%D \module
%D   [       file=page-com, % moved from page-imp
%D        version=1998.01.15,
%D          title=\CONTEXT\ Page Macros,
%D       subtitle=Page Comments,
%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.

%D This will become runtime loaded code.

\writestatus{loading}{ConTeXt Page Macros / Page Comments}

\unprotect

%D \macros
%D   {setuppagecomment,startpagecomment}
%D
%D This command is not yet documented. Usage:
%D
%D \starttyping
%D \setuppagecomment[state=start,location=right]
%D
%D \startpagecomment
%D \input knuth
%D \stoppagecomment
%D \stoptyping

\unexpanded\def\setuppagecomment
  {\dosingleempty\dosetuppagecomment}

\def\dosetuppagecomment[#1]%
  {\getparameters[\??pc][#1]%
   \doifelse\@@pcstate\v!start
     {\doifinsetelse\@@pclocation{\v!bottom,\v!top}
        {\setuppapersize[\c!left=\hskip\@@pcoffset]%
         \edef\@@pcpaperheight{\the\dimexpr\paperheight+\@@pcoffset+\@@pcoffset+\@@pcdistance+\@@pcheight}%
         \edef\@@pcpaperwidth {\the\dimexpr\paperwidth +\@@pcoffset+\@@pcoffset}%
         \defineoverlay[\v!pagecomment][\placepagecommentTB]}
        {\setuppapersize[\c!top=\vskip\@@pcoffset]%
         \edef\@@pcpaperheight{\the\dimexpr\paperheight+\@@pcoffset+\@@pcoffset}%
         \edef\@@pcpaperwidth {\the\dimexpr\paperwidth +\@@pcoffset+\@@pcoffset+\@@pcdistance+\@@pcwidth}%
         \defineoverlay[\v!pagecomment][\placepagecommentLR]}%
      \processaction
        [\@@pclocation]
        [ \v!bottom=>{\setuplayout[\c!location=]\setuppapersize[\c!bottom=\vss,\c!top   =\vskip\@@pcoffset]},
             \v!top=>{\setuplayout[\c!location=]\setuppapersize[\c!top   =\vss,\c!bottom=\vskip\@@pcoffset]},
            \v!left=>{\setuplayout[\c!location=]\setuppapersize[\c!left  =\hss,\c!right =\hskip\@@pcoffset]},
           \v!right=>{\setuplayout[\c!location=]\setuppapersize[\c!right =\hss,\c!left  =\hskip\@@pcoffset]}]%
      \definepapersize
        [\v!pagecomment]
        [\c!height=\@@pcpaperheight,
          \c!width=\@@pcpaperwidth]%
      \let\@@pcprintpapersize\printpapersize
      \setuppapersize[\papersize][\v!pagecomment]%
      \setupbackgrounds[\v!paper][\c!background=\v!pagecomment]}% todo append if already set
    {\doif\@@pcstate\v!stop % else initialization  invokes backgrounds
       {% this should be tested first
        % \normalexpanded{\noexpand\setuppapersize[\papersize][\@@pcprintpapersize]}%
        \setupbackgrounds[\v!paper][\c!background=]}}}

\def\@@pcprintpapersize{\printpapersize}

\unexpanded\def\placepagecommentTB
  {\vbox to \printpaperheight
     {%\forgetall
      \hsize\printpaperwidth
      \vskip\@@pcoffset
      \doifelse\@@pclocation\v!bottom{\vskip\dimexpr\paperheight+\@@pcdistance\relax}\vss
      \hskip\@@pcoffset
      \vbox to \@@pcheight
        {%\forgetall
         \hsize\paperwidth
         \ifpagecomment
           \getbuffer[\v!pagecomment]%
           \global\pagecommentfalse
         \fi}%
      \hfill
      \doifelse\@@pclocation\v!bottom\vss{\vskip\dimexpr\paperheight+\@@pcdistance\relax}%
      \vskip\@@pcoffset}}

\unexpanded\def\placepagecommentLR
  {\hbox to \printpaperwidth
     {\hskip\@@pcoffset
      \doifelse\@@pclocation\v!right{\hskip\paperwidth\hskip\@@pcdistance}\hss
      \vbox to \printpaperheight
        {%\forgetall
         \vskip\@@pcoffset
         \hsize\@@pcwidth
         \ifpagecomment
           \getbuffer[\v!pagecomment]%
           \global\pagecommentfalse
         \fi
         \vss}%
      \doifelse\@@pclocation\v!right\hss{\hskip\paperwidth\hskip\@@pcdistance}%
      \hskip\@@pcoffset}}

\newif\ifpagecomment

\setvalue{\e!start\v!pagecomment}%
  {\global\pagecommenttrue
   \grabbufferdatadirect\v!pagecomment{\e!start\v!pagecomment}{\e!stop\v!pagecomment}}

\setuppagecomment
  [\c!state=, % \v!stop would invoke background calculation
   \c!location=\v!bottom,
   \c!offset=.5cm,
   \c!distance=.5cm,
   \c!height=5cm,
   \c!width=10cm]

\protect \endinput