%D \module
%D   [       file=meta-imp-fen,
%D        version=2011.07.21,
%D          title=\METAPOST\ Graphics,
%D       subtitle=Fences,
%D         author=Wolfgang Schuster & Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

%D The shape and background example code was posted by Wolfgang on the
%D \CONTEXT\ list and due to request by Aditya has been turned into
%D library.

\startMPextensions
    vardef BasicBraceSymbol (expr rotation) =
        save p ; path p ;
        z1  = (-233,    0) ;
        z2  = (-220,   22) ;
        z3  = (-155,  211) ;
        z4  = (-200,  690) ;
        z5  = (-142, 1033) ;
        z6  = ( -97, 1106) ;
        z7  = ( -71, 1125) ;
        z8  = ( -61, 1104) ;
        z9  = ( -80, 1077) ;
        z10 = (-108, 1002) ;
        z11 = (-129,  666) ;
        z12 = (-117,  207) ;
        z13 = (-197,   19) ;
        z14 = (-208,    0) ;
        z15 = (-197,  -19) ;
        z16 = (-117, -207) ;
        z17 = (-129, -666) ;
        z18 = (-108,-1026) ;
        z19 = ( -80,-1077) ;
        z20 = ( -61,-1104) ;
        z21 = ( -71,-1125) ;
        z22 = ( -97,-1106) ;
        z23 = (-143,-1031) ;
        z24 = (-199, -673) ;
        z25 = (-155, -211) ;
        z26 = (-220,  -22) ;
        p := z1  for i= 2 upto 14 : .. z[i] endfor
          &  z14 for j=15 upto 26 : .. z[j] endfor
          .. z1
          &  cycle ;
        p := p rotated rotation ;
        p := p ysized 100 ;
        p shifted - center p
    enddef ;
    vardef RawLeftBraceSymbol =
        fill BasicBraceSymbol(0) ysized OverlayHeight  withcolor OverlayColor ;
    enddef ;
    vardef RawRightBraceSymbol =
        fill BasicBraceSymbol(180) ysized OverlayHeight withcolor OverlayColor ;
    enddef ;
    vardef RawTopBraceSymbol =
        fill BasicBraceSymbol(270) xsized OverlayWidth withcolor OverlayColor ;
    enddef ;
    vardef RawBottomBraceSymbol =
        fill BasicBraceSymbol(90) xsized OverlayWidth withcolor OverlayColor ;
    enddef ;
    vardef LeftBraceSymbol =
        save p, b ; path p, b ; b := fullsquare xscaled OverlayWidth yscaled OverlayHeight ;
        setbounds currentpicture to b ;
        p := BasicBraceSymbol(0) ysized OverlayHeight ;
        fill p shifted (-xpart lrcorner currentpicture + xpart lrcorner p,0) withcolor OverlayColor ;
        setbounds currentpicture to b ;
    enddef ;
    vardef RightBraceSymbol =
        save p, b ; path p, b ; b := fullsquare xscaled OverlayWidth yscaled OverlayHeight ;
        setbounds currentpicture to b ;
        p := BasicBraceSymbol(180) ysized OverlayHeight ;
        fill p shifted (xpart lrcorner currentpicture - xpart lrcorner p,0) withcolor OverlayColor ;
        setbounds currentpicture to b ;
    enddef ;
    vardef TopBraceSymbol =
        save p, b ; path p, b ; b := fullsquare xscaled OverlayWidth yscaled OverlayHeight ;
        setbounds currentpicture to b ;
        p := BasicBraceSymbol(270) xsized OverlayWidth ;
        fill p shifted (0,ypart ulcorner currentpicture - ypart ulcorner p) withcolor OverlayColor ;
        setbounds currentpicture to b ;
    enddef ;
    vardef BottomBraceSymbol =
        save p, b ; path p, b ; b := fullsquare xscaled OverlayWidth yscaled OverlayHeight ;
        setbounds currentpicture to b ;
        p := BasicBraceSymbol(90) xsized OverlayWidth ;
        fill p shifted (0,ypart lrcorner currentpicture - ypart lrcorner p) withcolor OverlayColor  ;
        setbounds currentpicture to b ;
    enddef ;
\stopMPextensions

\startuniqueMPgraphic{raw_brace_left}   RawLeftBraceSymbol   ; \stopuniqueMPgraphic
\startuniqueMPgraphic{raw_brace_right}  RawRightBraceSymbol  ; \stopuniqueMPgraphic
\startuniqueMPgraphic{raw_brace_top}    RawTopBraceSymbol    ; \stopuniqueMPgraphic
\startuniqueMPgraphic{raw_brace_bottom} RawBottomBraceSymbol ; \stopuniqueMPgraphic

\startuniqueMPgraphic{brace_left}   LeftBraceSymbol   ; \stopuniqueMPgraphic
\startuniqueMPgraphic{brace_right}  RightBraceSymbol  ; \stopuniqueMPgraphic
\startuniqueMPgraphic{brace_top}    TopBraceSymbol    ; \stopuniqueMPgraphic
\startuniqueMPgraphic{brace_bottom} BottomBraceSymbol ; \stopuniqueMPgraphic

\defineoverlay[leftbrace]  [\uniqueMPgraphic{brace_left}]
\defineoverlay[rightbrace] [\uniqueMPgraphic{brace_right}]
\defineoverlay[topbrace]   [\uniqueMPgraphic{brace_top}]
\defineoverlay[bottombrace][\uniqueMPgraphic{brace_bottom}]

\installleftframerenderer  {brace}{\uniqueMPgraphic{raw_brace_left}}
\installrightframerenderer {brace}{\uniqueMPgraphic{raw_brace_right}}
\installtopframerenderer   {brace}{\uniqueMPgraphic{raw_brace_top}}
\installbottomframerenderer{brace}{\uniqueMPgraphic{raw_brace_bottom}}

\continueifinputfile{meta-imp-fen.mkiv}

\starttext

\startTEXpage[offset=10pt]

    \framed
      [offset=1ex,
       leftframe=brace,
       rightframe=brace,
       topframe=brace,
       bottomframe=brace,
       background=color,
       backgroundcolor=red]
      {OEPS}

\stopTEXpage

\startTEXpage \uniqueMPgraphic{brace_left}   \stopTEXpage
\startTEXpage \uniqueMPgraphic{brace_right}  \stopTEXpage
\startTEXpage \uniqueMPgraphic{brace_top}    \stopTEXpage
\startTEXpage \uniqueMPgraphic{brace_bottom} \stopTEXpage

\framedtext
  [frame=off,
   offset=2em,
   background={leftbrace,rightbrace,topbrace,bottombrace},
   backgroundcolor=red]{\input{knuth}}

\setupTABLE[frame=off,offset=1ex]
\setupTABLE[row][each][align={middle,lohi}]

\bTABLE
   \bTR
     \bTD[nr=3,background=leftbrace] drei \eTD
     \bTD[nr=2,background=leftbrace] zwei \eTD
     \bTD f \eTD
     \bTD o \eTD
     \bTD u \eTD
     \bTD r \eTD
     \bTD [nr=3,background=rightbrace] three \eTD
   \eTR
   \bTR
     \bTD [background=leftbrace] eins \eTD
     \bTD [background={topbrace,bottombrace}] null \eTD
     \bTD [background=rightbrace] one \eTD
     \bTD [nr=2,background=rightbrace] two \eTD
   \eTR
   \bTR
     \bTD v \eTD
     \bTD i \eTD
     \bTD e \eTD
     \bTD r \eTD
   \eTR
\eTABLE

\stoptext