Thanks.
The problem happens in a case where there are no paragraph split between 2
pages. All pars are entirely either in page 1 or page 2 (these numbers are not
actual page numbers, but it’s for clarity).
I am trying to create a MWE but it’s not trivial. The situation as far as I
understand it is like the following :
I’ve added tracers for vspacing.synchronizepage function.
When page 1 ships, there are 2 paragraphs (1 + 3 lines) still pending because
they do not fit in page 1 so they will be shipped in page 2 (I think that what
is in texlists.page_head variable). Hence tex.prevgraf which was 0 is set to 4
(see this from traces in output log).
vspacing > page 4, prevdepth 2.56577pt => 2.56577pt, prevgraf 0 => 4
vspacing > list glue:topskip hlist:line penalty:userpenalty
penalty:userpenalty glue:baselineskip hlist:line penalty:linebreakpenalty
glue:baselineskip hlist:line penalty:linebreakpenalty glue:baselineskip
hlist:line glue:userskip
Next paragraph after the 2 pending pars I refer to above has a non zero
\hangindent and \hangafter (set to -1) and when it starts being processed (in
horizontal mode) prevgraf is already 4 so I think this cancels out that hanging
(that’s the effect I see in output, there is no indent in 1st line of 3rd par),
as IIRC TEX considers par has already 4 lines but in actuality it has 0. If I
read correctly the TeXBook, prevgraf value has some impact on \hangafter /
\hangindent
The value of \prevgraf affects line breaking only when TEX
is dealing with nonstandard \parshape or \hangindent.
Joseph
De : Hans Hagen
Envoyé le :jeudi 19 juillet 2018 00:00
À : Joseph Canedo; mailing list for ConTeXt users
Objet :Re: [NTG-context] Issues with vertical spacing in simple case
On 7/18/2018 10:33 PM, Joseph Canedo wrote:
> Thanks Hans.
>
> Picked up today beta and some code I have relying on value of
> tex.prevgraf starts breaking. This is lettrine related code that sets
> hangafter for 1st paragraph and eventually subsequent if lettrine is
> larger than 1st par.
>
> I see the function vspacing.synchronizepage() sets prevgraf value I
> guess to avoid bleeding also paragraph lines.
>
> Is there any possibility to get original unchanged tex.prevgraf value,
> possibly using some callback or some other tex.<Something> ?
you cannot rely on prevgraf crossing pages (so you get e.g. 8 at the top
of a page with 5 lines
where/how does it fail
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
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the
Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___________________________________________________________________________________
