[NTG-pdftex] pdfcurpageref -- does it make sense?

Hans Hagen pragma at wxs.nl
Mon Jan 17 10:11:31 CET 2005


The Thanh Han wrote:

> I wonder how Hans and other would solve this problem. tex doesn't have a
> concept of `current page' while processing the input token list. The
> page number can be detected reliably only using 2nd pass processing, as
> the page where some material ends up is known only at shipping phase.

I use two pass solutions for that.

I can imagine a primitive \pdfpageobjnum  that expands at shipout time, i.e.

   \pdfobj{.... \pdfpageobjnum\space 0 R}

in this case \pdfpageobjnum is like pdfsavepos, during shipout, those 
placeholders in the shipped out box  are resolved; outside the otr/shipout 
routine it's zero, so

   \count15=\pdfpageobjnum

leads to \count15 being 0

I guess that the reason for this request is that in media objects one needs to 
refer to the page where the object (or its visualization) ends up, a kin dof 
circular reference between definition and usage; since these page references 
remain in the object (and are not used elsewhere) the delayed resolution during 
shipout is ok;

> It is possible to provide a primitive which returns the *next* page object
> number, but IMHO it doesn't make any sense.

indeed, things can end up many pages later (think of intermediate float flushing)

Hans


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