%D \module
%D   [       file=grph-exp,
%D        version=2024.07.05,
%D          title=\CONTEXT\ Graphic Macros,
%D       subtitle=Figure Export,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\writestatus{loading}{ConTeXt Graphic Macros / Figure Export}

\unprotect

%D Assuming \type {test.tex}:
%D
%D \starttyping
%D \startmode [images]
%D      \collectexported
%D \stopmode
%D
%D \usemodule[article-basic]
%D
%D \setupbackend
%D   [export=yes]
%D
%D \setupinteraction
%D   [title={\documentvariable{title}}]
%D
%D \startdocument[title=Runtime graphics]
%D
%D \samplefile{tufte}
%D
%D \starttextdisplay
%D     \startimage
%D         \startMPcode
%D             fill fullcircle scaled 3cm withcolor darkred ;
%D         \stopMPcode
%D     \stopimage
%D \stoptextdisplay
%D
%D \samplefile{tufte}
%D
%D \stopdocument
%D \stoptyping
%D
%D This should do the job:
%D
%D \starttyping
%D mtxrun test
%D mtxrun --script epub --images test
%D \stoptyping

\newinteger\nofexportedboxes

\newconditional\c_grph_exported

\definesystemconstant{exported}

\def\grph_exported_discard#1%
  {\ctxlua{backends.codeinjections.discardpages(\ifcase#1\else true\fi)}}

\permanent\protected\def\collectexported
  {\grph_exported_discard\plusone
   \c_grph_exported\conditionaltrue
   \appendtoks
     \grph_exported_flush
   \to \everystoptext}

\aliased\let\dotagexported\relax

\appendtoks
   \enforced\let\dotagexported\grph_exported_tag
\to \everyenableelements

\permanent\protected\def\grph_exported_tag
  {\enforced\def \figurefileoriginal{\jobname-\s!exported-\the\nofexportedboxes.svg}%
   \enforced\let \figurefullname    \figurefileoriginal
   \enforced\let \figurefilepage    \!!plusone
   \enforced\let \figurelabel       \empty
   \enforced\edef\figurewidth       {\the\wd\b_grph_image}%
   \enforced\edef\figureheight      {\the\ht\b_grph_image}%
   \enforced\edef\figuredepth       {\the\dp\b_grph_image}%
   \dotagfigure}

\permanent\protected\def\grph_exported_flush
  {\page
   % todo block writing to the tuc file
   \grph_exported_discard\zerocount
   \dorecurse \nofexportedboxes {%
     \startTEXpage
       \dontleavehmode\directboxfromcache\s!exported{##1}%
     \stopTEXpage}%
   \writestatus\m!system\empty
   \writestatus\m!system{if needed run: mtxrun --script epub --images \jobname}%
   \writestatus\m!system\empty}

\newbox\b_grph_image

\permanent\protected\def\grph_start_image_tagged
  {\begingroup
   \global\advanceby\nofexportedboxes\plusone
   \dostarttagged\t!image{\the\nofexportedboxes}%
   \setbox\b_grph_image\hpack\bgroup
   \ignorepars
   \ignorespaces}

\permanent\protected\def\grph_stop_image_tagged
  {\removeunwantedspaces
   \egroup
   \dotagexported
   \dostoptagged
   \ifconditional\c_grph_exported
     \setbox\scratchbox\box\b_grph_image
     \putboxincache\s!exported{\the\nofexportedboxes}\scratchbox
   \fi
   \box\b_grph_image
   \endgroup}

%D We want to get compatible packaging (beware of spaces)

\permanent\protected\def\grph_start_image_normal
  {\hpack\bgroup
   \ignorepars
   \ignorespaces}

\permanent\protected\def\grph_stop_image_normal
  {\removeunwantedspaces
   \egroup}

\enforced\let\startimage\grph_start_image_normal
\enforced\let\stopimage \grph_stop_image_normal

\appendtoks
    \enforced\let\startimage\grph_start_image_tagged
    \enforced\let\stopimage \grph_stop_image_tagged
\to \everyenableelements

%D Maybe more hooks are needed. We need for instance to deal with
%D reuse and also need to be able to bypass background graphics. It is
%D anyway better to be explicit and just wrap in an image.

% \aliased\let\meta_process_graphic_start_normal\meta_process_graphic_start
% \aliased\let\meta_process_graphic_stop_normal \meta_process_graphic_stop
%
% \def\meta_process_graphic_start_tagged
%   {\startimage
%    \meta_process_graphic_start_normal}
%
% \def\meta_process_graphic_stop_tagged
%   {\meta_process_graphic_stop_normal
%    \stopimage}
%
% \appendtoks
%     \let\meta_process_graphic_start\meta_process_graphic_start_tagged
%     \let\meta_process_graphic_stop \meta_process_graphic_stop_tagged
% \to \everyenableelements

%D So we go for explicit wrapping plus an extra MP command:

\permanent\protected\def\startMPimage#1\stopMPimage
  {\startimage
   \startMPcode#1\stopMPcode
   \stopimage}

\permanent\protected\lettonothing\stopMPimage

% bonus

\newdimension\justimageoffset
\newdimension\justimagetopoffset
\newdimension\justimagebottomoffset
\newdimension\justimageleftoffset
\newdimension\justimagerightoffset

\permanent\protected\def\grph_start_image_only
  {\begingroup
   \setbox\b_grph_image\hpack\bgroup
   \ignorepars
   \ignorespaces}

\permanent\protected\def\grph_stop_image_only
  {\removeunwantedspaces
   \egroup
   \global\advanceby\nofexportedboxes\plusone
   \ifzeropt{%
          \justimageoffset
         +\justimageleftoffset
         +\justimagerightoffset
         +\justimagetopoffset
         +\justimagebottomoffset
       }%
     \setbox\scratchbox\box\b_grph_image
   \else
     \setbox\scratchbox\hpack\bgroup
       \kern{\justimageoffset+\justimageleftoffset}%
       \box\b_grph_image
       \kern{\justimageoffset+\justimagerightoffset}%
     \egroup
     \ht\scratchbox{\ht\scratchbox+\justimageoffset+\justimagetopoffset}%
     \dp\scratchbox{\dp\scratchbox+\justimageoffset+\justimagebottomoffset}%
   \fi
   \putboxincache\s!exported{\the\nofexportedboxes}\scratchbox
   \box\b_grph_image
   \endgroup}

\permanent\protected\def\justimages
  {\exportingtrue
   \ctxlua{backends.codeinjections.discardpages(true)}%
   \appendtoks
     \grph_exported_flush
   \to \everystoptext
   \enforced\let\startimage\grph_start_image_only
   \enforced\let\stopimage \grph_stop_image_only}

\protect \endinput