[cairo] Draw a rectangle with dash lines

Carl Worth cworth at cworth.org
Sat Feb 3 07:37:56 PST 2007


On Sat, 3 Feb 2007 10:02:47 -0500, Jeff Muizelaar wrote:
> I was able to reproduce the problem with cairo 1.3.7.

Yeah. :(

One other reason I originally postponed investigating the bug is that
I guessed it might be due to a peculiarity of the old tessellator. So
I had been hpoing that the new tessellator might make this bug go away
without us ever investigating it closely.

But we didn't end up that lucky.

>                                                  It looks like the
> problem is related to the dash offset. When I change it to -3.999 or
> 4.001 the triangle goes away.

It's probably only related to the dash offset in the sense that it's
related to most everything else as well, (rectangle width, stroke
width, etc.). Bugs like this are often extremely sensitive to input
leading to some particular arithmetic oddity.

But yes, we've never seen this bug in a non-dashed stroked rectangle,
for example.

-Carl
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