Re: Get rid of LuaTeX warning on duplicate destination identifier

[Hans Hagen <pragma@wxs.nl>]

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On 8/29/2013 10:15 AM, Hans Hagen wrote:
> On 8/29/2013 4:06 AM, Aditya Mahajan wrote:
>> Hi,
>>
>> I am trying to pick up on an old thread of creating an overview page
>> [1]. Basically, the idea is to create an overvew slide at the end of a
>> presentation that shows the first page of different sections in a
>> presentation. Based on Wolfgang's answer in that old thread, I save the
>> relevant pages in a box, and then display them again at the end of the
>> presentation.
>>
>> This works, except that I get a series of warnings:
>>
>> l.86 \placeoverviewpage
>>                       LuaTeX warning (ext4): destination with the same
>> identifier (name{aut:10}) has been already used, duplicate ignored
>>
>> How do I get rid of these?
>
> Tricky. The problem is that you flush a box (copy) so the message comes
> from deep inside the backend (for good reason) and so we cannot
> intercept it as "hey user, you use the same dest twice" simply because
> it's a copy and not re-rendered.
>
> There are two solutions:
>
> (1) strip the box before copying (i can make a helper for that - later
> as i have to go now): destinations, references, writes-to-lists etc
>
> (2) you copy the old file before processing and use that one
>
>   \def\placeoverviewpage
>     {\startstandardmakeup[\c!align=\v!middle]
>         \getfiguredimensions[temp.pdf]%
>
> \dorecurse{\noffigurepages}{\externalfigure[temp.pdf][\c!page=##1,\c!width=\overviewwidth]\relax\space}
>
>      \stopstandardmakeup}
>
>> I am afraid that I cannot create a small example illustrating this
>> warning, so I am attaching the complete test file.
>>
>> [1]: http://thread.gmane.org/gmane.comp.tex.context/72556/focus=72571
>
> [2] It has always been a wish of mine to have it as option in the engine
> (pdfetex) but in luatex it's not that hard to do it myself now (i
> already have a stripper so I can extend that one a bit).

attached ... you can run the module for an example (you need a new beta)


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% experimental, based on an idea by Aditya, messed up by Hans.

\unprotect

\installnamespace{overview}

\installsimplecommandhandler \????overview {overview}

\initializeboxstack{\????overview}

\let\overviewsection\empty

\let\overview_previous_headnumber\!!minusone
\let\overview_current_headnumber \!!zerocount

\unexpanded\def\overview_save_page#1%
  {\ifx\overviewsection\empty
     \page_shipouts_normal{#1}%
   \else
     \xdef\overview_current_headnumber{\somenamedheadnumber\overviewsection\c!current}%
     \setbox\nextbox\hbox{#1}%
     \ifx\overview_previous_headnumber\overview_current_headnumber \else
       \glet\overview_previous_headnumber\overview_current_headnumber
       \setbox\scratchbox\copy\nextbox
       \cleanupbox\scratchbox % remove nodes that should not be seen in the backend twice
       \writestatus{overview}{saving first page of \overviewsection\space\overview_current_headnumber}%
       \savebox{\????overview}{\overview_current_headnumber}{\box\scratchbox}%
     \fi
     \page_shipouts_normal{\box\nextbox}%
   \fi}

\installshipoutmethod{overview}\overview_save_page

\definelistalternative
  [overview]
  [\c!renderingsetup=\??listrenderings:overview]

\setuplistalternative
  [overview]
  [\c!before=\dontleavehmode,
   \c!after=\space,
   \c!width=.4\textwidth] % or \listparameter\c!width

\startsetups[\??listrenderings:overview]
    \doifboxelse{\????overview}{\currentlistentrynumber}
       {\listalternativeparameter\c!before
        \startcurrentlistentrywrapper
          \scale
            [\c!width=\listalternativeparameter\c!width]
            {\foundbox{\????overview}{\currentlistentrynumber}}%
        \stopcurrentlistentrywrapper
        \listalternativeparameter\c!after}
       {}%
\stopsetups

\unexpanded\def\placeoverviewpage
  {\startstandardmakeup[\c!align=\v!middle]
      \placelist
        [\overviewsection]
        [\c!criterium=\v!all,
         \c!alternative=overview]
   \stopstandardmakeup}

\appendtoks
    \ifx\overviewsection\empty
      \edef\overviewsection{\overviewparameter\c!level}%
      \ifx\overviewsection\empty
        \setuppaper[\c!method=\v!normal]%
      \else
        \setuppaper[\c!method=overview]%
      \fi
   \else
     \writestatus{overview}{level is already set to \overviewsection, ignoring \overviewparameter\c!level}%
   \fi
\to \everysetupoverview

\protect

\continueifinputfile{m-pageview.mkiv}

\usemodule[pageview]

\setupinteraction
  [state=start]

\setupoverview
  [level=section]

\setuppapersize
  [S4]

\starttext

\dorecurse{4}
  {\startsection[title={Section #1}]
      \dorecurse{3}{\input knuth \par}
    \stopsection
  \page}

\placeoverviewpage

\stoptext

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