On 11/30/2016 5:58 PM, Ulrike Fischer wrote:

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.

http://river-valley.zeeba.tv/%E2%80%9Cfake-spaces%E2%80%9D-with-pdftex%E2%80...

I assume that it just runs over the resulting list and replaces skips by spaces. One cannot in an earlier stage use spaces instead of skips simply because tex has a glue based model. So, one can kick in some callback (before shipout) and replace glue by space characters.

...

...

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:

\pdfinterwordspaceon \pdfmapline{=dummy-space

Well, just insert char 32 which is in most fonts ... (could even be a virtual char). We will not introduce such mechanisms in luatex, after all a macro package can decide for other criteria.

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).

One can recognize math. If context can do it (when a user enables it) ... any macro package can ... Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------