Re: ghostscript developments

[David Kastrup]

Jonas Hahnfeld via Discussions on LilyPond development
<lilypond-devel@gnu.org> writes:

> Am Dienstag, dem 25.05.2021 um 09:57 +0000 schrieb Werner LEMBERG:
>> This might be of interest:
>> 
>>   https://ghostscript.com/pdfi.html
>
> Unless I'm completely missing the point of the page, this is about the
> *PDF interpreter*, not the Postscript interpreter that LilyPond uses to
> produce PDF files. So I don't really see how this relates...

They are the same.

For example, preview-latex (and possibly some other quaint programs
unrelated to LilyPond) relies on pdf2dsc to write some wrapper file with
a superficial PostScript DSC (document structured comments or something)
wrapper structure to allow navigating the conversion of a PDF document
to bitmaps out-of-order while not really supporting any PDF
interpretation: the machinery is just using the resulting wrapper DSC as
a pseudo PostScript file.

It sounds like pdf2dsc would be a goner (with bad effects on
preview-latex).  Now this in particular is not affecting LilyPond.

But when the ultimate target is PDF (like when using the pdfwrite device
as LilyPond does), Ghostscript relies on non-standard PostScript
extensions to indicate things like bookmarks, page links, PDF metadata.
With the pressure to remove non-standard extensions from GhostScript,
those might be under considerably more pressure to change or require
specific setup code to activate.

So we likely need to watch more closely what is happening.

-- 
David Kastrup