001    /* ImageFilter.java -- Java class for filtering images
002       Copyright (C) 1999 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    import java.util.Hashtable;
042    
043    /**
044     * The <code>ImageFilter</code> class is a base class which can be
045     * extended to provide different types of filters for an image.  By
046     * default this class does nothing to an image passing through it.
047     *
048     * @author C. Brian Jones (cbj@gnu.org)
049     */
050    public class ImageFilter implements ImageConsumer, Cloneable
051    {
052      /**
053       * The consumer this filter is filtering an image data stream for.
054       * It is initialized in the method <code>getFilterInstance</code>.
055       */
056      protected ImageConsumer consumer = null;
057    
058      /**
059       * The <code>ImageConsumer</code> can use this method to request
060       * the pixels be delivered in top-down, left-right order.
061       * <br>
062       * The filter can respond in three different ways.
063       * <ul>
064       *   <li>The default behavior is to forward the request to the
065       *       <code>ImageProducer</code>
066       *       using the method <code>requestTopDownLeftRightResend</code>
067       *       and using the filter as the consumer.</li>
068       *   <li>The filter has the pixels and can retransmit them in the
069       *       top-down, left-right order.</li>
070       *   <li>The filter can do nothing when this method is called.</li>
071       * </ul>
072       */
073      public void resendTopDownLeftRight(ImageProducer ip)
074      {
075        ip.requestTopDownLeftRightResend(this);
076      }
077    
078      /**
079       * By default, returns a shallow copy of the object created by
080       * <code>Object.clone()</code>
081       *
082       * @see java.lang.Object#clone ()
083       */
084      public Object clone()
085      {
086        try
087          {
088            return super.clone();
089          }
090        catch (CloneNotSupportedException e)
091          {
092            // This should never happen as this class implements the
093            // Cloneable interface.
094            throw new InternalError ();
095          }
096      }
097    
098      /**
099       * This is the only method which can set the
100       * <code>ImageConsumer</code> for this filter.  By default a clone
101       * of this filter with the appropriate consumer set is returned.
102       *
103       * @see #clone ()
104       */
105      public ImageFilter getFilterInstance(ImageConsumer ic)
106      {
107        ImageFilter f = (ImageFilter)clone();
108        f.consumer = ic;
109        return f;
110      }
111    
112      /**
113       * An <code>ImageProducer</code> indicates the size of the image
114       * being produced using this method.  A filter can override this
115       * method to intercept these calls from the producer in order to
116       * change either the width or the height before in turn calling
117       * the consumer's <code>setDimensions</code> method.
118       *
119       * @param width the width of the image
120       * @param height the height of the image
121       */
122      public void setDimensions(int width, int height)
123      {
124        consumer.setDimensions(width, height);
125      }
126    
127      /**
128       * An <code>ImageProducer</code> can set a list of properties
129       * associated with this image by using this method.
130       *
131       * @param props the list of properties associated with this image
132       */
133      public void setProperties(Hashtable<?,?> props)
134      {
135        Hashtable copy = (Hashtable) props.clone();
136        Object o = copy.get("filters");
137        if (o == null)
138          copy.put("filters", toString());
139        else if (o instanceof String)
140          copy.put("filters", ((String) o) + toString());
141    
142        consumer.setProperties(copy);
143      }
144    
145      /**
146       * Override this method to process calls to this method from the
147       * <code>ImageProducer</code>.  By default the <code>setColorModel</code>
148       * method of the consumer is called with the specified <code>model</code>.
149       *
150       * @param model the color model to be used most often by setPixels
151       *
152       * @see ColorModel
153       */
154      public void setColorModel(ColorModel model)
155      {
156        consumer.setColorModel(model);
157      }
158    
159      /**
160       * The <code>ImageProducer</code> should call this method with a
161       * bit mask of hints from any of <code>RANDOMPIXELORDER</code>,
162       * <code>TOPDOWNLEFTRIGHT</code>, <code>COMPLETESCANLINES</code>,
163       * <code>SINGLEPASS</code>, <code>SINGLEFRAME</code> from the
164       * <code>ImageConsumer</code> interface.
165       *
166       * @param flags a bit mask of hints
167       * @see ImageConsumer
168       */
169      public void setHints(int flags)
170      {
171        consumer.setHints(flags);
172      }
173    
174      /**
175       * This function delivers a rectangle of pixels where any
176       * pixel(m,n) is stored in the array as a <code>byte</code> at
177       * index (n * scansize + m + offset).
178       *
179       * @param x the x coordinate of the rectangle
180       * @param y the y coordinate of the rectangle
181       * @param w the width of the rectangle
182       * @param h the height of the rectangle
183       * @param model the <code>ColorModel</code> used to translate the pixels
184       * @param pixels the array of pixel values
185       * @param offset the index of the first pixels in the <code>pixels</code> array
186       * @param scansize the width to use in extracting pixels from the <code>pixels</code> array
187       */
188      public void setPixels(int x, int y, int w, int h,
189                            ColorModel model, byte[] pixels, int offset,
190                            int scansize)
191      {
192        consumer.setPixels(x, y, w, h, model, pixels, offset, scansize);
193      }
194    
195      /**
196       * This function delivers a rectangle of pixels where any
197       * pixel(m,n) is stored in the array as an <code>int</code> at
198       * index (n * scansize + m + offset).
199       *
200       * @param x the x coordinate of the rectangle
201       * @param y the y coordinate of the rectangle
202       * @param w the width of the rectangle
203       * @param h the height of the rectangle
204       * @param model the <code>ColorModel</code> used to translate the pixels
205       * @param pixels the array of pixel values
206       * @param offset the index of the first pixels in the <code>pixels</code> array
207       * @param scansize the width to use in extracting pixels from the <code>pixels</code> array
208       */
209      public void setPixels(int x, int y, int w, int h,
210                            ColorModel model, int[] pixels, int offset,
211                            int scansize)
212      {
213        consumer.setPixels(x, y, w, h, model, pixels, offset, scansize);
214      }
215    
216      /**
217       * The <code>ImageProducer</code> calls this method to indicate a
218       * single frame or the entire image is complete.  The method is
219       * also used to indicate an error in loading or producing the
220       * image.
221       */
222      public void imageComplete(int status)
223      {
224        consumer.imageComplete(status);
225      }
226    }