Writing metadata to the PDF file

[Reinhold Kainhofer]

The request for PDF hyperlinks of \page-ref and \label reminded me that it 
might be a nice enhancement to write out some of the \header fields as DOCINFO 
fields (i.e. metadata) to the PDF file. The advantage would be that PDF readers 
would display the title (instead of the filename) in the window title, and the 
document information would contain more information about the author, title, 
etc.

All that needs to be done is to insert a DOCINFO pdfmark into the Postscript 
and gs will take care of it:
[ /Author string
  /Title string
  /Subject string
  /Keywords string
  /DOCINFO pdfmark

The DOCINFO pdfmark Postscript extension is documented by Adobe on page 28 of 
http://partners.adobe.com/public/developer/en/acrobat/sdk/pdf/pdf_creation_apis_and_specs/pdfmarkReference.pdf

Now, I'm looking at the ps backend, but I don't know how to get access to the 
global header object from the write-preamble function in scm/framework-ps.scm.

Any idea how to obtain the global header object so I can extract things like 
title or composer?

Thanks,
Reinhold

PS: Bug squad, can you please file this as an enhancement request, so that it 
doesn't get lost?
-- 
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Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org