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%D \module
%D   [       file=page-mbk,   % was part of page-mis.mkiv / 2008.11.17
%D        version=2011.11.23, % was part of page-flt.tex  / 2000.10.20
%D          title=\CONTEXT\ Page Macros,
%D       subtitle=Margin Floats,
%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 Page Macros / Margin Floats}

\unprotect

%D This is an old mechanism that is quite independent of other
%D floats. There is for instance no save/restore used here. When
%D there is need (and demand) we can use the float cache and then
%D flush them in the text when they are left over. On the other
%D hand, margin float are somewhat manual so it does not make too
%D much sense to complicate the code. As an alternative users can
%D fall back on margin texts: they do stack but don't float.
%D
%D \starttyping
%D \dorecurse{9} {
%D   \placefigure[margin]{#1}{}
%D   \input ward
%D }
%D \page \null % will flush them
%D \stoptyping

% status=start: in margin
% status=stop : in text
%
% todo: flush margin floats at end of text
% todo: separate boxes for left and right

\installcorenamespace{marginblock}
\installcorenamespace{marginblocklocation}

\installcommandhandler \??marginblock {marginblock} \??marginblock

\let\setupmarginblocks\setupmarginblock

\newconditional\c_page_margin_blocks_enabled % not really needed as we can check each time
\newconditional\c_page_margin_blocks_present

\newbox        \b_page_margin_blocks
\newbox        \b_page_margin_blocks_prepared

\appendtoks
   \doifelse{\rootmarginblockparameter\c!state}\v!start
     \settrue\setfalse\c_page_margin_blocks_enabled
\to \everysetupmarginblock

\setupmarginblocks
  [\c!state=\v!start,
   \c!location=\v!inmargin,
   \c!width=\rightmarginwidth,
  %\c!style=,
  %\c!color=,
  %\c!align=,
  %\c!left=,
  %\c!right=,
  %\c!top=,
  %\c!before=,
  %\c!after=,
   \c!inbetween=\blank,
   \c!bottom=\vfill]

\unexpanded\def\startmarginblock
  {\dosingleempty\page_margin_blocks_start_block}

\unexpanded\def\stopmarginblock
  {\page_margin_blocks_stop_block}

\def\page_margin_blocks_start_block[#tag]%
  {\begingroup
   \edef\currentmarginblock{#tag}%
   \doifelse{\marginblockparameter\c!state}\v!start
     \page_margin_blocks_start_block_yes
     \page_margin_blocks_start_block_nop}

\def\page_margin_blocks_stop_block
  {\doifelse{\marginblockparameter\c!state}\v!start
     \page_margin_blocks_stop_block_yes
     \page_margin_blocks_stop_block_nop
   \endgroup}

\def\page_margin_blocks_start_block_yes % 2 maal \vbox ivm \unvbox elders
  {\showmessage\m!layouts4\empty
   \global\settrue\c_page_margin_blocks_present
   \global\setbox\b_page_margin_blocks\vtop\bgroup\vbox\bgroup
     \hsize\marginblockparameter\c!width
     \ifvoid\b_page_margin_blocks\else
       \unvbox\b_page_margin_blocks
       \marginblockparameter\c!inbetween
     \fi
     \usealignparameter\marginblockparameter
     \usemarginblockstyleandcolor\c!style\c!color
     \begstrut
     \ignorespaces}

\def\page_margin_blocks_stop_block_yes
  {\removeunwantedspaces
   \endstrut
   \egroup
   \egroup}

\def\page_margin_blocks_start_block_nop
  {\showmessage\m!layouts5\empty
   \marginblockparameter\c!before
   \bgroup
   \usemarginblockstyleandcolor\c!style\c!color}

\def\page_margin_blocks_stop_block_nop
  {\egroup
   \marginblockparameter\c!after}

\def\page_margin_blocks_reshape
  {\ifdim\ht\b_page_margin_blocks_prepared>\zeropoint
     \beginofshapebox
     \unvbox\b_page_margin_blocks_prepared
     \endofshapebox
     \reshapebox
       {\box\shapebox}%
     \setbox\b_page_margin_blocks_prepared\vbox to \textheight
       {\marginblockparameter\c!top
        \flushshapebox
        \marginblockparameter\c!bottom}%
   \fi}

\unexpanded\def\checkmarginblocks
  {\ifvoid\b_page_margin_blocks
     \global\setfalse\c_page_margin_blocks_present
   \else
     \page_margin_blocks_check_indeed
   \fi}

\def\page_margin_blocks_check_indeed
  {\ifcsname\??marginblocklocation\marginblockparameter\c!location\endcsname
     \page_margin_blocks_prepare_box
     \csname\??marginblocklocation\marginblockparameter\c!location\endcsname
   \else
     \global\setbox\b_page_margin_blocks\emptybox
     \global\setfalse\c_page_margin_blocks_present
   \fi}

\def\page_margin_blocks_prepare_box
  {\setbox\b_page_margin_blocks_prepared\vbox
     {\forgetall
      \splittopskip\topskip
      \ifvoid\b_page_margin_blocks\else
        \ifdim\ht\b_page_margin_blocks>\textheight
          \vsplit\b_page_margin_blocks to \textheight
        \else
          \unvbox\b_page_margin_blocks
        \fi
      \fi}%
   \page_margin_blocks_reshape
   \setbox\b_page_margin_blocks_prepared\vbox
     {\marginblockparameter\c!before
      \box\b_page_margin_blocks_prepared
      \marginblockparameter\c!after}}

% inner outer

\setvalue{\??marginblocklocation\v!left    }{\page_margin_blocks_set_l_box}
\setvalue{\??marginblocklocation\v!right   }{\page_margin_blocks_set_r_box}
\setvalue{\??marginblocklocation\v!inmargin}{\doifbothsidesoverruled
                                             \page_margin_blocks_set_r_box
                                             \page_margin_blocks_set_r_box
                                             \page_margin_blocks_set_l_box}
\setvalue{\??marginblocklocation\v!middle  }{\doifbothsidesoverruled
                                             \page_margin_blocks_set_r_box
                                             \page_margin_blocks_set_l_box
                                             \page_margin_blocks_set_r_box}

\unexpanded\def\page_margin_blocks_place_r_yes
  {\setbox\b_page_margin_blocks_prepared\hbox to \rightmarginwidth
     {\marginblockparameter\c!left
      \box\b_page_margin_blocks_prepared
      \marginblockparameter\c!right}%
   \vsmashbox\b_page_margin_blocks_prepared
   \box\b_page_margin_blocks_prepared}

\unexpanded\def\page_margin_blocks_place_l_yes
  {\setbox\b_page_margin_blocks_prepared\hbox to \leftmarginwidth
     {\marginblockparameter\c!right
      \box\b_page_margin_blocks_prepared
      \marginblockparameter\c!left}%
   \vsmashbox\b_page_margin_blocks_prepared
   \box\b_page_margin_blocks_prepared}

\unexpanded\def\page_margin_blocks_place_r_nop{\hskip\rightmarginwidth}
\unexpanded\def\page_margin_blocks_place_l_nop{\hskip\leftmarginwidth}

\let\placerightmarginblock\page_margin_blocks_place_r_nop
\let\placeleftmarginblock \page_margin_blocks_place_l_nop

\def\page_margin_blocks_set_r_box{\let\placerightmarginblock\page_margin_blocks_place_r_yes}
\def\page_margin_blocks_set_l_box{\let\placeleftmarginblock \page_margin_blocks_place_l_yes}

% margin floats (keyword 'margin' in option list)

\unexpanded\def\page_margin_blocks_process_float
  {\doifelse{\marginblockparameter\c!state}\v!start
     \page_margin_blocks_process_float_yes
     \page_margin_blocks_process_float_nop}

\def\page_margin_blocks_process_float_yes
  {\global\setbox\b_page_margin_blocks\vbox
     {\hsize\marginblockparameter\c!width
      \unvcopy\b_page_margin_blocks
      \ifvoid\b_page_margin_blocks\else
        \expandafter\marginblockparameter\expandafter\c!inbetween
      \fi
      \box\floatbox
      \filbreak}%
   \ifdim\ht\b_page_margin_blocks>\textheight
   % page_floats_report_saved % no saving done anyway
   \else
     \page_floats_report_total
   \fi}

\def\page_margin_blocks_process_float_nop
  {\handlefloatmethod\v!here}

\def\page_margin_blocks_float_before
  {\ifconditional\c_page_margin_blocks_enabled
     \doifinset\v!margin\floatlocation\endgraf
   \fi}

\def\page_margin_blocks_float_set_hsize
  {\ifconditional\c_page_margin_blocks_enabled
     \doifinset\v!margin\floatlocation{\hsize\rootmarginblockparameter\c!width}%
   \fi}

\appendtoks
   \ifvoid\b_page_margin_blocks \else
     \writestatus\m!layouts{beware: there are left-over margin floats!}%
   \fi
\to \everystoptext

\unexpanded\def\flushmarginblocks
  {\page_otr_command_flush_margin_blocks}

\protect \endinput