[XeTeX] XeTeX : images as links

[Ross Moore]

Hi Phil,

On 21/09/2013, at 3:23 AM, Philip Taylor wrote:

> In a forthcoming PDF catalogue of Greek MSS, a number of "thumbnail"
> images of folia, bindings, etc., will appear, many if not all of
> which will be expected to function as hyperlinks to full-sized
> (or perhaps pannable/zoomable) versions of the same.  However,
> endeavouring to achieve this functionality using either Eplain's
> \hyperref or Eplain's \hlstart/\hlend fails to produce the desired
> effect -- whilst text can act as a clickable region for a hyperlink,
> an image included using \XeTeXpicfile seemingly cannot.	
> 
> The following, a verbatim copy from the test file, demonstrates
> the problem --

Can you post a PDF, preferably uncompressed,
so we can look at how the hyperlink is specified.

> 
> 
> 	\catcode `\< = \catcode `\@
> 		\input eplain
> 	\catcode `\< = \active
> 	
> 	\enablehyperlinks
> 	
> 	\uselanguage {UKenglish}
> 	
> 	\hlstart {url}{}{http://example.org/fullsize}
> 	\hbox
> 	\bgroup
> 	\XeTeXpicfile Images/LPL-MS-1214/JPG/f1r.jpg height 0,25\vsize
> 	\egroup
> 	\hlend
> 	
> 	\vskip \baselineskip
> 	
> 	\hbox
> 	\bgroup
> 	\hlstart {url}{}{http://example.org/fullsize}
> 	\XeTeXpicfile Images/LPL-MS-1214/JPG/f1r.jpg height 0,25\vsize
> 	\hlend
> 	\egroup
> 	
> 	\vskip \baselineskip
> 	
> 	\href{http://example.org/fullsize}{\hbox {\XeTeXpicfile
> Images/LPL-MS-1214/JPG/f1r.jpg height 0,25\vsize}}
> 	
> 	\end

What is this  0,25\vsize  ?
Should it not be  0.25\vsize  for TeX to get the correct
vertical dimension?

Try also:  
  \setbox0=\hbox{\XeTeXpicfile Images/LPL-MS-1214/JPG/f1r.jpg height 0,25\vsize }
then
  \message{height=\ht0 + \dp0, width=\wd0}
to see what height you are really getting.

Then set the link with:
  \href{http://example.org/fullsize}{\box0}

> 
> Needless to say, if any of the \XeTeXpicfiles are replaced by text,
> all works as expected.
> 
> Can anyone please explain why this does not work, and how the
> problem can best be transcended ?  (NB.  UNIV = Plain XeTeX, not XeLaTeX)
> 
> Philip Taylor
> 
> P.S. The catcode stuff at the top is because the real project goes on
> to load an XML file.


I'd doubt that there's any problem caused by this, with < and >
**unless**
 these are used internally by packages which you load *after* the
catcode changes.

e.g. conditionals may fail
   \ifnum ... < ....   
if the catcodes had not been setup robustly within the package.

But surely you would have noticed problems of this kind already,
if they were indeed going to occur with your larger document.


Cheers

	Ross

------------------------------------------------------------------------
Ross Moore                                       ross.moore at mq.edu.au 
Mathematics Department                           office: E7A-206      
Macquarie University                             tel: +61 (0)2 9850 8955
Sydney, Australia  2109                          fax: +61 (0)2 9850 8114
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