modifying kerning breaks opentype ligatures (and other features)

modifying kerning breaks opentype ligatures (and other features)

[mf]

Hello list,
i noticed that setting a different kerning breaks some features of 
opentype fonts; that is true, for example, for ligatures and fractions 
(frac feature).

It looks like a modified kerning inserts something between two adjacent 
character, making them no more adjacent.
That way the lookup of opentype tables fails.

"f", "l"            => "fl" ligature glyph

"f", [kerning], "l" => distinct "f" and "l" glyphs

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

"1", [kerning], "/", [kerning], "4" => distinct "1", "/", "4" glyphs 
(always with "frac" feature switched on)

MWE:

\definecharacterkerning[narrow][factor=-.015]
\definecharacterkerning[wide][factor=.015]

\definefontfeature[frac][frac=yes]

\starttext
\feature[+][frac]%
Some ligatures: float, finance, affine; a fraction: 1/4.

\setcharacterkerning[narrow]Some ligatures: float, finance, affine; a 
fraction: 1/4.

\setcharacterkerning[wide]Some ligatures: float, finance, affine; a 
fraction: 1/4.

\stoptext

In my XML to PDF workflow, fractions are marked up, so it's easy to 
switch the kerning off only for them.

Instead i have no solution for ligatures: parts of text with a modified 
kerning loose ligatures, and i end up with the same words, once with 
ligatures, once without, even in the same page.
Is there a workaround for this?

Massimiliano


___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[mf]

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
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[Hans Hagen]

On 12/10/2018 4:26 PM, mf wrote:
> Hello list,
> i noticed that setting a different kerning breaks some features of 
> opentype fonts; that is true, for example, for ligatures and fractions 
> (frac feature).
> 
> It looks like a modified kerning inserts something between two adjacent 
> character, making them no more adjacent.
> That way the lookup of opentype tables fails.
> 
> "f", "l"            => "fl" ligature glyph
> 
> "f", [kerning], "l" => distinct "f" and "l" glyphs
> 
> "1", "/", "4" => "¼" glyph (with "frac" feature switched on)
> 
> "1", [kerning], "/", [kerning], "4" => distinct "1", "/", "4" glyphs 
> (always with "frac" feature switched on)
> 
> MWE:
> 
> \definecharacterkerning[narrow][factor=-.015]
> \definecharacterkerning[wide][factor=.015]
> 
> \definefontfeature[frac][frac=yes]
> 
> \starttext
> \feature[+][frac]%
> Some ligatures: float, finance, affine; a fraction: 1/4.
> 
> \setcharacterkerning[narrow]Some ligatures: float, finance, affine; a 
> fraction: 1/4.
> 
> \setcharacterkerning[wide]Some ligatures: float, finance, affine; a 
> fraction: 1/4.
> 
> \stoptext
> 
> In my XML to PDF workflow, fractions are marked up, so it's easy to 
> switch the kerning off only for them.
> 
> Instead i have no solution for ligatures: parts of text with a modified 
> kerning loose ligatures, and i end up with the same words, once with 
> ligatures, once without, even in the same page.
> Is there a workaround for this?
character kerning is bad anyway ... say that we have:

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)


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[mf]

> 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
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[Hans Hagen]

On 12/10/2018 6:16 PM, mf wrote:

> 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.
ok, then don't use this characterkerning but use expansion (hz) ... you 
can do that extreme (larg evalues) if needed (after all, big publishers 
do that too)

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[mf]

> 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

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[Hans Hagen]

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




> \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
> 
> ___________________________________________________________________________________ 
> 
> If your question is of interest to others as well, please add an entry 
> to the Wiki!
> 
> maillist : ntg-context@ntg.nl / 
> http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________


-- 

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[mf]

> 
> 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
>>
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[Hans Hagen]

On 12/11/2018 1:45 PM, mf wrote:

hm that is quit emessy yes? I found another solution (that we used once) 
that I can turn into a helper ... I'll send it off list

>>> \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
 >>> -- a lot of lua code messing with xml

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[Rik Kabel]

[-- Attachment #1.1: Type: text/plain, Size: 1952 bytes --]

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


[-- Attachment #1.2: Type: text/html, Size: 2909 bytes --]

[-- Attachment #2: Type: text/plain, Size: 492 bytes --]

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: modifying kerning breaks opentype ligatures (and other features)

[Rik Kabel]

On 12/11/2018 15:54, Rik Kabel wrote:
> 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.
>
>
And I spoke too soon (not unusual, I know). The ſi ligature is not 
broken up, but it should be. Only ck, ct, ch, and ſt and tz should be 
preserved.

So it looks like manual intervention is still required. (There are a few 
LaTeX packages that handle this well, chief among the microtype.)

-- 
Rik

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________