[OpenJDK 2D-Dev] X11 uniform scaled wide lines and dashed lines; STROKE_CONTROL in Pisces

Jim Graham james.graham at oracle.com
Tue Dec 28 23:03:33 UTC 2010

Hi Denis,

I'm attaching a test program I wrote that compares the old and new 

Obviously the old one missed a bunch of solutions because it classified 
all solutions as 1 or 3, but the new one also sometimes misses a 
solution.  You might want to turn this into an automated test for the 
bug (and maybe use it as a stress test with a random number generator).

I think one problem might be that you use "is close to zero" to check if 
you should use special processing.  I think any tests which say "do it 
this way and get fewer roots" should be conservative and if we are on 
the borderline and we can do the code that generates more solutions then 
we should generate more and them maybe refine the roots and eliminate 
duplicates.  That way we can be (more) sure not to leave any roots unsolved.

The test as it is has a test case (I just chose random numbers to check 
and got lucky - d'oh!) that generates 1 solution from the new code even 
though the equation had 2 distinct solutions that weren't even near each 


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