[NTG-context] Can't manipulate glue added by tex.preparelinebreak

Hans Hagen j.hagen at freedom.nl
Tue Jul 26 10:06:26 CEST 2022


On 7/26/2022 8:18 AM, Max Chernoff via ntg-context wrote:
> Hi Hans,
> 
> The new tex.preparelinebreak is great (thanks again), but I can't seem
> to figure out how to manipulate the parfillskip nodes that it adds.
> 
> MWE:
> 
> \newbox\testbox
> 
>     \startluacode
>         function test(head)
>             if head.id ~= node.id "par" then
>                 return head
>             end
>     
>             new_head = node.copylist(head)
>             tex.preparelinebreak(new_head)
>     
>             local parfillskip = node.tail(new_head)
>             inspect(parfillskip) -- Confirm that this really is a parfillskip
>             parfillskip.stretchorder = 0
>             parfillskip.stretch = 0
>     
>             local broken = tex.linebreak(new_head)
>             tex.setbox("global", "testbox", broken)
>     
>             return head
>         end
>     \stopluacode
>     
>     \starttext
>         {\dorecurse{209}{Hello }\par}\page
>     
>         {\parfillskip=0pt\dorecurse{209}{Hello }\par}\page
>     
>         {\ctxlua{nodes.tasks.appendaction("processors", "after", "test")}
>          \dorecurse{209}{Hello }\par}\page
>     
>         \box\testbox
>     \stoptext
> 
> I would expect that pages 1 and 3 would be identical, and that pages 2
> and 4 would be identical. However, page 4 is the same as pages 1 and 3,
> which isn't what I'd expect. I can do a similar idea in LuaTeX/MkIV and
> get the expected results, so I'm not too sure what I'm doing wrong here.
> I'm probably just missing something obvious, but I'm not too sure what.
> Any ideas?
looks like i don't update something, i'll fix it (probably bin later today)

btw, you can do this:

         local h, t, pil, pir, pfl, pfr = tex.preparelinebreak(new_head)
         inspect(pfr)
         pfr.stretchorder = 0
         pfr.stretch = 0

as well as use

	tex.show(broken)

to see the result

Hans


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