[NTG-context] possible issues with mkii / pdftex

[NTG-context] possible issues with mkii / pdftex

[Hans Hagen via ntg-context]

Hi,

There are probably not that many mkii users but just in case you use it 
to make something that you include in mkiv / lmtx or similar cases, the 
current version of pdftex (tl 2025) has some issue:

\starttext
\startTEXpage
     this is a\externalfigure[t:/sources/cow.pdf][height=20pt]cow
\stopTEXpage
\stoptext

Basically anything at the bottom of a tight page setup with no depth, in 
the case of text it can be a whatsit, or rule mixed in, spaces don't 
matter, will trigger this.

It relates to "using space in the perspective of tagged pdf" features 
introduced in the engine that also interfere when that feature is not 
enables. We don't set up this feature in mkii but the issue occurs 
independent of it being set up.

As said, it's probably not that relevant for context users but I know 
that sometimes mkii is still used for imposition or independent 
graphics, like:

\starttext
\startTEXpage
     \startMPcode
         draw textext("xxx");
         draw unitcircle scaled 1cm ;
         draw textext("xxx") shifted (1cm,0) ;
     \stopMPcode
\stopTEXpage
\stoptext

So again, no depth, bottom of page, text mixed with non-text. This issue 
actually might impact mptopdf in combination with pdftex.

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
-----------------------------------------------------------------

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[NTG-context] Re: possible issues with mkii / pdftex

[Ulrike Fischer]

Am Tue, 30 Sep 2025 12:07:00 +0200 schrieb Hans Hagen via
ntg-context:

> Hi,
> 
> There are probably not that many mkii users but just in case you use it 
> to make something that you include in mkiv / lmtx or similar cases, the 
> current version of pdftex (tl 2025) has some issue:
> 
> \starttext
> \startTEXpage
>      this is a\externalfigure[t:/sources/cow.pdf][height=20pt]cow
> \stopTEXpage
> \stoptext
> 
> Basically anything at the bottom of a tight page setup with no depth, in 
> the case of text it can be a whatsit, or rule mixed in, spaces don't 
> matter, will trigger this.

I didn't test your example, but my guess is that is related to the
same issue that I reported yesterday to Thanh and Karl where the
denominator suddenly shifted:

\voffset=-72.27pt
\newbox\sabox
\setbox\sabox\hbox{abc $1 \over 2$ abc}
\setbox\sabox\hbox{\raise\dp\sabox\box\sabox}
\global\pdfpageheight=\dimexpr\ht\sabox %+1pt
\box\sabox
\bye



-- 
Ulrike Fischer 
http://www.troubleshooting-tex.de/

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[NTG-context] Re: possible issues with mkii / pdftex

[Hans Hagen via ntg-context]

On 9/30/2025 12:44 PM, Ulrike Fischer wrote:
> Am Tue, 30 Sep 2025 12:07:00 +0200 schrieb Hans Hagen via
> ntg-context:
> 
>> Hi,
>>
>> There are probably not that many mkii users but just in case you use it
>> to make something that you include in mkiv / lmtx or similar cases, the
>> current version of pdftex (tl 2025) has some issue:
>>
>> \starttext
>> \startTEXpage
>>       this is a\externalfigure[t:/sources/cow.pdf][height=20pt]cow
>> \stopTEXpage
>> \stoptext
>>
>> Basically anything at the bottom of a tight page setup with no depth, in
>> the case of text it can be a whatsit, or rule mixed in, spaces don't
>> matter, will trigger this.
> 
> I didn't test your example, but my guess is that is related to the
> same issue that I reported yesterday to Thanh and Karl where the
> denominator suddenly shifted:
> 
> \voffset=-72.27pt
> \newbox\sabox
> \setbox\sabox\hbox{abc $1 \over 2$ abc}
> \setbox\sabox\hbox{\raise\dp\sabox\box\sabox}
> \global\pdfpageheight=\dimexpr\ht\sabox %+1pt
> \box\sabox
> \bye

Mikael told me that there could be an issue so we checked it with 
context. It doesn't relate to math at all: any mixed in non-glyphs can 
trigger it so it's actually interesting that it didn't show up for mopre 
than a year (not seen? not tested?).

We can probably figure out where the issue and fix it but compiling 
pdftex is not somthing I want to set up here (and the problem is not 
critital enough for context anyway). So it was just a warning. (Also, 
adding some 8 sp depth can often be used as workaround.)

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
-----------------------------------------------------------------
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If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
webpage  : https://www.pragma-ade.nl / https://context.aanhet.net (mirror)
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___________________________________________________________________________________