1 /*
   2  * Copyright (c) 1997, 2014, 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  * @since 1.2
  40  */
  41 public class GrayFilter extends RGBImageFilter {
  42     private boolean brighter;
  43     private int percent;
  44 
  45     /**
  46      * Creates a disabled image
  47      *
  48      * @param i  an {@code Image} to be created as disabled
  49      * @return  the new grayscale image created from {@code i}
  50      */
  51     public static Image createDisabledImage (Image i) {
  52         GrayFilter filter = new GrayFilter(true, 50);
  53         ImageProducer prod = new FilteredImageSource(i.getSource(), filter);
  54         Image grayImage = Toolkit.getDefaultToolkit().createImage(prod);
  55         return grayImage;
  56     }
  57 
  58     /**
  59      * Constructs a GrayFilter object that filters a color image to a
  60      * grayscale image. Used by buttons to create disabled ("grayed out")
  61      * button images.
  62      *
  63      * @param b  a boolean -- true if the pixels should be brightened
  64      * @param p  an int in the range 0..100 that determines the percentage
  65      *           of gray, where 100 is the darkest gray, and 0 is the lightest
  66      */
  67     public GrayFilter(boolean b, int p) {
  68         brighter = b;
  69         percent = p;
  70 
  71         // canFilterIndexColorModel indicates whether or not it is acceptable
  72         // to apply the color filtering of the filterRGB method to the color
  73         // table entries of an IndexColorModel object in lieu of pixel by pixel
  74         // filtering.
  75         canFilterIndexColorModel = true;
  76     }
  77 
  78     /**
  79      * Overrides <code>RGBImageFilter.filterRGB</code>.
  80      */
  81     public int filterRGB(int x, int y, int rgb) {
  82         // Use NTSC conversion formula.
  83         int gray = (int)((0.30 * ((rgb >> 16) & 0xff) +
  84                          0.59 * ((rgb >> 8) & 0xff) +
  85                          0.11 * (rgb & 0xff)) / 3);
  86 
  87         if (brighter) {
  88             gray = (255 - ((255 - gray) * (100 - percent) / 100));
  89         } else {
  90             gray = (gray * (100 - percent) / 100);
  91         }
  92 
  93         if (gray < 0) gray = 0;
  94         if (gray > 255) gray = 255;
  95         return (rgb & 0xff000000) | (gray << 16) | (gray << 8) | (gray << 0);
  96     }
  97 }