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up vote 8 down vote favorite

Extract from dvipdfmx documentation:

Warning: No annotation will be constructed if the content between pdf:bann and pdf:eann is an empty box.

My MWE (via xelatex):

\documentclass{article}

\begin{document}

\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
http://www.tug.org%
\special{pdf:eann}

\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
\phantom{http://www.tug.org}%
\special{pdf:eann}

\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
\rule{1cm}{1cm}
\special{pdf:eann}

\end{document}

The second and third annotations do not work!

How to make a non-empy box with invisible content?

Subsidiary question: why this limitation?

share|improve this question
2  
With a "not really" empty box it works; for instance the TS1 encoding (\usepackage{textcomp}) has a \textcapitalcompwordmark invisible character and you can put it at the start and end of a box with the right dimensions. When fontenc is loaded, use some invisible character, such as U+00A0. – egreg Jan 27 at 15:38

3 Answers

up vote 10 down vote accepted

It seems that annotations require at least a real character, so \phantom or \rule don't do any good.

If you're using "standard" fonts, then you can use the textcomp package that sports a \textcapitalcompwordmark character which is invisible and as high as the capital letters. So

\documentclass{article}

\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{textcomp}
\newcommand{\myinvchar}{\textcapitalcompwordmark}

\newcommand{\emptybox}[1]{%
  \sbox0{#1}\makebox[\wd0][s]{\myinvchar\hss\myinvchar}%
}

\begin{document}

X\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
http://www.tug.org%
\special{pdf:eann}X

X\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
\emptybox{http://www.tug.org}%
\special{pdf:eann}X

\end{document}

will produce a "clickable space":

enter image description here

If you're using OpenType fonts via fontspec, an invisible character might be U+00A0:

\newcommand{\myinvchar}{\char\string"00A0 }
share|improve this answer
Thanks for these solutions. I need this to complete my ocgx package. Is textcomp solution (\textcapitalcompwordmark) usable in any case? (What do you mean by "standard" fonts?) – Paul Gaborit Jan 27 at 17:27
It seems so. You might want to do also \fontfamily{lmr}\selectfont in the box, in order to avoid spurious messages and do some tricks for adjusting the height. – egreg Jan 27 at 17:32
If I add \usepackage{fontspec} in your code, the height of annotation change. Why? – Paul Gaborit Jan 27 at 17:38
@PaulGaborit That's a good question. Also for the "non empty" box. – egreg Jan 27 at 17:41
up vote 8 down vote

It seems that you need a character there. If you are using a Unicode font you can use U200B which is a zero width space:

enter image description here

\documentclass{article}
\font\zzz="[lmroman10-regular]" at 10pt

\begin{document}
\zzz

\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
http://www.tug.org%
\special{pdf:eann}


a


\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
\mbox{\strut ^^^^200b\phantom{http://www.tug.org}^^^^200b}%
\special{pdf:eann}



b


\special{pdf:bann << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
 ^^^^200b\rule{1cm}{1cm} ^^^^200b
\special{pdf:eann}

\end{document}
share|improve this answer
why is the second box wider? (you said ^^^^200b took up no space). – jfbu Jan 27 at 16:44
@jfbu Because I left a space after the rule before the ^^^^200b. I must have done that on purpose, surely I wouldn't have left in white space by mistake:-) – David Carlisle Jan 27 at 16:47
ok, but I was referring to the phantom one... I must be missing something obvious! – jfbu Jan 27 at 16:49
@jfbu oh I see, no idea:-) – David Carlisle Jan 27 at 17:20
up vote 7 down vote

From this tugboat article you can use pdf:ann if you want a box taking up no space. I know nothing to all this but just tried:

\documentclass{article}

\begin{document}

A\special{pdf:ann bbox 0 0 12 12 << /Subtype /Link
  /BS << /Type /Border /W 0.5 /S /S >>
  /A << /S /URI
    /URI (http://www.tug.org) >> >>}%
B

\end{document}

And indeed the output contains a clickable box taking up no space (B follows A immediately). (it is as if the clickable area had been done with an rlap).

share|improve this answer
You can add \hspace*{12bp} in front of B. Or enclose the \special in \makebox[12bp][l]{...} – egreg Jan 27 at 16:32

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