Arabic weeks (months, actually)
During the past months I was a bit involved in a project which I consider to be the most refreshing take on layout and font technology that I have seen in years, DecoType's ACE. ACE is a layout engine for typesetting Arabic. It is available for use in InDesign ME as a plug-in called Tasmeem. But how to produce fonts for ACE?
Brief introduction
To understand ACE, one needs to know that it consists of three aspects:
• ACE: Typesetting technology – layout engine and font format – dedicated to the Arabic script. (The acronym ACE stands for 'Arabic Calligraphic Engine'. 'Calligraphic' is quite an unhappy term since ACE is a typographic engine of course.)
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• ACE fonts: Fonts produced for this layout engine. These are OpenType fonts that hold special tables qualifying them as ACE fonts.
• Tasmeem: A plug-in for InDesign ME which makes the ACE layout engine available in InDesign.
Maybe the core idea behind ACE, as typesetting technology, is that one letter can consist of more than just one glyph where 'glyph' is to be understood as a module. Let me translate what ACE does with Arabic into Latin – think of composing an 'n' of a stem glyph plus a shoulder glyph:
The DecoType team calls such a glyph or module a 'skeleton'. Given this modular approach, a relatively small number of glyphs (mind: 'glyph' here means 'part of a character') allows to cover a large number of characters and result in a connected and almost writing-like text image – provided that a given typeface requires this connected appearance.
(As a consequence of this, ACE does not know nor need ligatures. Since a glyph is a mere module and characters may consist of more than one glyph, and since there can be many different versions of a glyph, it is easy to imagine that depending on the context, the layout engine will choose glyph versions that – in a connected typeface – result in nice combinations. So ACE does not know ligatures but only ligation, or 'fusion' as Thomas Milo says.)
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Designing and producing an ACE font
DecoType made it rather easy for designers to create ACE fonts by providing template fonts for FontLab Studio. The production process itself is divided into two steps: design and calibration.
In a first step, the type designer receives a Design Template, to design the typeface and fill the glyph cells with outlines – always being aware that glyphs are modules rather than entire characters. The actual glyph set which is to be designed is rather small:
Green cells are glyphs, yellow cells are attachments like dots and vowels. In addition, there are some white cells (a few more than those shown above) covering numerals, punctuation marks, and possibly glyphs for other scripts than just Arabic.
Once the design work is completely finished, it is time for calibration work. For this, DecoType converts the Design Template into a Calibration Template. This contains a couple of additional cells, each of them filled with components. These cells are colorized so the type designer knows which ones to deal with next. Here is one block of calibration cells which serves to position the four-dot attachment:
The calibration work consists of moving components around, first, to make sure that glyphs connect nicely, and second, to define ideal positions for attachments. Initially, attachments sit to the left, glyphs to the right [see left image], and it is on the designer to move them to their proper place [see right image]:
This is done with four-dot, vowels and others. (The four-dot more or less serves as a placeholder for other dots for the simple reason that it is the biggest one.) The templates, in combination with a few scripts, make this a pretty straightforward procedure.
Once the calibration work is finished, DecoType will generate an ACE font from the Calibration Template.
Remarks
The advantage of these templates is that the type designer does not need to make up his mind about glyph sets, Unicode codepoints – not even features. All this has been done be the DecoType team already. The Calibration Template will serve as the source for generating a fully Unicode-compliant ACE font (which addresses a variety of Arabic-script based languages) and also provides the layout engine with alternate glyphs to choose from, based on the context.
Moreover: It is not necessary to spend much time on defining sidebearings, just set them to zero. (With connecting glyphs, there is a fixed negative overlap amount to the left.) ACE will do the spacing. Nor is it necessary to fumble out solutions for avoiding collisions among attachments, or between attachments and glyphs. ACE will take care.
One more remark on ACE technology
Reading an old Typophile discussion about OpenType and ACE again, I realize that a few more words about ACE technology are necessary.
ACE layout technology is not the same as OpenType layout technology. Each of them follows a different logic. For OpenType-trained minds like my own, ACE does things that seem highly 'complex' (choosing from alternate shapes or positioning attachments) and would require a lot of efforts to realize in OpenType – and slow down such an OpenType font's performance. But unlike OpenType, ACE achieves 'complex'-looking effects by 'simple' means. ACE fonts do more than OpenType fonts, and more efficiently.
Rather than making this note even longer, I just refer to
my comment to the above-mentioned Typophile discussion.
Further reading
Background articles:
Thomas Milo's
Arabic Script and Typography, published in John Berry's
Language Culture Type (Graphis Press 2002).
Thomas Milo's Creating Solutions for Arabic, see the three links to PDFs.
Thomas Milo's Authentic Arabic (PDF).
Thomas Milo's Some Comments on the Arabic Block in Unicode (PDF).
Presentations:
Thomas Milo talking about DecoType history and ACE technology (DTL
Type[&]Design 2009 conference, 18 November 2009, The Hague).
Thomas Milo demonstrating ACE technology by way of Tasmeem and DecoType's Naskh (Non-Latin Typeface Design conference, 2007, University of Reading).
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An Evening of Arabic Typography with Tarek Atrissi, Thomas Milo and Titus Nemeth (26 October 2008, Amsterdam). Presentations and discussion.
Thomas Milo demonstrating the power of ACE by flipping through all variant shapes of a word that 'script grammar' allows, and adding kashidas of different number and length (MOV). This is not a theoretical exercise, this is Tasmeem's Word Shaping at work.
Abdallah sez ... (MOV). Aphorisms set in Ruqah vs Naskh.
Official links:
DecoType is the inventor of ACE typesetting and font technology, as well as designer of several typefaces the last one of which is
Nastaliq.
WinSoft implemented the technology as an InDesign plug-in
Tasmeem.
InDesign CS4 ME and a much improved
Tasmeem 4 are now available. A one-month Tasmeem trial is automatically installed with InDesign, both with the trial version and the full version.
Brand new ACE fonts take advantage of Tasmeem's capabilities like special layout behavior and, first of all, support for all languages represented by the Arabic script.
¶ The fonts are included in the
InDesign/Tasmeem trial and are ready for being tested.
Tasmeem how-to videos:
WinSoft's Tasmeem 4.
Using Tasmeem's Text Shaper to fit text into a given text frame (MOV).
Using Tasmeem's Text Shaper to expand a line (MOV).
Using Tasmeem's Word Shaping to fine-tune the appearance of words (MOV).
Designing typefaces for ACE/Tasmeem:
Titus Nemeth's Tasmeem 4 Typefaces 2009 (PDF).
Titus Nemeth's Tasmeem · Typeface Design in Arabic. Presentation (2008, ATypI Conference) (PDF).
Titus Nemeth's A Primer for Arabic Typeface Design for the DecoType Arabic Calligraphic Engine in WinSoft Tasmeem (PDF).
Titus Nemeth's The Current State of Arabic Newspaper Type
and Typography. Dissertation, 2006, University of Reading (PDF).
Discussion:
Pascal Zoghbi's article, followed by a discussion being as vivid as informative.
Dan Reynold's report of both John Hudson's non-Latin script workshop and Thomas Milo's & Mirjam Somer's ACE font production workshop (spring 2008, University of Reading).
About Thoams Milo:
Thomas Milo on Arabic Script, War in Lebanon, and More, an interview.
Furthermore:
Arabic Editor, a useful tool.
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