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    1   /*
    2    * Copyright (c) 1997, 1998, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   package javax.swing;
   26   
   27   import java.awt;
   28   import java.awt.image;
   29   
   30   /**
   31    * An image filter that "disables" an image by turning
   32    * it into a grayscale image, and brightening the pixels
   33    * in the image. Used by buttons to create an image for
   34    * a disabled button.
   35    *
   36    * @author      Jeff Dinkins
   37    * @author      Tom Ball
   38    * @author      Jim Graham
   39    */
   40   public class GrayFilter extends RGBImageFilter {
   41       private boolean brighter;
   42       private int percent;
   43   
   44       /**
   45        * Creates a disabled image
   46        */
   47       public static Image createDisabledImage (Image i) {
   48           GrayFilter filter = new GrayFilter(true, 50);
   49           ImageProducer prod = new FilteredImageSource(i.getSource(), filter);
   50           Image grayImage = Toolkit.getDefaultToolkit().createImage(prod);
   51           return grayImage;
   52       }
   53   
   54       /**
   55        * Constructs a GrayFilter object that filters a color image to a
   56        * grayscale image. Used by buttons to create disabled ("grayed out")
   57        * button images.
   58        *
   59        * @param b  a boolean -- true if the pixels should be brightened
   60        * @param p  an int in the range 0..100 that determines the percentage
   61        *           of gray, where 100 is the darkest gray, and 0 is the lightest
   62        */
   63       public GrayFilter(boolean b, int p) {
   64           brighter = b;
   65           percent = p;
   66   
   67           // canFilterIndexColorModel indicates whether or not it is acceptable
   68           // to apply the color filtering of the filterRGB method to the color
   69           // table entries of an IndexColorModel object in lieu of pixel by pixel
   70           // filtering.
   71           canFilterIndexColorModel = true;
   72       }
   73   
   74       /**
   75        * Overrides <code>RGBImageFilter.filterRGB</code>.
   76        */
   77       public int filterRGB(int x, int y, int rgb) {
   78           // Use NTSC conversion formula.
   79           int gray = (int)((0.30 * ((rgb >> 16) & 0xff) +
   80                            0.59 * ((rgb >> 8) & 0xff) +
   81                            0.11 * (rgb & 0xff)) / 3);
   82   
   83           if (brighter) {
   84               gray = (255 - ((255 - gray) * (100 - percent) / 100));
   85           } else {
   86               gray = (gray * (100 - percent) / 100);
   87           }
   88   
   89           if (gray < 0) gray = 0;
   90           if (gray > 255) gray = 255;
   91           return (rgb & 0xff000000) | (gray << 16) | (gray << 8) | (gray << 0);
   92       }
   93   }

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