%D \module
%D   [       file=colo-ini,
%D        version=1997.4.1,
%D          title=\CONTEXT\ Color Macros,
%D       subtitle=Initialization,
%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 Color Macros}

%D To do: stroke versus fill color

\unprotect

%D Color support is not present in \TEX. Colorful output can
%D however be accomplished by using specials. This also means
%D that this support depends on the \DVI\ driver used. At the
%D moment this module was written, still no decent standard on
%D color specials has been agreed upon. We therefore decided to
%D implement a mechanism that is as independant as possible of
%D drivers.
%D
%D Color support shares with fonts that is must be implemented
%D in a way that permits processing of individual \DVI\ pages.
%D Furthermore it should honour grouping. The first condition
%D forces us to use a scheme that keeps track of colors at
%D page boundaries. This can be done by means of \TEX's
%D marking mechanism (\type{\mark}).
%D
%D When building pages, \TEX\ periodically looks at the
%D accumulated typeset contents and breaks the page when
%D suitable. At that moment, control is transfered to the
%D output routine. This routine takes care of building the
%D pagebody and for instance adds headers and footers. The page
%D can be broken in the middle of some colored text, but
%D headers and footers are often in black upon white or
%D background. If colors are applied there, they definitely
%D are used local, which means that they don't cross page
%D borders.
%D
%D Boxes are handled as a whole, which means that when we
%D apply colors inside a box, those colors don't cross page
%D boundaries, unless of course boxes are split or unboxed.
%D Especially in interactive texts, colors are often used in
%D such a local way: in boxes (buttons and navigational tools)
%D or in the pagebody (backgrounds).
%D
%D So we can distinguish local colors, that don't cross
%D pages from global colors, of which we can end many pages
%D later. The color macros will treat both types in a different
%D way, thus gaining some speed.
%D
%D This module also deals with gray scales. Because similar
%D colors can end up in the same gray scale when printed in
%D black and white, we also implement a palet system that deals
%D with these matters. Because of fundamental differences
%D between color and gray scale printing, in \CONTEXT\ we also
%D differ between these. For historic reasons |<|we first
%D implemented gray scales using patterns of tiny periods|>|
%D and therefore called them {\em rasters}. So don't be
%D surprised if this term shows up.

\startmessages  dutch  library: colors
  title: kleur
      1: systeem -- is globaal actief
      2: systeem -- is lokaal actief
      3: -- is niet gedefinieerd
      4: systeem -- wordt geladen
      5: onbekend systeem --
      6: palet -- is beschikbaar
      7: palet -- is niet beschikbaar
      8: specificatie -- bij -- wordt zwart
      9: -- kleurruimte wordt niet ondersteund
     10: -- kleurruimte wordt ondersteund
     11: kleur wordt vertaald in grijs
\stopmessages

\startmessages  english  library: colors
  title: color
      1: system -- is global activated
      2: system -- is local activated
      3: -- is not defined
      4: system -- is loaded
      5: unknown system --
      6: palette -- is available
      7: palette -- is not available
      8: specification -- at color -- becomes black
      9: -- color space is not supported
     10: -- color space is supported
     11: color is converted to gray
\stopmessages

\startmessages  german  library: colors
  title: farbe
      1: system -- ist global aktiviert
      2: system -- ist lokal aktiviert
      3: -- ist undefiniert
      4: system -- ist geladen
      5: unbekanntes System --
      6: palette -- ist verfuegbar
      7: palette -- ist nicht verfuegbar
      8: Spezifikation -- bei Farbe -- wird schwarz
      9: -- Farbraum wird nicht unterstuetzt
     10: -- Farbraum wird unterstuetzt
     11: Farbe wird in Grau umgewandelt
\stopmessages

\startmessages  czech  library: colors
  title: barva
      1: system -- je globalne aktivovana
      2: system -- je lokalne activovana
      3: -- neni definovana
      4: system -- je nacten
      5: neznamy system --
      6: palette -- je k dispozici
      7: palette -- neni k dispozici
      8: specifikace -- v barve -- bude cerna
      9: -- prostor barev neni podporovan
     10: -- prostor barev je podporovan
     11: barva je prevedena na sed
\stopmessages

\startmessages  italian  library: colors
  title: colore
      1: sistema -- attivato globalmente
      2: sistema -- attivato localmente
      3: -- non definito
      4: sistema -- caricato
      5: sistema -- sconosciuto
      6: tavolozza -- resa disponibile
      7: tavolozza -- non disponibile
      8: specifica -- del colore -- convertita in nero
      9: spazio dei colori -- non supportato
     10: spazio dei colori -- supportato
     11: il colore è convertito in grigio
\stopmessages

\startmessages  norwegian  library: colors
  title: farge
      1: system -- er aktivert globalt
      2: system -- er aktivert lokalt
      3: -- er udefinert
      4: system -- er lest inn
      5: ukjent system --
      6: palett -- er tilgjengelig
      7: palett -- er ikke tilgjengelig
      8: spesifikasjon -- for farge -- gir kun svart
      9: -- fargerom er ikke støttet
     10: -- fargerom er støttet
     11: fargen vil bli vist som grå
\stopmessages

\startmessages  romanian  library: colors
  title: culori
      1: sistem -- este activata global
      2: sistem -- este activata local
      3: -- nu este definita
      4: sistem -- este incarcata
      5: sistem -- necunoscuta
      6: paleta -- este disponibila
      7: palette -- nu este disponibila
      8: specificatia -- la culoarea -- devine neagra
      9: spatiul de culoare -- nu este suportat
     10: spatiul de culoare -- este suportat
     11: culoarea este convertita la gri
\stopmessages

%D We use a couple of local registers. That way we don't have
%D to group when converting colors. By the way, this is not
%D really faster. We can sqeeze half a second runtime for 50K
%D switches on a 1G machine, but the macros will become rather
%D ugly then. To mention one such improvement: no colon 
%D after the key character (.25 sec). 

\newdimen\colordimen
\newcount\colorcount

%D \macros
%D   {definecolor}
%D
%D We will enable users to specify colors in \kap{RGB} and
%D \kap{CMYK} color spaces or gray scales using
%D
%D \showsetup{\y!definecolor}
%D
%D For example:
%D
%D \starttypen
%D \definecolor [SomeKindOfRed] [r=.8,g=.05,b=.05]
%D \stoptypen
%D
%D Such color specifications are saved in a macro in the
%D following way:
%D
%D \starttypen
%D \setvalue{\??cr name}{R:r:g:b}
%D \setvalue{\??cr name}{C:c:m:y:k}
%D \setvalue{\??cr name}{S:s}
%D \stoptypen
%D
%D Gray scales are specified with the \type{s} parameter,
%D where the \type {s} is derived from {\em screen}.
%D 
%D Starting with \PDF\ 1.4 (2001) \CONTEXT\ supports
%D transparent colors. The transparency factor is represented
%D by a \type {t} and the transparency method by an \type {a}
%D (alternative). Later we will implement more control
%D (probably by symbolic methods. So, currently the data is 
%D stored as follows: 
%D 
%D \starttypen
%D \setvalue{\??cr name}{R:r:g:b:a:t}
%D \setvalue{\??cr name}{C:c:m:y:k:a:t}
%D \setvalue{\??cr name}{S:s:a:t}
%D \stoptypen

\let\colorlist\empty

\def\@@cl@@z{0}
\def\@@cl@@o{1}

\def\@@resetcolorparameters
  {\let\@@cl@@r\@@cl@@z\let\@@cl@@g\@@cl@@z\let\@@cl@@b\@@cl@@z
   \let\@@cl@@c\@@cl@@z\let\@@cl@@m\@@cl@@z\let\@@cl@@y\@@cl@@z
   \let\@@cl@@k\@@cl@@z\let\@@cl@@s\@@cl@@z
   \let\@@cl@@t\@@cl@@z\let\@@cl@@a\@@cl@@z}

\def\@@cl@@A{\@@cl@@a} % a hook for symbolic conversion, see below 

\def\colorZpattern{S:\@@cl@@z:\@@cl@@A:\@@cl@@t}
\def\colorSpattern{S:\@@cl@@s:\@@cl@@A:\@@cl@@t}
\def\colorCpattern{C:\@@cl@@c:\@@cl@@m:\@@cl@@y:\@@cl@@k:\@@cl@@A:\@@cl@@t}
\def\colorRpattern{R:\@@cl@@r:\@@cl@@g:\@@cl@@b:\@@cl@@A:\@@cl@@t}

\def\definecolor%
  {\dodoubleargument\dodefinecolor}

\def\dodefinecolor[#1][#2]% 
  {\addtocommalist{#1}\colorlist
   \doifassignmentelse{#2}
     {\@@resetcolorparameters
      \getparameters[\??cl @@][#2]%
      \doifelse{\@@cl@@r\@@cl@@g\@@cl@@b}{\@@cl@@z\@@cl@@z\@@cl@@z}
        {\doifelse{\@@cl@@c\@@cl@@m\@@cl@@y\@@cl@@k}{\@@cl@@z\@@cl@@z\@@cl@@z\@@cl@@z}
           {\doifelse{\@@cl@@s}{\@@cl@@z}
              {\showmessage{\m!colors}{8}{{[#2]},#1}%
               \setevalue{\??cr#1}{\colorZpattern}}
              {\setevalue{\??cr#1}{\colorSpattern}}}
           {\setevalue{\??cr#1}{\colorCpattern}}}
        {\setevalue{\??cr#1}{\colorRpattern}}}
     {\doifdefinedelse{\??cr#2}
        {\setevalue{\??cr#1}{\getvalue{\??cr#2}}}
        {\showmessage{\m!colors}{3}{#1}}}%
   \unexpanded\setvalue{#1}{\color[#1]}} % \unexpanded toegevoegd 

%D The names of colors are stored in a comma separated list
%D only for the purpose of showing them with \type {\showcolor}.
%D 
%D \typebuffer
%D \haalbuffer
%D
%D This color shows up as \color[SomeKindOfRed]{some kind
%D of red}.

%D \macros
%D   {setupcolor}
%D
%D Color definitions can be grouped in files with the name:
%D
%D \starttypen
%D \f!colorprefix-identifier.tex
%D \stoptypen
%D
%D where \type{\f!colorprefix} is \unprotect {\tttf \f!colorprefix}.
%D Loading such a file is done by \protect
%D
%D \showsetup{\y!setupcolor}
%D
%D Some default colors are specified in \type{colo-rgb.tex},
%D which is loaded into the format by:
%D
%D \starttypen
%D \setupcolor[rgb]
%D \stoptypen

\let\colorstyle\empty

\def\setupcolor%
  {\dosingleargument\dosetupcolor}

\def\dosetupcolor[#1]%
  {\doifnot{#1}{\colorstyle}
     {\def\colorstyle{#1}%
      \processcommalist[#1]\dodosetupcolor}}

\def\dodosetupcolor#1%
  {\makeshortfilename[\f!colorprefix\truefilename{#1}]%
   \readsysfile\shortfilename
     {\showmessage\m!colors4\colorstyle}
     {\showmessage\m!colors5\colorstyle}}

%D When typesetting for paper, we prefer using the \kap{CMYK}
%D color space, but for on||screen viewing we prefer \kap{RGB}
%D (the previous implementation supported only this scheme).
%D Independant of such specifications, we support some automatic
%D conversions:
%D
%D \startopsomming[opelkaar]
%D \som  convert all colors to \kap{RGB}
%D \som  convert all colors to \kap{CMYK}
%D \som  convert all colors to gray scales
%D \stopopsomming
%D
%D We also support optimization of colors to gray scales.
%D
%D \startopsomming[verder]
%D \som  reduce gray colors to gray scales
%D \som  reduce \kap{CMY} components to \kap{K}
%D \stopopsomming
%D
%D These options are communicated by means of:

\newif\ifRGBsupported
\newif\ifCMYKsupported
\newif\ifpreferGRAY
\newif\ifGRAYprefered
\newif\ifreduceCMYK

%D The last boolean controls reduction of \kap{CMYK} to
%D \kap{CMY} colors. When set to true, the black component
%D is added to the other ones.
%D 
%D Prefering gray is not the same as converting to gray.
%D Conversion treats each color components in a different way,
%D while prefering is just a reduction and thus a
%D space||saving option. 

%D The next (internal) switch suppresses duplicate messages. 

\newif\ifconverttoGRAY 

%D This module also needs:

% \newif\ifMPgraphics
% \newif\ifinpagebody

%D \macros
%D   {startcolormode,stopcolormode,permitcolormode}
%D
%D We use \type{\stopcolormode} to reset the color in
%D whatever color space and do so by calling the corresponding
%D special. Both commands can be used for fast color
%D switching, like in colored verbatim,

\newif\ifpermitcolormode \permitcolormodetrue

%D Since color is used frequently today (at least by the
%D author of this module) it makes sense to optimize switching
%D to the max. 
%D 
%D \starttypen 
%D \def\startcolormode#1%
%D   {\ifincolor\ifpermitcolormode
%D      \doifcolorelse{#1}
%D        {\getcurrentcolorspecs{#1}%
%D         \expandafter\dostartcolormode\currentcolorspecs\od}
%D        {\nostartcolormode}%
%D    \fi\fi}
%D \stoptypen 
%D
%D So, the more readable alternatives like the one above are 
%D gone now. 

\beginETEX \ifcsname

\def\dowithcolor#1#2% #1=\action #2=color 
  {\ifincolor\ifpermitcolormode
     \ifcsname\??cr\currentpalet#2\endcsname
       \@EAEAEA#1\csname\??cr\currentpalet#2\endcsname\od
     \else\ifcsname\??cr#2\endcsname
       \@EAEAEA#1\csname\??cr#2\endcsname\od
     \fi\fi
   \fi\fi}

\endETEX

\beginTEX

\def\dowithcolor#1#2% #1=\action #2=color 
  {\ifincolor\ifpermitcolormode
     \@EA\ifx\csname\??cr\currentpalet#2\endcsname\relax
       \@EA\ifx\csname\??cr#2\endcsname\relax \else
         \@EAEAEA#1\csname\??cr#2\endcsname\od
       \fi
     \else
       \@EAEAEA#1\csname\??cr\currentpalet#2\endcsname\od
     \fi\fi
   \fi\fi}

\endTEX

\def\startcolormode % includes \ifincolor\ifpermitcolormode
  {\dowithcolor\execcolorRCS}

\def\stopcolormode
  {\ifincolor\ifpermitcolormode
     \dostoptransparency
     \dostopcolormode
   \fi\fi}

%D Color modes are entered using the next set of commands.
%D The \type{\stop} alternatives are implemented in a way
%D that permits non||grouped use.
%D
%D The, for this module redundant, check if we are in color
%D mode is needed when we use these macros in other modules.

\def\execcolorRCS#1:%
  {\csname execcolor#1\endcsname}

\def\execcolorR#1:#2:#3:%
  {\edef\@@cl@@r{#1}\edef\@@cl@@g{#2}\edef\@@cl@@b{#3}%
   \ifpreferGRAY\ifx\@@cl@@r\@@cr@@g\ifx\@@cl@@r\@@cl@@b
     \GRAYpreferedtrue
   \fi\fi\fi
   \ifincolor\else\RGBsupportedfalse\CMYKsupportedfalse\fi
   \ifGRAYprefered
     \dostartgraycolormode\@@cl@@r
   \else\ifRGBsupported
     \dostartrgbcolormode\@@cl@@r\@@cl@@g\@@cl@@b
   \else\ifCMYKsupported
     \convertRGBtoCMYK\@@cl@@r\@@cl@@g\@@cl@@b
     \dostartcmykcolormode\@@cl@@c\@@cl@@m\@@cl@@y\@@cl@@k
   \else
     \convertRGBtoGRAY\@@cl@@r\@@cl@@g\@@cl@@b
     \dostartgraycolormode\@@cl@@s
   \fi\fi\fi
   \exectransparency}
   
\def\execcolorC#1:#2:#3:#4:%
  {\edef\@@cl@@c{#1}\edef\@@cl@@m{#2}\edef\@@cl@@y{#3}\edef\@@cl@@k{#4}%
   \ifpreferGRAY\ifx\@@cl@@k\@@cl@@z\ifx\@@cl@@c\@@cr@@m\ifx\@@cl@@c\@@cl@@y
     \GRAYpreferedtrue
   \fi\fi\fi\fi
   \ifincolor\else\RGBsupportedfalse\CMYKsupportedfalse\fi
   \ifGRAYprefered
     \dostartgraycolormode\@@cl@@c
   \else\ifCMYKsupported
     \ifreduceCMYK
       \convertCMYKtoCMY\@@cl@@c\@@cl@@m\@@cl@@y\@@cl@@k
     \fi
     \dostartcmykcolormode\@@cl@@c\@@cl@@m\@@cl@@y\@@cl@@k
   \else\ifRGBsupported
     \convertCMYKtoRGB\@@cl@@c\@@cl@@m\@@cl@@y\@@cl@@k
     \dostartrgbcolormode\@@cl@@r\@@cl@@g\@@cl@@b
   \else
     \convertCMYKtoGRAY\@@cl@@c\@@cl@@m\@@cl@@y\@@cl@@k
     \dostartgraycolormode\@@cl@@s
   \fi\fi\fi
   \exectransparency}
   
\def\execcolorS#1:%
  {\dostartgraycolormode{#1}%
   \exectransparency}

%D Transparency is handled similar for all three color modes. We 
%D can turn transparency off with the following switch:

\newif\iftransparancysupported \transparancysupportedtrue % todo 

\def\exectransparency
  {\iftransparancysupported
     \expandafter\doexectransparency
   \else
     \expandafter\noexectransparency
   \fi}

\def\doexectransparency#1:#2\od
  {\global\@EA\chardef\csname\@@currenttransparent\endcsname % nasty 
   \ifcase#1\space
     \zerocount
   \else
     \plusone
     \dostarttransparency{#1}{#2}%
   \fi}

\def\noexectransparency#1\od
  {}

%D Todo: minimize resets. 

\def\conditionalstoptransparancy
  {\ifcase\csname\@@currenttransparent\endcsname\or
     \dostoptransparency
   \fi}

%D We now use the \type {\@@cl@@A} hook to implement 
%D symbolic names. These are converted into numbers 
%D at definition time (which saves runtime). 

\def\definetransparency
  {\dodoubleargument\dodefinetransparency}

%\def\dodefinetransparency[#1][#2]%
%  {\@EA\chardef\csname\??cl-#1\endcsname#2\relax 
%     \ifundefined{\??cl-#2}#2\else\csname\??cl-#2\endcsname\fi} 

\def\dodefinetransparency[#1][#2]%
  {\@EA\chardef\csname\??cl-#1\endcsname#2\relax}

\def\transparencynumber#1%
  {\the\executeifdefined{\??cl-#1}\zerocount} 

\definetransparency [none]        [0]  \definetransparency  [0]  [0]
\definetransparency [normal]      [1]  \definetransparency  [1]  [1]
\definetransparency [multiply]    [2]  \definetransparency  [2]  [2]
\definetransparency [screen]      [3]  \definetransparency  [3]  [3]
\definetransparency [overlay]     [4]  \definetransparency  [4]  [4]
\definetransparency [softlight]   [5]  \definetransparency  [5]  [5]
\definetransparency [hardlight]   [6]  \definetransparency  [6]  [6]
\definetransparency [colordodge]  [7]  \definetransparency  [7]  [7]
\definetransparency [colorburn]   [8]  \definetransparency  [8]  [8]
\definetransparency [darken]      [9]  \definetransparency  [9]  [9]
\definetransparency [lighten]    [10]  \definetransparency [10] [10]
\definetransparency [difference] [11]  \definetransparency [11] [11]
\definetransparency [exclusion]  [12]  \definetransparency [12] [12]

%D Now we hook 'm into the patterns: 

\def\@@cl@@A{\transparencynumber\@@cl@@a}

%D \macros
%D   {startregistercolor,stopregistercolor,permitcolormode}
%D
%D If you only want to register a color, the switch \type
%D {\ifpermitcolormode} can be used. That way the nested
%D colors know where to go back to.

\def\startregistercolor[#1]%
  {\permitcolormodefalse\startcolor[#1]\permitcolormodetrue}

\def\stopregistercolor
  {\permitcolormodefalse\stopcolor\permitcolormodetrue}

%D We use these macros for implementing text colors 
%D (actually, the first application was in foreground 
%D colors). 
%D 
%D \starttypen 
%D \starttextcolor[red]
%D   \dorecurse{10}{\input tufte \color[green]{oeps} \par}
%D \stoptextcolor
%D \stoptypen 
%D
%D This is more efficient than the alternative: 
%D
%D \starttypen 
%D \setupbackgrounds[text][foregroundcolor=red]
%D \startregistercolor[red]
%D   \dorecurse{10}{\input tufte \color[green]{oeps} \par}
%D \stopregistercolor
%D \stoptypen 

\let\maintextcolor\empty

\def\starttextcolor[#1]% 
  {\doifsomething{#1}
     {\bgroup
      \def\stoptextcolor          % also goes ok with \page after 
        {\let\maintextcolor\empty % this one because the top of 
         \stopregistercolor       % page sets the color right (side 
         \egroup}%                % effect)   
      \def\starttextcolor[##1]%
        {\bgroup
         \let\stoptextcolor\egroup}% 
      \startregistercolor[#1]%
      \def\maintextcolor{#1}}}

\let\stoptextcolor\relax          

%D The following hook permits proper support at the text 
%D level. This definition actually belongs in another 
%D module. 

\ifx\initializemaintextcolor\undefined

  % \let\initializemaintextcolor\relax

  \def\initializemaintextcolor
    {\doifsomething{\@@cltekstkleur}
       {\appendtoks\starttextcolor[\@@cltekstkleur]\to\everystarttext 
        \appendtoks\stoptextcolor                  \to\everystoptext 
        \let\initializemaintextcolor\relax}}

\fi 

%D The next macro can be used to return to the (normal)
%D page color. This macro is used in the same way as 
%D \type {\color}. 

\def\restoretextcolor
  {\ifx\maintextcolor\empty
     \expandafter\dorestoretextcolor
   \else
     % obey main text color 
   \fi}

\def\dorestoretextcolor
  {\color[black]}

%D We use some reserved names for local color components.
%D Consistent use of these scratch variables saves us
%D unneccessary hash entries.
%D
%D \starttypen
%D \@@cl@@r \@@cl@@g \@@cl@@b
%D \@@cl@@c \@@cl@@m \@@cl@@y \@@cl@@k
%D \@@cl@@s
%D \stoptypen
%D
%D We implement several conversion routines.
%D
%D \starttypen
%D \convertRGBtoCMYK  {r} {g} {b}
%D \convertRGBtoGRAY  {r} {g} {b}
%D \convertCMYKtoRGB  {c} {m} {y} {k}
%D \convertCMYKtoGRAY {c} {m} {y} {k}
%D \convertCMYKtoCMY  {c} {m} {y} {k}
%D \stoptypen
%D
%D The relation between \kap{Gray}, \kap{RGB} and \kap{CMYK}
%D is:
%D
%D \plaatsformule[-]
%D   \startformule
%D   G = .30r + .59g + .11b
%D     = 1.0 - \min(1.0,\ .30c + .59m + .11y + k)
%D   \stopformule
%D
%D When converting from \kap{CMYK} to \kap{RGB} we use the
%D formula:
%D
%D \plaatsformule[-]
%D   \startformule
%D   \eqalign
%D     {r &= 1.0 - \min(1.0,\ c+k) \cr
%D      g &= 1.0 - \min(1.0,\ m+k) \cr
%D      b &= 1.0 - \min(1.0,\ y+k)}
%D   \stopformule
%D
%D In the conversion routine the color components are calculated
%D in three digits precision.

\def\realcolorvalue#1%
  {\ifnum#1<10   0.00\the#1\else
   \ifnum#1<100  0.0\the#1\else
   \ifnum#1<1000 0.\the#1\else
                 1\fi\fi\fi}

\def\doconvertCMYKtoRGB#1\k#2\to#3%
  {\ifdim#2\s!pt<#1\s!pt 
     \colordimen1\s!pt
     \advance\colordimen -#1\s!pt
     \advance\colordimen -#2\s!pt
     \multiply\colordimen 1000
     \colorcount\colordimen
     \advance\colorcount \medcard
     \divide\colorcount \maxcard
     \edef#3{\realcolorvalue\colorcount}%
   \else % k >= color
     \let#3\@@cl@@z
   \fi}

\def\convertCMYKtoRGB#1#2#3#4%
  {\doconvertCMYKtoRGB#1\k#4\to\@@cl@@r
   \doconvertCMYKtoRGB#2\k#4\to\@@cl@@g
   \doconvertCMYKtoRGB#3\k#4\to\@@cl@@b}

\def\doconvertRGBtoCMYK#1\to#2%
  {\colordimen#1\s!pt
   \multiply\colordimen 1000
   \colorcount\colordimen
   \advance\colorcount \medcard
   \divide\colorcount \maxcard
   \colorcount-\colorcount
   \advance\colorcount 1000
   \edef#2{\realcolorvalue\colorcount}}

\def\convertRGBtoCMYK#1#2#3%
  {\doconvertRGBtoCMYK#1\to\@@cl@@c
   \doconvertRGBtoCMYK#2\to\@@cl@@m
   \doconvertRGBtoCMYK#3\to\@@cl@@y
   \let\@@cl@@k\@@cl@@z}

%D The following switch is mainly meant for (hidden)
%D documentation purposes.

\newif\ifweightGRAY \weightGRAYtrue

\def\nGRAYfactor{333.333}
\def\rGRAYfactor{\ifweightGRAY300\else\nGRAYfactor\fi}
\def\gGRAYfactor{\ifweightGRAY590\else\nGRAYfactor\fi}
\def\bGRAYfactor{\ifweightGRAY110\else\nGRAYfactor\fi}

\def\convertRGBtoGRAY#1#2#3%
  {\colordimen#1\s!pt
   \colordimen\rGRAYfactor\colordimen
   \colorcount\colordimen
   \colordimen#2\s!pt
   \colordimen\gGRAYfactor\colordimen
   \advance\colorcount \colordimen
   \colordimen#3\s!pt
   \colordimen\bGRAYfactor\colordimen
   \advance\colorcount \colordimen
   \advance\colorcount \medcard
   \divide\colorcount \maxcard
   \edef\@@cl@@s{\realcolorvalue\colorcount}}

\def\convertCMYKtoGRAY#1#2#3#4%
  {\convertCMYKtoRGB{#1}{#2}{#3}{#4}%
   \convertRGBtoGRAY\@@cl@@r\@@cl@@g\@@cl@@b}

\def\doconvertCMYKtoCMY#1\k#2\to#3%
  {\colordimen#1\s!pt
   \advance\colordimen #2\s!pt\relax
   \ifdim\colordimen>1\s!pt
     \colordimen1\s!pt
   %\else
   % \colordimen\colordimen
   \fi
   \multiply\colordimen 1000
   \colorcount\colordimen
   \advance\colorcount \medcard
   \divide\colorcount \maxcard
   \edef#3{\realcolorvalue\colorcount}}

\def\convertCMYKtoCMY#1#2#3#4%
  {\doconvertCMYKtoCMY#1\k#4\to\@@cl@@c
   \doconvertCMYKtoCMY#2\k#4\to\@@cl@@m
   \doconvertCMYKtoCMY#3\k#4\to\@@cl@@y
   \let\@@cl@@k\@@cl@@z}

%D Before we present the color macros, we first define the
%D setup command. This command takes care of setting up the
%D booleans that control local and global behavior (more on
%D that later) and conversion to other color spaces.

\newif\ifincolor
\newif\iflocalcolor

\def\setupcolors%
  {\dosingleargument\dosetupcolors}

\def\dosetupcolors[#1]%
 {\getparameters[\??cl][#1]%
  \doifelse\@@clreductie\v!ja
    \reduceCMYKtrue
    \reduceCMYKfalse
  \doifelse\@@clrgb\v!nee
    {\ifRGBsupported     \showmessage\m!colors {9}\v!rgb\RGBsupportedfalse\fi}
    {\ifRGBsupported\else\showmessage\m!colors{10}\v!rgb\RGBsupportedtrue \fi}%
  \doifelse\@@clcmyk\v!nee
    {\ifCMYKsupported     \showmessage\m!colors {9}\v!cmyk\CMYKsupportedfalse\fi}
    {\ifCMYKsupported\else\showmessage\m!colors{10}\v!cmyk\CMYKsupportedtrue \fi}%
  \doifelse\@@clmpcmyk\v!nee
    {\ifMPcmyk     \showmessage\m!colors {9}{\v!mp\v!cmyk}\MPcmykfalse\fi}
    {\ifMPcmyk\else\showmessage\m!colors{10}{\v!mp\v!cmyk}\MPcmyktrue \fi}%
% \processaction
%   [\@@clconversie]
%   [    \v!ja=>\preferGRAYtrue,
%       \v!nee=>\preferGRAYfalse,
%    \v!altijd=>\preferGRAYtrue
%               \RGBsupportedfalse
%               \CMYKsupportedfalse,
%   \s!default=>\preferGRAYfalse,
%   \s!unknown=>\preferGRAYfalse]%
%
  \preferGRAYfalse
  \processaction
    [\@@clconversie]
    [    \v!ja=>\preferGRAYtrue,
     \v!altijd=>\preferGRAYtrue\RGBsupportedfalse\CMYKsupportedfalse]%
%
  \ifRGBsupported
    \converttoGRAYfalse
    \forcegrayMPcolorsfalse
  \else\ifCMYKsupported
    \converttoGRAYfalse
    \forcegrayMPcolorsfalse
    \convertMPcolorstrue
    \ifreduceCMYK
      \reduceMPcolorstrue
    \fi
  \else
    \ifconverttoGRAY\else\showmessage\m!colors{11}\empty\fi
    \converttoGRAYtrue
    \forcegrayMPcolorstrue
    \convertMPcolorsfalse
    \reduceMPcolorsfalse
  \fi\fi
  \processaction
    [\@@clstatus]
    [\v!globaal=>\ifincolor\else\showmessage\m!colors1\colorstyle\fi
                 \incolortrue\localcolorfalse,
      \v!lokaal=>\ifincolor\else\showmessage\m!colors2\colorstyle\fi
                 \incolortrue\localcolortrue,
       \v!start=>\ifincolor\else\showmessage\m!colors1\colorstyle\fi
                 \incolortrue\localcolorfalse
                 \let\@@clstatus\v!globaal,
        \v!stop=>\incolorfalse\localcolorfalse
                 \forcegrayMPcolorstrue]%
  \initializemaintextcolor}

%D \macros
%D   {doifcolorelse}
%D
%D Switching to a color is done by means of the following
%D command. Later on we will explain the use of palets.  We
%D define ourselves a color conditional first.

\let\currentpalet\empty

\beginETEX \ifcsname

\def\doifcolorelse#1%
  {\ifcsname\??cr\ifcsname\??cr\currentpalet#1\endcsname\currentpalet\fi#1\endcsname
     \expandafter\firstoftwoarguments
   \else
     \expandafter\secondoftwoarguments
   \fi}

% no longer needed 
% 
% \def\getcurrentcolorspecs#1%
%   {\edef\currentcolorspecs%
%      {\csname\??cr
%         \ifcsname\??cr\currentpalet#1\endcsname\currentpalet\fi
%       #1\endcsname}}

\endETEX

\beginTEX

\def\doifcolorelse#1%
  {\@EA\ifx\csname\??cr\@EA\ifx\csname\??cr\currentpalet#1\endcsname\relax\else\currentpalet\fi#1\endcsname\relax
     \expandafter\secondoftwoarguments
   \else
     \expandafter\firstoftwoarguments
   \fi}

% no longer needed 
% 
% \def\getcurrentcolorspecs#1%
%   {\edef\currentcolorspecs%
%      {\csname\??cr\@EA
%         \ifx\csname\??cr\currentpalet#1\endcsname\relax\else\currentpalet\fi
%       #1\endcsname}}

\endTEX

%D \macros
%D   {localstartcolor,localstopcolor}
%D
%D Simple color support, that is without nesting, is provided
%D by:

\def\localstartcolor
  {\ifincolor
     \localcolortrue
     \expandafter\doglobalstartcolor
   \else
     \expandafter\noglobalstartcolor
   \fi}

\def\localstopcolor
  {\ifincolor
     \doglobalstopcolor
   \else
     \noglobalstopcolor
   \fi}

%D \macros
%D   {startcolor,stopcolor}
%D
%D The more save method, the one that saves the current color
%D state and returns to this state afterward, is activated by:
%D
%D \showsetup{\y!startcolor}

\def\startcolor
  {\ifincolor
     \expandafter\doglobalstartcolor
   \else
     \expandafter\noglobalstartcolor
   \fi}

\def\stopcolor%
  {\ifincolor
     \doglobalstopcolor
   \else
     \noglobalstopcolor
   \fi}

%D This macros call the global color switching ones. Starting
%D a global, i.e. a possible page boundary crossing, color
%D mode also sets a \type{\mark} in \TEX's internal list.

\newcount\colorlevel

\letvalue{\??cl0C}\empty % saved color
\letvalue{\??cl0S}\empty % stop command

%D We keep a positive color stack for foreground colors, and
%D a negative one for backgrounds. Not that brilliant a
%D solution, but it suits. The signs are swapped when the
%D page ornaments are typeset.

\let\@@colorplus \plusone  
\let\@@colorminus\minusone 

\def\@@currentcolorname  {\??cl\the\colorlevel C}
\def\@@currentcolorstop  {\??cl\the\colorlevel S}
\def\@@currenttransparent{\??cl\the\colorlevel T}

\def\dodoglobalstartcolor
  {\global\@EA\let\@EA\currentcolor\csname\@@currentcolorname\endcsname
   \global\advance\colorlevel \@@colorplus
   \global\@EA\let\csname\@@currentcolorname\endcsname\@@askedcolor
  %\debuggerinfo{\m!colors}
  %  {start \@@askedcolor\space at level \the\colorlevel}%
   \ifx\@@askedcolor\empty
     \global\@EA\let\csname\@@currentcolorname\endcsname\currentcolor
     \global\@EA\let\csname\@@currentcolorstop\endcsname\donoglobalstopcolor
   \else\ifx\@@askedcolor\currentcolor
     \global\@EA\let\csname\@@currentcolorstop\endcsname\donoglobalstopcolor
   \else
     \doifcolorelse\@@askedcolor
       {\docolormark\@@askedcolor
        \global\@EA\let\csname\@@currentcolorstop\endcsname\dodoglobalstopcolor
        \startcolormode\@@askedcolor}
       {\global\@EA\let\csname\@@currentcolorstop\endcsname\donoglobalstopcolor
        \showmessage\m!colors3\@@askedcolor}%
   \fi\fi}

\def\doglobalstartcolor[#1]%
  {\edef\@@askedcolor{#1}%
   \ifcase\colorlevel\relax
     \ifx\@@askedcolor\empty
       \global\@EA\let\csname\@@currentcolorstop\endcsname\empty
     \else
       \dodoglobalstartcolor
     \fi
   \else
     \dodoglobalstartcolor
   \fi
   \ignorespaces}

\def\noglobalstartcolor[#1]%
  {}

\def\dodoglobalstopcolor
  {\ifcase\colorlevel \else
     \donoglobalstopcolor
     \global\@EA\let\@EA\previouscolor\csname\@@currentcolorname\endcsname
     \ifcase\colorlevel\relax
       \docolormark\empty
       \dostoptransparency
       \dostopcolormode
     \else % let's do a bit redundant testing here
       \docolormark\previouscolor
       \ifx\previouscolor\empty
         \dostoptransparency
         \dostopcolormode
       \else
         \doifcolorelse\previouscolor
           {\ifx\currentcolor\previouscolor\else
              \startcolormode\previouscolor
            \fi}
           {\dostoptransparency
            \dostopcolormode}%
       \fi
     \fi
   \fi}

\def\donoglobalstopcolor
  {\ifcase\colorlevel \else
     \global\@EA\let\@EA\currentcolor\csname\@@currentcolorname\endcsname
    %\debuggerinfo{\m!colors}
    %  {stop \currentcolor\normalspace at level \the\colorlevel}%
     \global\advance\colorlevel \@@colorminus 
   \fi}

\def\doglobalstopcolor
  {\csname\@@currentcolorstop\endcsname}

\let\noglobalstopcolor\relax

%D We don't use grouping and save each stop alternative. This
%D permits be especially useful in for instance local color
%D support in verbatim. Using \type{\bgroup}||\type{\egroup}
%D pairs could interfere with calling commands

%D This color mechanism takes care of nested colors, like in:
%D
%D \startbuffer
%D \kleur[groen]{groen \kleur[groen]{groen \kleur[rood]{rood}} groen}
%D \kleur[groen]{groen \kleur[]{groen \kleur[rood]{rood}} groen}
%D \kleur[groen]{groen \kleur[rood]{rood \kleur[rood]{rood}} groen}
%D \kleur[groen]{groen \kleur[groen]{groen \kleur[]{groen}} groen}
%D \kleur[groen]{groen \kleur[rood]{rood} groen}
%D \kleur[groen]{groen \kleur[]{groen} groen}
%D \kleur[]{zwart \kleur[rood]{rood} zwart}
%D \kleur[]{zwart}
%D \stopbuffer
%D
%D \typebuffer
%D
%D or
%D
%D \startvoorbeeld
%D \startregels
%D \haalbuffer
%D \stopregels
%D \stopvoorbeeld
%D
%D Crossing page boundaries is of course also handled.
%D Undefined or empty color specifications are treated as
%D efficient as possible.
%D
%D \startbuffer
%D \startkleur[groen]
%D   [groen] \input tufte [groen] \par
%D   \startkleur[]
%D     [groen] \input knuth [groen] \par
%D     \startkleur[rood]
%D       [rood] \input tufte [rood] \par
%D       \startkleur[geel]
%D         [geel] \input knuth [geel] \par
%D       \stopkleur
%D       [rood] \input tufte [rood] \par
%D     \stopkleur
%D     [groen] \input knuth [groen] \par
%D   \stopkleur
%D   [groen] \input tufte [groen] \par
%D \stopkleur
%D \stopbuffer
%D
%D \startopelkaar
%D \haalbuffer
%D \stopopelkaar
%D
%D These quotes are typeset by saying:
%D
%D \typebuffer

%D We already mentioned that colors interfere with building
%D the pagebody. This means that when the page is composed,
%D the colors temporary have to be reset. After the page is
%D shipped out, we have to revive the current color.
%D
%D We use \type{\marks} to keep track of colors across page
%D boundaries. Unfortunately standard \TEX\ supports only one mark,
%D and using this one for color support only would be a waste.
%D We therefore use an adapted version of J.~Fox's multiple mark
%D mechanism as (re|)|implemented in \module{supp-mrk}.

\doifdefinedelse{newmark}
  {\newmark\colormark}
  {\let\colormark\gobbleoneargument}

%D Using this mark mechanism with lots of colors has one
%D major drawback: \TEX's memory tends to overflow when
%D very colorful text is stored in a global box. Even worse is that
%D the processing time grows considerably. We therefore support
%D local as well as global color switching.
%D
%D Of the next macros, \type {\popcolor} is to be used after
%D the actual \type {\shipout} and \type {\startcolorpage} and
%D \type {\stopcolorpage} are called when entering and leaving
%D the \type {\pagebody} builder. In case of emergencies
%D \type {\pushcolor} can be used to undo the current color,
%D for instance when insertions are appended to the page.
%D
%D Out of efficiency we only use marks when needed. The next
%D macro tries to find out if indeed a mark should be set.
%D This macro uses the boolean \type {\ifinpagebody}, which can
%D be defined and set in the module that handles the pagebody.

\def\docolormark#1%
  {\iflocalcolor \else \ifinpagebody \else \ifinframed \else
     \dodocolormark{#1}%
   \fi \fi \fi}

\let\lastcolormark=\empty

\def\dodocolormark#1%
  {\edef\newcolormark{#1}%
   \ifx\newcolormark\lastcolormark\else
     \global\let\lastcolormark\newcolormark
     \@EA\setmark\@EA\colormark\@EA{\lastcolormark}%
   \fi}

%D \macros
%D   {pushcolor, popcolor}
%D
%D Pushing the current state in the output routine simply comes
%D to resetting the color to black, while popping restores the
%D color state to that of before the break.

\def\topofpagecolor{\getbotmark\colormark} % see postponing 

\def\pushcolor
  {\stopcolormode}

\def\popcolor
  {\doifsomething{\getbotmark\colormark}
     {%\debuggerinfo{\m!colors}{popping \getbotmark\colormark}%
      \startcolormode{\getbotmark\colormark}}}

\def\popsplitcolor%
  {\getsplitmarks\colormark  % hier wel
   \doifsomething{\getsplitbotmark\colormark}
     {%\debuggerinfo{\m!colors}{split popping \getsplitbotmark\colormark}%
      \startcolormode{\getsplitbotmark\colormark}}}

%D \macros
%D   {startcolorpage, stopcolorpage}
%D
%D Local use can be forced with the next two macros. Nesting
%D is still supported but colors are no longer marked.
%D
%D The next implementation makes (simple) color separation more
%D easy. It also supports nested colors in page backgrounds
%D and texts.

\def\startcolorpage%
  {\bgroup
   \let\@@colorplus \minusone 
   \let\@@colorminus\plusone
   \let\docolormark\gobbleoneargument
   \edef\savedcolorlevel{\the\colorlevel}%
   \global\colorlevel\zerocount % before \localstartcolor of
   \localstartcolor[black]}     % course, ugly bug removed

\def\stopcolorpage%
  {\localstopcolor
   \global\colorlevel\savedcolorlevel
   \egroup}

%D \macros
%D   {color,graycolor}
%D
%D This leaves the simple color command:
%D
%D \showsetup{\y!color}
%D \showsetup{\y!graycolor}
%D
%D Which can be used straightforward: \color[groen]{green as gras}.
%D We want color support to be similar to font support and
%D therefore implement \type{\color} as:

\unexpanded\def\color[#1]%
  {\groupedcommand
     {\startcolor[#1]}\stopcolor}

\unexpanded\def\graycolor[#1]% not \gray because this is a color
  {\groupedcommand
     {\RGBsupportedfalse\CMYKsupportedfalse\startcolor[#1]}\stopcolor}

\let\grey\graycolor

%D This implementation enables use of defined colors like:
%D
%D \starttypen
%D Look at the {\brightgreen bright} side of life and get
%D yourself no \red{red} head!
%D \stoptypen

%D \macros
%D   {colorvalue, grayvalue}
%D
%D We can typeset the color components using \type{\colorvalue} and
%D \type{\grayvalue}. The commands:
%D
%D \startbuffer
%D color value of SomeKindOfRed: \colorvalue{SomeKindOfRed} \crlf
%D gray value of SomeKindOfRed: \grayvalue{SomeKindOfRed}
%D \stopbuffer
%D
%D \typebuffer
%D
%D show us:
%D
%D \startvoorbeeld
%D \haalbuffer
%D \stopvoorbeeld
%D
%D We can speed the following macros a bit up, but this 
%D hardly pays off; they are only used in the manual. 

\def\realcolorformat#1%
  {\ifnum#1<10   0.00\the#1\else
   \ifnum#1<100  0.0\the#1\else
   \ifnum#1<1000 0.\the#1\else
                 1.000\fi\fi\fi}

\def\colorformatseparator{ }

\def\dodoformatcolor#1%
  {\colordimen#1\s!pt\relax
   \ifdim\colordimen>1\s!pt
     \colordimen1\s!pt
   \fi
   \multiply\colordimen 1000
   \colorcount\colordimen
   \advance\colorcount \medcard
   \divide\colorcount \maxcard \relax
   \realcolorformat\colorcount}

\def\doformatcolorR#1:#2:#3:#4:#5\od
  {\dodoformatcolor{#1}\colorformatseparator
   \dodoformatcolor{#2}\colorformatseparator
   \dodoformatcolor{#3}}

\def\doformatcolorC#1:#2:#3:#4:#5:#6\od
  {\dodoformatcolor{#1}\colorformatseparator
   \dodoformatcolor{#2}\colorformatseparator
   \dodoformatcolor{#3}\colorformatseparator
   \dodoformatcolor{#4}}

\def\doformatcolorS#1:#2:#3\od
  {\dodoformatcolor{#1}}

\def\doformatcolor#1:%
  {\getvalue{doformatcolor#1}}

\def\colorvalue
   {\dowithcolor\doformatcolor}

\def\doformatgrayR#1:#2:#3:#4:#5\od
  {\convertRGBtoGRAY{#1}{#2}{#3}%
   \dodoformatcolor\@@cl@@s}

\def\doformatgrayC#1:#2:#3:#4:#5:#6\od
  {\convertCMYKtoGRAY{#1}{#2}{#3}{#4}%
   \dodoformatcolor\@@cl@@s}

\def\doformatgrayS#1:#2:#3\od
  {\dodoformatcolor{#1}}

\def\doformatgray#1:%
  {\getvalue{doformatgray#1}}

\def\grayvalue%
   {\dowithcolor\doformatgray}

%D \macros
%D   {localstartraster,localstopraster,
%D    startraster,stopraster}
%D
%D The previous conversions are not linear and treat each color
%D component according to human perception curves. Pure gray
%D (we call them rasters) has equal color components. In
%D \CONTEXT\ rasters are only used as backgrounds and these
%D don't cross page boundaries in the way color does. Therefore
%D we don't need stacks and marks. Just to be compatible with
%D color support we offer both 'global' and 'local' commands.

\def\localstartraster[#1]%
  {\doifelsenothing{#1}
     {\dostartgraymode{\@@rsraster}}
     {\dostartgraymode{#1}}}

\def\localstopraster
  {\dostopgraymode}

\def\startraster
  {\localstartraster}

\def\stopraster
  {\localstopraster}

%D In this documentation we will not go into too much details
%D on palets. Curious users can find more information on this
%D topic in \uit[use of color].
%D
%D At the moment we implemented color in \CONTEXT\ color
%D printing was not yet on the desktop. In spite of this lack our
%D graphics designer made colorfull illustrations. When printed
%D on a black and white printer, distinctive colors can come
%D out equally gray. We therefore decided to use only colors
%D that were distinctive in colors as well as in black and
%D white print.
%D
%D Although none of the graphic packages we used supported
%D logical colors and global color redefition, we build this
%D support into \CONTEXT. This enabled us to experiment and
%D also prepared us for the future.

%D \macros
%D   {definepalet}
%D
%D Colors are grouped in palets. The colors in such a palet can
%D have colorful names, but best is to use names that specify
%D their use, like {\em important} or {\em danger}. As a sort
%D of example \CONTEXT\ has some palets predefined,
%D like:\voetnoot{At the time I wrote the palet support, I was
%D reading 'A hort history of time' of S.~Hawkins, so that's
%D why we stuck to quarks.}
%D
%D \starttypen
%D \definepalet
%D   [alfa]
%D   [     top=rood:7,
%D      bottom=groen:6,
%D          up=blauw:5,
%D        down=cyaan:4,
%D     strange=magenta:3,
%D       charm=geel:2]
%D \stoptypen
%D
%D It's formal definition is:
%D
%D \showsetup{\y!definepalet}
%D
%D Visualized, such a palet looks like:
%D
%D \startbuffer[palet]
%D \showpalet [alfa] [horizontaal,naam,nummer,waarde]
%D \stopbuffer
%D
%D \startregelcorrectie
%D \haalbuffer[palet]
%D \stopregelcorrectie
%D
%D This bar shows both the color and gray alternatives of the
%D palet components (not visible in black and white print).
%D
%D When needed, one can copy a palet by saying:
%D
%D \starttypen
%D \definepalet [TEXcolorpretty] [colorpretty]
%D \stoptypen
%D
%D This saves us some typing in for instance the modules that
%D deal with pretty verbatim typesetting.

\def\definepalet%
  {\dodoubleargument\dodefinepalet}

\def\dodefinepalet[#1][#2]%
  {\doifassignmentelse{#2}
     {\setvalue{\??pa#1}{}%
      \setevalue{\??pa\??pa#1}{#2}%
      \showmessage{\m!colors}{6}{#1}%
      \def\dodododefinepalet[##1=##2]%
        {\doifvaluesomething{\??pa#1}
           {\setevalue{\??pa#1}{\getvalue{\??pa#1},}}%
         \setevalue{\??pa#1}{\getvalue{\??pa#1}##1}%
         \doifdefinedelse{\??cr##2}
           {\setevalue{\??cr#1:##1}{\getvalue{\??cr##2}}}
           {\setevalue{\??cr#1:##1}{S:0:0:0}}}%
      \def\dododefinepalet##1%
        {\dodododefinepalet[##1]}%
      \processcommalist[#2]\dododefinepalet}
     {\doifdefined{\??pa#2}
        {\expanded{\dodefinepalet[#1][\getvalue{\??pa\??pa#2}]}}}}

%D \macros
%D   {setuppalet}
%D
%D Colors are taken from the current palet, if defined.
%D Setting the current palet is done by:
%D
%D \showsetup{\y!setuppalet}

\let\currentpalet\empty

\def\setuppalet%
  {\dosingleempty\dosetuppalet}

\def\dosetuppalet[#1]%
  {\edef\currentpalet{#1}%
   \ifx\currentpalet\empty 
     % seems to be a reset 
   \else
     % fast enough for tex and etex 
     \@EA\ifx\csname\??pa\currentpalet\endcsname\relax
       \showmessage\m!colors7\currentpalet
       \let\currentpalet\empty
     \else
       \def\currentpalet{#1:}%
     \fi
   \fi}

%D \macros
%D   {showpalet}
%D
%D The previous visualization was typeset with:
%D
%D \typebuffer[palet]
%D
%D This commands is defined as:
%D
%D \showsetup{\y!showpalet}

\fetchruntimecommand \showpalet {\f!colorprefix\s!run}

%D \macros
%D   {definecolorgroup}
%D
%D The naming of the colors in this palet suggests some
%D ordening, which in turn is suported by color grouping.
%D
%D \starttypen
%D \definecolorgroup
%D   [rood]
%D   [1.00:0.90:0.90,
%D    1.00:0.80:0.80,
%D    1.00:0.70:0.70,
%D    1.00:0.55:0.55,
%D    1.00:0.40:0.40,
%D    1.00:0.25:0.25,
%D    1.00:0.15:0.15,
%D    0.90:0.00:0.00]
%D \stoptypen
%D
%D In such a color group colors are numbered from~$1$ to~$n$.
%D
%D \showsetup{\y!definecolorgroup}
%D
%D This kind of specification is not only more compact than
%D defining each color separate, it also loads faster and takes
%D less bytes.

\def\definecolorgroup%
  {\dotripleempty\dodefinecolorgroup}

\def\dodefinecolorgroup[#1][#2][#3]%
  {\ifthirdargument
     \processaction
       [#2]
       [    \v!cmyk=>\edef\currentcolorspace{C},
             \v!rgb=>\edef\currentcolorspace{R},
            \v!gray=>\edef\currentcolorspace{S},
               \v!s=>\edef\currentcolorspace{S},
         \s!unknown=>\edef\currentcolorspace{R}]%
     \colorcount=0
     \def\dododefinecolorgroup##1%
       {\advance\colorcount 1
        \setevalue{\??cr#1:\the\colorcount}{\currentcolorspace:##1:0:0}}%
     \processcommalist[#3]\dododefinecolorgroup
   \else
     \doifinstringelse{:}{#2}
       {\definecolorgroup[#1][\v!rgb][#2]}
       {\doloop
          {\doifdefinedelse{\??cr#2:\recurselevel}
             {\setevalue{\??cr#1:\recurselevel}%
                {\getvalue{\??cr#2:\recurselevel}}}
             {\exitloop}}}%
   \fi}

%D \macros
%D   {showcolorgroup}
%D
%D We can show the group by:
%D
%D \startbuffer
%D \showcolorgroup [blauw] [horizontaal,naam,nummer,waarde]
%D \stopbuffer
%D
%D \typebuffer
%D
%D or in color:
%D
%D \startregelcorrectie
%D \haalbuffer
%D \stopregelcorrectie
%D
%D which uses:
%D
%D \showsetup{\y!showcolorgroup}

\fetchruntimecommand \showcolorgroup {\f!colorprefix\s!run}

%D There are ten predefined color groups, like
%D \color[groen]{\em groen}, \color[rood]{\em rood},
%D \color[blauw]{\em blauw}, \color[cyaan]{\em cyaan},
%D \color[magenta]{\em magenta} and \color[geel]{\em geel}.
%D
%D \startregelcorrectie
%D \hbox to \hsize
%D   {\hss
%D    \showcolorgroup [rood]    [vertikaal,naam,nummer]\hss
%D    \showcolorgroup [groen]   [vertikaal,naam]\hss
%D    \showcolorgroup [blauw]   [vertikaal,naam]\hss
%D    \showcolorgroup [cyaan]   [vertikaal,naam]\hss
%D    \showcolorgroup [magenta] [vertikaal,naam]\hss
%D    \showcolorgroup [geel]    [vertikaal,naam]\hss}
%D \stopregelcorrectie
%D
%D These groups are used to define palets {\em alfa} upto {\em
%D zeta}. As long as we don't use colors from the same row, we
%D get ourselves distinctive palets. By activating such a palet
%D one gains access to its members {\em top} to {\em charm} (of
%D course one should use more suitable names than these).
%D
%D \startregelcorrectie
%D \hbox to \hsize
%D   {\showpalet [alfa]    [vertikaal,naam,nummer]\hss
%D    \showpalet [beta]    [vertikaal,naam]\hss
%D    \showpalet [gamma]   [vertikaal,naam]\hss
%D    \showpalet [delta]   [vertikaal,naam]\hss
%D    \showpalet [epsilon] [vertikaal,naam]\hss
%D    \showpalet [zeta]    [vertikaal,naam]}
%D \stopregelcorrectie
%D
%D By using the keyword \type{\v!waarde} the individual color
%D components are shown too. When printed in color, these
%D showcases show both the colors and the gray value.

%D \macros
%D   {comparepalet}
%D
%D There are some more testing macros available:
%D
%D \startbuffer
%D \comparepalet [alfa]
%D \stopbuffer
%D
%D \typebuffer
%D
%D shows the palet colors against a background:
%D
%D \startregelcorrectie
%D \haalbuffer
%D \stopregelcorrectie
%D
%D The formal definition is:
%D
%D \showsetup{\y!comparepalet}

\fetchruntimecommand \comparepalet {\f!colorprefix\s!run}

%D \macros
%D   {comparecolorgroup}
%D
%D The similar command:
%D
%D \startbuffer
%D \comparecolorgroup [blauw]
%D \stopbuffer
%D
%D \typebuffer
%D
%D shows color groups:
%D
%D \startregelcorrectie
%D \haalbuffer
%D \stopregelcorrectie
%D
%D this commands are defined as:
%D
%D \showsetup{\y!comparecolorgroup}

\fetchruntimecommand \comparecolorgroup {\f!colorprefix\s!run}

%D \macros
%D   {showcolor}
%D
%D But let's not forget that we also have the more traditional
%D non||related colors. These show up after:
%D
%D \starttypen
%D \showcolor [name]
%D \stoptypen
%D
%D Where \type{name} for instance can be \type{rgb}.
%D
%D \showsetup{\y!showcolor}

\fetchruntimecommand \showcolor {\f!colorprefix\s!run}

%D \macros
%D   {negativecolorbox}
%D
%D Sometimes, especially when we deal with typesetting
%D devices, we want to reverse the color scheme. Instead of
%D recalculating all those colors, we use a quick and dirty
%D approach:
%D
%D \starttypen
%D \negativecolorbox0
%D \stoptypen
%D
%D will negate the colors in box zero.

\def\negatecolorbox#1%
  {\setbox#1=\hbox
     {\dostartnegative
      \localstartcolor[white]%
      \vrule\!!height\ht#1\!!depth\dp#1\!!width\wd#1%
      \localstopcolor
      \hskip-\wd#1%
      \box#1\dostopnegative}}

%D \macros
%D   {ifMPgraphics, ifMPcmyk, MPcolor}
%D
%D A very special macro is \type{\MPcolor}. This one can be
%D used to pass a \CONTEXT\ color to \METAPOST.
%D
%D \starttypen
%D \MPcolor{my own red}
%D \stoptypen
%D
%D This macro returns a \METAPOST\ triplet \type{(R,G,B)}.
%D Unless \CMYK\ color support is turned on with \type
%D {MPcmyk}, only \kap{RGB} colors and gray scales are
%D supported.

\newif\ifMPcmyk % \MPcmykfalse

\beginTEX

\def\MPcolor#1%
  {\ifMPgraphics
     \@EA\@EA\@EA\doMPcolor
       \csname\??cr\@EA
         \ifx\csname\??cr\currentpalet#1\endcsname\relax\else\currentpalet\fi
       #1\endcsname
     :::::::\end
   \else
     #1%
   \fi}

\endTEX

\beginETEX \ifcsname

\def\MPcolor#1%
  {\ifMPgraphics
     \@EA\@EA\@EA\doMPcolor
       \csname\??cr
         \ifcsname\??cr\currentpalet#1\endcsname\currentpalet\fi
       #1\endcsname
     :::::::\end
   \else
     #1%
   \fi}

\endETEX

%D Before we had transparancy available, the following 
%D conversion macro was available: 
%D 
%D \starttypen
%D \def\doMPcolor#1:#2:#3:#4:#5:#6:#7:#8\end
%D   {\if     #1R(#2,#3,#4)%
%D    \else\if#1C\ifMPcmyk cmyk(#2,#3,#4,#5)\else(1-#2-#5,1-#3-#5,1-#4-#5)\fi
%D    \else\if#1S(#2,#2,#2)%
%D    \else      (0,0,0)%
%D    \fi\fi\fi}
%D \stoptypen
%D 
%D In order to be useful, this macro is to be fully
%D expandabele. The next alternative also handles transparant
%D colors. We could have packaged everything in one macro, but
%D splitting it up is not only more readable, but also faster
%D (because less arguments have to be skipped) 

\def\doMPcolor#1:%
  {\if#1R%
     \@EA\doMPrgb
   \else\if#1C\ifMPcmyk
     \@EA\@EAEAEA\@EA\doMPcmykY
   \else
     \@EA\@EAEAEA\@EA\doMPcmykN
   \fi\else\if#1S%
     \@EA\@EAEAEA\@EA\doMPgray
   \else      
     \@EA\@EAEAEA\@EA\doMPblack
   \fi\fi\fi}

\def\transparentMP{transparent}
\def\cmykspecialMP{cmyk}

\def\doMPtransparent#1#2:#3:#4\end
  {\ifcase#2\space(#1)\else\transparentMP(#2,#3,(#1))\fi}

\def\doMPgray          #1:{\doMPtransparent{#1,#1,#1}}
\def\doMPrgb     #1:#2:#3:{\doMPtransparent{#1,#2,#3}}
\def\doMPcmykY#1:#2:#3:#4:{\doMPtransparent{\cmykspecialMP(#1,#2,#3,#4)}}
\def\doMPcmykN#1:#2:#3:#4:{\doMPtransparent{1-#1-#4,1-#2-#4,1-#3-#4}}

\def\doMPblack#1:#2:#3:#4:#5:#6:#7\end{(0,0,0)}

%D \macros
%D   {PDFcolor,FDFcolor}
%D
%D Similar alternatives are avaliable for \PDF:

\def\PDFcolor#1%
  {\@EA\@EA\@EA\doPDFcolor\csname\??cr#1\endcsname:::::::\end}

\def\doPDFcolor#1:#2:#3:#4:#5:#6:#7:#8\end
  {\if     #1R#2 #3 #4 rg%
   \else\if#1C#2 #3 #4 #5 k%
   \else\if#1S#2 g%
   \else      0 g%
   \fi\fi\fi}

\def\FDFcolor#1%
  {\@EA\@EA\@EA\doFDFcolor\csname\??cr#1\endcsname:::::::\end}

\def\doFDFcolor#1:#2:#3:#4:#5:#6:#7:#8\end
  {[\if     #1R#2 #3 #4%
    \else\if#1C#2 #3 #4 #5%
    \else\if#1S#2%
    \else      0%
    \fi\fi\fi]}

%D We default to the colors defined in \module{colo-rgb} and
%D support both \kap{RGB} and \kap{CMYK} output.

\setupcolors
  [\c!status=\v!stop,
   \c!conversie=\v!ja,
   \c!reductie=\v!nee,
   \c!rgb=\v!ja,
   \c!cmyk=\v!ja,
   \c!mp\c!cmyk=\@@clcmyk,
   \c!tekstkleur=]

\setupcolor
  [\v!rgb]

%D As we can see, color support is turned off by default.
%D Reduction of gray colors to gray scales is turned on.

\protect \endinput