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			296 lines
		
	
	
		
			9.9 KiB
		
	
	
	
		
			Java
		
	
	
	
			
		
		
	
	
			296 lines
		
	
	
		
			9.9 KiB
		
	
	
	
		
			Java
		
	
	
	
| /* BitwiseXORComposite.java -- Composite for emulating old-style XOR.
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|    Copyright (C) 2003, 2004  Free Software Foundation, Inc.
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| 
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| This file is part of GNU Classpath.
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| 
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| GNU Classpath is free software; you can redistribute it and/or modify
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| it under the terms of the GNU General Public License as published by
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| the Free Software Foundation; either version 2, or (at your option)
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| any later version.
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| 
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| GNU Classpath is distributed in the hope that it will be useful, but
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| WITHOUT ANY WARRANTY; without even the implied warranty of
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| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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| General Public License for more details.
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| 
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| You should have received a copy of the GNU General Public License
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| along with GNU Classpath; see the file COPYING.  If not, write to the
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| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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| 02110-1301 USA.
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| 
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| Linking this library statically or dynamically with other modules is
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| making a combined work based on this library.  Thus, the terms and
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| conditions of the GNU General Public License cover the whole
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| combination.
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| 
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| As a special exception, the copyright holders of this library give you
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| permission to link this library with independent modules to produce an
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| executable, regardless of the license terms of these independent
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| modules, and to copy and distribute the resulting executable under
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| terms of your choice, provided that you also meet, for each linked
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| independent module, the terms and conditions of the license of that
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| module.  An independent module is a module which is not derived from
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| or based on this library.  If you modify this library, you may extend
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| this exception to your version of the library, but you are not
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| obligated to do so.  If you do not wish to do so, delete this
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| exception statement from your version. */
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| 
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| 
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| package gnu.java.awt;
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| 
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| import java.awt.Color;
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| import java.awt.Composite;
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| import java.awt.CompositeContext;
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| import java.awt.Rectangle;
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| import java.awt.RenderingHints;
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| import java.awt.image.ColorModel;
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| import java.awt.image.DataBuffer;
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| import java.awt.image.Raster;
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| import java.awt.image.WritableRaster;
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| 
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| 
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| /**
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|  * A composite for emulating traditional bitwise XOR of pixel values.
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|  * Please note that this composite does <i>not</i> implement the Porter-Duff
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|  * XOR operator, but an exclusive or of overlapping subpixel regions.
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|  *
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|  * <p><img src="doc-files/BitwiseXORComposite-1.png" width="545"
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|  * height="138" alt="A screen shot of BitwiseXORComposite in action"
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|  * />
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|  *
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|  * <p>The above screen shot shows the result of applying six different
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|  * BitwiseXORComposites. They were constructed with the colors
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|  * white, blue, black, orange, green, and brown, respectively. Each
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|  * composite was used to paint a fully white rectangle on top of the
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|  * blue bar in the background.
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|  *
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|  * <p>The purpose of this composite is to support the {@link
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|  * Graphics#setXORMode(Color)} method in composite-aware graphics
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|  * implementations. Applications typically would use
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|  * <code>setXORMode</code> for drawing “highlights” such
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|  * as text selections or cursors by inverting colors temporarily and
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|  * then inverting them back.
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|  *
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|  * <p>A concrete <code>Graphics</code> implementation may contain
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|  * the following code:
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|  *
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|  * <p><pre> public void setXORMode(Color xorColor)
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|  * {
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|  *   setComposite(new gnu.java.awt.BitwiseXORComposite(xorColor));
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|  * }
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|  *
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|  * public void setPaintMode()
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|  * {
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|  *   setComposite(java.awt.AlphaComposite.SrcOver);
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|  * }</pre>
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|  *
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|  * @author Graydon Hoare (graydon@redhat.com)
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|  * @author Sascha Brawer (brawer@dandelis.ch)
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|  */
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| public class BitwiseXORComposite
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|   implements Composite
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| {
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|   /**
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|    * The color whose RGB value is xor-ed with the values of each
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|    * pixel.
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|    */
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|   protected Color xorColor;
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| 
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| 
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|   /**
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|    * Constructs a new composite for xor-ing the pixel value.
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|    *
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|    * @param xorColor the color whose pixel value will be bitwise
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|    * xor-ed with the source and destination pixels.
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|    */
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|   public BitwiseXORComposite(Color xorColor)
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|   {
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|     this.xorColor = xorColor;
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|   }
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| 
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| 
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|   /**
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|    * Creates a context object for performing the compositing
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|    * operation. Several contexts may co-exist for one composite; each
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|    * context may simultaneously be called from concurrent threads.
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|    *
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|    * @param srcColorModel the color model of the source.
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|    * @param dstColorModel the color model of the destination.
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|    * @param hints hints for choosing between rendering alternatives.
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|    */
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|   public CompositeContext createContext(ColorModel srcColorModel,
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|                                         ColorModel dstColorModel,
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|                                         RenderingHints hints)
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|   {
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|     if (IntContext.isSupported(srcColorModel, dstColorModel, hints))
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|       return new IntContext(srcColorModel, xorColor);
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| 
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|     return new GeneralContext(srcColorModel, dstColorModel, xorColor);
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|   }
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| 
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| 
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|   /**
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|    * A fallback CompositeContext that performs bitwise XOR of pixel
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|    * values with the pixel value of the specified <code>xorColor</code>.
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|    *
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|    * <p>Applying this CompositeContext on a 1024x1024 BufferedImage of
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|    * <code>TYPE_INT_RGB</code> took 611 ms on a lightly loaded 2.4 GHz
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|    * Intel Pentium 4 CPU running Sun J2SE 1.4.1_01 on GNU/Linux
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|    * 2.4.20. The timing is the average of ten runs on the same
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|    * BufferedImage. Since the measurements were taken with {@link
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|    * System#currentTimeMillis()}, they are rather inaccurate.
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|    *
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|    * @author Graydon Hoare (graydon@redhat.com)
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|    */
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|   private static class GeneralContext
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|     implements CompositeContext
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|   {
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|     ColorModel srcColorModel;
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|     ColorModel dstColorModel;
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|     Color xorColor;
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| 
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|     public GeneralContext(ColorModel srcColorModel,
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|                           ColorModel dstColorModel,
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|                           Color xorColor)
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|     {
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|       this.srcColorModel = srcColorModel;
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|       this.dstColorModel = dstColorModel;
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|       this.xorColor = xorColor;
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|     }
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| 
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| 
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|     public void compose(Raster src, Raster dstIn, WritableRaster dstOut)
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|     {
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|       Rectangle srcRect = src.getBounds();
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|       Rectangle dstInRect = dstIn.getBounds();
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|       Rectangle dstOutRect = dstOut.getBounds();
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| 
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|       int xp = xorColor.getRGB();
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|       int w = Math.min(Math.min(srcRect.width, dstOutRect.width),
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|                        dstInRect.width);
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|       int h = Math.min(Math.min(srcRect.height, dstOutRect.height),
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|                        dstInRect.height);
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| 
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|       Object srcPix = null, dstPix = null, rpPix = null;
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| 
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|       // Re-using the rpPix object saved 1-2% of execution time in
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|       // the 1024x1024 pixel benchmark.
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| 
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|       for (int y = 0; y < h; y++)
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|       {
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|         for (int x = 0; x < w; x++)
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|         {
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|           srcPix = src.getDataElements(x + srcRect.x, y + srcRect.y, srcPix);
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|           dstPix = dstIn.getDataElements(x + dstInRect.x, y + dstInRect.y,
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|                                          dstPix);
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|           int sp = srcColorModel.getRGB(srcPix);
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|           int dp = dstColorModel.getRGB(dstPix);
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|           int rp = sp ^ xp ^ dp;
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|           dstOut.setDataElements(x + dstOutRect.x, y + dstOutRect.y,
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|                                  dstColorModel.getDataElements(rp, rpPix));
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|         }
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|       }
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|     }
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| 
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| 
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|     /**
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|      * Disposes any cached resources. The default implementation does
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|      * nothing because no resources are cached.
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|      */
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|     public void dispose()
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|     {
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|     }
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|   }
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| 
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| 
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|   /**
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|    * An optimized CompositeContext that performs bitwise XOR of
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|    * <code>int</code> pixel values with the pixel value of a specified
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|    * <code>xorColor</code>.  This CompositeContext working only for
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|    * rasters whose transfer format is {@link DataBuffer#TYPE_INT}.
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|    *
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|    * <p>Applying this CompositeContext on a 1024x1024 BufferedImage of
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|    * <code>TYPE_INT_RGB</code> took 69 ms on a lightly loaded 2.4 GHz
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|    * Intel Pentium 4 CPU running Sun J2SE 1.4.1_01 on GNU/Linux
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|    * 2.4.20. The timing is the average of ten runs on the same
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|    * BufferedImage. Since the measurements were taken with {@link
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|    * System#currentTimeMillis()}, they are rather inaccurate.
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|    *
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|    * @author Sascha Brawer (brawer@dandelis.ch)
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|    */
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|   private static class IntContext
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|     extends GeneralContext
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|   {
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|     public IntContext(ColorModel colorModel, Color xorColor)
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|     {
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|       super(colorModel, colorModel, xorColor);
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|     }
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| 
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| 
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|     public void compose(Raster src, Raster dstIn,
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|                         WritableRaster dstOut)
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|     {
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|       int aX, bX, dstX, aY, bY, dstY, width, height;
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|       int xorPixel;
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|       int[] srcLine, dstLine;
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| 
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|       aX = src.getMinX();
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|       aY = src.getMinY();
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|       bX = dstIn.getMinX();
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|       bY = dstIn.getMinY();
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|       dstX = dstOut.getMinX();
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|       dstY = dstOut.getMinY();
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|       width = Math.min(Math.min(src.getWidth(), dstIn.getWidth()),
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|                        dstOut.getWidth());
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|       height = Math.min(Math.min(src.getHeight(), dstIn.getHeight()),
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|                         dstOut.getHeight());
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|       if ((width < 1) || (height < 1))
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|         return;
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| 
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|       srcLine = new int[width];
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|       dstLine = new int[width];
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| 
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|       /* We need an int[] array with at least one element here;
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|        * srcLine is as good as any other.
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|        */
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|       srcColorModel.getDataElements(this.xorColor.getRGB(), srcLine);
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|       xorPixel = srcLine[0];
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| 
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|       for (int y = 0; y < height; y++)
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|       {
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|         src.getDataElements(aX, y + aY, width, 1, srcLine);
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|         dstIn.getDataElements(bX, y + bY, width, 1, dstLine);
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| 
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|         for (int x = 0; x < width; x++)
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|           dstLine[x] ^= srcLine[x] ^ xorPixel;
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| 
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|         dstOut.setDataElements(dstX, y + dstY, width, 1, dstLine);
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|       }
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|     }
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| 
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| 
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|     /**
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|      * Determines whether an instance of this CompositeContext would
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|      * be able to process the specified color models.
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|      */
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|     public static boolean isSupported(ColorModel srcColorModel,
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|                                       ColorModel dstColorModel,
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|                                       RenderingHints hints)
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|     {
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|       // FIXME: It would be good if someone could review these checks.
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|       // They probably need to be more restrictive.
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| 
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|       int transferType;
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| 
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|       transferType = srcColorModel.getTransferType();
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|       if (transferType != dstColorModel.getTransferType())
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|         return false;
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| 
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|       if (transferType != DataBuffer.TYPE_INT)
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|         return false;
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| 
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|       return true;
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|     }
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|   }
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| }
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