%D \module
%D   [       file=page-txt, % copied from main-001,
%D        version=1997.03.31,
%D          title=\CONTEXT\ Page Macros,
%D       subtitle=Texts,
%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.

% where we can do some mkiv cleanup

% \setuplayouttext in manual

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

\unprotect

%D Interfacing between this and other modules is handled by
%D the following macros. The current state of a text line
%D (header, footer, etc.) is checked by:
%D
%D \starttyping
%D \resetlayouttextlines
%D \stoptyping
%D
%D The main text box is finished by the following macro:
%D
%D \starttyping
%D \getmainbox <box> <\vbox|\unvbox>
%D \stoptyping
%D
%D The text lines are collected with:
%D
%D \starttyping
%D \gettextboxes
%D \stoptyping
%D
%D It is possible to extens the default content of the text
%D areas by appending content to the following token list
%D registers:

\newtoks\toptextcontent     \newtoks\leftedgetextcontent
\newtoks\headertextcontent  \newtoks\leftmargintextcontent
\newtoks\footertextcontent  \newtoks\rightmargintextcontent
\newtoks\bottomtextcontent  \newtoks\rightedgetextcontent

\newtoks\texttextcontent

%D \macros
%D  {setuptop, setupheader, setuptext,
%D   setupfooter, setupbottom}
%D
%D The macros in this module sometimes look a bit more complicated
%D than needed, which is a direct result of the fact that their
%D ancestors are quite old and upward compatibility is a must.
%D
%D \showsetup{setuptop}
%D \showsetup{setupheader}
%D \showsetup{setuptext}
%D \showsetup{setupfooter}
%D \showsetup{setupbottom}

\unexpanded\def\setuplayouttext
  {\dotripleempty\dosetuplayouttext}

\def\dosetuplayouttext[#1][#2][#3]% beware, non global
  {\ifthirdargument
     \getparameters[\??tk#1#2][#3]%
   \else
    %\getparameters[\??tk#1\v!text][#2]%
     \edef\previoustextstate{\csname\??tk#1\c!state\endcsname}%
     \getparameters[\??tk#1][#2]%
     \edef\currenttextstate{\csname\??tk#1\c!state\endcsname}%
     \ifx\currenttextstate\previoustextstate
       % no change in state
     \else
       %\checkcurrentlayout % no
       % speed optimization (calculating backgrounds takes time)
       \doifcommon{\previoustextstate,\currenttextstate}{\v!high,\v!none}
         {\calculatevsizes
          \recalculatebackgrounds}%
     \fi
   \fi}

\unexpanded\def\setuptop    {\dotripleempty\dosetuplayouttext[\v!top]}
\unexpanded\def\setupheader {\dotripleempty\dosetuplayouttext[\v!header]}
\unexpanded\def\setuptext   {\dotripleempty\dosetuplayouttext[\v!text]}
\unexpanded\def\setupfooter {\dotripleempty\dosetuplayouttext[\v!footer]}
\unexpanded\def\setupbottom {\dotripleempty\dosetuplayouttext[\v!bottom]}

%D \macros
%D  {noheaderandfooterlines,notopandbottomlines}
%D
%D Although not really needed, the following shortcuts
%D sometimes come in handy.
%D
%D \showsetup{noheaderandfooterlines}
%D \showsetup{notopandbottomlines}

\def\noheaderandfooterlines
  {\setupheader[\c!state=\v!empty]%
   \setupfooter[\c!state=\v!empty]}

\def\notopandbottomlines
  {\setuptop   [\c!state=\v!empty]%
   \setupbottom[\c!state=\v!empty]}

%D \macros
%D  {setuptoptexts, setupheadertexts, setuptexttexts,
%D   setupfootertexts, setupbottomtexts}
%D
%D The next macros take one or more arguments. The exact setup
%D depends on the number of arguments. Although not that
%D intuitive, the current scheme evolved out of the original.
%D When margin and edge texts as well as middle texts showed
%D up, the current odd|/|even scheme surfaced.
%D
%D \showsetup{setuptoptexts}
%D \showsetup{setupheadertexts}
%D \showsetup{setuptexttexts}
%D \showsetup{setupfootertexts}
%D \showsetup{setupbottomtexts}

\unexpanded\def\setuptoptexts    {\dosixtupleempty\dosetuptexts[\v!top    ]}
\unexpanded\def\setupheadertexts {\dosixtupleempty\dosetuptexts[\v!header ]}
\unexpanded\def\setuptexttexts   {\dosixtupleempty\dosetuptexts[\v!text   ]}
\unexpanded\def\setupfootertexts {\dosixtupleempty\dosetuptexts[\v!footer ]}
\unexpanded\def\setupbottomtexts {\dosixtupleempty\dosetuptexts[\v!bottom ]}

%D The left, right and center variables can also be set
%D directly using the previously discussed macros.

\def\dosetuptexts[#1][#2][#3][#4][#5][#6]%
  {\ifsixthargument
     \setvalue{\??tk#1#2\c!lefttext}%
       {\dodoubletexts{#1}{#2}%
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#3}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#6}}%
     \setvalue{\??tk#1#2\c!righttext}%
       {\dodoubletexts{#1}{#2}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#4}%
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#5}}%
   \else\iffifthargument
     \setvalue{\??tk#1\v!text\c!lefttext}%
       {\dodoubletexts{#1}\v!text
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#2}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#5}}%
     \setvalue{\??tk#1\v!text\c!righttext}%
       {\dodoubletexts{#1}\v!text
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#3}%
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#4}}%
   \else\iffourthargument
     \setvalue{\??tk#1#2\c!lefttext}%
       {\dodoubletexts{#1}{#2}
          {\c!leftstyle\c!leftcolor\c!leftwidth}{#3}%
          {\c!leftstyle\c!leftcolor\c!leftwidth}{#3}}%
     \setvalue{\??tk#1#2\c!righttext}%
       {\dodoubletexts{#1}{#2}
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#4}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#4}}%
   \else\ifthirdargument
     \setvalue{\??tk#1\v!text\c!lefttext}%
       {\dodoubletexts{#1}\v!text
          {\c!leftstyle\c!leftcolor\c!leftwidth}{#2}%
          {\c!leftstyle\c!leftcolor\c!leftwidth}{#2}}%
     \setvalue{\??tk#1\v!text\c!righttext}%
       {\dodoubletexts{#1}\v!text
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#3}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#3}}%
   \else\ifsecondargument % new
     \letvalue{\??tk#1\v!text\c!lefttext  }\empty
     \letvalue{\??tk#1\v!text\c!righttext }\empty
     \setvalue{\??tk#1\v!text\c!middletext}{\dosingletexts{#1}\v!text\c!style\c!color\c!width{#2}}%
   \else
     \dosixtupleempty\dosetuptexts[#1][\v!text  ][][][][]%
     \dosixtupleempty\dosetuptexts[#1][\v!margin][][][][]%
     \dosixtupleempty\dosetuptexts[#1][\v!edge  ][][][][]%
   \fi\fi\fi\fi\fi}

%D Left and right texts are swapped on odd and even pages, but
%D only when double sided typesetting is enabled.

\def\dodoubletexts{\doifoddpageelse\dodoubletextsodd\dodoubletextseven}

\def\dodoubletextsodd #1#2#3#4#5#6{\dosingletexts{#1}{#2}#3{#4}} % #3 => provides three arguments
\def\dodoubletextseven#1#2#3#4#5#6{\dosingletexts{#1}{#2}#5{#6}} % #5 => provides three arguments

%D The next macro will be cleaned up and made less messy and
%D dependent.

\unexpanded\def\placetextlinestrut#1%
  {\doifvalue{#1\c!strut}\v!yes{\setstrut\strut}}

\def\dosingletexts#1#2#3#4#5#6%
  {\bgroup
   \defconvertedargument\ascii{#6}% no longer \defconvertedargument, this also does not permit \v!pagenumber (i.e. v!)
   \ifx\ascii\empty\else
     \dostartattributes{\??tk#1#2}#3#4\empty
       \placetextlinestrut{\??tk#1}% here !
       \doifelsemarking\ascii
         {\dolimitatetexts{\??tk#1#2#5}{\getmarking[\ascii][\v!first]}}%
         {\ifcsname\??tk->\ascii\endcsname
            \csname\??tk->\ascii\endcsname
          \else
            % #6{}{}{} -> {} needed for macros that look
            % ahead, like \uniqueMPgraphic
            \ignorecrlf\dolimitatetexts{\??tk#1#2#5}{#6{}{}{}}%
          \fi}%
     \dostopattributes
  \fi
  \egroup}

\setvalue{\??tk->\v!pagenumber}{\placelocationpagenumber}
\setvalue{\??tk->\v!date      }{\currentdate}

%D When specified, the texts are automatically limited in
%D length.

\def\dolimitatetexts#1#2%
  {\doifelsevaluenothing{#1}{#2}{\limitatetext{#2}{\csname#1\endcsname}{\unknown}}}

%D The placement of text is hooked into the token lists
%D associated to the area at hand.

\appendtoks \placelayouttextline\v!top   \topheight    \to \toptextcontent
\appendtoks \placelayouttextline\v!header\headerheight \to \headertextcontent
\appendtoks \placelayouttextline\v!text  \textheight   \to \texttextcontent
\appendtoks \placelayouttextline\v!footer\footerheight \to \footertextcontent
\appendtoks \placelayouttextline\v!bottom\bottomheight \to \bottomtextcontent

%D Texts can be disabled, moved up and ignored, depending in
%D the \type {status} variable. This is handled by the next
%D couple of macros.

% \def\settextlinestatus#1%
%   {\edef\textlinestatus{\csname\??tk#1\c!state\endcsname}}

\def\settextlinestatus#1%
  {\ifcase0\csname\??tk#1\c!n\endcsname\relax
     \edef\textlinestatus{\csname\??tk#1\c!state\endcsname}%
   \else
     \setxvalue{\??tk#1\c!n}{\the\numexpr\csname\??tk#1\c!n\endcsname-1}%
     \let\textlinestatus\v!stop
   \fi}

\appendtoks
   \doifinset\v!header\floatspecification{\setxvalue{\??tk\v!header\c!n}{1}}%
   \doifinset\v!footer\floatspecification{\setxvalue{\??tk\v!footer\c!n}{1}}%
\to \everybeforeflushedpagefloat

\def\resettextlinestatus#1% postpone
  {\expandafter\gdef\csname\??tk#1\s!reset\endcsname{\global\expandafter\let\csname\??tk#1\c!state\endcsname\v!normal}}

\unexpanded\def\placelayouttextline#1% #2
  {\settextlinestatus#1%
   \csname\??tk::\ifcsname\??tk::\textlinestatus\endcsname\textlinestatus\else\s!unknown\fi\endcsname#1} % {#2}

\def\doifelselayouttextline#1% shown or not
  {\edef\!!stringa{\csname\??tk#1\c!state\endcsname}%
   \ifx\!!stringa\v!normal
      \@EA\firstoftwoarguments
   \else\ifx\!!stringa\v!start
      \@EAEAEA\firstoftwoarguments
   \else
      \@EAEAEA\secondoftwoarguments
   \fi\fi}

\def\doifelselayoutsomeline#1% present or not
  {\edef\!!stringa{\csname\??tk#1\c!state\endcsname}%
   \ifx\!!stringa\v!none
     \@EA\secondoftwoarguments
   \else\ifx\!!stringa\v!high
     \@EAEAEA\secondoftwoarguments
   \else
     \@EAEAEA\firstoftwoarguments
   \fi\fi}

% \doplacelayouttextline does the actual placement (when a non-zero height)

\newconditional\resyncaftertextline

% there is no need for {#1} etc since we use symbolic names

\setvalue{\??tk::\v!normal}{\doplacelayouttextline}
\setvalue{\??tk::\empty   }{\doplacelayouttextline}

\setvalue{\??tk::\v!none  }#1#2{}
\setvalue{\??tk::\v!stop  }#1#2{}

\setvalue{\??tk::\v!high}#1#2%
  {\global\settrue\resyncaftertextline
   \resettextlinestatus#1}

\setvalue{\??tk::\v!empty}#1#2%
  {\resettextlinestatus#1}

\setvalue{\??tk::\v!start}#1#2%
  {\resettextlinestatus#1%
   \doplacelayouttextline#1#2}

\setvalue{\??tk::\v!nomarking}#1#2%
  {\bgroup
   \resettextlinestatus#1%
   \let\dogetmarking\nogetmarking
   \doplacelayouttextline#1#2%
   \egroup}

\setvalue{\??tk::\s!unknown}#1#2%
  {\global\settrue\resyncaftertextline
   \bgroup % new
   \resettextlinestatus#1%
   \csname\??tk#1\textlinestatus\endcsname
   \csname\??tk#1\v!text  \textlinestatus\endcsname
   \csname\??tk#1\v!margin\textlinestatus\endcsname
   \csname\??tk#1\v!edge  \textlinestatus\endcsname
   \doplacelayouttextline#1#2%
   \egroup}

%D The following macro has to be called after a page
%D is flushed.

\def\resetlayouttextline#1%
  {\csname\??tk#1\s!reset\endcsname
   \global\expandafter\let\csname\??tk#1\s!reset\endcsname\relax}

\def\resetlayouttextlines
  {\resetlayouttextline\v!top
   \resetlayouttextline\v!header
   \resetlayouttextline\v!text
   \resetlayouttextline\v!footer
   \resetlayouttextline\v!bottom
   \ifconditional\resyncaftertextline
     \calculateglobalvsizes
     \recalculatebackgrounds
     \global\setfalse\resyncaftertextline
   \fi}

% \settext[header][text][middle][xxx][yyy]

\def\settextcontent
  {\doquintupleempty\dosettextcontent}

\def\dosettextcontent[#1][#2][#3][#4][#5]% header text middle text/text
  {\iffifthargument
     \setvalue{\??tk#1#2\executeifdefined{:\c!text:#3:}\c!middletext}%
       {\dodoubletexts{\??tk#1}{#2}%
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#4}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#5}}%
   \else\iffourthargument
     \setvalue{\??tk#1#2\executeifdefined{:\c!text:#3:}\c!middletext}%
       {\dodoubletexts{\??tk#1}{#2}%
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#4}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#4}}%
   \else\ifthirdargument
     \setvalue{\??tk#1#2\c!middletext}%
       {\dodoubletexts{\??tk#1}{#2}%
          {\c!leftstyle \c!leftcolor \c!leftwidth }{#3}%
          {\c!rightstyle\c!rightcolor\c!rightwidth}{#3}}%
   \fi\fi\fi}

\def\resettextcontent
  {\dotripleempty\doresettextcontent}

\def\doresettextcontent[#1][#2][#3]% header text middle
  {\ifthirdargument
     \letvalue{\??tk#1#2\executeifdefined{:\c!text:#3:}\c!middletext}\empty
   \else\ifsecondargument
     \letvalue{\??tk#1#2\c!lefttext  }\empty
     \letvalue{\??tk#1#2\c!middletext}\empty
     \letvalue{\??tk#1#2\c!righttext }\empty
   \fi\fi}

\let\settext  \settextcontent    % downward compatibility
\let\resettext\resettextcontent  % downward compatibility

\setvalue{:\c!middle:\c!text:}{\c!middletext}
\setvalue{:\c!left  :\c!text:}{\c!lefttext  }
\setvalue{:\c!right :\c!text:}{\c!righttext }

%D The next series of macros is not that easy to read,
%D because they hook into the main page building macros. By
%D using token list registers for the text content, we can
%D easily hook in other code, like menu generators.
%D
%D Beware: the token lists are always expanded, also when the
%D height of an area is zero. This is because reset actions can
%D be part of them.

\newbox\scratchpagebox

\def\gettextboxes
  {\setbox\scratchpagebox\vbox
     {\dontcomplain
      \calculatereducedvsizes
      \swapmargins
      \offinterlineskip
      \vskip\dimexpr-\topheight-\topdistance\relax
      \the\toptextcontent
      \vskip\dimexpr\topheight+\topdistance\relax
      \the\headertextcontent
      \vskip\dimexpr\headerheight+\headerdistance\relax
      \placepositionanchors
      \vskip-\textheight
      \the\texttextcontent
      \vskip\textheight
      \the\everyendoftextbody
      \vskip\footerdistance
      \the\footertextcontent
      \vskip\dimexpr\footerheight+\bottomdistance\relax
      \the\bottomtextcontent
      \vskip\bottomheight
      \vfilll}%
  \smashbox\scratchpagebox
  \box\scratchpagebox}

\def\getmainbox#1#2%
  {\setbox\scratchpagebox\vbox
     {\offinterlineskip  % na \paginaletter !
      \calculatereducedvsizes
      \calculatehsizes
      \swapmargins
      \vskip\dimexpr\headerheight+\headerdistance+\layoutparameter\c!textdistance\relax
      \hbox to \makeupwidth
        {\bgroup
           \swapmargins
           \goleftonpage
           \ifdim\leftedgewidth>\zeropoint
             \the\leftedgetextcontent
             \hskip\leftedgewidth
           \fi
           \hskip\leftedgedistance
           \ifdim\leftmarginwidth>\zeropoint
             \the\leftmargintextcontent
             \hskip\leftmarginwidth
           \fi
           \hskip\leftmargindistance
         \egroup
         \mkprocesspagecontents{#2}%
         \settextpagecontent\scratchpagebox{#1}{#2}%
         \addtextbackground\scratchpagebox
         \addtextgridlayer\scratchpagebox
         \box\scratchpagebox
         \bgroup
           \hskip\rightmargindistance
           \ifdim\rightmarginwidth>\zeropoint
             \the\rightmargintextcontent
             \hskip\rightmarginwidth
           \fi
           \hskip\rightedgedistance
           \ifdim\rightedgewidth>\zeropoint
             \the\rightedgetextcontent
             \hskip\rightedgewidth
           \fi
         \egroup
         \hss}}%
   \smashbox\scratchpagebox
   \box\scratchpagebox}

%D The main text area has to be combined with some additional
%D (tracing) information.

% will be stored as normal and overloaded in page-lyr and later in
% page-spr we overload the the stored version .. evenatually i will
% clear up the experimental mess

\def\settextpagecontent#1#2#3% #2 and #3 will disappear
  {\setbox#1\hbox to \makeupwidth
     {\hss                     % so don't change this
      \setlayoutcomponentattribute\v!page\v!text
      \vbox \layoutcomponentboxattribute to \textheight
        {\offinterlineskip
         \freezetextwidth
         \hsize\textwidth      % local variant of \sethsize
         \boxmaxdepth\maxdepth
         \noindent             % content can be < \hsize
         \dopagecontents#2#3}%
      \hss}%
   \dp#1\zeropoint}

%D The placement of a whole line is handled by the next two
%D macros. These are hooked into the general purpose token
%D list registers mentioned before.

\def\ignoredlinebreak{\unskip\space\ignorespaces}

% \def\doplacelayouttextline#1#2%
%   {\ifdim#2>\zeropoint\relax  % prevents pagenumbers when zero height
%      \goleftonpage
%      \hbox
%        {\setbox\scratchpagebox\vbox to #2
%           {\vsize#2\relax
%            \normalbaselines
%            \let\\\ignoredlinebreak
%            \let\crlf\ignoredlinebreak
%            \csname\??tk#1\c!before\endcsname
%            \doifbothsidesoverruled
%              {\dodoplacelayouttextline#1\c!lefttext \c!middletext\c!righttext\zerocount\plusone}
%              {\dodoplacelayouttextline#1\c!lefttext \c!middletext\c!righttext\zerocount\plusone}
%              {\dodoplacelayouttextline#1\c!righttext\c!middletext\c!lefttext \plusone\zerocount}%
%            \csname\??tk#1\c!after\endcsname
%            \kern\zeropoint}% keep the \dp, beware of \vtops, never change this!
%         \dp\scratchpagebox\zeropoint
%         \box\scratchpagebox}%
%      \vskip-#2\relax
%    \fi}
%
% \def\dodoplacelayouttextline#1#2#3#4#5#6% \hsize toegevoegd, \hss's niet meer wijzigen
%   {\hbox
%      {\ifdim\leftedgewidth>\zeropoint
%         \dododoplacelayouttextline\leftedgewidth#1\v!edge
%           {\hss\csname\??tk#1\v!edge#2\endcsname}%
%         \hskip\leftedgedistance
%       \fi
%       \ifdim\leftmarginwidth>\zeropoint
%         \dododoplacelayouttextline\leftmarginwidth#1\v!margin
%           {\hbox to \leftmarginwidth
%              {\hss\csname\??tk#1\v!margin#2\endcsname}%
%            \hskip-\leftmarginwidth
%            \hbox to \leftmarginwidth
%              {\hss\ifcase#5\or\csname\??tk#1\v!margin\c!margintext\endcsname\fi}}%
%         \hskip\leftmargindistance
%       \fi
%       \ifdim\makeupwidth>\zeropoint
%         \dododoplacelayouttextline\makeupwidth{#1}\v!text
%           {\hbox to \makeupwidth
%              {\ifcase#5\or\@@nmpre{\csname\??tk#1\v!text\c!marginedgetext\endcsname}\fi
%               \csname\??tk#1\v!text#2\endcsname\hss}%
%            \hskip-\makeupwidth
%            \hbox to \makeupwidth
%              {\hss\csname\??tk#1\v!text#3\endcsname\hss}%
%            \hskip-\makeupwidth
%            \hbox to \makeupwidth
%              {\hss\csname\??tk#1\v!text#4\endcsname
%               \ifcase#6\or\@@nmpos{\csname\??tk#1\v!text\c!marginedgetext\endcsname}\fi}}%
%       \fi
%       \ifdim\rightmarginwidth>\zeropoint
%         \hskip\rightmargindistance
%         \dododoplacelayouttextline\rightmarginwidth{#1}\v!margin
%           {\hbox to \rightmarginwidth
%              {\csname\??tk#1\v!margin#4\endcsname\hss}%
%            \hskip-\rightmarginwidth
%            \hbox to \rightmarginwidth
%              {\ifcase#6\or\csname\??tk#1\v!margin\c!margintext\endcsname\fi\hss}}%
%       \fi
%       \ifdim\rightedgewidth>\zeropoint
%         \hskip\rightedgedistance
%         \dododoplacelayouttextline\rightedgewidth{#1}\v!edge
%           {\csname\??tk#1\v!edge#4\endcsname\hss}%
%       \fi}}
%
% \def\dododoplacelayouttextline#1#2#3#4%
%   {\vbox % to \vsize
%      {\hsize#1\relax
%       \csname\??tk#2#3\c!before\endcsname
%       \setlayoutcomponentattribute#2#3%
%       \hbox \layoutcomponentboxattribute to #1{#4}%
%       \csname\??tk#2#3\c!after\endcsname}}

\def\doplacelayouttextline#1#2%
  {\let\currentlayouttextline#1%
   \ifdim#2>\zeropoint\relax  % prevents pagenumbers when zero height
     \doplacelayouttextlineindeed{#2}%
   \fi}

\def\doplacelayouttextlineindeed#1%
  {\goleftonpage
   \hbox
     {\setbox\scratchpagebox\vbox to #1
        {\vsize#1\relax
         \normalbaselines
         \let\\\ignoredlinebreak
         \let\crlf\ignoredlinebreak
         \csname\??tk\currentlayouttextline\c!before\endcsname
         \doifbothsidesoverruled\dodoplacelayouttextlineright\dodoplacelayouttextlineright\dodoplacelayouttextlineleft
         \csname\??tk\currentlayouttextline\c!after\endcsname
         \kern\zeropoint}% keep the \dp, beware of \vtops, never change this!
      \dp\scratchpagebox\zeropoint
      \box\scratchpagebox}%
   \vskip-#1\relax}

\def\dodoplacelayouttextlineright{\dodoplacelayouttextline\c!lefttext \c!middletext\c!righttext\zerocount\plusone}
\def\dodoplacelayouttextlineleft {\dodoplacelayouttextline\c!righttext\c!middletext\c!lefttext \plusone\zerocount}

\def\dodoplacelayouttextline#1#2#3#4#5% \hsize toegevoegd, \hss's niet meer wijzigen
  {\hbox
     {\ifdim\leftedgewidth>\zeropoint
        \dododoplacelayouttextline\leftedgewidth\currentlayouttextline\v!edge{\thelayoutleftedgeline#1}%
        \hskip\leftedgedistance
      \fi
      \ifdim\leftmarginwidth>\zeropoint
        \dododoplacelayouttextline\leftmarginwidth\currentlayouttextline\v!margin{\thelayoutleftmarginline#1#4}%
        \hskip\leftmargindistance
      \fi
      \ifdim\makeupwidth>\zeropoint
        \dododoplacelayouttextline\makeupwidth\currentlayouttextline\v!text{\thelayouttextline#1#2#3#4#5}%
      \fi
      \ifdim\rightmarginwidth>\zeropoint
        \hskip\rightmargindistance
        \dododoplacelayouttextline\rightmarginwidth\currentlayouttextline\v!margin{\thelayoutrightmarginline#3#5}%
      \fi
      \ifdim\rightedgewidth>\zeropoint
        \hskip\rightedgedistance
        \dododoplacelayouttextline\rightedgewidth\currentlayouttextline\v!edge{\thelayoutrightedgeline#3}%
      \fi}}

\def\thelayoutleftedgeline#1%
  {\hss\csname\??tk\currentlayouttextline\v!edge#1\endcsname}%

\def\thelayoutrightedgeline#1%
  {\csname\??tk\currentlayouttextline\v!edge#1\endcsname\hss}

\def\thelayoutleftmarginline#1#2%
  {\hbox to \leftmarginwidth{\hss\csname\??tk\currentlayouttextline\v!margin#1\endcsname}%
   \hskip-\leftmarginwidth
   \hbox to \leftmarginwidth{\hss\ifcase#2\or\csname\??tk\currentlayouttextline\v!margin\c!margintext\endcsname\fi}}

\def\thelayoutrightmarginline#1#2%
  {\hbox to \rightmarginwidth{\csname\??tk\currentlayouttextline\v!margin#1\endcsname\hss}%
   \hskip-\rightmarginwidth
   \hbox to \rightmarginwidth{\ifcase#2\or\csname\??tk\currentlayouttextline\v!margin\c!margintext\endcsname\fi\hss}}

\def\thelayoutedgetextline{\csname\??tk\currentlayouttextline\v!text\c!marginedgetext\endcsname}

\def\thelayouttextline#1#2#3#4#5%
  {\hbox to \makeupwidth{\ifcase#4\or\@@nmpre\thelayoutedgetextline\fi\csname\??tk\currentlayouttextline\v!text#1\endcsname\hss}%
   \hskip-\makeupwidth
   \hbox to \makeupwidth{\hss\csname\??tk\currentlayouttextline\v!text#2\endcsname\hss}%
   \hskip-\makeupwidth
   \hbox to \makeupwidth{\hss\csname\??tk\currentlayouttextline\v!text#3\endcsname\ifcase#5\or\@@nmpos\thelayoutedgetextline\fi}}

\def\dododoplacelayouttextline#1#2#3#4%
  {\vbox % to \vsize
     {\hsize#1\relax
      \csname\??tk#2#3\c!before\endcsname
      \setlayoutcomponentattribute#2#3%
      \hbox \layoutcomponentboxattribute to #1{#4}%
      \csname\??tk#2#3\c!after\endcsname}}

%D Although it is far better to use backgrounds for this
%D purpose, one can add a rule in the following way. This
%D method makes the rules disappear in case of an empty text
%D line. Consider this a feature.
%D
%D \starttyping
%D \setupheadertexts[left][right]
%D
%D \setupheader[text][after=\hrule,style=bold]
%D
%D \starttext
%D   \input tufte \page
%D   \setupheader[state=empty]
%D   \input tufte \page
%D \stoptext
%D \stoptyping

%D The next twosome will be done differently (using an
%D existing auxiliary macro).

% \def\@@nmpre#1{\setbox0\hbox{#1}\ifdim\wd0=\zeropoint\else\unhbox0\tfskip\fi}
% \def\@@nmpos#1{\setbox0\hbox{#1}\ifdim\wd0=\zeropoint\else\tfskip\unhbox0\fi}

% cleaner
%
% \def\@@nmpre#1{\doiftext{#1}{{#1}\tfskip}}
% \def\@@nmpos#1{\doiftext{#1}{\tfskip{#1}}}
%
% newer
%
% \def\@@nmprepos#1#2#3#4#5%
%   {\doifelsenothing\@@nmwidth
%      {\doiftext{#5}{#1{#5}#2}}
%      {\doiftext{#5}{\hbox to \@@nmwidth{#3{#5}#4}}}}
%
% \def\@@nmpre{\@@nmprepos\empty\tfskip\relax\hss}
% \def\@@nmpos{\@@nmprepos\tfskip\empty\hss\relax}
%
% faster

\def\@@nmpre#1%
  {\begingroup
   \setbox\scratchbox\normalhbox{\trialtypesettingtrue\ignorespaces#1\removeunwantedspaces}%
   \ifzeropt\wd\scratchbox\else
     \doifelsenothing\@@nmwidth
       {\box\scratchbox\tfskip}
       {\hbox to \@@nmwidth{\box\scratchbox\hss}}%
   \fi
   \endgroup}

\def\@@nmpos#1%
  {\begingroup
   \setbox\scratchbox\normalhbox{\trialtypesettingtrue\ignorespaces#1\removeunwantedspaces}%
   \ifzeropt\wd\scratchbox\else
     \doifelsenothing\@@nmwidth
       {\tfskip\box\scratchbox}
       {\hbox to \@@nmwidth{\hss\box\scratchbox}}%
   \fi
   \endgroup}

%D This code will move to \type {page-flt.tex}.

\appendtoks \placerightmarginblock \hskip-\rightmarginwidth \to \rightmargintextcontent
\appendtoks \placeleftmarginblock  \hskip-\leftmarginwidth  \to \leftmargintextcontent

%D The next hook will later be used for keeping track of
%D positions, i.e.\ it will provide a proper (page
%D dependent) reference point.

\ifx\undefined\placepositionanchors
  \unexpanded\def\placepositionanchors{\vskip\textheight}
\fi

%D \macros
%D   {definetext}
%D
%D Some macros ago, we implemented the \type {status} option
%D \type {unknown}. This one is used to take care of
%D symbolic texts handlers.
%D
%D \showsetup{definetext}
%D
%D The next example demonstrates how we can use this
%D mechanism to provide page (event) dependent text lines.
%D
%D \starttyping
%D \definetext[chapter][footer][pagenumber]
%D \setuphead[chapter][header=high,footer=chapter]
%D \setupheadertexts[pagenumber]
%D \setupfootertexts[left][right]
%D \chapter{eerste} \dorecurse{20}{\input tufte \relax}
%D \chapter{tweede} \dorecurse{20}{\input tufte \relax}
%D \stoptyping

\unexpanded\def\definetext
  {\doseventupleempty\dodefinetext}

\def\dodefinetext[#1][#2][#3][#4][#5][#6][#7]%
  {\ifseventhargument
     \setvalue{\??tk#2#3#1}{\dosixtupleempty\dosetuptexts[#2][#3][#4][#5][#6][#7]}%
   \else\ifsixthargument
     \setvalue{\??tk  #2#1}{\dosixtupleempty\dosetuptexts[#2][#3][#4][#5][#6]}%
   \else\iffifthargument
     \setvalue{\??tk#2#3#1}{\dosixtupleempty\dosetuptexts[#2][#3][#4][#5]}%
   \else\iffourthargument
     \setvalue{\??tk  #2#1}{\dosixtupleempty\dosetuptexts[#2][#3][#4]}%
   \else
     \setvalue{\??tk  #2#1}{\dosixtupleempty\dosetuptexts[#2][#3]}%
   \fi\fi\fi\fi}

%D The rest of this file is dedicated to setting up the
%D texts. This code is not that impressive.

\setupheadertexts [\v!text]   [] []
\setupheadertexts [\v!margin] [] []
\setupheadertexts [\v!edge]   [] []

\setupfootertexts [\v!text]   [] []
\setupfootertexts [\v!margin] [] []
\setupfootertexts [\v!edge]   [] []

\setuptexttexts   [\v!text]   [] []
\setuptexttexts   [\v!margin] [] []
\setuptexttexts   [\v!edge]   [] []

\setupbottomtexts [\v!text]   [] []
\setupbottomtexts [\v!margin] [] []
\setupbottomtexts [\v!edge]   [] []

\setuptoptexts    [\v!text]   [] []
\setuptoptexts    [\v!margin] [] []
\setuptoptexts    [\v!edge]   [] []

% alternative
%
% \def\resetlayouttekst%
%   {\dodoubleempty\doresetlayouttekst}
%
% \def\doresetlayouttekst[#1][#2]%
%   {\ifsecondargument
%      \dodoresetlayouttekst[#1][#2]%
%    \else
%      \dodoresetlayouttekst[#1][\v!tekst]%
%    \fi}
%
% \def\dodoresetlayouttekst[#1][#2]%
%   {...}
%
% \def\docommand#1%
%   {\resetlayouttekst[#1][\v!tekst]%
%    \resetlayouttekst[#1][\v!marge]%
%    \resetlayouttekst[#1][\v!rand]}

%D We combine a lot of similar settings in a macro that
%D we will later dispose.

\def\dodocommand[#1][#2]%
  {\getparameters
     [\??tk#1#2]
     [%\c!state=\v!normal, % moved
      \c!before=,% both global and local are used
      \c!after=,%  both global and local are used
      \c!strut=,%  the local one, not (yet) used
      \c!style=\csname\??tk#1\c!style\endcsname,% hm, got lost
      \c!color=\csname\??tk#1\c!color\endcsname,% hm, got lost
      \c!lefttext=,
      \c!middletext=,
      \c!righttext=,
      \c!marginedgetext=,
      \c!margintext=,
      \c!width=]%
   \inheritparameter[\??tk#1#2][\c!leftstyle ][\c!style ]%
   \inheritparameter[\??tk#1#2][\c!rightstyle][\c!style ]%
   \inheritparameter[\??tk#1#2][\c!leftcolor ][\c!color  ]%
   \inheritparameter[\??tk#1#2][\c!rightcolor][\c!color  ]%
   \inheritparameter[\??tk#1#2][\c!leftwidth ][\c!width]%
   \inheritparameter[\??tk#1#2][\c!rightwidth][\c!width]}

\def\docommand#1%
  {\dodocommand[#1][\v!text]%
   \dodocommand[#1][\v!margin]%
   \dodocommand[#1][\v!edge]}

\docommand\v!top
\docommand\v!header
\docommand\v!footer
\docommand\v!text
\docommand\v!bottom

\let\docommand  \relax
\let\dodocommand\relax

%D While the header and footer lines are moved away from the
%D main text, the top and bottom lines are centered.

\setuptop   [\c!state=\v!normal,\c!n=0,\c!before=\vss,\c!after=\vss,\c!strut=]
\setupheader[\c!state=\v!normal,\c!n=0,\c!before=,    \c!after=\vss,\c!strut=\v!yes]
\setuptext  [\c!state=\v!normal,\c!n=0,\c!before=\vss,\c!after=\vss,\c!strut=]
\setupfooter[\c!state=\v!normal,\c!n=0,\c!before=\vss,\c!after=,    \c!strut=\v!yes]
\setupbottom[\c!state=\v!normal,\c!n=0,\c!before=\vss,\c!after=\vss,\c!strut=]

\setuptop   [\c!style=,\c!color=]
\setupheader[\c!style=,\c!color=]
\setuptext  [\c!style=,\c!color=]
\setupfooter[\c!style=,\c!color=]
\setupbottom[\c!style=,\c!color=]

\protect \endinput