Re: Concrete definition/macro problem, connected with Re: Lout syntax etc.

[Michael Piotrowski]

> > one point in that direction is that they also want PDF with links
> > ... and I ALWAYS need diagrams!
> 
> This is why I have been lobbying for direct pdfmark support in the
> PostScript backend.

And me, too :-)

> [...]
> 
> Thus PDF backend has links but misses @Diag &co.  PostScript backend
> has @Diag &co but misses links.
> 
> Fortunately, `pdfmark' allows to have the best of two worlds in the
> PostScript backend, providing you have a distiller that will convert
> @Diag assembly into PDF images.
> 
> `pdfmark' services can be wrapped in a set of builtin abstractions
> that will emit `pdfmark' for PostScript backend and will translate
> into appropriate PDF constructs for the PDF backend.
> 
> One example might be:
> 
>     builtin @NamedDestination left @Tag right @Object
>     builtin @HyperLink left @Destination right @Object
> 
> and, say in @LargeScaleStructure
> 
>     tag @NamedDestination {
>         headingfont @Font
>         headingbreak @Break { @LongNum headingformat title }
>     }
> 
> and then we can use smth like
> 
>     see { some.section } @HyperLink { section @NumberOf some.section }.

As you might remember, I've already played around with pdfmark generation 
some time ago.  This project is currently on hold due to exams, but I 
intend to pick it up again afterwards.

Generating WebLinks is easy.  I've also made some modifications to doc and 
dl, and can now generate a clickable table of contents and bookmarks 
(without nesting for now, this is probably the hardest part), and some 
other stuff like the initial page mode and the initial page.  Hyperlinks to 
sections and arbitrary positions in the document should be easily 
implementable on this basis.

Check <http://www.linguistik.uni-erlangen.de/~mxp/software#Lout> for an 
example PDF which was distilled from PostScript with pdfmarks inserted from 
Lout.

> Since pdfmark needs page coordinates for several attributes, it's
> impossible to (ab)use @Graphics (that puts you in the gsave/grestore
> sandbox) to sprinkle `pdfmark' in the PostScript output.

For the functionality I have, @Graphics is sufficient, and I think it would 
be for most other features, too.  You can break out of the "sandbox" and I 
remember doing it once for pdfmarks, but in the current code I can't find a 
trace of it.  So either it proved to be unnecessary, or I've thrown it away 
because it was useless without more Lout code (the PostScript did work, 
though), or I simply can't find it right now.

> PDF backend already have this functionality implemented - it should be
> relatively painless, I guess, to share this code with PostScript
> backend and add a set of builtins to export this functionality in the
> uniform manner into the Lout world.  Then one can produce PostScript

Builtin hyperlinking support would be the best, of course.

-- 
Michael Piotrowski                         <address@hidden>
                              <http://www.linguistik.uni-erlangen.de/~mxp/>
Department of Computational Linguistics --- University of Erlangen, Germany