From: Hans Hagen <j.hagen@xs4all.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: Getting width of text to be typeset
Date: Sat, 23 May 2020 00:18:55 +0200 [thread overview]
Message-ID: <639ff2c9-65f6-b818-1d8f-9249331a9b8a@xs4all.nl> (raw)
In-Reply-To: <e7ebbe94-0dbf-5113-8dc2-9af6cc6a8d82@xs4all.nl>
On 5/23/2020 12:03 AM, Hans Hagen wrote:
> On 5/22/2020 11:22 AM, context@vivaldi.net wrote:
>> Hello,
>>
>> is it possible to get somehow the width of the "material" (box?) of
>> the current line which is "ready" to be typeset?
>>
>> See the case:
>>
>> ----
>> \starttext
>>
>> some text
>>
>> pqrs % Here I need to get width (or content) of the text from the
>> begin of the current line,
>> % i.e. width of the text "pqrs".
>> % (Depending of the width I will decide what to do later.)
>>
>> \stoptext
>> ----
>>
>> I am too laical to know how to "inject" TeX workflow or whether to
>> access LuaTeX internals (nodes?) to get the desired information.
>>
>> - Is it possible somehow?
> Too easy ...
>
> \startluacode
> function document.whatever()
> context(nodes.hpack(tex.getnest().head.next).width)
> end
> \stopluacode
>
> \unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax}
>
> \starttext
>
> \dorecurse {10} {
> snippet #1\scratchdimen\widthuptohere\ has \the\scratchdimen\
> width\par
> }
>
> \stoptext
>
> but still you have to wikify it ... maybe i'll make it a low level
> helper (but than you also need to wikify that because i have no clue
> where to explain it)
Actually, one needs to flush a bit
\startluacode
function document.whatever()
local h = nodes.hpack(tex.getnest().head.next)
local w = h.width
h.list = nil
nodes.free(h)
context(w)
end
\stopluacode
\unexpanded\def\widthuptohere{\dimexpr\ctxlua{document.whatever()}sp\relax}
\starttext
\dorecurse {10} {
snippet #1\scratchdimen\widthuptohere\ has \the\scratchdimen\
width\par
}
\stoptext
not that it matters much, because it's unlikely that you leak more than
a dozen nodes in a run.
Hans
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next prev parent reply other threads:[~2020-05-22 22:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 9:22 context
2020-05-22 22:03 ` Hans Hagen
2020-05-22 22:18 ` Hans Hagen [this message]
2020-05-22 23:49 ` Rik Kabel
2020-05-23 11:04 ` Gerben Wierda
2020-05-23 13:52 ` Rik Kabel
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