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 
 109         if (image == null) {
 110             image = new PainterMultiResolutionCachedImage(c, w, h, args);
 111             cache.setImage(key, config, w, h, args, image);
 112         }
 113 
 114         // Render to the passed in Graphics
 115         paintImage(c, g, x, y, w, h, image, args);
 116     }
 117 
 118     /**
 119      * Paints the representation to cache to the supplied Graphics.
 120      *
 121      * @param c Component painting to, may be null.
 122      * @param image Image to paint to
 123      * @param g Graphics to paint to, obtained from the passed in Image.
 124      * @param w Width to paint to
 125      * @param h Height to paint to
 126      * @param args Arguments supplied to <code>paint</code>
 127      */
 128     protected abstract void paintToImage(Component c, Image image, Graphics g,
 129                                          int w, int h, Object[] args);
 130 
 131 
 132     /**
 133      * Paints the image to the specified location.
 134      *
 135      * @param c Component painting to
 136      * @param g Graphics to paint to
 137      * @param x X coordinate to paint to
 138      * @param y Y coordinate to paint to
 139      * @param w Width to paint to
 140      * @param h Height to paint to
 141      * @param image Image to paint
 142      * @param args Arguments supplied to <code>paint</code>
 143      */
 144     protected void paintImage(Component c, Graphics g,
 145                               int x, int y, int w, int h, Image image,
 146                               Object[] args) {
 147         g.drawImage(image, x, y, null);
 148     }
 149 
 150     /**
 151      * Creates the image to cache.  This returns an opaque image, subclasses
 152      * that require translucency or transparency will need to override this
 153      * method.
 154      *
 155      * @param c Component painting to
 156      * @param w Width of image to create
 157      * @param h Height to image to create
 158      * @param config GraphicsConfiguration that will be
 159      *        rendered to, this may be null.
 160      * @param args Arguments passed to paint
 161      */
 162     protected Image createImage(Component c, int w, int h,
 163                                 GraphicsConfiguration config, Object[] args) {
 164         if (config == null) {
 165             return new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
 166         }
 167         return config.createCompatibleVolatileImage(w, h);
 168     }
 169 
 170     /**
 171      * Clear the image cache
 172      */
 173     protected void flush() {
 174         synchronized(CachedPainter.class) {
 175             getCache(getClass()).flush();
 176         }
 177     }
 178 
 179     private GraphicsConfiguration getGraphicsConfiguration(Component c) {
 180         if (c == null) {
 181             return null;
 182         }
 183         return c.getGraphicsConfiguration();
 184     }
 185 
 186     class PainterMultiResolutionCachedImage extends AbstractMultiResolutionImage {
 187 
 188         private final int baseWidth;
 189         private final int baseHeight;
 190         private final Component c;
 191         private final Object[] args;
 192 
 193         public PainterMultiResolutionCachedImage(Component c, int w, int h,
 194                                                  Object[] args) {
 195             this.c = c;
 196             this.args = args;
 197             this.baseWidth = w;
 198             this.baseHeight = h;
 199         }
 200 
 201         @Override
 202         public Image getResolutionVariant(double destWidth, double destHeight) {
 203 
 204             int w = (int) Math.ceil(destWidth);
 205             int h = (int) Math.ceil(destHeight);
 206 
 207             Object key = this;
 208             GraphicsConfiguration config = getGraphicsConfiguration(c);
 209             ImageCache cache = getCache(key);
 210             Image image = cache.getImage(key, config, w, h, args);
 211             int attempts = 0;
 212             do {
 213                 boolean draw = false;
 214                 if (image instanceof VolatileImage) {
 215                     // See if we need to recreate the image
 216                     switch (((VolatileImage) image).validate(config)) {
 217                         case VolatileImage.IMAGE_INCOMPATIBLE:
 218                             ((VolatileImage) image).flush();
 219                             image = null;
 220                             break;
 221                         case VolatileImage.IMAGE_RESTORED:
 222                             draw = true;
 223                             break;
 224                     }
 225                 }
 226                 if (image == null) {
 227                     // Recreate the image
 228                     image = createImage(c, w, h, config, args);
 229                     cache.setImage(key, config, w, h, args, image);
 230                     draw = true;
 231                 }
 232                 if (draw) {
 233                     // Render to the Image
 234                     Graphics g2 = image.getGraphics();
 235                     paintToImage(c, image, g2, w, h, args);
 236                     g2.dispose();
 237                 }
 238 
 239                 // If we did this 3 times and the contents are still lost
 240                 // assume we're painting to a VolatileImage that is bogus and
 241                 // give up.  Presumably we'll be called again to paint.
 242             } while ((image instanceof VolatileImage)
 243                     && ((VolatileImage) image).contentsLost() && ++attempts < 3);
 244 
 245             return image;
 246         }
 247 
 248         @Override
 249         protected Image getBaseImage() {
 250             return getResolutionVariant(baseWidth, baseHeight);
 251         }
 252 
 253         @Override
 254         public java.util.List<Image> getResolutionVariants() {
 255             return Arrays.asList(
 256                     getResolutionVariant(baseWidth, baseHeight),
 257                     getResolutionVariant(2 * baseWidth, 2 * baseHeight)
 258             );
 259         }
 260     }
 261 }