Re: xdvipdfmx fails with some regtests (“Invalid object”)

[Jonas Hahnfeld]

Am Freitag, den 19.06.2020, 15:11 +0200 schrieb Jonas Hahnfeld:
> Am Freitag, den 19.06.2020, 14:49 +0200 schrieb Han-Wen Nienhuys:
> > On Fri, Jun 19, 2020 at 12:50 PM Jonas Hahnfeld <hahnjo@hahnjo.de> wrote:
> > > No changes for me. Please also keep in mind that the same command
> > > string works via the API interpreter. It could be that this is related
> > > to processing other files before the "empty" one...
> > > I'll try to write a small wrapper around the API so we can test outside
> > > of LilyPond what actually triggers the broken PDF.
> > 
> > Your hunch is correct. No need to write a wrapper, the following in a
> > .ly file works if you replace SCM_UNDEFINED with SCM_UNSPECIFIED in
> > ly:gs-api
> > 
> > [...]
> > 
> > [hanwen@t460-wlan lilypond]$ qpdf --qdf --object-streams=disable
> > broken2.pdf /dev/stdout  | grep Contents
> >   /Contents 7 0 R
> > %% Contents for page 1
> > [hanwen@t460-wlan lilypond]$ qpdf --qdf --object-streams=disable
> > broken1.pdf /dev/stdout  | grep Contents
> 
> Looking into the generated source code, this comes from Ghostscript
> file devices/vector/gdevpdf.c:
> ===
> /*   
>  * The PDF documentation allows, and this code formerly emitted,
>  * a Contents entry whose value was an empty array.  Acrobat Reader
>  * 3 and 4 accept this, but Acrobat Reader 5.0 rejects it.
>  * Fortunately, the Contents entry is optional.
>  */
> if (page->contents_id != 0)
>     pprintld1(s, "/Contents %ld 0 R\n", page->contents_id);
> ===
> So it claims omitting the entry is correct, but xdvipdfmx disagrees.
> This reduces the problem to finding out why contents_id is different
> for the two invocations...

I think I got it, the magic words are "newpath fill" between setdevice
and run. This comes from Resource/Init/gs_pdfwr.ps where I noticed the
following comment: "Note, this may not work if the initial device is
not pdfwrite". Was suspicious enough to give it a try and my broken.pdf
is now accepted by xelatex. Let me run this through a full 'make doc'..

Jonas

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