Re: [PATCH] GrayFilter cache

[Roman Kennke]

Hi Oleg,

> I'm not a swing developer, but I'd suggest to not use static field for 
> cache, but have per-AppContext cache instead (due to security reasons) 

Whoops. I have to get used to that .. Improved patch attached.

Cheers, Roman


-- 
Dipl.-Inform. (FH) Roman Kennke, Software Engineer, http://kennke.org
aicas Allerton Interworks Computer Automated Systems GmbH
Haid-und-Neu-Straße 18 * D-76131 Karlsruhe * Germany
http://www.aicas.com   * Tel: +49-721-663 968-0
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Geschäftsführer: Dr. James J. Hunt

diff -r a36c38fe9ff1 src/share/classes/javax/swing/GrayFilter.java
--- a/src/share/classes/javax/swing/GrayFilter.java	Tue Apr 22 16:57:20 2008 +0200
+++ b/src/share/classes/javax/swing/GrayFilter.java	Wed Apr 23 15:18:48 2008 +0200
@@ -26,6 +26,11 @@ package javax.swing;
 
 import java.awt.*;
 import java.awt.image.*;
+import java.util.Collections;
+import java.util.Map;
+import java.util.WeakHashMap;
+
+import sun.awt.AppContext;
 
 /**
  * An image filter that "disables" an image by turning
@@ -38,6 +43,10 @@ import java.awt.image.*;
  * @author      Jim Graham
  */
 public class GrayFilter extends RGBImageFilter {
+
+    private final static Object GRAY_IMAGE_CACHE_KEY =
+        new StringBuilder("GRAY_IMAGE_CACHE_KEY");
+
     private boolean brighter;
     private int percent;
 
@@ -45,10 +54,41 @@ public class GrayFilter extends RGBImage
      * Creates a disabled image
      */
     public static Image createDisabledImage (Image i) {
-        GrayFilter filter = new GrayFilter(true, 50);
-        ImageProducer prod = new FilteredImageSource(i.getSource(), filter);
-        Image grayImage = Toolkit.getDefaultToolkit().createImage(prod);
+        Image grayImage;
+        Map<Image,Image> grayImageCache = getGrayImageCache();
+        Image cached = grayImageCache.get(i);
+        if (cached == null) {
+            GrayFilter filter = new GrayFilter(true, 50);
+            ImageProducer prod = new FilteredImageSource(i.getSource(),
+                    filter);
+            grayImage = Toolkit.getDefaultToolkit().createImage(prod);
+            grayImageCache.put(i, grayImage);
+        } else {
+            grayImage = cached;
+        }
         return grayImage;
+    }
+
+    /**
+     * Returns the gray image cache from the current app context. Creates
+     * a new one, if the current app context doesn't have a cache already.
+     *
+     * @return the gray image cache from the current app context
+     */
+    private static Map<Image,Image> getGrayImageCache() {
+
+        AppContext ctx = AppContext.getAppContext();
+        Object cacheObj;
+        synchronized (ctx) {
+            cacheObj = ctx.get(GRAY_IMAGE_CACHE_KEY);
+            if (cacheObj == null) {
+                WeakHashMap<Image,Image> map = new WeakHashMap<Image,Image>();
+                cacheObj = Collections.synchronizedMap(map);
+                ctx.put(GRAY_IMAGE_CACHE_KEY, cacheObj);
+            }
+        }
+
+        return (WeakHashMap<Image,Image>) cacheObj;
     }
 
     /**