src/org/xwt/Picture.java

   1 // Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
   2 package org.xwt;
   3 import java.io.*;
   4 import org.xwt.js.*;
   5 import org.xwt.util.*;
   6 import org.xwt.translators.*;
   7
   8 /**
   9  *    <p>
  10  *    The in-memory representation of a PNG or GIF image. It is
  11  *    read-only. It is usually passed to PixelBuffer.drawPicture()
  12  *    </p>
  13  *
  14  *    <p>
  15  *    Implementations of the Platform class should return objects
  16  *    supporting this interface from the createPicture() method. These
  17  *    implementations may choose to implement caching strategies (for
  18  *    example, using a Pixmap on X11).
  19  *    </p>
  20  */
  21 public abstract class Picture {
  22
  23     /** the resource that created this Picture */
  24     public Res res = null;
  25
  26     /** the height of the picture */
  27     public abstract int getHeight();
  28
  29     /** the width of the picture */
  30     public abstract int getWidth();
  31
  32     /** Pictures, cache keyed by Res instance */
  33     private static Cache cache = new Cache(100);
  34     private static GIF gif = new GIF();
  35
  36     public static class Holder {
  37         public Picture picture = null;
  38     }
  39
  40     /** turns a resource into a Picture.Source and passes it to the callback */
  41     public static Holder fromRes(final Res r, final Scheduler.Task callback) {
  42         Holder ret = (Holder)cache.get(r);
  43         if (ret == null) {
  44             ret = new Holder();
  45             cache.put(r, ret);
  46             if (callback == null) return null;
  47         }
  48         final Holder holder = ret;
  49         if (callback != null)
  50             new java.lang.Thread() { public void run() {
  51                 try {
  52                     final byte[] b = InputStreamToByteArray.convert(r.getInputStream());
  53                     Scheduler.add(new Scheduler.Task() { public void perform() {
  54                         try {
  55                             Picture p = null;
  56                             InputStream pbis = new ByteArrayInputStream(b);
  57                             if ((b[0] & 0xff) == 'G') p = gif.fromInputStream(pbis, "some picture");
  58                             else if ((b[0] & 0xff) == 137) p = new PNG().fromInputStream(pbis, "some picture");
  59                             else if ((b[0] & 0xff) == 0xff) p = Platform.decodeJPEG(pbis, "some picture");
  60                             else throw new JSExn("couldn't figure out image type from first byte");
  61                             p.res = r;
  62                             holder.picture = p;
  63                             Scheduler.add(callback);
  64                         } catch (Exception e) {
  65                             Log.log(Picture.class, e);
  66                         } } });
  67                 } catch (IOException e) {
  68                     Log.log(Picture.class, e);
  69                     return;
  70                 }
  71             } }.start();
  72         return ret;
  73     }
  74 }