But i should consider all the text parts with a modified kerning and
disable kerning around character sequences like "ff", "ffi", "fl" and
so on. Luckily, the XHTML markup "knows" where the kerning is modified:
<p class="wide">A paragraph with a modified kerning</p>
should become
<p class="wide">A paragraph with a modi<dk>fi</dk>ed kerning</p>
Where <dk>...</dk> (dk=Disable Kerning) are tags to be inserted
automatically before feeding the XHTML into ConTeXt.
I'm not very happy or proud about it, but it can be done.
Do you think it can be better done inside ConTeXt?
I nearly managed to do it in ConTeXt, but I can't create the "<dk>"
elements right (the "new_dk_element" function is wrong):
\startbuffer[test]
<text>
<p>Some ligatures: float, finance, affine, affluent.</p>
<p>Modified kerning:</p>
<p class="narrow">Some ligatures: float, finance, affine, affluent.</p>
<p class="wide">Some ligatures: float, finance, affine, affluent.</p>
</text>
\stopbuffer
\startluacode
local function new_dk_element( parent, text )
return {
tag = "dk",
ns = "",
rn = "",
dt = { text },
at = {},
command = "xml:dk",
__p__ = parent
}
--[[
local t = xml.toxml( "<dk>" .. text .. "</dk>" )
t.__p__ = parent
return t
]]--
end
local append = table.insert
local function saveLigaturesFromKerning( t )
if t and t.dt then
local dt = t.dt
local t_copy = {}
for k,v in pairs( t ) do
if k ~= "dt" then t_copy[ k ] = v end
end
local new_dt = {}
local i
local child
local b, e
for i = 1, #dt, 1 do
child = dt[ i ]
if type( child ) == "string" then
local s = child
repeat
b, e = string.find( s, "f?f[il]" )
if b then
if b > 1 then append( new_dt, string.sub( s, 1, b - 1 ) ) end
append( new_dt, new_dk_element( t, string.sub( s, b, e ) ) )
-- append( new_dt, "[" .. string.sub( s, b, e ) .. "]" )
s = string.sub( s, e + 1 )
else
append( new_dt, s )
end
until not b
else
append( new_dt, child )
end
end
t.dt = new_dt
end
return t
end
function xml.functions.textWithKerning( t )
local kt = saveLigaturesFromKerning( t )
lxml.flush( kt )
end
\stopluacode
\definecharacterkerning[narrow][factor=-.02]
\definecharacterkerning[wide][factor=.02]
\def\Narrow#1{\bgroup\setcharacterkerning[narrow]#1\egroup}
\def\Wide#1{\bgroup\setcharacterkerning[wide]#1\egroup}
\def\NoKerning#1{\bgroup\resetcharacterkerning #1\egroup}
\startxmlsetups xml:test
\xmlsetsetup{#1}{text|p|dk}{xml:*}
\xmlsetsetup{#1}{{p.narrow}}{xml:p:narrow}
\xmlsetsetup{#1}{{p.wide}}{xml:p:wide}
\stopxmlsetups
\xmlregistersetup{xml:test}
\startxmlsetups xml:text
\xmlflush{#1}
\stopxmlsetups
\startxmlsetups xml:p
\xmlflush{#1}\par
\stopxmlsetups
\startxmlsetups xml:p:narrow
\Narrow{\xmlfunction{#1}{textWithKerning}}\par
\stopxmlsetups
\startxmlsetups xml:p:wide
\Wide{\xmlfunction{#1}{textWithKerning}}\par
\stopxmlsetups
\startxmlsetups xml:dk
\NoKerning{\red\xmlflush{#1}}
\stopxmlsetups
\starttext
\xmlprocessbuffer{xml:test}{test}{}
\stoptext
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