dest, src.width - right, top, right, regionH, edge);
301        
302        return dest;  
303      }
304      
305      /**
306       * Fills a range of pixels (typically at the edge of a raster) with either
307       * zero values (if <code>edgeOp</code> is <code>EDGE_ZERO_FILL</code>) or the 
308       * corresponding pixel values from the source raster (if <code>edgeOp</code>
309       * is <code>EDGE_NO_OP</code>).  This utility method is called by the 
310       * {@link #fillEdge(Raster, WritableRaster, int, int, int, int, int)} method.
311       * 
312       * @param src  the source raster.
313       * @param dest  the destination raster.
314       * @param x  the x-coordinate of the top left pixel in the range.
315       * @param y  the y-coordinate of the top left pixel in the range.
316       * @param w  the width of the pixel range.
317       * @param h  the height of the pixel range.
318       * @param edgeOp  indicates how to determine the values for the range
319       *     (either {@link #EDGE_ZERO_FILL} or {@link #EDGE_NO_OP}).
320       */
321      private void fillEdge(Raster src, WritableRaster dest, int x, int y, int w, 
322                            int h, int edgeOp) 
323      {
324        if (w <= 0)
325          return;
326        if (h <= 0)
327          return;
328        if (edgeOp == EDGE_ZERO_FILL)  // fill region with zeroes
329          {
330            float[] zeros = new float[src.getNumBands() * w * h];
331            dest.setPixels(x, y, w, h, zeros); 
332          }
333        else  // copy pixels from source
334          {
335            float[] pixels = new float[src.getNumBands() * w * h];
336            src.getPixels(x, y, w, h, pixels);
337            dest.setPixels(x, y, w, h, pixels);
338          }
339      }
340    
341      /* (non-Javadoc)
342       * @see java.awt.image.RasterOp#createCompatibleDestRaster(java.awt.image.Raster)
343       */
344      public WritableRaster createCompatibleDestRaster(Raster src)
345      {
346        return src.createCompatibleWritableRaster();
347      }
348    
349      /* (non-Javadoc)
350       * @see java.awt.image.BufferedImageOp#getBounds2D(java.awt.image.BufferedImage)
351       */
352      public final Rectangle2D getBounds2D(BufferedImage src)
353      {
354        return src.getRaster().getBounds();
355      }
356    
357      /* (non-Javadoc)
358       * @see java.awt.image.RasterOp#getBounds2D(java.awt.image.Raster)
359       */
360      public final Rectangle2D getBounds2D(Raster src)
361      {
362        return src.getBounds();
363      }
364    
365      /**
366       * Returns the corresponding destination point for a source point. Because
367       * this is not a geometric operation, the destination and source points will
368       * be identical.
369       * 
370       * @param src The source point.
371       * @param dst The transformed destination point.
372       * @return The transformed destination point.
373       */
374      public final Point2D getPoint2D(Point2D src, Point2D dst)
375      {
376        if (dst == null) return (Point2D)src.clone();
377        dst.setLocation(src);
378        return dst;
379      }
380    }