New subject: Typescript/fallbacks problem

26 May 2017

      The following email had large attachments (more than 100K).  I uploaded
everything here:
http://mhbateni.com/context/bug-04/

On Thu, May 25, 2017 at 11:40 PM, Mohammad Hossein Bateni 
wrote:
...
Hello Hans,
I'm going to explain a strange problem which came about, as far as I can
tell, in beta 2017.04.27 01:00.  The same beta had introduced some other
issues with fallbacks, which you fixed already.  Thanks a lot for that!
I am now using the latest beta, version 2017.05.25 12:50.  Unfortunately I
don't know what is going on precisely.  Here is a sort-of-minimal
non-working example.
%%%%%%%%%%%%%%%%%%%%%%%%%
\definefontfeature[slanted][slant=.4]
\starttypescript [serif][sahel][name]
\resetfontfallback [dejavudefault]
\definefontfallback[dejavudefault][dejavusans]
[range=generalpunctuation,check=yes,force=no]
%
\definefontsynonym [SahelReg]    [Sahel][features={arabic,
tlig},fallbacks=dejavudef]
%% NOTE 1
%  \definefontsynonym [SahelReg] [Sahel][features={arabic,tlig}]
\definefontsynonym [SahelBd]       [SahelBold][features={arabic,
tlig},fallbacks=dejavudef]
\definefontsynonym [SahelIt]         [Sahel][features={arabic,tlig,
slanted},fallbacks=dejavudef]
\definefontsynonym [SahelBdIt]     [SahelBold][features={arabic,
tlig,slanted},fallbacks=dejavudef]
%
\definefontsynonym [Serif] [SahelReg]
\definefontsynonym [SerifBold] [SahelBd]
\definefontsynonym [SerifItalic] [SahelIt]
\definefontsynonym [SerifBoldItalic] [SahelBdIt]
\stoptypescript
\starttypescript [math] [modern] [name]
\definefontsynonym [MathRoman] [name:modern] [features=math\mathsizesuffix]
\stoptypescript
\starttypescript [myfont]
\definetypeface [myfont][rm] [serif][sahel] [default]
%% NOTE 2
\definetypeface [myfont][mm] [math] [modern][default]
\stoptypescript
\setupbodyfont[myfont,rm]
%% NOTE 3
%\definedfont[Serif]
\def\Sample{{\lefttoright Salam} {\righttoleft سلام} }
\starttext
rm:\Sample
{\bf bf:\Sample}
{\it it:\Sample}
{\bi bi:\Sample}
%% NOTE 4
\definedfont[SahelReg]\Sample
\definedfont[Serif]\Sample
\stoptext
%%%%%%%%%%%%%%%%%%%%%%%%%
*Background*:
Commenting/uncommenting some of the lines produces three outputs, only one
of which seems correct to me.  I have attached the three.  Betas before
4/27 always produced the correct solution.
I am using a free open-source Farsi font, whose English glyphs come from
Open Sans font.  I am attaching the specific versions of the Farsi font to
reproduce the same results.
[https://github.com/rastikerdar/sahel-font]
[https://github.com/google/fonts/tree/master/apache/opensans]
*Explanation*:
Compiling the MWE above produces wrong-1.pdf in recent betas.  The serif
font has not been set up properly on the first line of output.  Instead the
default Latin Modern has been used, which looks different and misses the
Farsi glyphs.
Strangely there is nothing wrong with the second line of text, which shows
Serif and SahelReg fonts are both set up just fine.  See "NOTE 4" in the
MWE.
Replacing the line above "NOTE 1" with the line below it—i.e., if I remove
the fallbacks for definition of SahelReg—generates correct.pdf as output.
I get the same correct output if uncomment the line below "NOTE 3," which
should be a no-op in my opinion.  Notice that setting the fallback for
bold, italic and bold italic has not caused any issues.  It's only the
serif itself that's acting up weirdly.
Finally when I comment the math definition below "NOTE 2," I get
wrong-2.pdf as output.  Here everything seems okay except that the serif on
the first line—but strangely not on the second line—misses the Arabic
features: the letters are not joined.
I spent quite some time investigating the changes to the GitHub
repository on 4/27, to pinpoint what might have caused this issue, but my
efforts didn't go anywhere.  I hope you can spot the issue.
Thanks a lot for your attention!
—MHB

Re: [NTG-context] Typescript/fallbacks problem

Mohammad Hossein Bateni

Otared Kavian

Hans Hagen

Mohammad Hossein Bateni

Hans Hagen

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participants (3)