Aleph in ConTeXt: A Guide to the Perplexed

Aleph in ConTeXt: A Guide to the Perplexed

[Idris Samawi Hamid]

Aleph in ConTeXt: A Guide to the Perplexed (with apologies to Maimonides)

Dear gang,

I have been helping a number of ConTeXt users off-list with getting aleph  
running, along with right-to-left typesetting. The following notes are  
meant to help ConTeXt users who want to do RL typesetting, particularly  
Arabic script, get started with a minimal of fuss, as well as point to  
more advanced applications. This is much more complete than my last post  
(and hence the wiki as well)

I hope that someone can take this and add it to the wiki. I can then edit  
the wiki myself and improve the clarity, etc. Perhaps I will also write an  
augmentation to Hans' Aleph manual later.

I also have a support utlities package that could be placed on the wiki or  
somewhere else. Is there anyone who can upload it for me?

==============================================
I. 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.

a. In particular, the RL-LR code works excellently for the most part  
(minor bugs, easy to work around).

b. 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 eTeX201, 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.

II. Installing.

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

http://www.pragma-ade.com/context/install/mswincontext.zip

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

1. 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

C:\ConTeXt\tex\texmf-mswin\web2c\aleph

and one in

C:\ConTeXt\tex\texmf-mswin\web2c\pdfetex

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

2. Some configuration points:

a. Make sure you have the following line in

ConTeXt\tex\texmf-local\context\config\texexec.ini

set to "true", viz.,

set  UseEnginePath      to  true

b. In

texmf-local\web2c\texmf.cnf,
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

% tex=aleph output=dvipdfmx

at the beginning of every aleph file.

=================omarb.tex================
% tex=aleph output=dvipdfmx
\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
=========================================

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:

===============m-arabic-enc.tex================
% tex=aleph output=dvipdfmx
%\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

=========================================

III. 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\

1. 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:

C:\ConTeXt\tex\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

C:\ConTeXt\tex\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.

2. 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
    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.

6. Don't forget the rest of the accounting:

a) adding lines to a map file and pointing dvips/dvipdfm to it;
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

==============================================
[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
==============================================

3. For more info, there is also the (mostly cryptic) Omega manual:

http://omega.enstb.org/roadmap/doc-1.12.ps

Don't ask me why it's not in pdf-(

See also

http://omega.enstb.org/papers/tsukuba-arabic97.pdf

IV. Misc.

1. 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.

2. 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...

3. See also

http://www.dtek.chalmers.se/~d97ost/omega-example.html

V. To the future:

1. 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.

2. 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.

3. 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...

4. 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.

==============================================
==============================================

Ok, there is your (almost?) complete guide to getting going with aleph.  
Feel free to make suggestions for improving this document. I hope you all  
find it useful. Again, we need a volunteer to edit this for the wiki, and  
a place to upload the utilities.

All the Best
Idris

-- 
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Re: Aleph in ConTeXt: A Guide to the Perplexed

[Idris Samawi Hamid]

On Wed, 18 Jan 2006 15:47:51 -0700, Idris Samawi Hamid  
<ishamid@colostate.edu> wrote:

> I have been helping a number of ConTeXt users off-list with getting  
> aleph running, along with right-to-left typesetting. The following notes  
> are meant to help ConTeXt users who want to do RL typesetting,  
> particularly Arabic script, get started with a minimal of fuss, as well  
> as point to more advanced applications.

Note that Aleph is equally useful for Latin script, particularly any large  
character sets. See part IV.

Best
Idris
-- 
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Re: Aleph in ConTeXt: A Guide to the Perplexed

[Henning Hraban Ramm]

Am 2006-01-18 um 23:47 schrieb Idris Samawi Hamid:

> I hope that someone can take this and add it to the wiki. I can  
> then edit the wiki myself and improve the clarity, etc. Perhaps I  
> will also write an augmentation to Hans' Aleph manual later.

Ok, just working on it, see http://wiki.contextgarden.net/Aleph_Guide
(I didn't want to delete the "old" Aleph page yet.)

> I also have a support utlities package that could be placed on the  
> wiki or somewhere else. Is there anyone who can upload it for me?

Why don't you do it yourself?


Greetlings from Lake Constance!
Hraban
---
http://www.fiee.net/texnique/
http://contextgarden.net
http://www.cacert.org (I'm an assurer)

Re: Aleph in ConTeXt: A Guide to the Perplexed

[Idris Samawi Hamid]

On Wed, 18 Jan 2006 16:48:14 -0700, Henning Hraban Ramm <hraban@fiee.net>  
wrote:

>> I also have a support utlities package that could be placed on the wiki  
>> or somewhere else. Is there anyone who can upload it for me?
>
> Why don't you do it yourself?

Sure, just tell me how and where-)

Best
Idris
-- 
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Re: Aleph in ConTeXt: A Guide to the Perplexed

[Idris Samawi Hamid]

On Wed, 18 Jan 2006 16:48:14 -0700, Henning Hraban Ramm <hraban@fiee.net>  
wrote:

>> I hope that someone can take this and add it to the wiki. I can then  
>> edit the wiki myself and improve the clarity, etc. Perhaps I will also  
>> write an augmentation to Hans' Aleph manual later.
>
> Ok, just working on it, see http://wiki.contextgarden.net/Aleph_Guide
> (I didn't want to delete the "old" Aleph page yet.)

Thank you very much, Hraban!

Best
Idris

-- 
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Re: Aleph in ConTeXt: A Guide to the Perplexed

[Henning Hraban Ramm]

Am 2006-01-19 um 01:05 schrieb Idris Samawi Hamid:

>>> I also have a support utlities package that could be placed on  
>>> the wiki or somewhere else. Is there anyone who can upload it for  
>>> me?
>> Why don't you do it yourself?
> Sure, just tell me how and where-)

http://wiki.contextgarden.net/Special:Upload

And please fix the Arabic etc. text at http://wiki.contextgarden.net/ 
Aleph_Guide
it unfortunately got mixed up in the mail.

BTW: Is there a special reason that you use
\input m-gamma
instead of
\usemodule[gamma]
?


Greetlings from Lake Constance!
Hraban
---
http://www.fiee.net/texnique/
http://contextgarden.net
http://www.cacert.org (I'm an assurer)

Re: Aleph in ConTeXt: A Guide to the Perplexed

[Idris Samawi Hamid]

On Wed, 18 Jan 2006 17:57:36 -0700, Henning Hraban Ramm <hraban@fiee.net>  
wrote:

> Am 2006-01-19 um 01:05 schrieb Idris Samawi Hamid:
>
>>>> I also have a support utlities package that could be placed on the  
>>>> wiki or somewhere else. Is there anyone who can upload it for me?
>>> Why don't you do it yourself?
>> Sure, just tell me how and where-)
>
> http://wiki.contextgarden.net/Special:Upload
>
> And please fix the Arabic etc. text at http://wiki.contextgarden.net/ 
> Aleph_Guide
> it unfortunately got mixed up in the mail.

Ok, I did the utf-8 part. But you can't have 3 different encodings in the  
same web page, so iso and win are still in enriched ascii. But the file  
will still compile just fine.

>
> BTW: Is there a special reason that you use
> \input m-gamma
> instead of
> \usemodule[gamma]

Not at all, my mistake-)

Thnx for the wonderful job on the wiki!

Best
Idris

-- 
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/