Difference between revisions of "Aleph Guide"

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(Idris wrote this to the ML; first save)
 
(should be readable now. I'm tired.)
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by Prof. Idris Samawi Hamid
 
by Prof. Idris Samawi Hamid
 +
 +
< [[Aleph]] | [[Arabian and Hebrew]] >
  
 
==Introduction==
 
==Introduction==
  
Aleph is a typesetting engine derived from Omega and eTeX. Reasons for Aleph:
+
[[Aleph]] is a typesetting engine derived from Omega and eTeX. Reasons for Aleph:
  
 
# ConTeXt depends on the eTeX extensions, and even LaTeX now defaults to pdfeTeX.
 
# ConTeXt depends on the eTeX extensions, and even LaTeX now defaults to pdfeTeX.
Line 20: Line 22:
  
 
''Aleph'', inheriting from ''Omega'', provides many ready-to-go filters, using a Times Roman like font for Latin, Greek, and Cyrillic scripts.
 
''Aleph'', inheriting from ''Omega'', provides many ready-to-go filters, using a Times Roman like font for Latin, Greek, and Cyrillic scripts.
The ConTeXt module for this setup is called ''Gamma'' ([[source:m-gamma.tex]]); this is a port of the ''Lambda'' (i.e., LaTeX) style files to ConTeXt. The font typescript is called type-omg.
+
The ConTeXt module for this setup is called ''Gamma'' ([[source:m-gamma.tex|m-gamma.tex]]); this is a port of the ''Lambda'' (i.e., LaTeX) style files to ConTeXt. The font typescript is called type-omg.
  
 
==Installing==
 
==Installing==
Line 33: Line 35:
  
 
* Some configuration points:
 
* Some configuration points:
 +
** Make sure you have the following line in <tt>texexec.ini</tt> set to "true": "<code>set  UseEnginePath      to  true</code>"
 +
** In <tt>texmf-local\web2c\texmf.cnf</tt>, <tt>texmf-local\web2c\context.cnf</tt>, and <tt>texmf\web2c\texmf.cnf</tt>comment this line as follows
 +
<texcode>%extra_mem_bot.context    = 2000000</texcode>
 +
otherwise Aleph will crash under some conditions, like overfull boxes and the like...
 +
The [[XeTeX]] developer found the source to this bug, and a fix; hopefully Giuseppe will get to it :-))
  
a. Make sure you have the following line in
+
* Get the omega support files [http://www.ctan.org/get?fn=/systems/win32/fptex/0.7/package/omega.zip omega.zip] and [http://www.ctan.org/get?fn=/systems/win32/fptex/0.7/package/omegafonts.zip omegafonts.zip].
  
ConTeXt\tex\texmf-local\context\config\texexec.ini
+
* Get rid of two directories from omega.zip (not really necessary but if you want to be efficient): <tt>texmf/eomega</tt> and <tt>texmf/omega/encodings</tt>
  
set to "true", viz.,
+
* Put support files in <tt>texmf-local</tt>.
  
set  UseEnginePath      to  true
+
* Compile the Aleph format:
  
b. In
+
  mktexlsr
 
+
 
texmf-local\web2c\texmf.cnf,
+
  texexec --make en -tex=aleph
texmf-local\web2c\context.cnf, and
 
texmf\web2c\texmf.cnf,
 
 
 
comment this line as follows
 
 
 
%extra_mem_bot.context    = 2000000
 
 
 
otherwise aleph will crash under some conditions, like overfull boxes and the like... The XeTeX developer found the source to this bug, and a fix; hopefully Giuseppe will get to it-))
 
 
 
3. Get the omega support files:
 
 
 
http://www.ctan.org/get?fn=/systems/win32/fptex/0.7/package/omega.zip
 
http://www.ctan.org/get?fn=/systems/win32/fptex/0.7/package/omegafonts.zip
 
 
 
4. Get rid of the following directories from omega.zip (not really necessary but if u want to be
 
efficient):
 
 
 
texmf/eomega
 
texmf/omega/encodings
 
 
 
5. Put support files in texmf-local;
 
 
 
6. Compile the Aleph format:
 
 
 
mktexlsr
 
 
 
texexec --make en -tex=aleph
 
 
 
7. Here is a test file. Note the preamble
 
  
 +
* Here is a test file. Note the preamble
 +
<texcode>
 
% tex=aleph output=dvipdfmx
 
% tex=aleph output=dvipdfmx
 +
</texcode>
 +
at the beginning of every Aleph file.
  
at the beginning of every aleph file.
+
===omarb.tex===
 
 
'''omarb.tex'''
 
 
<texcode>
 
<texcode>
 
% tex=aleph output=dvipdfmx
 
% tex=aleph output=dvipdfmx
\input m-gamma.tex
+
\usemodule[gamma]  % or \input m-gamma.tex
 
\input type-omg.tex
 
\input type-omg.tex
  
Line 156: Line 136:
 
</texcode>
 
</texcode>
  
8. For Arabic script you will probably want to use an encoding that supports direct Arabic-script editing. There are three: utf-8, iso-8859-6 (apple-unix), and cp1256 (micro$oft). We can define the following, using ConTeXt macros for managing filter sequences. Maybe I will add these to m-gamma and ask Hans to distribute. In the meantime, here are some definitions, samples of all three encodings, and an example of mixed lr-rl text:
+
* For Arabic script you will probably want to use an [[Encodings_and_Regimes|encoding]] that supports direct Arabic-script editing. There are three: utf-8, iso-8859-6 (Apple/Unix), and cp1256 (Microsoft). We can define the following, using ConTeXt macros for managing filter sequences. Maybe I will add these to [[source:m-gamma-tex|m-gamma]] and ask Hans to distribute. In the meantime, here are some definitions, samples of all three encodings, and an example of mixed lr-rl text:
 +
 
 +
{{todo|the Unicode characters got mixed up in the mail, please fix it, Idris!}}
  
'''m-arabic-enc.tex'''
+
===m-arabic-enc.tex===
 
<texcode>
 
<texcode>
 
% tex=aleph output=dvipdfmx
 
% tex=aleph output=dvipdfmx
%\input m-gamma.tex
+
%\usemodule[gamma] \input m-gamma.tex
\input type-omg.tex
+
%\input type-omg.tex
 
\usetypescriptfile[type-omg]
 
\usetypescriptfile[type-omg]
 
\usetypescript[OmegaArab]
 
\usetypescript[OmegaArab]
Line 305: Line 287:
 
==Going beyond==
 
==Going beyond==
  
The last example shows how to make and apply your own filter sequences beyond the basic Gamma module. To go further u need to learn some low-level business. You will also need some working utilities. I have put together a windows package that you can unzip to C:\ConTeXt. These utilities do work, but they are cobbled together from old fpTeX and MiKTeX versions. just place the tree in C:\ConTeXt\
+
The last example shows how to make and apply your own filter sequences beyond the basic Gamma module. To go further you need to learn some low-level business. You will also need some working utilities. I have put together a windows package that you can unzip to <tt>C:\ConTeXt</tt>. These utilities do work, but they are cobbled together from old fpTeX and MiKTeX versions.
 +
 
 +
{{todo|store the utilities on the wiki server and link to them}}
  
1. Example: If you want to get the final Persian kaaf instead of the default Arabic one:
+
===Example: If you want to get the final Persian kaaf instead of the default Arabic one===
  
 
Check to see if your glyph is in the Arabic font. The Arabic font is made of 6 raw fonts: 3 regular and three bold:
 
Check to see if your glyph is in the Arabic font. The Arabic font is made of 6 raw fonts: 3 regular and three bold:
 
+
  texmf-local/fonts/type1/public/omega
C:\ConTeXt\tex\texmf-local\fonts\type1\public\omega
+
  omsea1, omsea1b, ... omsea3b
 
 
omsea1, omsea1b,...omsea3b
 
  
 
Using a font viewer or editor you will find the Persian final kaaf in omsea2, named kafswashfin.
 
Using a font viewer or editor you will find the Persian final kaaf in omsea2, named kafswashfin.
  
 
Now go to
 
Now go to
 
+
<tt>texmf-local/omega/lambda/misc</tt>
C:\ConTeXt\tex\texmf-local\omega\lambda\misc
 
 
 
 
and open
 
and open
 
+
<tt>omarab.cfg</tt>
omarab.cfg
 
 
 
 
you will find a line
 
you will find a line
  
04AA N kafswashfin
+
  04AA N kafswashfin
  
 
This means that the 044A is the virtual font position for kafswashfin. Open cuni2oar.otp and add the following at line 263:
 
This means that the 044A is the virtual font position for kafswashfin. Open cuni2oar.otp and add the following at line 263:
  
%@"E343 => @"04AA;
+
  %@"E343 => @"04AA;
  
 
Following this line you should see
 
Following this line you should see
  
% remaining Arabic glyphs
+
  % remaining Arabic glyphs
@"E000-@"E3FF => #(\1 - @"DF00);
+
  @"E000-@"E3FF => #(\1 - @"DF00);
  
 
Basically, in uni2cuni.otp final-kaaf gets mapped to E343. In the font, we want it mapped to kafswashfin, so we did that. Now recompile the otp:
 
Basically, in uni2cuni.otp final-kaaf gets mapped to E343. In the font, we want it mapped to kafswashfin, so we did that. Now recompile the otp:
  
otp2ocp cuni2oar
+
  otp2ocp cuni2oar
  
 
Now you will get kafswashfin for the final kaaf.
 
Now you will get kafswashfin for the final kaaf.
  
2. Want new fonts (Arabic or Latin). Here are the instructions:
+
===Want new fonts (Arabic or Latin). Here are the instructions===
 
 
1. Read the following two papers carefully again and again; they are
 
  your friends:-)
 
 
 
http://omega.enstb.org/papers/tsukuba-methods97.pdf
 
http://omega.enstb.org/papers/ridt-omega98.pdf
 
 
 
2. Make a pfb file containing the glyphs you need, or use an existing font
 
 
 
3.Make a cfg file a la texmf\omega\lambda\misc\omlgc.cfg Make sure u list your glyph
 
  positions in hexadecimal notation.
 
 
 
5. Get the following from an old TeXLive distro: \support\makeovp.zip,
 
  containing makeovp.pl.  There is a SH file with a sample of its use
 
  using omlgc.
 
  
4. Following are instructions for cooking omarab.ovf. You want your
+
* Read the following two papers carefully again and again; they are your friends :-)
  own ovf, say, omlgcch.ovf (<ch> for <cherokee>). Generate an afm
+
** [http://omega.enstb.org/papers/tsukuba-methods97.pdf tsukuba-methods]
  file for your private glyph pfb/pfa plus the afm files that are
+
** [http://omega.enstb.org/papers/ridt-omega98.pdf ridt-omega]
  listed in the SH file (base files for omlgc found in
+
* Make a pfb file containing the glyphs you need, or use an existing font
  \texmf\fonts\afm\public\omega )
+
* Make a cfg file a la <tt>texmf\omega\lambda\misc\omlgc.cfg</tt>. Make sure you list your glyph positions in hexadecimal notation.
 +
* Get the following from an old TeXLive distro: <tt>\support\makeovp.zip</tt>, containing <tt>makeovp.pl</tt>. There is a SH file with a sample of its use using omlgc.
 +
* Following are instructions for cooking omarab.ovf.
 +
** You want your own ovf, say, omlgcch.ovf (<ch> for <cherokee>).
 +
** Generate an afm file for your private glyph pfb/pfa plus the afm files that are listed in the SH file (base files for omlgc found in <tt>\texmf\fonts\afm\public\omega</tt>)
 +
** Using the instructions below and the SH file ('''ignore''' the kernings.afm file!) you can figure out how to make your own ovp and ovf.
 +
** Before making the ovf file, examine the ovp file created, especially the first few lines, to see how the font-metric info from the afm's are concatenated. Very instructive.
 +
* Don't forget the rest of the accounting:
 +
** adding lines to a map file and pointing dvips/dvipdfm to it;
 +
** create a typescript file;
 +
** edit your otp's. If you get stuck be sure to read [http://omega.enstb.org/papers/tsukuba-arabic97.pdf tsukuba-arabic]
  
Using the instructions below and the SH file (IGNORE the kernings.afm
+
====How to cook omarab.ovf====
file!) you can figure out how to make your own ovp and ovf. Before
+
Ingredients: omarab.cfg, omseco.afm, omsea1.afm, omsea2.afm, omsea3.afm
making the ovf file, examine the ovp file created, especially the
 
first few lines, to see how the font-metric info from the afm's are
 
concatenated. Very instructive.
 
  
6. Don't forget the rest of the accounting:
+
  #perl makeovp.pl omarab.cfg omseco.afm omsea1.afm omsea2.afm omsea3.afm omarab.ovp
 +
  #pltotf omseco.pl omseco.tfm
 +
  #pltotf omsea1.pl omsea1.tfm
 +
  #pltotf omsea2.pl omsea2.tfm
 +
  #pltotf omsea3.pl omsea3.tfm
 +
  #ovp2ovf omarab.ovp omarab.ovf omarab.ofm
  
a) adding lines to a map file and pointing dvips/dvipdfm to it;
+
If the last line does not work, try
b) create a typescript file;
 
c) edit your otp's. If u get stuck be sure to read
 
  
http://omega.enstb.org/papers/tsukuba-arabic97.pdf
+
  #ovp2ovf omarab.ovp omarab.ovf omarab.tfm
  
<code>
+
rename omarab.tfm to omarab.ofm --> ofm directory
[How to cook omarab.ovf:]
 
[Ingredients: omarab.cfg, omseco.afm, omsea1.afm, omsea2.afm, omsea3.afm]
 
  
#perl makeovp.pl omarab.cfg omseco.afm omsea1.afm omsea2.afm omsea3.afm omarab.ovp
+
====How to distill omarab.ovp from omarab.ovf:====
#pltotf omseco.pl omseco.tfm
+
Use a different directory or a different name for the output ovp so that omarab.ovp created above is not overwritten.
#pltotf omsea1.pl omsea1.tfm
 
#pltotf omsea2.pl omsea2.tfm
 
#pltotf omsea3.pl omsea3.tfm
 
#ovp2ovf omarab.ovp omarab.ovf omarab.ofm
 
  
[If the last line does not work, try
+
get omarab.ofm & rename to omarab.tfm
#ovp2ovf omarab.ovp omarab.ovf omarab.tfm
 
rename omarab.tfm to omarab.ofm ===> ofm directory]
 
  
-----------------------------
+
  #ovf2ovp omarab.ovf omarab.tfm omarab.ovp
[How to distill omarab.ovp from omarab.ovf:]
 
  
[Use a different directory or a different name for
+
====How to cook omarabb.ovf====
the output ovp so that omarab.ovp created above is not overwritten]
+
Ingredients: omarab.cfg, omsecob.afm, omsea1b.afm, omsea2b.afm, omsea3b.afm
  
[get omarab.ofm & rename to omarab.tfm]
+
  #perl makeovp.pl omarab.cfg omsecob.afm omsea1b.afm omsea2b.afm omsea3b.afm omarabb.ovp
 +
  #pltotf omsecob.pl omsecob.tfm
 +
  #pltotf omsea1b.pl omsea1b.tfm
 +
  #pltotf omsea2b.pl omsea2b.tfm
 +
  #pltotf omsea3b.pl omsea3b.tfm
 +
  #ovp2ovf omarabb.ovp omarabb.ovf omarabb.ofm
  
#ovf2ovp omarab.ovf omarab.tfm omarab.ovp
 
=========================================================
 
[How to cook omarabb.ovf:]
 
[Ingredients: omarab.cfg, omsecob.afm, omsea1b.afm, omsea2b.afm, omsea3b.afm]
 
  
#perl makeovp.pl omarab.cfg omsecob.afm omsea1b.afm omsea2b.afm omsea3b.afm omarabb.ovp
+
If the last line does not work, try
#pltotf omsecob.pl omsecob.tfm
 
#pltotf omsea1b.pl omsea1b.tfm
 
#pltotf omsea2b.pl omsea2b.tfm
 
#pltotf omsea3b.pl omsea3b.tfm
 
#ovp2ovf omarabb.ovp omarabb.ovf omarabb.ofm
 
  
[If the last line does not work, try
+
  #ovp2ovf omarabb.ovp omarabb.ovf omarabb.tfm
#ovp2ovf omarabb.ovp omarabb.ovf omarabb.tfm
 
rename omarab.tfm to omarab.ofm ===> ofm directory]
 
-----------------------------
 
[How to distill omarabb.ovp from omarabb.ovf:]
 
  
[Use a different directory or a different name for
+
rename omarab.tfm to omarab.ofm --> ofm directory
the output ovp so that omarabb.ovp created above is not overwritten]
 
  
[get omarab.ofm & rename to omarab.tfm]
+
====How to distill omarabb.ovp from omarabb.ovf====
 +
Use a different directory or a different name for the output ovp so that omarabb.ovp created above is not overwritten
  
#ovf2ovp omarabb.ovf omarabb.tfm omarabb.ovp
+
get omarab.ofm & rename to omarab.tfm
</code>
 
  
3. For more info, there is also the (mostly cryptic) Omega manual [http://omega.enstb.org/roadmap/doc-1.12.ps in PS-Format]. Don't ask me why it's not in PDF. <tt>:-(</tt>
+
  #ovf2ovp omarabb.ovf omarabb.tfm omarabb.ovp
  
See also http://omega.enstb.org/papers/tsukuba-arabic97.pdf
+
* For more info, there is also the (mostly cryptic) Omega manual [http://omega.enstb.org/roadmap/doc-1.12.ps in PS-Format]. Don't ask me why it's not in PDF. <tt>:-(</tt>
 +
See also [http://omega.enstb.org/papers/tsukuba-arabic97.pdf tsukuba-arabic]
  
 
==Miscellaneous==
 
==Miscellaneous==
  
# Some people have gotten large OpenType fonts to work in Aleph/Omega. Probably they used FontForge to convert to CFF-enriched type1. FF can produce ofm files (large tfms) so that's a help too.
+
* Some people have gotten large OpenType fonts to work in Aleph/Omega. Probably they used [http://fontforge.sourceforge.net FontForge] to convert to CFF-enriched type1. FF can produce ofm files (large tfms) so that's a help too.
# Me, I'm working on an advanced Arabic-script typesetting system that really pushes Aleph to the max. At present I don't actually use m-gamma, etc, but my own macros. I really hope to release something this year...
+
* Me, I'm working on an advanced Arabic-script typesetting system that really pushes Aleph to the max. At present I don't actually use [[source:m-gamma.tex|m-gamma]], etc, but my own macros. I really hope to release something this year...
#See also http://www.dtek.chalmers.se/~d97ost/omega-example.html
+
* See also [http://www.dtek.chalmers.se/~d97ost/omega-example.html Omega example]
  
 
==To the future==
 
==To the future==
  
# The otp mechanism does not seem well suited to support, e.g., opentype GPOS tables, important for really advanced Arabic (though GDEF and GSUB should work fine with the present mechanism for most purposes). We need a better model for horizontal and vertical glyph substitutions.
+
* The otp mechanism does not seem well suited to support, e.g., opentype GPOS tables, important for really advanced Arabic (though GDEF and GSUB should work fine with the present mechanism for most purposes). We need a better model for horizontal and vertical glyph substitutions.
# The low-level filtersequence mechanism needs to abstract language processing from font mapping. Right now both are hardwired into a single sequence, so setting up more than one font for a single language is more of a pain than it should be.
+
* The low-level filtersequence mechanism needs to abstract language processing from font mapping. Right now both are hardwired into a single sequence, so setting up more than one font for a single language is more of a pain than it should be.
# The otp language is a bit cryptic. Hans has suggested switching otp's to a new language (like lua or io) but I don't know how hard that will be...
+
* The otp language is a bit cryptic. Hans has suggested switching otp's to a new language (like lua or io) but I don't know how hard that will be...
# One very important feature which may work better at the primitive/engine level by extending the pdfetex engine:
+
* One very important feature which may work better at the primitive/engine level by extending the pdfeTeX engine: glyph substitution that depends on the paragraph. For example: In traditional Arabic typography, one way to compensate for "underfull" paragraphs is to substitute a "swash" version of a letter. Another way is by stretching the cursive tie between joining characters (which is already implemented in my own Arabic system). Combined with HZ we can get some pretty interesting high-level options, effects, etc. that the user can choose etc.
glyph substitution that depends on the paragraph. For example: In traditional Arabic typography, one way to
 
compensate for "underfull" paragraphs is to substitute a "swash" version of a letter. Another way is by
 
stretching the cursive tie between joining characters (which is already implemented in my own Arabic
 
system). Combined with HZ we can get some pretty interesting high-level options, effects, etc. that the user can choose etc.
 

Revision as of 00:41, 19 January 2006

Aleph in ConTeXt: A Guide to the Perplexed

(with apologies to Maimonides)

by Prof. Idris Samawi Hamid

< Aleph | Arabian and Hebrew >

Introduction

Aleph is a typesetting engine derived from Omega and eTeX. Reasons for Aleph:

  1. ConTeXt depends on the eTeX extensions, and even LaTeX now defaults to pdfeTeX.
  2. Omega provides a nice foundation for multilingual typesetting with large (>256) character sets, including large virtual fonts, but a stable, dependable version has not been a priority with its developers.
    1. In particular, the RL-LR code works excellently for the most part (minor bugs, easy to work around).
    2. Omega 1.15 was the last relatively stable bugfix version, as far as usability is concerned.
  3. Some users need a dependable LR-RL TeX engine now.

Aleph weds Omega 1.15 and eTeX 201, removes some extraneous stuff, and fixes a few bugs. I use it for production purposes. It uses dvipdfmx for pdf production, and can take advantage of most of ConTeXt's capabilities. Giuseppe Bilotta has done virtually all of the development work.

In addition to large character sets, Aleph inherits the filter sequence mechanism for script processing (extension ocp, compile from text-editable otp). So you can script whatever input encoding you like to whatever output font encoding you like. It is mechanism powerful enough to do contextual analysis of Arabic script for example, but not powerful enough for things like vertical glyph positioning for cursive scripts and the like.

Aleph, inheriting from Omega, provides many ready-to-go filters, using a Times Roman like font for Latin, Greek, and Cyrillic scripts. The ConTeXt module for this setup is called Gamma (m-gamma.tex); this is a port of the Lambda (i.e., LaTeX) style files to ConTeXt. The font typescript is called type-omg.

Installing

This install is based on the stand-alone ConTeXt for Win32 package.

Users of MiKTeX and other OS's will need to adjust the following instructions to their own setups.

  • Make sure you have a very recent version of ConTeXt that supports the engine path mechanism. This mechanism allows texexec to manage two, e.g., cont-en.fmt files at once, one in texmf/web2c/aleph and one in texmf/web2c/pdfetex

How recent, you ask? Just be safe and get the latest :-)

  • Some configuration points:
    • Make sure you have the following line in texexec.ini set to "true": "set UseEnginePath to true"
    • In texmf-local\web2c\texmf.cnf, texmf-local\web2c\context.cnf, and texmf\web2c\texmf.cnfcomment this line as follows
%extra_mem_bot.context    = 2000000

otherwise Aleph will crash under some conditions, like overfull boxes and the like... The XeTeX developer found the source to this bug, and a fix; hopefully Giuseppe will get to it :-))

  • Get rid of two directories from omega.zip (not really necessary but if you want to be efficient): texmf/eomega and texmf/omega/encodings
  • Put support files in texmf-local.
  • Compile the Aleph format:
 mktexlsr
 
 texexec --make en -tex=aleph
  • Here is a test file. Note the preamble
% tex=aleph output=dvipdfmx

at the beginning of every Aleph file.

omarb.tex

% tex=aleph output=dvipdfmx
\usemodule[gamma]  % or \input m-gamma.tex
\input type-omg.tex

\setupbodyfont[omlgc,12pt]

\starttext

\startlatin

This is a test

\bf This is a test

\stoplatin

\startgreek

A B G D a b g d

{\bf A B G D a b g d}

\stopgreek

\startarab

`rby:

A b t th j H kh

{\bf \ A b t th j H kh}

fArsy:

A b p t th j ch H kh

{\bf A b p t th j ch H kh}

\starturdu

ArdU:

A b p t 't th j ch H kh

{\bf A b p t 't th j ch H kh}

\stopurdu

\blank

\tfc

`rby:

bsm ALLah Al-rrHmn Al-rrHym

fArsy:

bh nAm khdAwnd b-kh-sh-nde mhrbAn

\starturdu

\tfc

ArdU:

ALLah kE nAm sE jw rHmAn w rHym hE

\stopurdu

\stoparab

\stoptext
  • For Arabic script you will probably want to use an encoding that supports direct Arabic-script editing. There are three: utf-8, iso-8859-6 (Apple/Unix), and cp1256 (Microsoft). We can define the following, using ConTeXt macros for managing filter sequences. Maybe I will add these to m-gamma and ask Hans to distribute. In the meantime, here are some definitions, samples of all three encodings, and an example of mixed lr-rl text:

TODO: the Unicode characters got mixed up in the mail, please fix it, Idris! (See: To-Do List)


m-arabic-enc.tex

% tex=aleph output=dvipdfmx
%\usemodule[gamma] \input m-gamma.tex
%\input type-omg.tex
\usetypescriptfile[type-omg]
\usetypescript[OmegaArab]

\hoffset=0pt

%% Individual Filters

% Input filters (from what you type)

\definefiltersynonym [UTF8]      [inutf8]
\definefiltersynonym [ISO8859-6] [in88596]
\definefiltersynonym [CP1256]    [incp1256]

% Contextual filter

\definefiltersynonym [UniCUni]            [uni2cuni]

% Output filters (font mapping)

\definefiltersynonym [CUniArab]           [cuni2oar]

%% Filter Sequences

\definefiltersequence
  [UTFArabic]
  [UTF8,UniCUni,CUniArab]

\definefiltersequence
  [ISOArabic]
  [ISO8859-6,UniCUni,CUniArab]

\definefiltersequence
  [WINArabic]
  [CP1256,UniCUni,CUniArab]

% For inner paragraph control within an LR paragraph

\def\ArabicTextUTF#1{{\textdir TRT\usefiltersequence[UTFArabic]%
                     \switchtobodyfont[omarb]#1\textdir TLT
                     \clearocplists}}

\def\ArabicTextISO#1{{\textdir TRT\usefiltersequence[ISOArabic]%
                     \switchtobodyfont[omarb]#1\textdir TLT
                     \clearocplists}}

\def\ArabicTextWIN#1{{\textdir TRT\usefiltersequence[WINFArabic]%
                     \switchtobodyfont[omarb]#1\textdir TLT
                     \clearocplists}}

% For global Arabic script

\def\ArabicDirGlobal{%
\pagedir TRT\bodydir TRT\textdir TRT\pardir TRT %
\hoffset=-8.88cm} % compensate for a bug in \bodydir TRT

\def\ArabicUTF{\ArabicDirGlobal\usefiltersequence[UTFArabic]
                \switchtobodyfont[omarb]}

\def\ArabicISO{\ArabicDirGlobal\usefiltersequence[ISOArabic]
                \switchtobodyfont[omarb]}

\def\ArabicWIN{\ArabicDirGlobal\usefiltersequence[WINArabic]
                \switchtobodyfont[omarb]}

% For separate Arabic-script paragraphs

\def\ArabicDirPar{\textdir TRT\pardir TRT}

\definestartstop
  [arabutf]
  [commands=%
    {\usefiltersequence[UTFArabic]
     \switchtobodyfont[omarb]%
     \ArabicDirPar}]

\definestartstop
  [arabiso]
  [commands=%
    {\usefiltersequence[ISOArabic]
     \switchtobodyfont[omarb]%
     \ArabicDirPar}]

\definestartstop
  [arabwin]
  [commands=%
    {\usefiltersequence[WINArabic]
     \switchtobodyfont[omarb]%
     \ArabicDirPar}]

\showframe[text]

\starttext

\startarabutf

اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ وَ
آلِ مُحَمَّدٍ وَ ارْزُقْنِي
الْيَقِينَ وَ حُسْنَ الظَّنِّ بِكَ
وَ أَثْبِتْ رَجَاءَكَ فِي قَلْبِي
وَ اقْطَعْ رَجَائِي عَمَّنْ سِوَاكَ
حَتَّى لَا أَرْجُوَ غَيْرَكَ وَ لَا
أَثِقَ إِلَّا بِك‏

\stoparabutf

\blank

\startarabiso

Çääñîçïåñî Õîäñð Ùîäîé åïÍîåñîÏí èî Âäð åïÍîåñîÏí èî ÇÑòÒïâòæðê
Çäòêîâðêæî èî ÍïÓòæî ÇäØñîæñð Èðãî èî ÃîËòÈðÊò ÑîÌîÇÁîãî áðê
âîäòÈðê èî Çâò×îÙò ÑîÌîÇÆðê Ùîåñîæò ÓðèîÇãî ÍîÊñîé äîÇ ÃîÑòÌïèî
ÚîêòÑîãî èî äîÇ ÃîËðâî ÅðäñîÇ Èðã

\stoparabiso

\blank

\startarabwin

Çááøóåõãøó Õóáøö Úóáóì ãõÍóãøóÏò æó Âáö ãõÍóãøóÏò æó ÇÑúÒõÞúäöí
ÇáúíóÞöíäó æó ÍõÓúäó ÇáÙøóäøö Èößó æó ÃóËúÈöÊú ÑóÌóÇÁóßó Ýöí
ÞóáúÈöí æó ÇÞúØóÚú ÑóÌóÇÆöí Úóãøóäú ÓöæóÇßó ÍóÊøóì áóÇ ÃóÑúÌõæó
ÛóíúÑóßó æó áóÇ ÃóËöÞó ÅöáøóÇ Èößþ

\stoparabwin

\blank

Here is some mixed {\em Arabic-} (\ArabicTextUTF{عربي}) and
Latin-script. As you can see, Aleph does a very good job mixing
{\em LR} (\ArabicTextUTF{يسار-يمين}) and {\em RL}
(\ArabicTextUTF{يمين-يسار}) texts. \ArabicTextUTF{و
هنا جملة منقطعة في وسط قرينة
لاتينية}. Aleph even does a great job breaking Arabic
phrases across lines.

\stoptext

Going beyond

The last example shows how to make and apply your own filter sequences beyond the basic Gamma module. To go further you need to learn some low-level business. You will also need some working utilities. I have put together a windows package that you can unzip to C:\ConTeXt. These utilities do work, but they are cobbled together from old fpTeX and MiKTeX versions.


TODO: store the utilities on the wiki server and link to them (See: To-Do List)


Example: If you want to get the final Persian kaaf instead of the default Arabic one

Check to see if your glyph is in the Arabic font. The Arabic font is made of 6 raw fonts: 3 regular and three bold:

 texmf-local/fonts/type1/public/omega
 omsea1, omsea1b, ... omsea3b

Using a font viewer or editor you will find the Persian final kaaf in omsea2, named kafswashfin.

Now go to texmf-local/omega/lambda/misc and open omarab.cfg you will find a line

 04AA N kafswashfin

This means that the 044A is the virtual font position for kafswashfin. Open cuni2oar.otp and add the following at line 263:

 %@"E343 => @"04AA;

Following this line you should see

 % remaining Arabic glyphs
 @"E000-@"E3FF => #(\1 - @"DF00);

Basically, in uni2cuni.otp final-kaaf gets mapped to E343. In the font, we want it mapped to kafswashfin, so we did that. Now recompile the otp:

 otp2ocp cuni2oar

Now you will get kafswashfin for the final kaaf.

Want new fonts (Arabic or Latin). Here are the instructions

  • Read the following two papers carefully again and again; they are your friends :-)
  • Make a pfb file containing the glyphs you need, or use an existing font
  • Make a cfg file a la texmf\omega\lambda\misc\omlgc.cfg. Make sure you list your glyph positions in hexadecimal notation.
  • Get the following from an old TeXLive distro: \support\makeovp.zip, containing makeovp.pl. There is a SH file with a sample of its use using omlgc.
  • Following are instructions for cooking omarab.ovf.
    • You want your own ovf, say, omlgcch.ovf (<ch> for <cherokee>).
    • Generate an afm file for your private glyph pfb/pfa plus the afm files that are listed in the SH file (base files for omlgc found in \texmf\fonts\afm\public\omega)
    • Using the instructions below and the SH file (ignore the kernings.afm file!) you can figure out how to make your own ovp and ovf.
    • Before making the ovf file, examine the ovp file created, especially the first few lines, to see how the font-metric info from the afm's are concatenated. Very instructive.
  • Don't forget the rest of the accounting:
    • adding lines to a map file and pointing dvips/dvipdfm to it;
    • create a typescript file;
    • edit your otp's. If you get stuck be sure to read tsukuba-arabic

How to cook omarab.ovf

Ingredients: omarab.cfg, omseco.afm, omsea1.afm, omsea2.afm, omsea3.afm

 #perl makeovp.pl omarab.cfg omseco.afm omsea1.afm omsea2.afm omsea3.afm omarab.ovp
 #pltotf omseco.pl omseco.tfm
 #pltotf omsea1.pl omsea1.tfm
 #pltotf omsea2.pl omsea2.tfm
 #pltotf omsea3.pl omsea3.tfm
 #ovp2ovf omarab.ovp omarab.ovf omarab.ofm

If the last line does not work, try

 #ovp2ovf omarab.ovp omarab.ovf omarab.tfm

rename omarab.tfm to omarab.ofm --> ofm directory

How to distill omarab.ovp from omarab.ovf:

Use a different directory or a different name for the output ovp so that omarab.ovp created above is not overwritten.

get omarab.ofm & rename to omarab.tfm

 #ovf2ovp omarab.ovf omarab.tfm omarab.ovp

How to cook omarabb.ovf

Ingredients: omarab.cfg, omsecob.afm, omsea1b.afm, omsea2b.afm, omsea3b.afm

 #perl makeovp.pl omarab.cfg omsecob.afm omsea1b.afm omsea2b.afm omsea3b.afm omarabb.ovp
 #pltotf omsecob.pl omsecob.tfm
 #pltotf omsea1b.pl omsea1b.tfm
 #pltotf omsea2b.pl omsea2b.tfm
 #pltotf omsea3b.pl omsea3b.tfm
 #ovp2ovf omarabb.ovp omarabb.ovf omarabb.ofm


If the last line does not work, try

 #ovp2ovf omarabb.ovp omarabb.ovf omarabb.tfm

rename omarab.tfm to omarab.ofm --> ofm directory

How to distill omarabb.ovp from omarabb.ovf

Use a different directory or a different name for the output ovp so that omarabb.ovp created above is not overwritten

get omarab.ofm & rename to omarab.tfm

 #ovf2ovp omarabb.ovf omarabb.tfm omarabb.ovp
  • For more info, there is also the (mostly cryptic) Omega manual in PS-Format. Don't ask me why it's not in PDF. :-(

See also tsukuba-arabic

Miscellaneous

  • Some people have gotten large OpenType fonts to work in Aleph/Omega. Probably they used FontForge to convert to CFF-enriched type1. FF can produce ofm files (large tfms) so that's a help too.
  • Me, I'm working on an advanced Arabic-script typesetting system that really pushes Aleph to the max. At present I don't actually use m-gamma, etc, but my own macros. I really hope to release something this year...
  • See also Omega example

To the future

  • The otp mechanism does not seem well suited to support, e.g., opentype GPOS tables, important for really advanced Arabic (though GDEF and GSUB should work fine with the present mechanism for most purposes). We need a better model for horizontal and vertical glyph substitutions.
  • The low-level filtersequence mechanism needs to abstract language processing from font mapping. Right now both are hardwired into a single sequence, so setting up more than one font for a single language is more of a pain than it should be.
  • The otp language is a bit cryptic. Hans has suggested switching otp's to a new language (like lua or io) but I don't know how hard that will be...
  • One very important feature which may work better at the primitive/engine level by extending the pdfeTeX engine: glyph substitution that depends on the paragraph. For example: In traditional Arabic typography, one way to compensate for "underfull" paragraphs is to substitute a "swash" version of a letter. Another way is by stretching the cursive tie between joining characters (which is already implemented in my own Arabic system). Combined with HZ we can get some pretty interesting high-level options, effects, etc. that the user can choose etc.