%D \module
%D   [       file=page-lay,
%D        version=2000.10.20, % copied from main-001
%D          title=\CONTEXT\ Page Macros,
%D       subtitle=Layout Specification,
%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 Page Macros / Layout Specification}

%D Before you start wondering why some of the page related
%D modules skip upward or left in order to place elements, you
%D must realize that the reference point is the top left
%D corner of the main typesetting area. One reason for this
%D choice is that it suited some viewers that displayed page
%D areas. Another reason is that margins, edges and top and
%D bottom areas are kind of virtual, while the header, text
%D and footer areas normally determine the text flow.

\unprotect

%D First we get rid of the funny \TEX\ offset defaults of one
%D inch by setting them to zero.

\voffset = 0pt % setting this to -1in let's go metapost crazy
\hoffset = 0pt % setting this to -1in let's go metapost crazy

%D The dimensions related to layout areas are represented by
%D real dimensions.

\newdimen\paperheight          \paperheight          = 297mm
\newdimen\paperwidth           \paperwidth           = 210mm
\newdimen\paperoffset          \paperoffset          =   0mm

\newdimen\printpaperheight     \printpaperheight     = \paperheight
\newdimen\printpaperwidth      \printpaperwidth      = \paperwidth

\newdimen\makeupheight                               % calculated
\newdimen\makeupwidth                                % calculated

\newdimen\textheight                                 % calculated
\newdimen\textwidth                                  % calculated

\newdimen\topspace             \topspace             = 2cm
\newdimen\backspace            \backspace            = \topspace
\newdimen\cutspace             \cutspace             = 0pt
\newdimen\bottomspace          \bottomspace          = 0pt

\newdimen\headerheight         \headerheight         = 2cm
\newdimen\footerheight         \footerheight         = \headerheight

\newdimen\topoffset            \topoffset            = 0pt
\newdimen\backoffset           \backoffset           = \topoffset

\newdimen\leftmarginwidth      \leftmarginwidth      = 3cm
\newdimen\rightmarginwidth     \rightmarginwidth     = \leftmarginwidth

\newdimen\leftedgewidth        \leftedgewidth        = 3cm
\newdimen\rightedgewidth       \rightedgewidth       = \leftedgewidth

\newdimen\topheight            \topheight            = 0cm
\newdimen\bottomheight         \bottomheight         = \topheight

\newcount\layoutlines          \layoutlines          = 0
\newcount\layoutcolumns        \layoutcolumns        = 0
\newdimen\layoutcolumndistance \layoutcolumndistance = 0pt
\newdimen\layoutcolumnwidth    \layoutcolumnwidth    = 0pt

%D We can save some tokens and fuzzy parameters by using a
%D symbolic name for the current set of layout parameters.

\let\currentlayout\empty

\def\layoutparameter#1%
  {\csname\??ly\ifcsname
     \??ly\currentlayout#1\endcsname\currentlayout
   \fi#1\endcsname}

\def\namedlayoutparameter#1#2%
  {\csname\??ly\ifcsname\??ly            #1#2\endcsname#1\else
               \ifcsname\??ly\currentlayout#2\endcsname\currentlayout
   \fi\fi#2\endcsname}

%D Beause normal \TEX\ has at most 256 dimensions (of which a
%D substantial part is already in use), we provide a way to
%D generate a format with macro based alternatives. For a long
%D time, this used to be the default case. Beware: only fixed
%D dimensions can be used in calculations! By the way, the
%D gain in speed can hardly be called impressive and is roughly
%D 1 second on a 35 second run of 850 empty pages with a
%D couple of backgrounds only (which is far less than one
%D percent on a normal document).

%D The next series of dimensions are complemented by left
%D and rights ones.

\newdimen \margindistance
\newdimen \edgedistance
\newdimen \marginwidth
\newdimen \edgewidth

%D Because a distance does not really makes sense when there
%D is no area, we use a zero distance in case there is no
%D area.

%D The horizontal distances are:

\newdimen \leftedgedistance
\newdimen \rightedgedistance
\newdimen \leftmargindistance
\newdimen \rightmargindistance

%D The vertical distances are:

\newdimen \topdistance
\newdimen \headerdistance
\newdimen \footerdistance
\newdimen \bottomdistance

%D We need to calculate the extra distances:

\newdimen\naturalmarginwidth
\newdimen\naturaledgewidth
\newdimen\naturalmargindistance
\newdimen\naturaledgedistance
\newdimen\naturalleftedgedistance
\newdimen\naturalrightedgedistance
\newdimen\naturalleftmargindistance
\newdimen\naturalrightmargindistance
\newdimen\naturaltopdistance
\newdimen\naturalheaderdistance
\newdimen\naturalfooterdistance
\newdimen\naturalbottomdistance

\def\layoutdistance#1#2{\ifdim\zeropoint<#1#2\else\zeropoint\fi}

\def\setlayoutdimensions
  {\global\naturalmarginwidth        \layoutparameter\c!margin
   \global\naturaledgewidth          \layoutparameter\c!edge
   \global\naturalmargindistance     \layoutparameter\c!margindistance
   \global\naturaledgedistance       \layoutparameter\c!edgedistance
   \global\naturalleftedgedistance   \layoutparameter\c!leftedgedistance
   \global\naturalrightedgedistance  \layoutparameter\c!rightedgedistance
   \global\naturalleftmargindistance \layoutparameter\c!leftmargindistance
   \global\naturalrightmargindistance\layoutparameter\c!rightmargindistance
   \global\naturaltopdistance        \layoutparameter\c!topdistance
   \global\naturalheaderdistance     \layoutparameter\c!headerdistance
   \global\naturalfooterdistance     \layoutparameter\c!footerdistance
   \global\naturalbottomdistance     \layoutparameter\c!bottomdistance
   %
   \global\marginwidth          \naturalmarginwidth
   \global\edgewidth            \naturaledgewidth
   \global\margindistance       \naturalmargindistance
   \global\edgedistance         \naturaledgedistance
   %
   \global\leftedgedistance     \layoutdistance\leftedgewidth   \naturalleftedgedistance
   \global\rightedgedistance    \layoutdistance\rightedgewidth  \naturalrightedgedistance
   \global\leftmargindistance   \layoutdistance\leftmarginwidth \naturalleftmargindistance
   \global\rightmargindistance  \layoutdistance\rightmarginwidth\naturalrightmargindistance
   \global\topdistance          \layoutdistance\topheight       \naturaltopdistance
   \global\headerdistance       \layoutdistance\headerheight    \naturalheaderdistance
   \global\footerdistance       \layoutdistance\footerheight    \naturalfooterdistance
   \global\bottomdistance       \layoutdistance\bottomheight    \naturalbottomdistance
  }

\def\setlayoutdistances % local in \setreducedvsize
  {\headerdistance\layoutdistance\headerheight\naturalheaderdistance
   \footerdistance\layoutdistance\footerheight\naturalfooterdistance}

% these are wrong in the running text, assumes some swapping, needs a cleanup

\def\outermarginwidth   {\rightorleftpageaction\rightmarginwidth   \leftmarginwidth }
\def\innermarginwidth   {\rightorleftpageaction\leftmarginwidth    \rightmarginwidth}
\def\outermargindistance{\rightorleftpageaction\rightmargindistance\leftmargindistance }
\def\innermargindistance{\rightorleftpageaction\leftmargindistance \rightmargindistance}

\def\outeredgewidth     {\rightorleftpageaction\rightedgewidth   \leftedgewidth }
\def\inneredgewidth     {\rightorleftpageaction\leftedgewidth    \rightedgewidth}
\def\outeredgedistance  {\rightorleftpageaction\rightedgedistance\leftedgedistance }
\def\inneredgedistance  {\rightorleftpageaction\leftedgedistance \rightedgedistance}

\def\outerspacewidth    {\rightorleftpageaction\cutspace\backspace}
\def\innerspacewidth    {\rightorleftpageaction\backspace\cutspace}

\newtoks\extralayoutcalculations \def\calculatelayoutextras{\the\extralayoutcalculations}

% \appendtoks
%   non etex calculations used to go here
% \to \extralayoutcalculations

\newtoks\everyswapmargins % watch the order !

\appendtoks
   \swapdimens\leftmargindistance\rightmargindistance
   \swapdimens\leftedgedistance  \rightedgedistance
   \swapdimens\leftmarginwidth   \rightmarginwidth
   \swapdimens\leftedgewidth     \rightedgewidth
\to \everyswapmargins

\appendtoks
  \swapmacros\leftmargintotal \rightmargintotal
  \swapmacros\leftedgetotal   \rightedgetotal
  \swapmacros\leftsidetotal   \rightsidetotal
  \swapmacros\leftcombitotal  \rightcombitotal
  \swapmacros\innermargintotal\outermargintotal
  \swapmacros\inneredgetotal  \outeredgetotal
  \swapmacros\innercombitotal \outercombitotal
  \swapmacros\innersidetotal  \outersidetotal
\to \everyswapmargins

%D \macros
%D   {definepapersize}
%D
%D Before we start calculating layout dimensions, we will
%D first take care of paper sizes. The first argument can be
%D either an assignment (for defaults) or an identifier, in
%D which case the second argument is an assignment.
%D
%D \showsetup{definepapersize}

\unexpanded\def\definepapersize
  {\dodoubleempty\dodefinepapersize}

\unexpanded\def\definepapersize
  {\dotripleempty\dodefinepapersize}

\def\dodefinepapersize[#1][#2][#3]%
  {\ifsecondargument
     \doifsomething{#1} % to be sure
       {\doifassignmentelse{#2}
          {\getparameters
             [\??pp#1] % geen \c!scale, scheelt hash ruimte
             [\c!width=\@@ppwidth,\c!height=\@@ppheight,\c!offset=\@@ppoffset,#2]}
          {\setvalue{\??pp:1:#1}{#2}%
           \setvalue{\??pp:2:#1}{#3}}}%
   \else
     \getparameters[\??pp][#1]%
     \setuppapersize % hm. this will freeze !
   \fi}

%D For the moment we need to fake this macro.

\ifx\setuppapersize\undefined
  \let\setuppapersize\relax
\fi

%D We set the defaults to the dimensions of an A4 sheet of
%D paper.

\definepapersize
  [\c!width=210mm,\c!height=297mm,\c!offset=\zeropoint]

%D Yet undocumented, let's see if it gets noticed.
%D
%D \starttyping
%D \definepapersize[main] [A4]          [A4]
%D \definepapersize[extra][A4,landscape][A4,landscape]
%D
%D \starttext
%D     \setuppapersize[main]
%D     Page 1. \page
%D     Page 2. \page
%D     \setuppapersize[extra]
%D     Page 2 \page
%D     \setuppapersize[main]
%D     Page 3. \page
%D     Page 4. \page
%D     \adaptpapersize[extra]
%D     Page 5. \page
%D     Page 6. \page
%D \stoptext
%D \stoptyping

%D \macros
%D   {setuppaper,setuppapersize}
%D
%D When setting up the papersize on which to typeset and
%D print, we can also determine some more characteristics.
%D
%D \showsetup{setuppapersize}
%D
%D We keep track of these features with the following
%D variables.

\newconditional\papermirror      \newconditional\printmirror
\newconstant   \paperorientation \newconstant   \printorientation
\newconstant   \paperreverse     \newconstant   \printreverse
\newconditional\paperlandscape   \newconditional\printlandscape

\let\papersize\empty \let\printpapersize\empty

\def\paperscale{1} \newif\ifnegateprintbox

\unexpanded\def\setuppaper[#1]%
  {\getparameters[\??pp][\c!paper=,\c!page=,#1]%
   \edef\@@ppxy{\the\numexpr\@@ppnx*\@@ppny\relax}%
   \doifelsenothing\@@pppage
     {\doifelsenothing\@@pppaper
        {} % {\setuppapersize} % added, removed, no need for, too tricky, mag-01 (fixed by freezing pp's)
        {\dodosetuppapersize[\papersize][\@@pppaper]}}
     {\doifelsenothing\@@pppaper
        {\dodosetuppapersize[\@@pppage][\printpapersize]}
        {\dodosetuppapersize[\@@pppage][\@@pppaper]}}}

\unexpanded\def\setuppapersize
  {\dodoubleempty\dosetuppapersize}

\def\dosetuppapersize[#1][#2]%
  {\doifassignmentelse{#1}
     {\setuppaper[#1]}
     {\doifelsenothing{#2}
        {\expanded{\dodosetuppapersize
           [\executeifdefined{\??pp:1:#1}{#1}]%
%            [\executeifdefined{\??pp:2:#1}{\v!default}]}}
           [\executeifdefined{\??pp:2:#1}{#1}]}}
        {\doifassignmentelse{#2}
           {\getparameters[\??pp\executeifdefined{\??pp:1:#1}{#1}][#2]}
           {\expanded{\dodosetuppapersize
              [\executeifdefined{\??pp:1:#1}{#1}]%
              [\executeifdefined{\??pp:1:#2}{#2}]}}}}}

\let\reinstatepapersize\relax

\def\adaptpapersize
  {\global\let\reinstatepapersize\restorepapersize
   \setuppapersize}

\appendtoks
  \reinstatepapersize
  \global\let\reinstatepapersize\relax
\to \everyaftershipout

\def\dodosetuppapersize[#1][#2]%
  {\ifsecondargument
     \expanded{\dododosetuppapersize[#1][#2]}%
     \calculatehsizes
     \calculatevsizes
     \recalculatebackgrounds
     \recalculatelayout
   \else\iffirstargument
     \setuppapersize[#1][#2]%
   \else\ifx\papersize\undefined\else
     \restorepapersize
   \fi\fi\fi}

% dimen freeze is a bit tricky, but catches local redundant calls
% with values where e.g width is defined in terms of \paperwidth

\def\dododosetuppapersize[#1][#2]%
  {\xdef\restorepapersize{\noexpand\setuppapersize[#1][#2]}%
   \dosetuppaperorientation{#1}\paperlandscape\paperorientation\paperreverse\papermirror
   \dosetuppaperorientation{#2}\printlandscape\printorientation\printreverse\printmirror
   \def\docommand##1%
     {\doifsomething{##1}{\doifdefined{\??pp##1\c!width}
        {\global\paperwidth \getvalue{\??pp##1\c!width}%
         \global\paperheight\getvalue{\??pp##1\c!height}%
         \ifinpagebody
           \setevalue{\??pp##1\c!height}{\the\paperheight}%
           \setevalue{\??pp##1\c!width }{\the\paperwidth }%
         \fi
         \calculatepaperoffsets{##1}%
         \xdef\papersize{##1}}}}%
   \processcommacommand[#1]\docommand
   \doifdefinedelse{\??pp#1\c!scale}
     {\edef\paperscale{\getvalue{\??pp#1\c!scale}}}
     {\edef\paperscale{1}}%
   \def\docommand##1%
     {\doifsomething{##1}{\doifdefined{\??pp##1\c!width}
        {\global\printpaperwidth \getvalue{\??pp##1\c!width}%
         \global\printpaperheight\getvalue{\??pp##1\c!height}%
         \ifinpagebody
           \setevalue{\??pp##1\c!height}{\the\printpaperheight}%
           \setevalue{\??pp##1\c!width }{\the\printpaperwidth}%
         \fi
         \xdef\printpapersize{##1}}}}%
   \processcommacommand[#2]\docommand
   \global\setdimentoatleast\paperwidth      \onepoint
   \global\setdimentoatleast\paperheight     \onepoint
   \global\setdimentoatleast\printpaperwidth \onepoint
   \global\setdimentoatleast\printpaperheight\onepoint
   \ifconditional\paperlandscape
     \doglobal\swapdimens\paperwidth\paperheight
   \fi
   \ifconditional\printlandscape
     \doglobal\swapdimens\printpaperwidth\printpaperheight
   \fi
   % this check can be confusing, so we've added the possibility
   % to bypass this test: \setuppapersize[option=fit]
   \doif\@@ppoption\v!max % \v!fit is
     {\bgroup
      % we need to pre-swap else we get the wrong paper size
      \ifnum\paperorientation=\rightrotatioangle
        \swapdimens\paperwidth\paperheight
      \else\ifnum\paperorientation=\leftrotatioangle
        \swapdimens\paperwidth\paperheight
      \fi\fi
      \ifnum\printorientation=\rightrotatioangle
        \swapdimens\printpaperwidth\printpaperheight
      \else\ifnum\printorientation=\leftrotatioangle
        \swapdimens\printpaperwidth\printpaperheight
      \fi\fi
      \ifdim\paperheight>\printpaperheight
        \global\printpaperheight\paperheight
        \writestatus\m!system{print height forced to paper height}%
      \fi
      \ifdim\paperwidth>\printpaperwidth
        \global\printpaperwidth\paperwidth
        \writestatus\m!system{print width forced to paper width}%
      \fi
      \egroup}}

\def\dosetuppaperorientation#1#2#3#4#5%
  {\global\setfalse#2%
   \global\setfalse#5%
   \global#3\uprotationangle
   \global#4\uprotationangle
   \global\negateprintboxfalse
   \processallactionsinset
     [#1]
     [ \v!landscape=>\global\settrue#2,
        \v!mirrored=>\global\settrue#5,
         \v!rotated=>\global#3\rightrotatioangle
                     \global#4\leftrotatioangle,
        \v!negative=>\global\negateprintboxtrue,
                 90=>\global#3\rightrotatioangle
                     \global#4\leftrotatioangle,
                180=>\global#3\downrotatioangle
                     \global#4\zerocount,
                270=>\global#3\leftrotatioangle
                     \global#4\rightrotatioangle]}

\ifx\calculatepaperoffsets\undefined

  \def\calculatepaperoffsets#1%
    {\scratchdimen\getvalue{\??pp#1\c!offset}%
     \global\advance\paperwidth -2\scratchdimen
     \global\advance\paperheight-2\scratchdimen}

\fi

\let\restorepapersize\relax

% \def\docheckforems#1%
%   {\beforesplitstring#1\at em\to\asciia
%    \doifnot\asciia{#1}
%      {\aftersplitstring\asciia\at=\to\asciia
%       \doifsomething\asciia{\showmessage\m!system{10}{#1}}}}
%
% \def\checkforems[#1]%
%   {\processcommalist[#1]\docheckforems}

\ifx\setups\undefined \unexpanded\def\setups[#1]{\setdefaultpenalties} \fi

% \newtoks \everybeforelayout \relax
% \newtoks \everyafterlayout  \relax

\def\recalculatelayout
  {\doifsomething{\layoutparameter\c!page\layoutparameter\c!paper}
     {\expanded{\dododosetuppapersize[\layoutparameter\c!page][\layoutparameter\c!paper]}}%
   \dorecalculatelayout}

\ifdefined\docheckgridsnapping \else \let\docheckgridsnapping\relax \fi

\def\dorecalculatelayout
  {%\the\everybeforelayout
   \setups[\layoutparameter\c!preset]%
   \global\leftmarginwidth \layoutparameter\c!leftmargin
   \global\rightmarginwidth\layoutparameter\c!rightmargin
   \global\leftedgewidth   \layoutparameter\c!leftedge
   \global\rightedgewidth  \layoutparameter\c!rightedge
   \global\headerheight    \layoutparameter\c!header
   \global\footerheight    \layoutparameter\c!footer
   \global\bottomheight    \layoutparameter\c!bottom
   \global\topheight       \layoutparameter\c!top
   \global\backspace       \layoutparameter\c!backspace
   \global\topspace        \layoutparameter\c!topspace
   \setlayoutdimensions % the rest of the `dimensions'
   \docheckgridsnapping
   \doprocesslocalsetups{\layoutparameter\c!setups}% depends on gridsnapping !
   \simplesetupwhitespace
   \simplesetupblank
   \setupinterlinespace[\v!reset]% \synchronizegloballinespecs
   \global\cutspace\layoutparameter\c!cutspace
   \relax
   \doifelse{\layoutparameter\c!width}\v!middle
     {\ifdim\cutspace=\zeropoint
        \global\cutspace\backspace
      \fi
      \global\makeupwidth\dimexpr\paperwidth-\backspace-\cutspace\relax}
     {\doifelse{\layoutparameter\c!width}\v!fit
        {\ifdim\cutspace=\zeropoint
           \global\cutspace\backspace
         \fi
         \global\makeupwidth\dimexpr\paperwidth-\cutspace\relax
         \scratchdimen\dimexpr\backspace
           -\leftedgewidth  -\leftedgedistance
           -\leftmarginwidth-\leftmargindistance\relax
         \ifdim\scratchdimen<\zeropoint
           \scratchdimen\zeropoint
         \fi
         \global\advance\makeupwidth\dimexpr
           -\rightmargindistance-\rightmarginwidth
           -\rightedgedistance  -\rightedgewidth
           -\scratchdimen\relax}
        {\global\makeupwidth\layoutparameter\c!width\relax
         \ifdim\cutspace=\zeropoint
           \global\cutspace\dimexpr\paperwidth-\makeupwidth-\backspace\relax
        % \else
            % A kind of inconsistent specification, but used
            % in for instance s-pre-19.tex; the cutspace is
            % used only for determining some kind of right
            % margin; don't use this in doublesided mode
         \fi}}%
   \scratchdimen\layoutparameter\c!bottomspace\relax
  %\ifdim\scratchdimen=\zeropoint
  %  \scratchdimen\topspace
  %\fi
   \global\bottomspace\layoutparameter\c!bottomspace\relax
   \global\layoutlines0\number\layoutparameter\c!lines\relax % may be empty
   \ifcase\layoutlines
     \doifelse{\layoutparameter\c!height}\v!middle
       {\ifdim\bottomspace=\zeropoint
          \global\bottomspace\topspace
        \fi
        \global\makeupheight\dimexpr\paperheight-\topspace-\bottomspace\relax}
       {\doifelse{\layoutparameter\c!height}\v!fit
          {\ifdim\bottomspace=\zeropoint
            \global\bottomspace\topspace
           \fi
           \global\makeupheight\dimexpr\paperheight-\bottomspace\relax
           \scratchdimen\dimexpr\topspace-\topheight-\topdistance\relax
           \ifdim\scratchdimen<\zeropoint
             \scratchdimen\zeropoint
           \fi
           \global\advance\makeupheight\dimexpr-\bottomdistance-\bottomheight-\scratchdimen\relax}
          {\global\makeupheight\layoutparameter\c!height\relax
           \ifdim\bottomspace=\zeropoint
             \global\bottomspace\dimexpr\paperheight-\makeupheight-\topspace\relax
           \else
             % inconsistent specification
           \fi}}%
   \else
     % beware, when the bodyfont changes (switched) this will change as well; implementing
     % a global lineheight is tricky: should we take the bodyfont interlinespace or the one set
     % independent of the bodyfont (before or after a layout spec); way too fuzzy, so we
     % stick to the current method (after a night of experimenting ...2003/10/13)
     \global\makeupheight\dimexpr
        \layoutparameter\c!lines\lineheight-\strutheight+\topskip+
        \headerdistance+\headerheight+\footerdistance+\footerheight\relax
   \fi
   \backoffset\layoutparameter\c!horoffset
   \topoffset \layoutparameter\c!veroffset
   \global\setdimentoatleast\makeupwidth\onepoint
   \global\setdimentoatleast\makeupheight \onepoint
   % \checkcurrentlayout % here ?
   % \the\everyafterlayout
   \calculatelayoutextras
   \calculatehsizes
   \calculatevsizes
   \calculatepseudocolumns
   \recalculatebackgrounds}

\def\calculatepseudocolumns
  {\global\layoutcolumns\layoutparameter\c!columns
   \global\layoutcolumndistance\layoutparameter\c!columndistance
   \global\layoutcolumnwidth\dimexpr\makeupwidth-\layoutcolumns\layoutcolumndistance+\layoutcolumndistance\relax
   \global\divide\layoutcolumnwidth\layoutcolumns
   \dorecurse\layoutcolumns
     {\setxvalue{\??ly:c:\recurselevel}%
        {\the\numexpr\recurselevel-\plusone\relax\dimexpr\layoutcolumnwidth+\layoutcolumndistance\relax}}}

%\dorecurse\layoutcolumns
%  {\setxvalue{\??ly:c:\recurselevel}{\the\dimexpr
%     (\numexpr(\recurselevel-1)\dimexpr(\layoutcolumnwidth+\layoutcolumndistance))}}

\def\layoutcolumnoffset#1%
  {\executeifdefined{\??ly:c:#1}\zeropoint}

\def\checklayout
  {\ifdim\makeupheight=\layoutlines\lineheight \else \recalculatelayout \fi}

\appendtoks \checklayout \to \everystarttext

% document:
%
% \setuplayout[odd][state=stop] \setuplayout[even][state=stop] \setuplayout[page]
%
% \startstandardmakeup[page=blank] ... \stopstandardmakeup

\def\changetolayout#1%
  {%\writestatus\m!layouts{changing to layout #1}%
   \xdef\currentlayout{#1}\recalculatelayout}

\def\checkcurrentoddlayout
  {\ifcsname\??ly\v!odd\c!state\endcsname
     \doifvalue{\??ly\v!odd\c!state}\v!start{\changetolayout\v!odd}%
   \fi}

\def\checkcurrentevenlayout
  {\ifcsname\??ly\v!even\c!state\endcsname
     \doifvalue{\??ly\v!even\c!state}\v!start{\changetolayout\v!even}%
   \fi}

\ifx\lastpage\undefined \def\lastpage{1} \fi

\def\reverserealfolio
  {\ifnum\lastpage>\plusone
     \ifnum\lastpage=\realfolio
       \v!last
     \else\ifnum\plusone=\realfolio
       \v!first
     \else
       \the\numexpr\realfolio-\lastpage\relax
     \fi\fi
   \else
     \!!zerocount
   \fi}

\def\checkcurrentlayout % public and used in naw, so keep this name
  {\ifcsname\??ly\realfolio\c!state\endcsname
     \doifvalue{\??ly\realfolio\c!state}\v!start{\changetolayout\realfolio}%
   \else\ifcsname\??ly\reverserealfolio\c!state\endcsname
     \doifvalue{\??ly\reverserealfolio\c!state}\v!start{\changetolayout\reverserealfolio}%
   \else\ifcsname\??ly\v!current\c!state\endcsname
     \changetolayout\v!current % no start test ?
   \else
     \doifoddpageelse\checkcurrentoddlayout\checkcurrentevenlayout
   \fi\fi\fi}

% testcase
%
% \setuppagenumbering[alternative=doublesided]
%
% \setuplayout         [width=11cm]
% \definelayout [odd]  [backspace=1cm]
% \definelayout [even] [backspace=4cm]
% \definelayout [5]    [backspace=5cm]
% \definelayout [6]    [backspace=5cm]
% \definelayout [-2]   [backspace=0cm,cutspace=0cm]
% \definelayout [last] [backspace=0cm,cutspace=0cm]
%
% \checkcurrentlayout \showframe
%
% \starttext
%     \dorecurse{20} {\input knuth \endgraf \input tufte \endgraf}
% \stoptext

%appendtoks \checkcurrentlayout \to \everyaftershipout % no
\appendtoks \checkcurrentlayout \to \everystarttext

\appendtoks
  \dochecknextlayout
\to \everyaftershipout

% \def\dochecknextlayout
%   {\ifx\currentlayout\v!current
%      % prevent redundant calculations
%    \else
%      \globallet\currentlayout\empty
%      \global\letbeundefined{\??ly\v!current\c!state}%
%      \checkcurrentlayout
%    \fi}
%
% this breaks after a standardmakeup

\def\dochecknextlayout{\checkcurrentlayout}

\newif\ifdoublesidedprint

\newconditional\page_location_is_set

\def\page_location_reset
  {\setfalse\page_location_is_set
   \let\page_location_left_fill  \relax
   \let\page_location_right_fill \relax
   \let\page_location_top_fill   \relax
   \let\page_location_bottom_fill\relax}

\page_location_reset

\setvalue{\??ly:\c!location:\v!right      }{\settrue\page_location_is_set
                                            \let\page_location_left_fill  \hss}
\setvalue{\??ly:\c!location:\v!left       }{\settrue\page_location_is_set
                                            \let\page_location_right_fill \hss}
\setvalue{\??ly:\c!location:\v!bottom     }{\settrue\page_location_is_set
                                            \let\page_location_top_fill   \vss}
\setvalue{\??ly:\c!location:\v!top        }{\settrue\page_location_is_set
                                            \let\page_location_bottom_fill\vss}
\setvalue{\??ly:\c!location:\v!middle     }{\settrue\page_location_is_set
                                            \let\page_location_left_fill  \hss
                                            \let\page_location_right_fill \hss
                                            \let\page_location_top_fill   \vss
                                            \let\page_location_bottom_fill\vss}
\setvalue{\??ly:\c!location:\empty        }{\setfalse\page_location_is_set % default also signal to scrn_
                                            \let\page_location_right_fill \hss
                                            \let\page_location_bottom_fill\hss}
\setvalue{\??ly:\c!location:\v!doublesided}{\doublesidedprinttrue}
\setvalue{\??ly:\c!location:\v!singlesided}{\doublesidedprintfalse}

\def\dopresetcenterpagebox#1%
  {\ifcsname\??ly:\c!location:#1\endcsname\csname\??ly:\c!location:#1\endcsname\fi}

\def\presetcenterpagebox
  {\doublesidedprintfalse
   \page_location_reset
   \processcommacommand[\@@lylocation]\dopresetcenterpagebox}

\unexpanded\def\definelayout
  {\dodoubleargument\dodefinelayout}

\def\dodefinelayout[#1][#2]%
  {\getparameters[\??ly#1][\c!state=\v!start,#2]}

\def\dodosetuplayout[#1][#2]%
  {\doifnot{#2}\v!reset{\getparameters[\??ly#1][#2]}}

% global needed for non-doublesided standardmakeup

\unexpanded\def\setuplayout
  {\dodoubleempty\dosetuplayout}

\def\dosetuplayout[#1][#2]%
  {\globallet\currentlayout\empty
   \ifsecondargument
     \dodosetuplayout[#1][#2]%
   \else\iffirstargument
     \doifassignmentelse{#1}
       {\dodosetuplayout[][#1]}
       {\doifelse{#1}\v!reset
          {\let\@@lymethod\v!normal}% hardcodes, assumes a definition
          {\xdef\currentlayout{#1}}}%
   \fi\fi
   \recalculatelayout
  %\checkcurrentlayout % here?
   \dochecknextlayout  % here?
   \presetcenterpagebox}

\def\installlayouthandler#1#2%
  {\setgvalue{\??ly:\c!method:#1}{#2}}

\installlayouthandler\v!default
  {\checkcurrentlayout}

\installlayouthandler\v!normal
  {\checkcurrentlayout}

\def\dochecknextlayout
  {\executeifdefined{\??ly:\c!method:\@@lymethod}\checkcurrentlayout}

\let\@@zaheight\!!zeropoint

\def\dopushpagedimensions
  {\xdef\oldtextheight  {\the\textheight  }%
   \xdef\oldfooterheight{\the\footerheight}%
   \global\let\@@zaheight\@@zaheight}

\def\dopoppagedimensions
  {\global\textheight  \oldtextheight
   \global\footerheight\oldfooterheight
   \recalculatelayout
   \global\let\pushpagedimensions\dopushpagedimensions
   \global\let\poppagedimensions\relax}

\let\poppagedimensions \relax
\let\pushpagedimensions\dopushpagedimensions

% Elke \csname ... \endcsname wordt ook aangemaakt, dus ook
% in een test met \doifdefined. Bij veel bladzijden kan dit
% te veel macro's kosten. Vandaar de set \adaptedpages. Het
% kost tijd, maar scheelt macro's.

\let\adaptedpages\empty

\def\adaptpagedimensions
  {\ifx\adaptedpages\empty\else
     \adaptpagedimensionsindeed
   \fi}

\def\adaptpagedimensionsindeed
  {\rawdoifinset\realfolio\adaptedpages
     {\removefromcommalist\realfolio\adaptedpages
      \getvalue{\??za\realfolio}%
      \letbeundefined{\??za\realfolio}}}

\def\checkpagedimensions
  {\poppagedimensions
   \adaptpagedimensions}

\def\reportpagedimensions
  {\ifx\poppagedimensions\relax \else
     \space\the\dimexpr\@@zaheight\relax\space-\space
   \fi
   \realfolio}

\def\dodoadaptlayout[#1]%
  {\getparameters[\??za][\c!height=,\c!lines=0,#1]%
   \pushpagedimensions
   \ifcase\@@zalines\relax
     \showmessage\m!layouts1{\@@zaheight,\realfolio}%
   \else
     \showmessage\m!layouts1{\@@zalines\space\v!lines,\realfolio}%
     \def\@@zaheight{\@@zalines\openlineheight}%
   \fi
   \doifelse\@@zaheight\v!max
     {\balancedimensions\textheight\footerheight\footerheight}
     {\balancedimensions\textheight\footerheight\@@zaheight}%
   \ifdim\footerheight<\zeropoint
     \global\advance\textheight \footerheight
     \global\footerheight\zeropoint
     \global\xdef\@@zaheight{\layoutparameter\c!footer\space(\v!max)}%
   \fi
   \setvsize
   \global\pagegoal\vsize  % nog corrigeren voor insertions ?
   \recalculatebackgrounds
   \global\let\pushpagedimensions\relax
   \global\let\poppagedimensions\dopoppagedimensions}

\def\doadaptlayout[#1][#2]%
  {\doifelsenothing{#2}
     {\dodoadaptlayout[#1]}
     {\def\docommand##1%
        {\addtocommalist{##1}\adaptedpages
         \setgvalue{\??za##1}{\dodoadaptlayout[#2]}}%
      \processcommalist[#1]\docommand
      \adaptpagedimensions}}

\def\adaptlayout
  {\dodoubleempty\doadaptlayout}

% describe interface

%D Centering the paper area on the print area is determined
%D by the \type {top}, \type {bottom}, \type {left} and \type
%D {right} parameters.

\def\centerpagebox#1% we could test for a difference (saves packing)
  {\printpaperwidth \paperscale\printpaperwidth
   \printpaperheight\paperscale\printpaperheight
   \ifdim\printpaperheight>\ht#1\relax
     \donetrue
   \else\ifdim\printpaperwidth>\wd#1\relax
     \donetrue
   \else
     \donefalse
   \fi\fi
   \ifdone
     \setbox#1\vbox to \printpaperheight
       {\@@pptop
        \page_location_top_fill
        \hbox to \printpaperwidth
          {\ifdoublesidedprint
             \doifbothsides
               {\@@ppleft \page_location_left_fill \box#1\page_location_right_fill\@@ppright}%
               {\@@ppleft \page_location_left_fill \box#1\page_location_right_fill\@@ppright}%
               {\@@ppright\page_location_right_fill\box#1\page_location_left_fill \@@ppleft }%
           \else
                \@@ppleft \page_location_left_fill \box#1\page_location_right_fill\@@ppright
           \fi}%
        \par
        \page_location_bottom_fill
        \@@ppbottom}%
   \fi}

\def\offsetprintbox#1%
  {\ifdim\topoffset=\zeropoint % \relax
     \ifdim\backoffset=\zeropoint
       \donefalse
     \else
       \donetrue
     \fi
   \else
     \donetrue
   \fi
   \ifdone
     \edef\next{\wd#1\the\wd#1\ht#1\the\ht#1\dp#1\the\dp#1}%
     \setbox#1\vbox
       {\offinterlineskip
        \vskip\topoffset
        \hskip\doifbothsides\backoffset\backoffset{-\backoffset}%
        \box#1}%
     \next
   \fi}

\def\replicatepagebox#1%
  {\ifnum\@@lynx>\plusone
     \donetrue
   \else\ifnum\@@lyny>\plusone
     \donetrue
   \else
     \donefalse
   \fi\fi
   \ifdone
     \setbox#1\vbox
       {\offinterlineskip
        \dorecurse\@@lyny
          {\hbox{\dorecurse\@@lynx{\copy#1\hskip\@@lydx}\unskip}%
           \vskip\@@lydy}
        \unskip}%
   \fi}

\def\orientpagebodybox#1#2#3%
  {\ifnum\number#1\number#2>\zerocount
     \setbox#3\vbox
       {\edef\somerotation{\number\ifdoublesided\ifodd\realpageno#1\else#2\fi\else#1\fi}%
        \dorotatebox\somerotation\hbox{\box#3}}%
   \fi}

\def\orientpaperbox{\orientpagebodybox\paperorientation\paperreverse}
\def\orientprintbox{\orientpagebodybox\printorientation\printreverse}

\def\mirrorpagebodybox#1#2%
  {\ifconditional#1\relax
     \setbox#2\vbox{\domirrorbox\vbox{\box#2}}%
   \fi}

\def\mirrorpaperbox{\mirrorpagebodybox\papermirror}
\def\mirrorprintbox{\mirrorpagebodybox\printmirror}

\def\scalepagebox#1%
  {\ifdim\@@lyscale\points=\onepoint
     \ifdim\@@lysx\points=\onepoint
       \ifdim\@@lysy\points=\onepoint
       \else
         \doscalepagebox{#1}\@@lysx\@@lysy
       \fi
     \else
       \doscalepagebox{#1}\@@lysx\@@lysy
     \fi
   \else
     \doscalepagebox{#1}\@@lyscale\@@lyscale
   \fi}

\def\doscalepagebox#1#2#3%
  {\setbox#1\vbox{\scale[\c!sx=#2,\c!sy=#3]{\box#1}}%
   \paperwidth #2\paperwidth
   \paperheight#3\paperheight}

\def\negateprintbox#1%
  {\ifnegateprintbox
     \negatecolorbox{#1}%
   \fi}

\def\pagecutmarksymbol    {\the\realpageno}
\def\pagecutmarklength    {.5cm}
\let\pagecutmarktoptext    \empty
\let\pagecutmarkbottomtext \empty

\def\extrapagecutmarkbottomtext
  {\rlap{\jobname}\hfill\currentdate\space-\space\currenttime\hfill\llap{\realfolio}}

\def\makepagecutbox % #1
  {\let\cutmarksymbol    \pagecutmarksymbol
   \let\cutmarklength    \pagecutmarklength
   \let\cutmarktoptext   \pagecutmarktoptext
   \let\cutmarkbottomtext\pagecutmarkbottomtext
   \makecutbox}

\setvalue{\??ly:n:\c!marking:\v!on}%
  {\makepagecutbox}

\setvalue{\??ly:n:\c!marking:\v!page}% only at outer when nx/ny > 0
  {\makepagecutbox}

\setvalue{\??ly:n:\c!marking:\v!empty}%
  {\let\pagecutmarksymbol\empty
   \let\pagecutmarktoptext\empty
   \let\pagecutmarkbottomtext\empty
   \makepagecutbox}

\setvalue{\??ly:n:\c!marking:\v!text}%
  {\let\pagecutmarksymbol\empty
   \let\pagecutmarkbottomtext\extrapagecutmarkbottomtext
   \makepagecutbox}

\setvalue{\??ly:c:\c!marking:\v!color}%
  {\doaddpagecolormarks\colormarkbox}

\setvalue{\??ly:c:\c!marking:\v!screen}%
  {\doaddpagecolormarks\rastermarkbox}

\letvalue{\??ly:c:\c!marking:\v!unknown}\gobbleoneargument
\letvalue{\??ly:n:\c!marking:\v!unknown}\gobbleoneargument

% \def\addpagecutmarks  {\executeifdefined{\??ly:n:\c!marking:\@@lymarking}\gobbleoneargument}
% \def\addpagecolormarks{\executeifdefined{\??ly:c:\c!marking:\@@lymarking}\gobbleoneargument}

\def\addpagecutmarks  {\expandcheckedcsname{\??ly:n:\c!marking:}\@@lymarking\s!unknown}
\def\addpagecolormarks{\expandcheckedcsname{\??ly:c:\c!marking:}\@@lymarking\s!unknown}

\def\doaddpagecolormarks#1#2%
  {\makepagecutbox{#2}%
   \ifnum\horizontalcutmarks>\plustwo \def\colormarkoffset{\plusfour}\fi
   \ifnum\verticalcutmarks  >\plustwo \def\colormarkoffset{\plusfour}\fi
   #1{#2}}

% NOG EENS NAGAAN WANNEER NU GLOBAL EN WANNEER NIET

\ifx\doifelselayoutsomeline\undefined % defined in page-txt
    \let\doifelselayoutsomeline\secondofthreearguments
\fi

\def\compensatevsizeheader             {\advance\textheight-\dimexpr\headerheight+\headerdistance\relax}
\def\compensatevsizefooter             {\advance\textheight-\dimexpr\footerheight+\footerdistance\relax}
\def\globalcompensatevsizeheader{\global\advance\textheight-\dimexpr\headerheight+\headerdistance\relax}
\def\globalcompensatevsizefooter{\global\advance\textheight-\dimexpr\footerheight+\footerdistance\relax}

\def\compensatevsizeheaderzero{\headerheight\zeropoint\setlayoutdistances}
\def\compensatevsizefooterzero{\footerheight\zeropoint\setlayoutdistances}

\def\calculatevsizes
  {\textheight\makeupheight
   \doifelselayoutsomeline\v!header\compensatevsizeheader\donothing
   \doifelselayoutsomeline\v!footer\compensatevsizefooter\donothing
   \setvsizemodes
   \resetglobal
   \setvsize}

\def\calculateglobalvsizes
  {\global\textheight\makeupheight
   \doifelselayoutsomeline\v!header\globalcompensatevsizeheader\donothing
   \doifelselayoutsomeline\v!footer\globalcompensatevsizefooter\donothing
   \setvsizemodes
   \setvsize}

\def\setvsizemodes
  {\ifzeropt\headerheight
     \resetsystemmode\v!header
   \else
     \setsystemmode\v!header
   \fi
   \ifzeropt\footerheight
     \resetsystemmode\v!footer
   \else
     \setsystemmode\v!footer
   \fi}

\def\calculatereducedvsizes
  {\textheight\makeupheight
   \doifelselayoutsomeline\v!header\compensatevsizeheader\compensatevsizeheaderzero
   \doifelselayoutsomeline\v!footer\compensatevsizefooter\compensatevsizefooterzero}

\newdimen\innermakeupwidth  % special purpose
\newdimen\innermakeupmargin % special purpose

\newconditional\innermakeupcompensation \settrue\innermakeupcompensation

\def\compensatedinnermakeupmargin
  {\dimexpr\ifconditional\innermakeupcompensation+\innermakeupmargin\else\zeropoint\fi\relax}

\def\freezetextwidth      % \makeupwidth may be set to \textwidth
  {\textwidth\makeupwidth % which is a tricky but valid value
   \doifsomething{\layoutparameter\c!textwidth}
     {\textwidth\layoutparameter\c!textwidth}%         % local
   \global\innermakeupwidth\textwidth
   \doifelsenothing{\layoutparameter\c!textmargin}
     {\global\innermakeupmargin\zeropoint}
     {\global\innermakeupmargin\layoutparameter\c!textmargin}%
   \global\advance\innermakeupwidth-\dimexpr\innermakeupmargin+\innermakeupmargin\relax
   \advance\textwidth-\dimexpr\innermakeupmargin+\innermakeupmargin\relax}   % local

\def\calculatehsizes
  {\freezetextwidth
   \sethsize}

% De onderstaande macro voert commando's uit, afhankelijk van
% het karakter van het paginanummer.
%
% \doifoddpageelse{then-commando}{else-commando}

%D When we start at an even page, we need to swap the layout
%D differently. We cannot adapt the real page number, since
%D it is used in cross referencing. The next switch is set
%D when we start at an even page.

% We could use nested if here plus some \@EAEAEA's but but the
% next variant has less expansion which is nicer in tracing.

\def\doifoddpageelse   {\ifodd\pagenoshift\expandafter\doifoddpageelseyes  \else\expandafter\doifoddpageelsenop  \fi}
\def\doifoddpageelseyes{\ifodd\realpageno \expandafter\secondoftwoarguments\else\expandafter\firstoftwoarguments \fi}
\def\doifoddpageelsenop{\ifodd\realpageno \expandafter\firstoftwoarguments \else\expandafter\secondoftwoarguments\fi}

\let\doifonevenpaginaelse\doifoddpageelse

\def\redoifoddpageelse#1{\doifoddpageelse}

\def\doifbothsidesoverruled
  {\ifdoublesided
     \expandafter\redoifoddpageelse
   \else
     \expandafter\firstofthreearguments
   \fi}

\def\doifbothsides% #1 #2 #3
  {\ifdoublesided
     \expandafter\doifbothsidesindeed
   \else
     \expandafter\firstofthreearguments
   \fi}

\def\doifbothsidesindeed
  {\ifsinglesided
     \expandafter\firstofthreearguments
   \else
     \expandafter\redoifoddpageelse
   \fi}

\newdimen\texthoffset

\def\settexthoffset
  {\texthoffset\doifbothsides\backspace\backspace{\dimexpr\paperwidth-\backspace-\makeupwidth\relax}}

% The next hack is too tricky as we may shipout more pages:
%
% \def\freezepagestatechecks
%   {\the\everyfreezepagestatechecks}
%
% \newtoks \everyfreezepagestatechecks
%
% \appendtoks
%     \doifbothsides
%       {\let\doifbothsides\firstofthreearguments}%
%       {\let\doifbothsides\secondofthreearguments}%
%       {\let\doifbothsides\thirdofthreearguments}%
%     \rightorleftpageaction
%       {\let\rightorleftpageaction\firstoftwoarguments}%
%       {\let\rightorleftpageaction\secondoftwoarguments}%
%     \doifmarginswapelse
%       {\let\doifmarginswapelse\firstoftwoarguments}%
%       {\let\doifmarginswapelse\secondoftwoarguments}%
% \to \everyfreezepagestatechecks
%
% \prependtoks
%     \freezepagestatechecks
% \to \everybeforeshipout

\def\goleftonpage
  {\hskip-\dimexpr\leftmargindistance+\leftmarginwidth+\leftedgedistance+\leftedgewidth\relax}

\def\doifmarginswapelse#1#2%
  {\doifbothsides{#1}{#1}{#2}}

\def\swapmargins
  {\doifmarginswapelse\relax\doswapmargins}

\def\doswapmargins
  {\let\swapmargins  \relax % to prevent local swapping
   \let\doswapmargins\relax % to prevent local swapping
   \the\everyswapmargins}

\def\rightorleftpageaction
  {\ifdoublesided
     \expandafter\rightorleftpageactionindeed
   \else
     \expandafter\firstoftwoarguments
   \fi}

\def\rightorleftpageactionindeed
  {\ifsinglesided
     \expandafter\firstoftwoarguments
   \else
     \expandafter\doifoddpageelse
   \fi}

\def\outermarginwidth   {\rightorleftpageaction\rightmarginwidth   \leftmarginwidth }
\def\innermarginwidth   {\rightorleftpageaction\leftmarginwidth    \rightmarginwidth}
\def\outermargindistance{\rightorleftpageaction\rightmargindistance\leftmargindistance }
\def\innermargindistance{\rightorleftpageaction\leftmargindistance \rightmargindistance}

\def\outeredgewidth     {\rightorleftpageaction\rightedgewidth   \leftedgewidth }
\def\inneredgewidth     {\rightorleftpageaction\leftedgewidth    \rightedgewidth}
\def\outeredgedistance  {\rightorleftpageaction\rightedgedistance\leftedgedistance }
\def\inneredgedistance  {\rightorleftpageaction\leftedgedistance \rightedgedistance}

\def\outerspacewidth    {\rightorleftpageaction\cutspace \backspace}
\def\innerspacewidth    {\rightorleftpageaction\backspace\cutspace }

\def\leftmargintotal    {\dimexpr\leftmarginwidth +\leftmargindistance \relax}
\def\rightmargintotal   {\dimexpr\rightmarginwidth+\rightmargindistance\relax}
\def\leftedgetotal      {\dimexpr\leftedgewidth   +\leftedgedistance   \relax}
\def\rightedgetotal     {\dimexpr\rightedgewidth  +\rightedgedistance  \relax}

\def\leftsidetotal      {\dimexpr\leftmarginwidth +\leftedgetotal \relax}
\def\rightsidetotal     {\dimexpr\rightmarginwidth+\rightedgetotal\relax}
\def\leftcombitotal     {\dimexpr\leftmargintotal +\leftedgetotal \relax}
\def\rightcombitotal    {\dimexpr\rightmargintotal+\rightedgetotal\relax}

\def\innermargintotal   {\dimexpr\innermarginwidth+\innermargindistance\relax}
\def\outermargintotal   {\dimexpr\outermarginwidth+\outermargindistance\relax}
\def\inneredgetotal     {\dimexpr\inneredgewidth  +\inneredgedistance  \relax}
\def\outeredgetotal     {\dimexpr\outeredgewidth  +\outeredgedistance  \relax}

\def\innercombitotal    {\dimexpr\innermargintotal+\inneredgetotal\relax}
\def\outercombitotal    {\dimexpr\outermargintotal+\outeredgetotal\relax}
\def\innersidetotal     {\dimexpr\innermarginwidth+\inneredgetotal\relax}
\def\outersidetotal     {\dimexpr\outermarginwidth+\outeredgetotal\relax}

%D \macros
%D   {startlocallayout}
%D
%D These macros should be used with care. They permit local
%D layouts (as used in fitting pages, see \type {page-app.tex}).

%D This is kind of obsolete now that we have \type
%D {\definelayout}, so this hack will disappear in future
%D versions.

\unexpanded\def\startlocallayout
  {\globalpushmacro\restorepapersize
   \globalpushmacro\currentlayout}

\unexpanded\def\stoplocallayout
  {\globalpopmacro\currentlayout
   \globalpopmacro\restorepapersize
   \restorepapersize
   \setuplayout}

%D \macros
%D   {showprint, showframe, showlayout, showsetups}
%D
%D We predefine a couple of tracing macros.
%D
%D \showsetup{showprint}
%D \showsetup{showframe}
%D \showsetup{showlayout}
%D \showsetup{showsetups}
%D %showsetup{showmargins}

\fetchruntimecommand \showprint   {page-run}
\fetchruntimecommand \showframe   {page-run}
\fetchruntimecommand \showlayout  {page-run}
\fetchruntimecommand \showsetups  {page-run}
\fetchruntimecommand \showmargins {page-run}

%D The default dimensions are quite old and will not change.
%D The funny fractions were introduced when we went from fixed
%D dimensions to relative ones. Since \CONTEXT\ is a dutch
%D package, the dimensions are based on the metric system. The
%D asymmetrical layout is kind of handy for short
%D quick||and||dirty stapled documents.
%D
%D Although valid, it is not a real good idea to use
%D dimensions based on the \type {em} unit. First of all,
%D since there are no fonts loaded yet, this dimension makes
%D no sense, and second, you would loose track of values,
%D since they could change while going to a new page,
%D depending on the current font setting.

\setuppaper % (size) % only used in XY imposition
  [\c!width=\zeropoint,
   \c!height=\zeropoint,
   \c!topspace=\zeropoint,
   \c!backspace=\zeropoint,
   \c!dx=\zeropoint,
   \c!dy=\zeropoint,
   \c!nx=1,
   \c!ny=1,
   \c!method=\v!normal]

\setuppapersize
  [\c!option=\v!max,
   \c!top=,
   \c!bottom=,
   \c!left=,
   \c!right=,
   \c!location=]

\setuplayout
  [             \c!topspace=.08417508418\paperheight,  %  2.5cm
                     \c!top=\zeropoint,
             \c!topdistance=\zeropoint,
                  \c!header=.06734006734\paperheight,  %  2.0cm
          \c!headerdistance=\zeropoint,
                  \c!height=.84175084175\paperheight,  % 25.0cm
          \c!footerdistance=\layoutparameter\c!headerdistance,
                  \c!footer=.06734006734\paperheight,  %  2.0cm
          \c!bottomdistance=\layoutparameter\c!topdistance,
                  \c!bottom=\zeropoint,
               \c!backspace=.11904761905\paperwidth, %  2.5cm
                    \c!edge=\zeropoint,
            \c!edgedistance=\layoutparameter\c!margindistance,
                  \c!margin=.12649983170\paperwidth, %  snijwit-2*afstand
          \c!margindistance=.02008341748\paperwidth, %  12.0pt
                \c!leftedge=\layoutparameter\c!edge,
        \c!leftedgedistance=\layoutparameter\c!edgedistance,
              \c!leftmargin=\layoutparameter\c!margin,
      \c!leftmargindistance=\layoutparameter\c!margindistance,
                   \c!width=.71428571429\paperwidth, %  15.0cm \dimexpr\
     \c!rightmargindistance=\layoutparameter\c!margindistance,
             \c!rightmargin=\layoutparameter\c!margin,
       \c!rightedgedistance=\layoutparameter\c!edgedistance,
               \c!rightedge=\layoutparameter\c!edge,
               \c!veroffset=\zeropoint,
             \c!bottomspace=\zeropoint,
               \c!horoffset=\zeropoint,
                \c!cutspace=\zeropoint,
               \c!textwidth=, % dangerous option -> centered / local
              \c!textmargin=, % dangerous option -> both sides
            \c!textdistance=\zeropoint, % shift down on grid
                   \c!style=,
                   \c!color=,
                 \c!marking=\v!off,
                \c!location=,% \v!singlesided, but unset is signal (no other default, spoils arrange)
                   \c!scale=1,
                      \c!sx=1,
                      \c!sy=1,
                      \c!nx=1,
                      \c!ny=1,
                      \c!dx=\zeropoint,
                      \c!dy=\zeropoint,
                    \c!grid=\v!no,
                  \c!preset=,
                  \c!setups=\systemsetupsprefix\s!default,
              \c!clipoffset=\zeropoint,
                   \c!lines=0,
                   \c!paper=, % for foxet
                    \c!page=, % for foxet
                 \c!columns=1,
          \c!columndistance=\zeropoint]

%D First we define a whole range of (DIN) papersizes,
%D of which the A-series makes most sense. We enable checking.

\definepapersize [A0]  [\c!width=841mm,\c!height=1189mm]
\definepapersize [A1]  [\c!width=594mm,\c!height=841mm]
\definepapersize [A2]  [\c!width=420mm,\c!height=594mm]
\definepapersize [A3]  [\c!width=297mm,\c!height=420mm]
\definepapersize [A4]  [\c!width=210mm,\c!height=297mm]
\definepapersize [A5]  [\c!width=148mm,\c!height=210mm]
\definepapersize [A6]  [\c!width=105mm,\c!height=148mm]
\definepapersize [A7]  [\c!width=74mm,\c!height=105mm]
\definepapersize [A8]  [\c!width=52mm,\c!height=74mm]
\definepapersize [A9]  [\c!width=37mm,\c!height=52mm]
\definepapersize [A10] [\c!width=26mm,\c!height=37mm]

\definepapersize [B0]  [\c!width=1000mm,\c!height=1414mm]
\definepapersize [B1]  [\c!width=707mm,\c!height=1000mm]
\definepapersize [B2]  [\c!width=500mm,\c!height=707mm]
\definepapersize [B3]  [\c!width=353mm,\c!height=500mm] % [\c!width=354mm,\c!height=500mm]
\definepapersize [B4]  [\c!width=250mm,\c!height=353mm] % [\c!width=250mm,\c!height=354mm]
\definepapersize [B5]  [\c!width=176mm,\c!height=250mm] % [\c!width=177mm,\c!height=250mm]
\definepapersize [B6]  [\c!width=125mm,\c!height=176mm] % [\c!width=125mm,\c!height=177mm]
\definepapersize [B7]  [\c!width=88mm,\c!height=125mm]
\definepapersize [B8]  [\c!width=62mm,\c!height=88mm]   % [\c!width=63mm,\c!height=88mm]
\definepapersize [B9]  [\c!width=44mm,\c!height=62mm]   % [\c!width=44mm,\c!height=63mm]
\definepapersize [B10] [\c!width=31mm,\c!height=44mm]

\definepapersize [C0]  [\c!width=917mm,\c!height=1297mm]
\definepapersize [C1]  [\c!width=648mm,\c!height=917mm] % [\c!width=649mm,\c!height=917mm]
\definepapersize [C2]  [\c!width=458mm,\c!height=648mm] % [\c!width=459mm,\c!height=649mm]
\definepapersize [C3]  [\c!width=324mm,\c!height=458mm] % [\c!width=324mm,\c!height=459mm]
\definepapersize [C4]  [\c!width=229mm,\c!height=324mm]
\definepapersize [C5]  [\c!width=162mm,\c!height=229mm]
\definepapersize [C6]  [\c!width=114mm,\c!height=162mm] % [\c!width=115mm,\c!height=162mm]
\definepapersize [C7]  [\c!width=81mm,\c!height=114mm]  % [\c!width=81mm,\c!height=115mm]
\definepapersize [C8]  [\c!width=57mm,\c!height=81mm]
\definepapersize [C9]  [\c!width=40mm,\c!height=57mm]
\definepapersize [C10] [\c!width=28mm,\c!height=40mm]

%D Per August 2004 the rounding of some (seldom used) sizes
%D were corrected top the latest DIN specifications. Peter
%D Rolf came up with these and a few more missing sizes.
%D Watch out: spaces and slashes!

\definepapersize [4 A0]  [\c!width=1682mm,\c!height=2378mm]
\definepapersize [2 A0]  [\c!width=1189mm,\c!height=1682mm]
\definepapersize [C6/C5] [\c!width=114mm,\c!height=229mm]

%D Because there are no standardized screen sizes, we define
%D a bunch of sizes with $4:3$ ratios. The \type {S6} size is
%D nearly as wide as a sheet of \type {A4} paper.

\definepapersize [S3] [\c!width=300pt,\c!height=225pt]
\definepapersize [S4] [\c!width=400pt,\c!height=300pt]
\definepapersize [S5] [\c!width=500pt,\c!height=375pt]
\definepapersize [S6] [\c!width=600pt,\c!height=450pt]
\definepapersize [S8] [\c!width=800pt,\c!height=600pt]
\definepapersize [SW] [\c!width=800pt,\c!height=450pt]
\definepapersize [SM] [\c!width=720pt,\c!height=450pt]

%D These are handy too:

\definepapersize [S33] [\c!width=300pt,\c!height=300pt]
\definepapersize [S44] [\c!width=400pt,\c!height=400pt]
\definepapersize [S55] [\c!width=500pt,\c!height=500pt]
\definepapersize [S66] [\c!width=600pt,\c!height=600pt]

%D One may wonder if \TEX\ should be used for typesetting
%D \CDROM\ covers, but it does not hurt to have the paper size
%D ready.

\definepapersize [CD] [\c!width=120mm,\c!height=120mm]

%D The next series is for our English speaking friends who
%D decided to stick to non metric values. Thanks to Nelson
%D Beebe for completing the inch based list.

\definepapersize [letter]    [\c!width=8.5in,\c!height=11in]
\definepapersize [ledger]    [\c!width=11in,\c!height=17in]
\definepapersize [tabloid]   [\c!width=17in,\c!height=11in]

\definepapersize [legal]     [\c!width=8.5in,\c!height=14in]
\definepapersize [folio]     [\c!width=8.5in,\c!height=13in]
\definepapersize [executive] [\c!width=7.25in,\c!height=10.5in]

\definepapersize [A] [\c!width=8.5in,\c!height=11in] % 1 sheet
\definepapersize [B] [\c!width=11in,\c!height=17in]  % 2 sheets
\definepapersize [C] [\c!width=17in,\c!height=22in]  % 4 sheets

%D The next set is for Tobias Burnus, who gave me the sizes.

\definepapersize [envelope 9]  [\c!width=8.88in,\c!height=3.88in]
\definepapersize [envelope 10] [\c!width=9.5in,\c!height=4.13in]
\definepapersize [envelope 11] [\c!width=10.38in,\c!height=4.5in]
\definepapersize [envelope 12] [\c!width=11.0in,\c!height=4.75in]
\definepapersize [envelope 14] [\c!width=11.5in,\c!height=5.0in]
\definepapersize [monarch]     [\c!width=7.5in,\c!height=3.88in]
\definepapersize [check]       [\c!width=8.58in,\c!height=3.88in]
\definepapersize [DL]          [\c!width=110mm,\c!height=220mm] % [\c!width=220mm,\c!height=110mm]
\definepapersize [E4]          [\c!width=280mm,\c!height=400mm]

%D The next three sets are supplied by Taco:

\definepapersize [RA0]  [\c!width=860mm,\c!height=1220mm]
\definepapersize [RA1]  [\c!width=610mm,\c!height=860mm]
\definepapersize [RA2]  [\c!width=430mm,\c!height=610mm]
\definepapersize [RA3]  [\c!width=305mm,\c!height=430mm]
\definepapersize [RA4]  [\c!width=215mm,\c!height=305mm]

%D ISO SRA (supplementary raw A) sizes:

\definepapersize [SRA0]  [\c!width=900mm,\c!height=1280mm]
\definepapersize [SRA1]  [\c!width=640mm,\c!height=900mm]
\definepapersize [SRA2]  [\c!width=450mm,\c!height=640mm]
\definepapersize [SRA3]  [\c!width=320mm,\c!height=450mm]
\definepapersize [SRA4]  [\c!width=225mm,\c!height=320mm]

%D Swedish thesis formats:

\definepapersize [G5]  [\c!width=169mm,\c!height=239mm]
\definepapersize [E5]  [\c!width=155mm,\c!height=220mm]

%D Industry invention:

\definepapersize [A3plus] [\c!width=329mm,\c!height=483mm]

%D We can now default to a reasonable size. We match the print
%D paper size with the typeset paper size. This setting should
%D come after the first layout specification (already done).

% \definepapersize
%   [\v!default]
%   [ \c!width=\paperwidth,
%    \c!height=\paperheight]

% \definepapersize
%   [samesized]
%   [ \c!width=\paperwidth,
%    \c!height=\paperheight]

\definepapersize
  [oversized]
  [ \c!width=\dimexpr\paperwidth +1.5cm\relax,
   \c!height=\dimexpr\paperheight+1.5cm\relax]

\definepapersize
  [doublesized]
  [ \c!width=\dimexpr \paperwidth \relax,
   \c!height=\dimexpr2\paperheight\relax]

\definepapersize
  [doubleoversized]
  [ \c!width=\dimexpr \paperheight+1.5cm\relax,
   \c!height=\dimexpr2\paperwidth +1.5cm\relax]

% \setuppapersize
%   [A4][A4]

\setuppapersize
  [A4][samesized]

%D A few goodies:

%D For orthogonality:

\definepapersize
  [undersized]
  [ \c!width=\dimexpr\paperwidth -1.5cm\relax,
   \c!height=\dimexpr\paperheight-1.5cm\relax]

\definelayout
  [\v!page]
  [\c!backspace=\zeropoint,
   \c!cutspace=\zeropoint,
   \c!topspace=\zeropoint,
   \c!bottomspace=\zeropoint,
   \c!margin=\zeropoint,
   \c!edge=\zeropoint,
   \c!header=\zeropoint,
   \c!footer=\zeropoint,
   \c!top=\zeropoint,
   \c!bottom=\zeropoint,
   \c!leftmargin=\zeropoint,
   \c!rightmargin=\zeropoint,
   \c!leftedge=\zeropoint,
   \c!rightedge=\zeropoint,
   \c!textdistance=\zeropoint,
   \c!width=\v!middle,
   \c!height=\v!middle,
   \c!lines=0,
   \c!grid=\v!no]

\definelayout
  [\v!middle]
  [\c!width=\v!middle,
   \c!height=\v!middle]

\protect \endinput