[NTG-context] "fake" space for better reflow

Ulrike Fischer news3 at nililand.de
Wed Nov 30 17:58:17 CET 2016

Am Wed, 30 Nov 2016 12:45:17 +0100 schrieb Hans Hagen:

> On 11/30/2016 10:09 AM, Ulrike Fischer wrote:
>> If I compile a small document
>> \starttext
>> \input knuth
>> \stoptext
>> and then use in the adobe reader "view->zoom->reflow" I get as
>> result
>> Thus,Icametotheconclusionthatthedesignerofanewsystemmustnotonlybetheimplementerandfirstlarge--scaleuser;thedesignershoulda
> Cut and paste goes well so I think it's a bug in acrobat then.

I'm not sure. Imho cut and paste use an heurisitic more or less
based on the size of the space (there are quite a number of
questions on tex.SX where the heuristic fails, e.g. in code
listings), while reflow seems to need glyphs. The speech of Ross
Moore on TUG14 seems to indicate that \pdfinterwordspaceon was
introduced in pdftex to get around this problem. 


>> I know it is due to the missing space glyph. With pdflatex I would
>> try to use \pdfinterwordspaceon but this primitive never found its
>> way into luatex. Is there any solution? (One that could be
>> translated to lualatex would be best).
> One can write a filter that does it before shipout. Typically a case for 
> callbacks.

Well the main question is, what is the "does it" in this case.
pdftex inserts a space from a dummy.pdf. One use the fake space more
or less like this:

\pdfmapline{=dummy-space <dummy-space.pfb}

But this doesn't sound like the correct way to go in a unicode/open
type world.  

(I'm also not quite if shipout is the correct time. Imho one would
probably avoid to add spaces e.g. in math).

Ulrike Fischer 

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