colo-ext.mkii / last modification: 2020-01-30 14:15
%D \module
%D   [       file=colo-ext, % mostof thsi code used to be in colo-ini.tex
%D        version=1997.04.01,
%D          title=\CONTEXT\ Color Macros,
%D       subtitle=Extras,
%D         author=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.

\writestatus{loading}{ConTeXt Color Macros / Extras}

\unprotect

%D \macros
%D   {negatecolorcomponent, 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 \starttyping
%D \negativecolorbox0
%D \stoptyping
%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 There are in principle two ways to handle overprint: bound to colors
%D or independent. For the moment we only support independent overprint
%D handling. Here we deal with a per-document setting.

\setupcolors
  [\c!intent=\v!none]

\def\starttextoverprint
  {\doifelse\@@clintent\v!overprint
     {\glet\stoptextoverprint \dostopoverprint
      \glet\starttextoverprint\dostartoverprint
      \dostartoverprint}
     {\glet\stoptextoverprint\donothing}}

\let\stoptextoverprint\donothing

\appendtoks \starttextoverprint \to \everystarttextproperties
\appendtoks \stoptextoverprint  \to \everystoptextproperties

\protect \endinput