gray levels are SLOW

• To: clim@BBN.COM
• Subject: gray levels are SLOW
• From: Peter Karp <pkarp>
• Date: Wed, 6 May 92 14:16:38 PDT
• Cc: clim-support@lucid.com

I have discovered some very odd behavior with regard to CLIM gray
levels.  The bottom line is: 
  o Drawing with gray levels G where 1.0 < G < 0.0 is extremely slow.
  o If in a given session you draw with gray colors, later drawing
    of pure black-and-white pictures is much slower for the rest of
    the session.

I am using Lucid CLIM 1.0-beta on a Sparc 1+ with a high-resolution
monochrome monitor.

I am working on a graph-drawing application.

(a) When I draw a graph with nodes and edges black, it requires 12 
seconds for 200 nodes plus 200 edges.
(b) If I then draw nodes in gray level .5, the same graph requires
31 seconds to draw.
(c) If I then draw edges in gray level .5, the same graph requires
135 seconds to draw!
(d) Furthermore, if I now go back to drawing the same graph with both
nodes and edges in black (gray level 1.0), the graph now takes 61
seconds to draw, rather than 12 seconds.  In addition, the graph 
requires noticably more time to scroll.

My guess is that (c) takes so long because edges have triangular
arrowheads that are drawn using filled polygons.

Although all these numbers are quite surprising to me, (d) is quite
amazing.  It suggests that CLIM has begun using some different type of
drawing model.

Comments?  Will any of this be improved in CLIM 1.1 or 2.0?

Use of gray levels is not crucial for us, but I thought I'd let people
know about this.

Peter

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