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List:       kde-kimageshop
Subject:    Re: Two backtraces ... and a hangup
From:       Richard Theil <Richard.Theil () web ! de>
Date:       2015-04-10 12:30:21
Message-ID: 7AE715A0-DE1A-4C84-9B5E-79D61B7C65D8 () web ! de
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Am 10.04.2015 um 13:02 schrieb Boudewijn Rempt:

> I think that we shouldn't build the Neon packages with asserts enabled.. I can \
> replace the asserts by returns, then that wouldn't happen.

Hehe; not exactly my idea of software development ;) They're there for a reason and \
from what I can see, it would not be a good idea to call setControlPoint1 with \
Not-A-Number (or Infinity?) values in the first place.

> From what you say, it sounds like it's really easy for you to reproduce, but I \
> haven't managed yet! Could you install the debug symbols and try to reproduce?

I'll have a look into it as i get some play time. However, I just gave it a quick \
look again, just using the mouse, to see whether issues are maybe dependent on the \
ancient Wacom hardware. Test case was painting the kanji chars at unicode 5b50, 5f8b, \
and 76f4. Wacom was disconnected, Mouse was an Apple trackball mouse. Built in T500 \
TrackPad/Point available, but untouched.

I ran into a hangup after about a dozen characters drawn. Not a crash, but a \
seemingly (*) endless looping output of "reached MAX_RECURSIVE_DEPTH" in \
KarbonSimplifyPath::subdivideAux. That function in turn calls \
KoPathPoint::setControlPoint1. Coincidence?

(*) As I read some "calligra-2.9.2" code on the web, It should limit the subdivisions \
off at MAX_RECURSIVE_DEPTH. So it might not have been technically endless, but just \
an attept to print around 1024^2/2 lines, which would occur if some input value of \
the original curve is so NaN that the final comparison in isSufficentlyFlat always \
returns false.

Rich

by the way, in isSufficentlyFlat, you could factor out the division by \
(SUBDIVISION_COEFF*SUBDIVISION_COEFF) to save a few cycles. Might even help, because \
that's probably called rather often.

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