Re: [Texmacs-dev] Pdf marks and Re: adding pdf hyperlink support

[Sam Liddicott]

On 01/09/11 12:00, Joris van der Hoeven wrote:
> Dear Sam,
>
> On Tue, Jun 28, 2011 at 06:15:17PM +0100, Sam Liddicott wrote:
> > I'm determined to add PDF hyperlink support to texmacs.
> Thanks for your work on this issue. I was indeed surprised to
> discover that various links were added to a Pdf export.
>
> There are a few quirks though: the locus_boxes are only used
> for "inactive non line-breakable markup". For instance,
> hyperlinks do not work with the current implementation.
>
> If you have some time, then this whould be the way around this:
> instead of (or in addition to?) using the locus_boxes in order to
> determine what should be linked to what, you should scan all subtrees
> of the document tree, and determine whether there are links attached
> to them. For instance, look at the 'link-active-upwards' scheme
> routine (even though scanning should be fast and written in C++).
>  From the subtrees to which we attached links, you should next
> determine the corresponding bounding boxes (or regions);
> see edit_interface_rep::update_active_loci for how this works.

The way I was planning to implement this is the same way in which 
hlink's are coloured. I found the rendering which changes the 
environment to set the link colour while rendering the link and then 
restoring it. In a similar manner and location in the code I planned to 
set the link destination in the environment. This might open the way 
more generally to annotate any part of the document with PDF attributes 
or renderer attributes. I think this rendering links this way might be 
done sooner as it requires me to become acquainted with less of the code 
before I do it.

> Another related question concerns alpha-trasparency;
> I tried to add this to the last version 1.0.7.11
> (enable using Debug ->  Experimental ->  Alpha transparency,
> after which you may try to draw a graphics using alpha
> transparency, or try Insert ->  Presentation tag ->  Greyed,
> on top of some non uniform background).
>
> However, contrary to linking info, it seems that ghostscript
> does not support this extension.

I know there has been discussion on this on the ghostscript list, and gs 
9 releases may have it (as we know thought, gs9 has other problems for 
us as it can no longer safely be used to properly create eps files using 
the pswrite target. An epswrite target was planned for gs9 and may be 
done now).

> I would be interested to
> know whether my code does work with Acrobat distiller.
> It would be nice if someone could incite the ghostscript
> people to correctly implement alpha transparency Pdf marks
> when converting from Postscript to Pdf. It seems that they
> already did most of the work anyway.

I'm on the gs9 mailing list so I'll search and then ask what progress 
has been with respect to this and also the epswrite target.

Sam

> Best, --Joris
>
> _______________________________________________
> Texmacs-dev mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/texmacs-dev