[squeak-dev] Re: Bezier filled shape rendering artifacts

Igor Stasenko siguctua at gmail.com
Tue Mar 25 02:48:01 UTC 2008

On 25/03/2008, Klaus D. Witzel <klaus.witzel at cobss.com> wrote:
> >>  But I'm currently more interested to get rid of the problems with the
>  >>  path/bezier segments of
>  >>
>  >>  - http://squeak.cobss.ch/JSesh/resources/glyphs/varia/Y4.svg
>  >>
>  >
>  > Well, i tested another files located in same directory, and they seem
>  > rendered well.
> Sure, the ones with just plain line segments (like Z24) render perfectly
>  ...
>  > I don't know why this particular glyph not rendered correctly, i can
>  > only suppose that it
>  > was defined with sequence of data, which wrongly parsed by SVGMorph.
>  > Why i think it's not engine? Because engine can't twist point
>  > coordinates of shape, it can only fail to fill shape correctly. And in
>  > this glyph i see twisting coordinates, look like somewhere SVG morph
>  > starts feeding engine with wrong coordinates.
> Huh? I've spent hours checking Gary's parsing code (before posting
>  anything here in squeak-dev) and until now saw [said the possibly blind
>  man] no wrongdoing (even compared to a Javanese implementation which has
>  no rendering bug). Some typos in SVGMorph's parsing method, quadratic*
>  v.s. qubic*, but these lines wheren't used especially for A1.svg,A4.svg
>  (which I tested most).
>  So you found something suspicious; please tell what and where (did you
>  mean in Y4.svg?). I could use a point where to start debugging from. In
>  which segment did you see twisted coordinates? TIA.

Yes, if i find something suspicious, i'll let you know.
In attachment is a comparable rendering results from Opera (gray) and
SVGMorph (black).
Looks like i was wrong about twisting - the glyph is so small that its
hard to say what is there, unless you zoom it in.

I think you can try to remove drawing parts/segments step by step from
original svg to see where it breaking. And then you can trace why.

Best regards,
Igor Stasenko AKA sig.
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