An example of local correction, but it's not automatic: \definecharacterkerning[narrow][factor=-.02] \definecharacterkerning[wide][factor=.02] \definefontfeature[frac][frac=yes] \def\Narrow#1{\bgroup\setcharacterkerning[narrow]#1\egroup} \def\Wide#1{\bgroup\setcharacterkerning[wide]#1\egroup} \def\NoKerning#1{\bgroup\resetcharacterkerning #1\egroup} \starttext \feature[+][frac]% Some ligatures: float, finance, affine; a fraction: 1/4. \blank Modified kerning: \Narrow{Some ligatures: float, finance, affine; a fraction: 1/4.} \Wide{Some ligatures: float, finance, affine; a fraction: 1/4.} \blank Same as above, but locally corrected: \Narrow{Some ligatures: \NoKerning{fl}oat, \NoKerning{fi}nance, a\NoKerning{ffi}ne; a fraction: \NoKerning{1/4}.} \Wide{Some ligatures: \NoKerning{fl}oat, \NoKerning{fi}nance, a\NoKerning{ffi}ne; a fraction: \NoKerning{1/4}.} \stoptext PS: (errata corrige)

"1", "/", "4" => "¼" glyph (with "frac" feature switched on)

"1", "/", "4" => "smaller 1" glyph moved up, fraction line glyph, "smaller 4" glyph moved left and down

character kerning is bad anyway ...

I'm using it to get a paragraph one line shorter or longer, or to tune what in TeX is set with \parfillskip. I'm using ConTeXt with a mindset developed on other typesetting softwares. That's not right, i know, but for now i'm finding easier to work with character kerning than with \looseness, \parfillskip and \emergencystretch. \looseness=-1 quite never reduces the lines' number, because the inter-word spaces are already very well optimized. \looseness=1 quite always produces a short last line, so that i often work on \emergencystretch and \parfillskip to make it wider. But this way i have to work on 3 parameters; with kerning you have only one: uglier for ligatures but easier. I suspect TeX has better ways to deal with that problem, but i don't know them (hints are welcome).

effe

and this is

e ff e

you definitely don't want to kern like

e kern ff kern ff

but

e kern f kern f kern e

so, ligatures are pretty useless with intercharacter kerning (as per definecharacterning) ... just conceptually incomatible

(it is possible to turn it on but it really isnot what you want)

yes, the ligature would not get the same shrinkage or stretch of the rest, but i don't modify the kerning that much (factor=.02 is the maximum value). It's still acceptable. 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? Massimiliano

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

did you play with

\definefontfeature[whatever][keepligatures=auto]

\definecharacterkerning [extrakerning] [factor=0.125,features=whatever]

\starttext     \setcharacterkerning[extrakerning]     effe fietsen \stoptext

Great! Thanks! This now works: \definefontfeature[frac][frac=yes] \definefontfeature[klig][keepligatures=auto] \definecharacterkerning[narrow][factor=-.02,features=klig] \definecharacterkerning[wide][factor=.02,features=klig] \def\Narrow#1{\dontleavehmode\bgroup\setcharacterkerning[narrow]#1\egroup} \def\Wide#1{\dontleavehmode\bgroup\setcharacterkerning[wide]#1\egroup} \def\NoKerning#1{\dontleavehmode\bgroup\resetcharacterkerning #1\egroup} \starttext \feature[+][frac]% Some ligatures: float, finance, affine; a fraction: 1/4. \blank Modified kerning: \Narrow{Some ligatures: float, finance, affine; a fraction: 1/4.} \Wide{Some ligatures: float, finance, affine; a fraction: 1/4.} \stoptext BTW, back to the automatic insertion of tags, how can i create children elements? In other words, how should i rewrite new_dk_element? The problem is this: - you have an element t and t.dt = { "float, finance, affine, affluent" } - t.dt should become = { DK1, "oat", DK2, "nance, a", DK3, "ne, a", DK4, "uent" } - where DK1 ... DK4 are children elements of t with tg="dk" and dt respectively equal to { "fl" }, { "fi" }, { "ffi" }, { "ffl" } My new_dk_element function should create such DKn elements, but they are not created right, because they look ignored by \xmlflush.

...

\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

On 12/11/2018 07:06, Hans Hagen wrote:

On 12/11/2018 11:34 AM, mf wrote:

...

...

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):

did you play with

\definefontfeature[whatever][keepligatures=auto]

\definecharacterkerning [extrakerning] [factor=0.125,features=whatever]

\starttext     \setcharacterkerning[extrakerning]     effe fietsen \stoptext

Nice! It recognizes the difference between ccmp and liga, so now we have (almost perfect) support for Sperrdruck! There is a ZWNJ in the following example (between t and z inZeitzone) that gets expanded, leaving an enlarged gap. \mainlanguage [deo] \definefontfeature[frak][ccmp=yes,liga=yes] \definefont [FrakXIX] [UnifrakturMaguntia19.ttf*frak] \definefontfeature[whatever][keepligatures=auto] \definecharacterkerning [extrakerning] [factor=0.25,features=whatever] \define\Test{{\FrakXIX ſitzen/beſchütze/Zeit‌zone}} \starttext \tex{setcharacterkerning}\par \Test\par {\setcharacterkerning[extrakerning]\Test}\par \Test\par \blank \tex{kerncharacters}\par \Test\par {\kerncharacters[.25]{\Test}\par \Test\par \stoptext -- Rik