%D \module
%D   [       file=pack-obj,
%D        version=1998.01.15,
%D          title=\CONTEXT\ Packaging Macros,
%D       subtitle=Objects,
%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 Packaging Macros / Objects}

\unprotect

\registerctxluafile{pack-obj}{autosuffix}

%D \macros
%D   {setobject,getobject,ifinobject}
%D
%D Boxes can be considered reuable objects. Traditionally once passed to the \DVI\
%D file, such objects cannot be reused. In \PDF\ however, reusing is possible and
%D sometimes even a necessity. Therefore, \CONTEXT\ supports reusable objects and
%D \LUATEX\ has native support for so called box resources.
%D
%D The first application of objects in \CONTEXT\ concerned \METAPOST\ graphics and
%D fill||in form fields. Reusing resources can save lots of bytes and sometimes also
%D runtime.
%D
%D \starttyping
%D \setobject{class}{name}\somebox{}
%D \getobject{class}{name}
%D \stoptyping
%D
%D Here \type {\somebox} can be whatever box specification suits \TEX. Although the
%D implementation in \MKIV\ is somewhat different the principles have not changed.

\installcorenamespace {objects}

\mutable\def\objectoffset{1cm} % Still public but use with care!

\newif       \ifinobject
\newbox      \b_pack_objects
\newdimension\d_pack_objects_offset \permanent\def\objectmargin{\the\d_pack_objects_offset}
\newdimension\d_pack_objects_width  \permanent\def\objectwidth {\the\d_pack_objects_width}
\newdimension\d_pack_objects_height \permanent\def\objectheight{\the\d_pack_objects_height}
\newdimension\d_pack_objects_depth  \permanent\def\objectdepth {\the\d_pack_objects_depth}

%D If I have time I will use the unreferenced variant for e.g. mp reuse. This can be
%D rewritten in \LUA\ anyway.

%D Tagging doesn't provide a local structure for an xform so if tagging is needed than one
%D should not use object reuse with content that demands it. Figuring out a work around is
%D not worth the trouble.

\permanent\protected\def\setreferencedobject       #1#2{\begingroup\taggingpause\synctexpause\d_pack_objects_offset\objectoffset\inobjecttrue\dowithnextbox{\pack_objects_set_yes{#1}{#2}}}
\permanent\protected\def\settightreferencedobject  #1#2{\begingroup\taggingpause\synctexpause\d_pack_objects_offset\zeropoint   \inobjecttrue\dowithnextbox{\pack_objects_set_yes{#1}{#2}}}
\permanent\protected\def\setunreferencedobject     #1#2{\begingroup\taggingpause\synctexpause\d_pack_objects_offset\objectoffset\inobjecttrue\dowithnextbox{\pack_objects_set_nop{#1}{#2}}}
\permanent\protected\def\settightunreferencedobject#1#2{\begingroup\taggingpause\synctexpause\d_pack_objects_offset\zeropoint   \inobjecttrue\dowithnextbox{\pack_objects_set_nop{#1}{#2}}}

\aliased\let\setobject     \setreferencedobject
\aliased\let\settightobject\settightreferencedobject

%D We can get subtle differences in boundingboxes but both methods work ok.

% How useful is this ... delayed but refered objects .. messy concept.
%
% \def\InitIt{%
%     \c_pack_objects_delay\plusone
%     \setobject{test}{1}\hbox{test me 1}
%     \c_pack_objects_delay\zerocount
% }
%
% \def\GetIt{%
%     \c_pack_objects_delay\plusone
%     \getobject{test}{1}
%     \c_pack_objects_delay\zerocount
% }
%
% \def\SetIt{%
%     \c_pack_objects_delay\plustwo
%     \setobject{test}{1}\hbox{\bf HERE}% we cannot have interactivity in xforms
%     \c_pack_objects_delay\zerocount
% }

\newconstant\c_pack_objects_offset_mode % 0=tex 1=box
\newconstant\c_pack_objects_delay       % 0=immediate 1=delay

\protected\def\pack_objects_set_yes#1#2%
  {\ifcase\c_pack_objects_offset_mode
     \ifzeropt\d_pack_objects_offset
       \pack_objects_package_nop\nextbox
     \else
       \pack_objects_package_yes\nextbox
     \fi
   \else
     \pack_objects_package_nop\nextbox
   \fi
   \clf_registerreferencedobject
     {#1}{#2}%
     \b_pack_objects
     \d_pack_objects_offset
     \c_pack_objects_offset_mode
     \c_pack_objects_delay
   \synctexresume
   \endgroup}

\protected\def\pack_objects_set_nop#1#2%
  {\ifcase\c_pack_objects_offset_mode
     \ifzeropt\d_pack_objects_offset
       \pack_objects_package_nop\nextbox
     \else
       \pack_objects_package_yes\nextbox
     \fi
   \else
     \pack_objects_package_nop\nextbox
   \fi
   \clf_registerobject
     {#1}{#2}%
     \b_pack_objects
     \d_pack_objects_offset
     \c_pack_objects_offset_mode
     \c_pack_objects_delay
   \synctexresume
   \endgroup}

\def\pack_objects_package_nop#1% we pack because otherwise \ruledhbox is still tight
  {\setbox\b_pack_objects\hpack{\box#1}}

\def\pack_objects_package_yes#1%
  {\d_pack_objects_width {\wd#1+2\d_pack_objects_offset}%
   \d_pack_objects_height{\ht#1+ \d_pack_objects_offset}%
   \d_pack_objects_depth {\dp#1+ \d_pack_objects_offset}%
   \setbox\b_pack_objects\hpack{\hskip\d_pack_objects_offset\box#1}%
   \wd\b_pack_objects\d_pack_objects_width
   \ht\b_pack_objects\d_pack_objects_height
   \dp\b_pack_objects\d_pack_objects_depth}

\permanent\protected\def\getobject#1#2%
  {\begingroup
   \synctexpause
   \clf_restoreobject{#1}{#2}%
   \ifzeropt\d_pack_objects_offset\else
     \d_pack_objects_offset-\d_pack_objects_offset
     \pack_objects_package_yes\b_pack_objects
   \fi
   \box\b_pack_objects
   \synctexresume
   \endgroup}

%D If needed one can ask for the dimensions of an object with:
%D
%D \starttyping
%D \getobjectdimensions{class}{name}
%D \stoptyping
%D
%D The results are reported in \type {\objectwidth}, \type {\objectheight} and \type
%D {\objectdepth} as well as \type {\objectoffset}.

% \getobjectdimensions #1#2 % defined at the lua end

%D \macros
%D   {doifobjectfoundelse,doifobjectreferencefoundelse}
%D
%D To prevent redundant definition of objects, one can use the next tests:
%D
%D \starttyping
%D \doifobjectfoundelse{class}{object}{do then}{do else}
%D \doifobjectreferencefoundelse{class}{object}{do then}{do else}
%D \stoptyping

\permanent\def\defaultobjectreference{0}
\permanent\def\defaultobjectpage     {\realfolio}

% \getobjectreference           {#1}{#2\csname % define at the lua end
% \getobjectreferencepage       {#1}{#2\csname % define at the lua end
% \doifelseobjectfound          {#1}{#2}       % defined atthe lua end
% \doifelseobjectreferencefound {#1}{#2}       % defined atthe lua end

\aliased\let\dogetobjectreference    \getobjectreference     % for now, will go away
\aliased\let\dogetobjectreferencepage\getobjectreferencepage % for now, will go away

\aliased\let\doifobjectfoundelse         \doifelseobjectfound
\aliased\let\doifobjectreferencefoundelse\doifelseobjectreferencefound

%D For the moment here:

\mutable\lettonothing\lastpredefinedsymbol % some day we can do more at the lua end

% maybe \s!SYM

%D This is the only place wehere we still test and access objects so we might as
%D well move more to \LUA.

\permanent\protected\def\predefinesymbol[#1]%
  {\begingroup
   \xdef\lastpredefinedsymbol{#1}%
   \settightobject{SYM}\lastpredefinedsymbol\hbox{\symbol[#1]}% to be checked ... maybe only fitting
   \clf_registerbackendsymbol
     \lastpredefinedsymbol
     {\objectreference{SYM}\lastpredefinedsymbol}\relax
   \endgroup}

\protect \endinput