libjava/gnu/gcj/xlib/Drawable.java

   1 /* Copyright (C) 1999, 2000  Free Software Foundation
   2
   3    This file is part of libgcj.
   4
   5 This software is copyrighted work licensed under the terms of the
   6 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   7 details.  */
   8
   9 package gnu.gcj.xlib;
  10
  11 import java.awt.Rectangle;
  12
  13 /** An X11 drawable.
  14  *
  15  * @author Rolf W. Rasmussen <rolfwr@ii.uib.no>
  16  */
  17 public class Drawable extends XID
  18 {
  19   private GC[] gcCache = new GC[10];
  20   private int gcCachedCount = 0;
  21
  22   public Drawable(Display display, int xid)
  23   {
  24     super(display, xid);
  25   }
  26
  27   /**
  28    * Gets as much as possible of the image data within the requested
  29    * region. Data from obscured parts of windows may not be
  30    * retrievable.
  31    *
  32    * @param dest where to place the image data.
  33    *
  34    * @return the actual region of image data that was retrieved.
  35    */
  36   public Rectangle copyIntoXImage(XImage dest, Rectangle bounds,
  37                                   int destX, int destY)
  38   {
  39     Rectangle newBounds = null;
  40     int tries = 5;
  41     while (!bounds.isEmpty())
  42       {
  43         if (copyIntoXImageImpl(dest, bounds.x, bounds.y,
  44                                bounds.width, bounds.height,
  45                                destX, destY))
  46           return bounds;
  47
  48         // failed, likely due to wrong bounds...
  49
  50         newBounds = getBounds(newBounds);
  51
  52         bounds = newBounds.intersection(bounds);
  53
  54         tries--;
  55
  56         if (tries < 0)
  57         throw new RuntimeException("copyIntoXImage is buggy");
  58
  59       }
  60
  61     return bounds; // always empty
  62   }
  63
  64
  65
  66   /**
  67    * Performs an XGetSubImage. This method will fail if the X server
  68    * does not possess the requested image data. This might occur when
  69    * requesting the image date of a window that is partially obscured.
  70    *
  71    * @param desitantionImage where to place the image data
  72    *
  73    * @return false if method was unable to read the requested region.
  74    */
  75   private native boolean copyIntoXImageImpl(XImage destinationImage,
  76                                             int x, int y,
  77                                             int width, int height,
  78                                             int destX, int destY);
  79
  80   public native Rectangle getBounds(Rectangle rv);
  81
  82   public native int getDepth ();
  83
  84   private static final String MSG_XGETSUBIMAGE_FAILED =
  85     "XGetSubImage() failed.";
  86
  87   protected void finalize() throws Throwable
  88   {
  89     // Dispose all the cached GCs, to reduce X server resource usage
  90     for (int i=0; i<gcCachedCount; i++)
  91       gcCache[i].disposeImpl ();
  92     gcCachedCount = 0;
  93     super.finalize();
  94   }
  95
  96   /** Put a GC in the cache for this drawable, so it can be retrieved later.
  97    * @param gc The GC to put
  98    */
  99   void putGCInCache (GC gc)
 100   {
 101     if (gcCachedCount >= gcCache.length)
 102     {
 103       // List full - extend it to double its present size
 104       GC[] oldList = gcCache;
 105       gcCache = new GC[oldList.length*2];
 106       System.arraycopy (oldList,0,gcCache,0,oldList.length);
 107     }
 108     gcCache[gcCachedCount++] = gc;
 109   }
 110
 111   /** Get a GC from the cache, if available
 112    * @return A GC from the cache, or null if the cache is empty
 113    */
 114   GC getGCFromCache ()
 115   {
 116     return (gcCachedCount>0) ? gcCache[--gcCachedCount] : null;
 117   }
 118 }