%D \module
%D   [       file=pack-mis, % moved from e.g. core-mis
%D        version=1998.01.29,
%D          title=\CONTEXT\ Core Macros,
%D       subtitle=Miscelaneous,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
%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 Packing Macros / Misc Commands}

\unprotect

% a quite old mechanism already (but inheritance added)
%
% \defineplacement[name][settings]
% \setupplacement [name][settings]
% \placement      [name][settings]
% \place<name>          [settings]

\installcommandhandler \??pl {placement} \??pl

\appendtoks
   \setuevalue{\e!place\currentplacement}{\pack_placement{\currentplacement}}%
\to \everydefineplacement

\setupplacement
  [\c!left=\hss,
   \c!right=\hss,
   \c!linecorrection=\v!off,
   \c!depthcorrection=\v!off,
   \c!grid=\v!middle,
  %\c!before=,
  %\c!after=,
   \c!margin=\v!standard]

\unexpanded\def\placement[#tag]%
  {\pack_placement{#tag}}

\unexpanded\def\pack_placement#tag%
  {\bgroup
   \edef\currentplacement{#tag}%
   \dosingleempty\pack_placement_indeed}

\def\pack_placement_indeed[#settings]% set test can be sped up but non critical
  {\iffirstargument
     \setupcurrentplacement[#settings]%
   \fi
   \dowithnextboxcontent{\forgetall}{\pack_placement_flush\egroup}\vbox}

\def\pack_placement_flush
  {\setlocalhsize
   \placementparameter\c!before
   \begingroup
   \disableparpositions
   \setbox\nextbox\hbox to \localhsize
     {\placementparameter\c!left
      \flushnextbox
      \placementparameter\c!right}%
   \ifinsidefloat \else
     \addlocalbackgroundtobox\nextbox
   \fi
   \ifgridsnapping
     \doifinset{\placementparameter\c!margin}{\v!standard,\v!yes}\noindent % unchecked
     \doifelsenothing{\placementparameter\c!grid}
       {\snaptogrid[\v!middle]}
       {\snaptogrid[\placementparameter\c!grid]}%
       \hbox{\flushnextbox}%
   \else
     \doif{\placementparameter\c!linecorrection}\v!on \startbaselinecorrection
     \doifinset{\placementparameter\c!margin}{\v!standard,\v!yes}\noindent
     \flushnextbox
     \doif{\placementparameter\c!depthcorrection}\v!on\baselinecorrection
     \doif{\placementparameter\c!linecorrection }\v!on\stopbaselinecorrection
   \fi
   \endgroup
   \placementparameter\c!after}

\protect \endinput