EVALUATION

Using the approach described above, it appears that we can improve performance
of a number of common operations.  For example, on Solaris/SPARC with XVR-1200:

Operation           Performance
---------           -----------
20x20 fillRect()       +45%
20x20 drawLine()       +52%
20x20 drawImage()      +20%
20x20 copyArea()       +10%

There are a few other operations that will also likely improve using these
techniques (e.g. setClip(), MaskFill, MaskBlit).
###@###.### 2005-05-20 00:07:37 GMT

Similar improvements are seen on Linux as well (JDS, Nvidia GF FX 5600,
7590 drivers, 2x 2.6GHz P4):

Operation           Performance
---------           -----------
20x20 fillRect()       + 3%
20x20 drawLine()       +37%
20x20 drawImage()      +17%
20x20 copyArea()       +26%

###@###.### 2005-05-20 05:45:28 GMT

While the proposed changes certainly improve performance, the approach is
a bit clunky ("round peg, square hole").  If we are getting to the point
where we are using tricks to get better performance out of NIO ByteBuffers,
why not just write a thin Unsafe wrapper that meets our needs?  We are
already going out of our way to maintain 4-byte alignment, so only a few
more changes would be required to achieve 8-byte alignment when necessary
(i.e. when adding long and double parameters to the buffer).  This approach
has a couple added benefits:
  - interface is mostly compatible with NIO classes
  - performance gains for all existing code without creating view buffers
    and such, as suggested earlier
  - no temporary object creation (before, we would create one or more
    view buffers for each drawGlyphList() call; while not too expensive,
    it would be nice to avoid this)

Here are some updated performance numbers with these changes in place
(on the Solaris/SPARC configuration listed above):

Operation             Performance
---------             -----------
  1x1   fillRect()       +64%
 20x20  fillRect()       +52%
  1x1   drawLine()       +57%
 20x20  drawLine()       +64%
100x100 drawLine()       +39%
  1x1   drawImage()      +34%
 20x20  drawImage()      +32%
100x100 drawImage()      + 6%
  1x1   copyArea()       +11%
 20x20  copyArea()       +11%
  4 ch  drawString()     +20%
 32 ch  drawString()     +17%

And on my Windows XP machine (2x 2.6GHz P4, GF FX 5600):

Operation             Performance
---------             -----------
  1x1   fillRect()       +41%
 20x20  fillRect()       +33%
  1x1   drawLine()       +49%
 20x20  drawLine()       +47%
100x100 drawLine()       +46%
  1x1   drawImage()      +68%
 20x20  drawImage()      +69%
100x100 drawImage()      + 3%
 20x20  copyArea()         0% (known driver slowness)
  4 ch  drawString()     +38%
 32 ch  drawString()     + 6%

###@###.### 2005-05-25 23:44:30 GMT