* How to go through a vbox line by line in Lua?
@ 2017-04-26 21:10 Henri Menke
2017-04-26 21:19 ` Hans Hagen
0 siblings, 1 reply; 2+ messages in thread
From: Henri Menke @ 2017-04-26 21:10 UTC (permalink / raw)
To: mailing list for ConTeXt users
Dear list,
Recently I answered a question on TeX.SX where it was necessary to go
through an already typeset vbox and examine it line by line. Therefore
I used the macro \eatlines from Viktor Eijkhout's "TeX by Topic", here
a version tailored to my needs:
\def\eatlines{%
\setbox\scratchbox=\lastbox
\ifvoid\scratchbox\else
\unskip\unpenalty
{\eatlines}%
\setbox\scratchbox=\hbox{\unhbox\scratchbox}%
% Do something with scratchbox, e.g. examine width
\fi
}
It is then used like
\vbox{ ... some content ... \par\eatlines}
The macro goes through all hboxes (lines) in the vertical list until
there is none left (\ifvoid) and unpacks each hbox into a new one.
I was wondering, can the same thing be done in Lua (with probably less
and more readable code)?
Kind regards,
Henri
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* Re: How to go through a vbox line by line in Lua?
2017-04-26 21:10 How to go through a vbox line by line in Lua? Henri Menke
@ 2017-04-26 21:19 ` Hans Hagen
0 siblings, 0 replies; 2+ messages in thread
From: Hans Hagen @ 2017-04-26 21:19 UTC (permalink / raw)
To: ntg-context
On 4/26/2017 11:10 PM, Henri Menke wrote:
> Recently I answered a question on TeX.SX where it was necessary to go
> through an already typeset vbox and examine it line by line. Therefore
> I used the macro \eatlines from Viktor Eijkhout's "TeX by Topic", here
> a version tailored to my needs:
>
> \def\eatlines{%
> \setbox\scratchbox=\lastbox
> \ifvoid\scratchbox\else
> \unskip\unpenalty
> {\eatlines}%
> \setbox\scratchbox=\hbox{\unhbox\scratchbox}%
> % Do something with scratchbox, e.g. examine width
> \fi
> }
>
> It is then used like
>
> \vbox{ ... some content ... \par\eatlines}
>
> The macro goes through all hboxes (lines) in the vertical list until
> there is none left (\ifvoid) and unpacks each hbox into a new one.
>
> I was wondering, can the same thing be done in Lua (with probably less
> and more readable code)?
it depends on what you want to do. In any case you neet to be aware of
possible side effects then.
Hans
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________
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