%D \module
%D   [      file=s-pre-08,
%D        version=1999.09.01,
%D          title=\CONTEXT\ Style File,
%D       subtitle=Presentation Environment 8,
%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.

%D This is one of the 6 styles made for the \NTS\ presentation
%D at \EUROTEX\ 1999. The idea was to demonstrate a couple of
%D nasty things that one can do with \PDFTEX, being an example
%D of an extension. Afterwards it was provded that this could
%D also be done using traditional \TEX.
%D
%D This version is nearly the same as the original, although
%D since then the \METAPOST\ related macro have become more
%D smooth. The original used a couple of boxes, skipt and
%D fills, while this version uses the layer mechanism that
%D came available in fall 2000. This style is actually more a
%D demonstration gimmick than a real useful one.

%D You may want to turn on layer tracing:
%D
%D \starttyping
%D \tracelayerstrue
%D \stoptyping

\setuppapersize
  [S6][S6]

\setupbodyfont
  [pos,10pt]

%D We use the whole page and have no margins.

\setuplayout
  [topspace=0cm,
   backspace=0cm,
   header=0pt,
   footer=0pt,
   width=middle,
   height=middle]

\setupcolors
  [state=start]

\definecolor[TextColor][s=.9]
\definecolor[PageColor][r=.5,g=.4,b=.3]
\definecolor[LineColor][r=.7,g=.6,b=.5]

\definecolor[ColorPage][r=.5,g=.6,b=.7]
\definecolor[ColorLine][r=.3,g=.4,b=.5]

\setupinteraction
  [state=start,
   display=new]

\setupinteractionscreen
  [option=max]

%D The page, sample text and pagenumber will have a background 
%D graphic. 

\defineoverlay [page]         [\uniqueMPgraphic{page}]
\defineoverlay [graphic]      [\uniqueMPgraphic{graphic}]
\defineoverlay [number]       [\uniqueMPgraphic{number}]

%D Each element will also be a button. 

\defineoverlay [nextpage]     [\overlaybutton{nextpage}]
\defineoverlay [previouspage] [\overlaybutton{previouspage}]
\defineoverlay [forward]      [\overlaybutton{forward}]

%D We are going to put all three elements on a layer. 

\definelayer   [main]
\defineoverlay [main] [\composedlayer{main}]

%D The page backgrounds are as follows: 

\setupbackgrounds
  [page]
  [background={previouspage,page}]

%D We could have put the main layer on the page overlay, but
%D the next solution makes us independent of the back and top
%D margins. The \type {idea} layer is for user purposes. 

\setupbackgrounds
  [text]
  [background={main,idea}]

%D The page number, sample text and explanation all have 
%D associated framed texts. The two overlays \type {sample} 
%D and \type {text} and there for special (user) purposes. 

\defineframedtext
  [PageText]
  [width=fit,offset=.5cm,
   before=,after=,frame=off,background={number,forward}]

\defineframedtext
  [SampleText]
  [width=.6\makeupwidth,height=fit,offset=2cm,align=middle,
   before=,after=,frame=off,background={graphic,sample,nextpage}]

\defineframedtext
  [TextText]
  [width=.6\makeupwidth,height=fit,offset=2cm,align=middle,
   before=,after=,frame=off,background={text,nextpage}]

%D Nothing goes on the page directly, since we use layers. The
%D \type {\null} command makes sure that at least something is
%D on the page so that the page is flushed. Here we also take 
%D care of placing the page number. 

\def\StartIdea
  {\null \dontcomplain}

\def\StopIdea
  {\setlayer
     [main]
     [x=\makeupwidth,y=.5cm,hoffset=-.5cm,location=lb]
     {\PageText{\pagenumber}}
   \page}

%D Both texts get their position registered. 

\def\StartSample
  {\setlayer
     [main]
     [hoffset=.75cm,voffset=.75cm]
     \bgroup \hpos {SampText:\realfolio} \bgroup \startSampleText [none]}

\def\StopSample
  {\stopSampleText \egroup \egroup}

%D Here the position of the sample text and explanationary 
%D text are passed on to the graphic that concerns the latter. 

% use setlayertext instead 

\def\StartText
  {\setMPpositiongraphic
     {TextText:\realfolio}{text}{other=SampText:\realfolio} 
   \setlayer
     [main]
     [x=\makeupwidth,y=\makeupheight,
      hoffset=-.75cm,voffset=-.75cm,
      location=lt]
     \bgroup \noindent \hpos {TextText:\realfolio} \bgroup \startTextText [none]}

\def\StopText
  {\stopTextText \egroup \egroup}

%D The graphics that encircle the two texts are related to
%D their position. This is because when they overlay, a shine
%D through is shown. This only shows up when there is enough
%D text to make them overlap.

\startuniqueMPgraphic{page}
  StartPage ; 
    pickup pencircle scaled .5cm ;
    fill Page withcolor \MPcolor{PageColor} ;
    draw Page withcolor \MPcolor{LineColor} ;
  StopPage ;
\stopuniqueMPgraphic

\startuniqueMPgraphic{number}
  path p ; p := fullcircle xscaled OverlayWidth yscaled OverlayHeight;
  pickup pencircle scaled .25cm ;
  fill p withcolor \MPcolor{TextColor} ;
  draw p withcolor (white-\MPcolor{PageColor}) ;
\stopuniqueMPgraphic

\startuniqueMPgraphic{graphic}
  path p ; p := fullcircle xscaled OverlayWidth yscaled OverlayHeight;
  pickup pencircle scaled .5cm ;
  fill p withcolor \MPcolor{TextColor} ;
  draw p withcolor \MPcolor{LineColor} ;
\stopuniqueMPgraphic

%D This graphic is calculated when a position is flushed that 
%D has this graphics as attached. The \type {self} reference 
%D is provided by \CONTEXT\ itself. 

\startMPpositiongraphic{text}
  initialize_box(\MPpos{\MPvar{other}}) ;
  path p ; p := fullcircle xscaled wxy yscaled hxy shifted cxy ;
  initialize_box(\MPpos{\MPvar{self}}) ;
  path q ; q := fullcircle xscaled wxy yscaled hxy shifted cxy ;
  pickup pencircle scaled .5cm ;
  fill q withcolor \MPcolor{TextColor} ;
  draw p withcolor (white-\MPcolor{PageColor}) ;
  clip currentpicture to q ;
  draw q withcolor \MPcolor{LineColor} ;
  anchor_box(\MPanchor{\MPvar{self}}) ;
\stopMPpositiongraphic

%D In order to be complete, we also define a title page. 
%D Here suddenly the text background shows up. 

\def\StartTitlePage
  {\startstandardmakeup
   \dontcomplain
   \setupframedtexts[TextText][width=fit]
   \StartText
   \bfd\setupinterlinespace
   \def\\{\blank\bfc\setupinterlinespace\def\\{\blank}}}

\def\StopTitlePage
  {\StopText
   \stopstandardmakeup}

\def\TitlePage#1%
  {\StartTitlePage#1\StopTitlePage}

%D For this purpose, we redefine the position graphic to 
%D handle a text only case: 

\startMPpositiongraphic{text}
  if box_found(\MPpos{\MPvar{other}}) :   
    initialize_box(\MPpos{\MPvar{other}}) ;
    path p ; p := fullcircle xscaled wxy yscaled hxy shifted cxy ;
  fi ; 
  initialize_box(\MPpos{\MPvar{self}}) ;
  path q ; q := fullcircle xscaled wxy yscaled hxy shifted cxy ;
  pickup pencircle scaled .5cm ;
  fill q withcolor \MPcolor{TextColor} ;
  if box_found(\MPpos{\MPvar{other}}) :   
    draw p withcolor (white-\MPcolor{PageColor}) ;
    clip currentpicture to q ;
    draw q withcolor \MPcolor{LineColor} ;
  else : 
    draw q withcolor (white-\MPcolor{PageColor}) ;
  fi ; 
  anchor_box(\MPanchor{\MPvar{self}}) ;
% setbounds currentpicture to boundingbox origin ;
\stopMPpositiongraphic

\doifnotmode{demo}{\endinput}

\starttext

\TitlePage 
  {Fancy Styles:\\layers}

\StartIdea
  \StartSample
    \input tufte
  \StopSample
  \StartText
    \input reich
  \StopText
\StopIdea

\StartIdea
  \StartSample
    \input knuth
  \StopSample
  \StartText
    \input reich
  \StopText
\StopIdea

\stoptext