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%D \module [
%D file=t-letterspace,
%D version=2011-03-15T12:59:48+0100 or later,
%D title=\CONTEXT\ User Module,
%D subtitle=Letterspacing commands,
%D author=Philipp Gesang,
%D date=\currentdate,
%D copyright=Philipp Gesang,
%D license=2-clause BSD,
%D ]
%C Read the license conditions in the file \type{COPYING}.
\writestatus{loading}{ConTeXt User Module / Letterspace}
\startmodule [letterspace]
\startinterface all
\setinterfacevariable {letterspace} {letterspace}
\setinterfacevariable {factor} {factor}
\setinterfacevariable {spaceskip} {spaceskip}
\setinterfacevariable {suppresskern}{suppresskern}
\stopinterface
\unprotect
\definenamespace [\v!letterspace] [
command=yes,
comment=Letterspace module,
name=\v!letterspace,
\s!parent=\v!letterspace,
setup=list,
style=no,
type=module,
version=hg-rev:3+,
]
%D \macros
%D {letterspace}
%D
%D \useURL [wschuster] [https://bitbucket.org/wolfs/] [] [Wolfgang Schuster]
%D \from[wschuster]’s {\em fancybreak} and {\em annotation}
%D modules served as the primary source for the following code.
%D You’ll have to thank him if it works and blame me if it doesn’t.
\appendtoks
\setuevalue{\currentletterspace }{\doletterspace[\currentletterspace]}%
\setuevalue{\e!start\currentletterspace}{\dostartletterspace[\currentletterspace]}%
\setuevalue{\e!stop \currentletterspace}{\dostopletterspace}%
\to \everydefineletterspace
\definecharacterkerning [letterspace:current]
\unexpanded\def\doletterspace[#1]{%
\edef\currentletterspace{#1}%
\dosingleempty\dodoletterspace%
}
\def\dodoletterspace[#1]{%
\iffirstargument
\doifassignment{#1}{%
\setupletterspace[\currentletterspace][#1]%
}%
\fi
\dododoletterspace%
}
\definefontfeature [letterspace:kerning] [kern=yes]
\def\letterspace_truevalues{true,yep,yes}
\def\dododoletterspace#1{%
\def\currentobject{#1}%
\dontleavehmode
\setupcharacterkerning[letterspace:current][factor=\letterspaceparameter{factor}]%
\def\letterspace_setstuff{%
\setcharacterkerning[letterspace:current]%
\advance \spaceskip \letterspaceparameter{spaceskip}%
\advance \xspaceskip \letterspaceparameter{spaceskip}%
\doifinset{\letterspaceparameter{suppresskern}}{\letterspace_truevalues}{%
\subtractfontfeaturefromfont{letterspace:kerning}%
}%
}%
\ifhmode\ifnum\lastnodetype=\@@gluenode
\unskip{\letterspace_setstuff\ }%
\fi
\fi%
{\letterspace_setstuff\currentobject}%
\doifnextspace{%
{\letterspace_setstuff\ }%
\gobblespacetokens%
}%
}
%D This is a partial ripoff of a couple of macros from
%D \type{syst-aux.mkiv}.
%D \useURL [flet] [http://www.tug.org/TUGboat/Articles/tb09-3/tb22bechtolsheim.pdf] [] [\type{futurelet}]
%D Very helpful for further understanding of what’s exactly going
%D on: Stephan von Bechtolsheim’s tutorial on \from[flet].
%D
%D In short: the trick is checking whether the token following
%D the command is a space, that is: whether it expands to
%D \type{\blankspace}. If the test succeeds, a space will be
%D added that has the correct parameters and all space tokens
%D following the command will be gobbled. Otherwise -- the next
%D token being anything else -- \type{\letterspace} will proceed
%D without changing anything.
\def\doifnextspace#1{%
\def\!!string{#1}%
\futurelet\nexttoken\inspectnexttoken%
}
\def\inspectnexttoken{%
\ifx\nexttoken\blankspace
\@EA\!!string
\fi%
}
%D \macros
%D {startletterspace,stopletterspace}
%D
%D These rely even more shamelessly on \from[wschuster]’s code
%D from the {\em fancybreak} module.
%D
%D The \type{\[start|stop]letterspace} environment is provided
%D for sake of completeness.
\unexpanded\def\dostartletterspace[#1]{%
\edef\currentletterspace{#1}%
\dosingleempty\dodostartletterspace%
}
\def\dodostartletterspace[#1]{%
\iffirstargument
\setupletterspace[\currentletterspace][#1]%
\fi
\dododoletterspace\bgroup%
}
\let\dostopletterspace\egroup
%D \macros
%D {setupletterspace}
%D
%D Initial setup.
%D The factor by which the {\em letter space} (i.e. space between
%D glyphs) will be increased is specified via the
%D \type{factor} key.
%D Additionally, it is wise with respect to legibility to enlarge
%D the {\em interword space} as well. That is what the
%D \type{spaceskip} key is for. The {\em spaceskip} should be an
%D ordinary dimension.
\setupletterspace [
\v!factor=.125,
\v!spaceskip=.5em,
\v!suppresskern=false,
]
\defineletterspace[\v!letterspace]
\protect \stopmodule \endinput
% vim:ft=context:sw=2:ts=2
|
