[NTG-context] Changing decimals points to Persian ones via font features

Hans Hagen pragma at wxs.nl
Mon Aug 8 17:36:00 CEST 2016


On 8/8/2016 5:24 PM, Mohammad Hossein Bateni wrote:
> Thanks, Hans!
>
> I see; this does work except for the trouble of annotating with \digits
> macro.  Would it be possible if I wrote a processor in Lua to do the work?
>
> nodes.tasks.appendaction ("processors", "before", "fix_persian_mathperiod")
>
> Can I find out if a node is inside math?  If I look at the corresponding
> font, how can I find out if this is a math font or not?

it's doable but then you also have to fight exceptions and that is no fun

>
> I take it that in math fonts, kerning does not work, either?  In my
> case, the Persian decimal separator usually has a part below the
> baseline that extends to the left, and because all (Persian) digits are
> above the baseline, I get an ugly space in the middle.  If kerning is
> not possible at all, I can try to change the dimensions of Persian
> decimal separator symbol because the kern is always necessary.  Is it
> possible to change the dimensions of the symbol or is that also fixed
> and unchangeable?

probably best is to collect all that info, also for different math 
fonts, and then cook up some virtual font support for it (across fonts), 
if only because digits is one aspect if bidi math and there is more needed

> Thanks a lot!
> —MHB
>
>
>
> On Mon, Aug 8, 2016 at 10:44 AM, Hans Hagen <pragma at wxs.nl
> <mailto:pragma at wxs.nl>> wrote:
>
>     On 8/2/2016 9:54 PM, Mohammad Hossein Bateni wrote:
>
>         Could the problem be because math fonts use mode=base instead of
>         mode=node?  Or is it because in math fonts, the digits and/or
>         full-stop
>         have different codes?
>
>
>     math fonts are defined and then don't change i.e. they are quite
>     static and all juggling with individual symbols of sequences is done
>     using predictable methods
>
>         —MHB
>
>         On Mon, Aug 1, 2016 at 9:46 AM, Mohammad Hossein Bateni
>         <bateni at gmail.com <mailto:bateni at gmail.com>
>         <mailto:bateni at gmail.com <mailto:bateni at gmail.com>>> wrote:
>
>             Dear list,
>
>             I want to add a customized font feature to the math font, to
>             automatically change the decimal point (unicode 0x2E) to the
>             Arabic/Farsi version (unicode 0x66B).  This will go well
>         with the
>             mapping from Latin digits to Farsi digits (done in a sample with
>             mathdigits fallback).
>
>             For instance, I want to code in $123.45$ and get a result like
>             ۱۲۳٫۴۵.  However, I do not want to simply map 0x2E to 0x66B,
>         because
>             then "full stop" outside a number will also change.  In
>         particular,
>             I'd like to have the mapping only when full-stop is preceded and
>             succeeded by a digit.  This will, among other things, leave the
>             end-of-equation periods unchanged.
>
>             Here is how I tried to achieve it.
>
>
>             \startluacode
>             digits = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
>         0x38, 0x39 }
>             -- 0x66B instead of 0x2F gives an error!
>             replacements = { [0x002E] = { 0x2F } }
>             fonts.handlers.otf.addfeature {
>               name = "mpf",
>               type = "chainsubstitution",
>               lookups = { {
>                 type = "multiple",
>                 data = replacements,
>               } },
>               data = {
>                 rules = {
>                   {
>                     current = { { 0x002E } },
>                     after   = { digits },
>                     before  = { digits },
>                     lookups = { 1 },
>                   }
>                 }
>               }
>             }
>             \stopluacode
>
>             \definefontfeature[mathperiod][mpf=yes]
>
>             \resetfontfallback [mathdigits]
>
>         %\definefontfallback[mathdigits][dejavusansmono][digitsextendedarabicindic][check=yes,force=yes,offset=digitsnormal]
>
>             \definefontsynonym
>
>         [MathRoman][name:modern][features={math\mathsizesuffix,mathperiod},goodies=lm-math,fallbacks=mathdigits]
>
>             \starttext
>             $123.45.$
>
>             123.45.
>
>             \addff{mathperiod}
>             123.45.
>             \stoptext
>
>
>             Though this font feature works outside math, it does not seem to
>             have any effect within the math font.  Why is that?  Can we
>         add font
>             feature to the math font?  Are the character codes different?
>
>             Notice that I could not get it to work, so I commented out the
>             fallback for Persian digits, to make things simpler.  To get the
>             proof of concept, I am trying to change period to forward
>         slash (see
>             below).
>
>             Is the syntax I use for having two features in
>         \defontfontsynonym
>             correct?  Actually, I did try with only mathperiod and it
>         does not
>             work, either.
>
>             When I change 0x2F (slash) to 0x066B in "replacements", I get an
>             error as follows.
>
>
>             fonts           > otf chain > feature 'mpf', type
>             'gsub_contextchain', chain lookup 'mpf': rule 1 matches at char
>             U+0002E (period) for (1,1,1) chars, lookuptype 'gsub_multiple'
>
>             error:
>
>         ...ext/tex/texmf-context/tex/context/base/mkiv/font-ots.lua:1232:
>             attempt to index field '?' (a nil value)
>
>             tex error       > tex error on line 1 in file
>             /Users/bateni/farsitex/context/bostan/examples/mathfa/1.tex: ?
>
>             \page ->\par
>                          \dosingleempty \page_breaks_process
>             \strc_pagenumbers_flush_final_page ...\else \page
>
>             [\p_strc_pagenumbers_page ...
>             \dostoptext ...\strc_pagenumbers_flush_final_page
>                                                               \page \the
>             \everystoptext ...
>             l.1 \dostoptext
>
>             \clf_stoptext ->\luafunction \16>>clf_stoptext
>
>             l.46 \stoptext
>
>
>
>             Best,
>             MHB
>
>
>
>
>         ___________________________________________________________________________________
>         If your question is of interest to others as well, please add an
>         entry to the Wiki!
>
>         maillist : ntg-context at ntg.nl <mailto:ntg-context at ntg.nl> /
>         http://www.ntg.nl/mailman/listinfo/ntg-context
>         <http://www.ntg.nl/mailman/listinfo/ntg-context>
>         webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
>         archive  : http://foundry.supelec.fr/projects/contextrev/
>         <http://foundry.supelec.fr/projects/contextrev/>
>         wiki     : http://contextgarden.net
>         ___________________________________________________________________________________
>
>
>
>     --
>
>     -----------------------------------------------------------------
>                                               Hans Hagen | PRAGMA ADE
>                   Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>            tel: 038 477 53 69 | www.pragma-ade.nl
>     <http://www.pragma-ade.nl> | www.pragma-pod.nl
>     <http://www.pragma-pod.nl>
>     -----------------------------------------------------------------
>     ___________________________________________________________________________________
>     If your question is of interest to others as well, please add an
>     entry to the Wiki!
>
>     maillist : ntg-context at ntg.nl <mailto:ntg-context at ntg.nl> /
>     http://www.ntg.nl/mailman/listinfo/ntg-context
>     <http://www.ntg.nl/mailman/listinfo/ntg-context>
>     webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
>     archive  : http://foundry.supelec.fr/projects/contextrev/
>     <http://foundry.supelec.fr/projects/contextrev/>
>     wiki     : http://contextgarden.net
>     ___________________________________________________________________________________
>
>
>
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context at ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> 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
-----------------------------------------------------------------


More information about the ntg-context mailing list