[Cdk-jchempaint] rendering bug in Jchempaint 3.1.2. wavy bonds

[Jules K. <J.K...@cm...>]

Hello JChempaint people,

I found something which I think qualifies as a bug in Jchempaint.
I hope this list is a proper channel to report it, the jchempaint TRAC
mentioned on the wiki was broken, and my initial search didn't produce
a 'jchempaint-devel' list or something similar. I'm also not sure if
this was already treated in one of the 15 patches. I'm new enough to
development that I've never applied a sourcecode patch before.
My apologies if I missed anything, please ask me to elaborate if necessary :-)

Bug report:
'wavy' bonds (undefined E/Z bonds) are rendered incorrectly when drawn
at other angles than 0, 90, 180, 270 degrees. (Image attached).
It seems the individual circle-segments used to build the wavy line
rotate exactly opposite to the direction they're supposed to go. E.G.
when the bond is drawn at a +15 degree angle, the circle segments are
rendered for a -15 degree angle. The positioning of the arc-centers is
still correct however.
The clearest illustration is when you attempt to draw a wavy bond and
rotate the drawing direction. The circle arcs will appear to rotate
counter to the bond's rotation.
I guess a simple sign-flip in an angle somewhere in
'calculateCircleArc' method would solve the problem, but I have no
clue where that should be.

Version:
JChempaint version 3.1.2 (in unmodified JAR downloaded from the
sourceforge repository)

Kind regards,
Jules Kerssemakers