1 /*
   2  * Copyright (c) 2004, 2015, 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 sun.swing;
  26 
  27 import java.awt.*;

  28 import java.awt.image.*;
  29 import java.util.*;
  30 
  31 /**
  32  * A base class used for icons or images that are expensive to paint.
  33  * A subclass will do the following:
  34  * <ol>
  35  * <li>Invoke <code>paint</code> when you want to paint the image,
  36  *     if you are implementing <code>Icon</code> you'll invoke this from
  37  *     <code>paintIcon</code>.
  38  *     The args argument is useful when additional state is needed.
  39  * <li>Override <code>paintToImage</code> to render the image.  The code that
  40  *     lives here is equivalent to what previously would go in
  41  *     <code>paintIcon</code>, for an <code>Icon</code>.
  42  * </ol>
  43  * The two ways to use this class are:
  44  * <ol>
  45  * <li>Invoke <code>paint</code> to draw the cached reprensentation at
  46  *     the specified location.
  47  * <li>Invoke <code>getImage</code> to get the cached reprensentation and
  48  *     draw the image yourself.  This is primarly useful when you are not
  49  *     using <code>VolatileImage</code>.
  50  * </ol>
  51  *
  52  *
  53  */
  54 public abstract class CachedPainter {
  55     // CacheMap maps from class to ImageCache.
  56     private static final Map<Object,ImageCache> cacheMap = new HashMap<>();
  57 
  58     private static ImageCache getCache(Object key) {
  59         synchronized(CachedPainter.class) {
  60             ImageCache cache = cacheMap.get(key);
  61             if (cache == null) {
  62                 cache = new ImageCache(1);
  63                 cacheMap.put(key, cache);
  64             }
  65             return cache;
  66         }
  67     }
  68 
  69     /**
  70      * Creates an instance of <code>CachedPainter</code> that will cache up
  71      * to <code>cacheCount</code> images of this class.
  72      *
  73      * @param cacheCount Max number of images to cache
  74      */
  75     public CachedPainter(int cacheCount) {
  76         getCache(getClass()).setMaxCount(cacheCount);
  77     }
  78 
  79     /**
  80      * Renders the cached image to the passed in <code>Graphic</code>.
  81      * If there is no cached image <code>paintToImage</code> will be invoked.
  82      * <code>paintImage</code> is invoked to paint the cached image.
  83      *
  84      * @param c Component rendering to, this may be null.
  85      * @param g Graphics to paint to
  86      * @param x X-coordinate to render to
  87      * @param y Y-coordinate to render to
  88      * @param w Width to render in
  89      * @param h Height to render in
  90      * @param args Variable arguments that will be passed to paintToImage
  91      */
  92     public void paint(Component c, Graphics g, int x,
  93                          int y, int w, int h, Object... args) {
  94         if (w <= 0 || h <= 0) {
  95             return;
  96         }
  97         synchronized (CachedPainter.class) {
  98             paint0(c, g, x, y, w, h, args);
  99         }
 100     }
 101 
 102     private void paint0(Component c, Graphics g, int x,
 103                          int y, int w, int h, Object... args) {
 104         Object key = getClass();
 105         GraphicsConfiguration config = getGraphicsConfiguration(c);
 106         ImageCache cache = getCache(key);
 107         Image image = cache.getImage(key, config, w, h, args);
 108         int attempts = 0;
 109         do {
 110             boolean draw = false;
 111             if (image instanceof VolatileImage) {
 112                 // See if we need to recreate the image
 113                 switch (((VolatileImage)image).validate(config)) {
 114                 case VolatileImage.IMAGE_INCOMPATIBLE:
 115                     ((VolatileImage)image).flush();
 116                     image = null;
 117                     break;
 118                 case VolatileImage.IMAGE_RESTORED:
 119                     draw = true;
 120                     break;
 121                 }
 122             }
 123             if (image == null) {
 124                 // Recreate the image
 125                 image = createImage(c, w, h, config, args);
 126                 cache.setImage(key, config, w, h, args, image);
 127                 draw = true;
 128             }
 129             if (draw) {
 130                 // Render to the Image
 131                 Graphics g2 = image.getGraphics();
 132                 paintToImage(c, image, g2, w, h, args);
 133                 g2.dispose();
 134             }
 135 
 136             // Render to the passed in Graphics
 137             paintImage(c, g, x, y, w, h, image, args);
 138 
 139             // If we did this 3 times and the contents are still lost
 140             // assume we're painting to a VolatileImage that is bogus and
 141             // give up.  Presumably we'll be called again to paint.
 142         } while ((image instanceof VolatileImage) &&
 143                  ((VolatileImage)image).contentsLost() && ++attempts < 3);





























 144     }
 145 
 146     /**
 147      * Paints the representation to cache to the supplied Graphics.
 148      *
 149      * @param c Component painting to, may be null.
 150      * @param image Image to paint to
 151      * @param g Graphics to paint to, obtained from the passed in Image.
 152      * @param w Width to paint to
 153      * @param h Height to paint to
 154      * @param args Arguments supplied to <code>paint</code>
 155      */
 156     protected abstract void paintToImage(Component c, Image image, Graphics g,
 157                                          int w, int h, Object[] args);
 158 
 159 
 160     /**
 161      * Paints the image to the specified location.
 162      *
 163      * @param c Component painting to
 164      * @param g Graphics to paint to
 165      * @param x X coordinate to paint to
 166      * @param y Y coordinate to paint to
 167      * @param w Width to paint to
 168      * @param h Height to paint to
 169      * @param image Image to paint
 170      * @param args Arguments supplied to <code>paint</code>
 171      */
 172     protected void paintImage(Component c, Graphics g,
 173                               int x, int y, int w, int h, Image image,
 174                               Object[] args) {
 175         g.drawImage(image, x, y, null);
 176     }
 177 
 178     /**
 179      * Creates the image to cache.  This returns an opaque image, subclasses
 180      * that require translucency or transparency will need to override this
 181      * method.
 182      *
 183      * @param c Component painting to
 184      * @param w Width of image to create
 185      * @param h Height to image to create
 186      * @param config GraphicsConfiguration that will be
 187      *        rendered to, this may be null.
 188      * @param args Arguments passed to paint
 189      */
 190     protected Image createImage(Component c, int w, int h,
 191                                 GraphicsConfiguration config, Object[] args) {
 192         if (config == null) {
 193             return new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
 194         }
 195         return config.createCompatibleVolatileImage(w, h);
 196     }
 197 
 198     /**
 199      * Clear the image cache
 200      */
 201     protected void flush() {
 202         synchronized(CachedPainter.class) {
 203             getCache(getClass()).flush();
 204         }
 205     }
 206 
 207     private GraphicsConfiguration getGraphicsConfiguration(Component c) {
 208         if (c == null) {
 209             return null;
 210         }
 211         return c.getGraphicsConfiguration();
 212     }


























































 213 }
--- EOF ---