Re: PDF hyperlinks

[Reinhold Kainhofer]

Am Montag, 27. Dezember 2010, um 01:34:47 schrieb Dan Eble:
> The only mention I can find of PDF hyperlinks is for the point-and-click
> feature.  

LilyPond also supports URL hyperlinks with the \with-url command. They are 
written out to the intermediate .ps file as pdfmark and correctly converted to 
PDF. 

> I would like to create a PDF with page references
> (toc/index/etc.) that jump to the page when clicked.

Internal links (to a particular position marked by a \label) are not supported 
so far.

> Is that something that can be done in scheme?  If so, in which file and
> functions should I begin?

I don't think it can be done in Scheme alone. I don't think it would be too 
hard, though. Basically, it can be done with pdfmark, too. For the 
specification of the pdfmark Postscript extension see
http://partners.adobe.com/public/developer/en/acrobat/sdk/pdf/pdf_creation_apis_and_specs/pdfmarkReference.pdf


What needs to be done is:

1) In the Postscript backend (scm/famework-ps.scm or scm/output-ps.scm) 
written in Scheme:

  -) Write out each \label as a named destination to the .ps file. The code is
        [ /Dest /nameOfYourLabel /DEST pdfmark
    and needs to be inserted on the page where the label was placed.

  -) For the link, you also need to insert 
        [ /Rect [70 650 210 675]
          /Dest /nameOfYourLabel
          /Subtype /Link
          /ANN pdfmark
    where the [70 650 210 675] specify the exact rectangle for the link.

2) Of course, the non-trivial part of all this is how to get the information 
about label and link to the ps backend... I don't have a clear idea how to 
propagate that information from the markup interpretation to the backend. It 
might be able to do this in Scheme, but maybe also some C++ is required.
From a quick look at the code, all labels are collected in the label-page-
table variable of the paper object, but I don't know if this is available in 
the backend...
  

In any case, this is a very good enhancement request, so bug squad, please 
open a bug report (enhancement request) for this.

Cheers,
Reinhold

-- 
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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