Re: Be serious about setstrokeadjust in PostScript primitives (issue 8663044)

[Janek Warchoł]

2013/4/14  <address@hidden>:
> On 2013/04/14 20:38:12, janek wrote:
>> i'm sorry, but i don't understand what the code does.
>> Obviously, it would help if i knew Postscript ;) but
>> unfortunately i don't have time to learn it now.
>
> The most important resource is PLRM.pdf (available on Adobe's website,
> though the location changes).

Yeah, i've downloaded it.  900 pages... you may have to wait a bit for
my review.... (not that i'm going to read it whole, but anyway its a
lot of material and i'm *really* busy (don't be surprised if i
disappear from the lists for a couple of days)

>> Since i suppose that quite a few devs may be in a similar situation, i
>> think that adding some comments would be a good idea,
>> even if they were completely
>> obvious for people knowing PostScript.
>
> There is a reason this file is commented sparingly: it appears in
> every PostScript file produced by LilyPond.

Hmm.
Does it appear in pdfs too?

> PostScript is a rather idiosyncratic language, so one can't really
> replace knowing the language with liberal amounts of commenting.

Too bad.
So, just from the description: i understand that there's some sort of
strokeadjusted border drawn around the actual rectangle (i'm referring
to the thing you called "clipping path").  This strikes me as
suspicious: how are we to fit 3 "layers" (strokes or whatever) into
something that renders at about 1 pixel width?  I mean, when we have a
stem (rounded rectangle), its usually ~1px on screen, and in that 1
pixel we squeze strokeadjusted left edge, the rectangle, and the
strokeadjusted right edge?  Isn't that too much, and isn't this what's
causing this "disappearing lines" effect in poppler?

>> By the way: do i understand correctly that a rounded rectangle is
>> created as two objects - a "sharp" rectangle and a "rounded" line
>> around it?
>
> There is no such things as a "rounded" line, but the corner join style
> might be producing circles.

That's what i meant by the "rounded line".  Obviously you know the
terminology better :)

> At any rate, this kind of rendition is only used when all of width,
> height, and corner diameter are non-zero.  And calling painting
> operations "objects" is a somewhat strange view.

See the second sentence above.
Anyway, thanks for explanation.

Janek