%D \module
%D   [       file=typo-krn,
%D        version=2009.03.27, % code moved from core-spa.mkiv
%D          title=\CONTEXT\ Typesetting Macros,
%D       subtitle=Spacing,
%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 Typesetting Macros / Kerning}

\unprotect

\registerctxluafile{typo-krn}{1.001}

\definesystemattribute[kern][public]

% more
%
% {\setcharacterkerning[extrakerning]\input davis\relax}

\installcorenamespace{characterkerning}

\installcommandhandler \??characterkerning {characterkerning} \??characterkerning

\unexpanded\def\setcharacterkerning[#1]%
  {\edef\currentcharacterkerning{#1}%
   \ifx\currentcharacterkerning\s!reset
     \resetcharacterkerning
   \else
     \typo_kerning_set
   \fi}

% \def\typo_kerning_set
%   {\ctxcommand{setcharacterkerning(\characterkerningparameter\c!factor)}}

\def\typo_kerning_set
  {\usecharacterkerningstyleandcolor\c!style\c!color % goodie, maybe also strut
   \ctxcommand{setcharacterkerning(\characterkerningparameter\c!factor)}}

\unexpanded\def\resetcharacterkerning % fast one
  {\attribute\kernattribute\attributeunsetvalue}

\appendtoks
    \resetcharacterkerning
\to \everyresettypesetting

\definecharacterkerning [extrakerning] [\c!factor=.125] % used in manuals

%D Added after discussion on list (posted by WS, adapted abit by HH)
%D \unknown\ this needs to be interfaced (\type {\v!kerncharacters}).
%D
%D \starttyping
%D \setuphead[section][style=\sca,textstyle={\kerncharacters[.5]}] \section{Section}
%D \stoptyping
%D
%D We could combine this with the previous definition command but
%D then we always would get a command defined which is not beforehand
%D a good idea.

\def\v!kerncharacters{kerncharacters} % no time now for translations

\definecharacterkerning [\v!kerncharacters] [\c!factor=.125]

% Here we need to keep the groupedcommand solution as it is
% used as modifier.

\unexpanded\def\kerncharacters
  {\doifnextoptionalelse\typo_kerning_apply_yes\typo_kerning_apply_nop}

\def\typo_kerning_apply_yes[#1]%
  {\groupedcommand{\typo_kerning_apply_yes_indeed{#1}}\donothing}

\def\typo_kerning_apply_nop
  {\groupedcommand\typo_kerning_apply_nop_indeed\donothing}

\def\typo_kerning_apply_yes_indeed#1%
  {\let\currentcharacterkerning\v!kerncharacters
   \setupcurrentcharacterkerning[\c!factor=#1]%
   \typo_kerning_set}

\def\typo_kerning_apply_nop_indeed
  {\let\currentcharacterkerning\v!kerncharacters
   \typo_kerning_set}

\protect \endinput