[pdftex] layer-based presentations

[Pawel Jackowski]

CV Radhakrishnan wrote:

> I am interested in it very much.
> 
> Thanks in advance.

Hi,

the attached file contains generic sample (pdfeTeX) and result pdf file 
with log. eTeX features are not essential but convenient in this case. I 
don't have an alfa-implementation already. Working on it.

Best regards, Pawel


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This is pdfeTeXk, Version 3.141592-1.11a-2.1 (Web2c 7.5.2) (format=pdfetex 2003.10.28)  7 NOV 2004 13:58
entering extended mode
\write18 enabled.
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 (d:/TeX/texmf/web2c/cp8bit.tcx)
**lay-nav.tex
(./lay-nav.tex{d:/TeX/texmf/pdftex/config/pdftex.cfg} [1{d:/TeX/texmf/fonts/map
/pdftex/updmap/pdftex.map}] [2] ){d:/TeX/texmf/dvips/tetex/f7b6d320.enc}<d:/TeX
/texmf/fonts/type1/bluesky/cm/cmr10.pfb><d:/TeX/texmf/fonts/type1/bluesky/cm/cm
bx10.pfb>
Output written on lay-nav.pdf (2 pages, 20151 bytes).
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% to see what happens

\pdfcompresslevel=0
\pdfpagewidth=10cm
\pdfpageheight=10cm
\pdfhorigin=1cm
\pdfvorigin=1cm
\hsize=8cm
\vsize=8cm

% handy macros

\def\obj{\immediate\pdfobj}

\def\objref#1{\space\expandafter\doobjref\number#1\relax}
\def\doobjref#1\relax{#1 0 R}

\def\objrefs#1{%
 \ifx#1\relax
  \space
 \else
  \objref{#1}\expandafter\objrefs
 \fi}

\def\lastobjref{\objref\pdflastobj}
\def\thisobjref{\objref{\numexpr\pdflastobj+1\relax}}
\def\nextobjref{\objref{\numexpr\pdflastobj+2\relax}} % eTeX needed

% lets make 3 layers

\def\openlayer{ BDC}
\def\closelayer{ EMC}

\obj{<< /Type /OCG /Name (Issue 1) >>}
\def\onercname{/OC1}             % resource name
\edef\oneobjnum{\the\pdflastobj} % object number
\edef\one{ /OC \onercname}       % code for \pdfliteral

\obj{<< /Type /OCG /Name (Issue 2) >>}
\def\tworcname{/OC2}
\edef\twoobjnum{\the\pdflastobj}
\edef\two{ /OC \tworcname}

\obj{<< /Type /OCG /Name (Issue 3) >>}
\def\threercname{/OC3}
\edef\threeobjnum{\the\pdflastobj}
\edef\three{ /OC \threercname}

% we have to add layer information to page resources...

\obj{% map names to objcts
<<
 \onercname\space\objref\oneobjnum     \space
 \tworcname\space\objref\twoobjnum     \space
 \threercname\space\objref\threeobjnum \space
>>
}

\edef\layersnames{\lastobjref}

\edef\next{\pdfpageresources={/Properties \layersnames}}
\next

% ... and to document catalog (layers are global!)

\edef\layersorder{\objrefs\oneobjnum\twoobjnum\threeobjnum\relax}
\edef\layerson{\objrefs\oneobjnum\relax}
\edef\layersoff{\objrefs\twoobjnum\threeobjnum\relax}

\obj{% layers default configuration
<<
 /Order [\layersorder] \space
 /ON    [\layerson   ] \space
 /OFF   [\layersoff  ] \space
>>
}

\edef\layersconfig{\lastobjref}

\pdfcatalog{%
/OCProperties
<<
 /OCGs [\layersorder ]\space
 /D     \layersconfig \space
>>
}

% now we can put some text on layers (Acrobat 6 needed to see layers)

{\bf Main content of the page}

\pdfliteral{\one\openlayer}
-- layer 1
\pdfliteral{\closelayer}

\pdfliteral{\two\openlayer}
-- layer 2
\pdfliteral{\closelayer}

\pdfliteral{\three\openlayer}
-- layer 3
\pdfliteral{\closelayer}

% \end

% now the navigation part

% example of action that affects layers

\def\togglelayers{/S /SetOCGState /State [ /Toggle \layersorder ]}

\bigskip
\pdflinkmargin=2bp
Test:
\pdfstartlink
 user{/Subtype /Link /A << \togglelayers\space >>}TogGle LaYerS!%
\pdfendlink

% sub-page navigation works in presentation mode only,
% so we enter fullscreen mode

\pdfcatalog{/PageMode /FullScreen}

% first we define actions to perform on user request (arrow buttons)

\obj{<<
/S /SetOCGState
/State [ /OFF \objrefs\oneobjnum\twoobjnum\threeobjnum\relax ]
>>}

\edef\actionzero{\lastobjref} % all layers off

\obj{<<
/S /SetOCGState
/State [
 /ON  \objrefs\oneobjnum\relax
 /OFF \objrefs\twoobjnum\threeobjnum\relax ]
>>}

\edef\actionone{\lastobjref}

\obj{<<
/S /SetOCGState
/State [
 /ON  \objrefs\oneobjnum\twoobjnum\relax
 /OFF \objrefs\threeobjnum\relax ]
>>}

\edef\actiontwo{\lastobjref}

\obj{%
<<
/S /SetOCGState
/State [ /ON \objrefs\oneobjnum\twoobjnum\threeobjnum\relax ]
>>}

\edef\actionthree{\lastobjref} % all layers on

\obj{<< /S /Named /N /NextPage >>}

\edef\actionnextpage{\lastobjref}

% each page state is represented by a navigation node

\obj{% root node
<<
 /Type /NavNode
 /NA   \actionone
 /PA   \actionzero % ?
 /Next \nextobjref
 /Prev \thisobjref % avoid loosing current navigation node
>>}

\edef\rootnode{\lastobjref} % for page attributes

\obj{% next
<<
 /NA \actiontwo    % next action
 /PA \actionzero   % previous action
 /Next \nextobjref % next node
 /Prev \lastobjref % previous node (root in this case)
>>}

\obj{% next
<<
 /NA \actionthree
 /PA \actionone
 /Next \nextobjref
 /Prev \lastobjref
>>}

\obj{% last node on the page
<<
 /NA \actionnextpage
 /PA \actiontwo
 /Prev \lastobjref
>>}

\edef\next{\pdfpageattr={/PresSteps \rootnode}}
\next

\vfill\eject
\pdfpageattr{} % forget navigation nodes for this page

\bf
Details in PDF 1.5 spec, chapter 8.

\end