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https://github.com/n8willis/opentype-shaping-documents

Documentation of OpenType shaping behavior
https://github.com/n8willis/opentype-shaping-documents

complex-scripts opentype opentype-features opentype-fonts unicode

Last synced: 5 months ago
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Documentation of OpenType shaping behavior

Awesome Lists containing this project

README 

          
```{include} /_global.md

```



# OpenType shaping documents #



Sponsored by [YesLogic](https://yeslogic.com/) 



_Thanks also to the developers of HarfBuzz and AllSorts, plus many other font engineers and text-encoding experts for their generosity of time and insightful contributions._



##         🆆 🅰 🆁 🅽 🅸 🅽 🅶 ##

>

> This repository is an active WORK IN PROGRESS.

>

> NONE of the documents you currently see here are complete

> nor are they suitable for reference. PLEASE do not use

> them as a guide or as a general information source.

>

> As long as this warning text remains visible, the above 

> holds true. 



At present, we are seeking comments and bugfixes on the Indic-script,

Arabic-like, Hangul, Hebrew, Thai/Lao, Tibetan, Khmer, Myanmar,

default, and USE documents. Interested readers and contributors can

begin at the



  - [Indic General](opentype-shaping-indic-general.md) 

    - (Devanagari, Bengali, Gujarati, Gurmukhi, Kannada, Malayalam,

      Oriya, Tamil, Telugu, Sinhala) 

  - [Arabic General](opentype-shaping-arabic-general.md)

    - (Arabic, N'Ko, Syriac, Mongolian)

  - [Hangul](opentype-shaping-hangul.md)

  - [Hebrew](opentype-shaping-hebrew.md)

  - [Khmer](opentype-shaping-khmer.md)

  - [Thai and Lao](opentype-shaping-thai-lao.md)

  - [Tibetan](opentype-shaping-tibetan.md)

  - [Myanmar](opentype-shaping-myanmar.md)

  - [Universal Shaping Engine (USE)](opentype-shaping-use.md)

    - All complex scripts that are not handled by a dedicated

      script-specific shaping model

  - [Default](opentype-shaping-default.md)

    - All non-complex scripts

  - [Emoji](opentype-shaping-emoji.md)

    - Emoji sequences do not constitute a separate shaping model,

      but handling emoji sequences can incorporate many of the same

      Opentype mechanisms and should not be overlooked

  

shaping documents and are encouraged to submit their feedback

on the text or images of any of the linked scripts. The documents are

organized by script; where there are multiple shaping models for a

particular script (including deprecated models), the various models are

all addressed in the same script-specific document.



The documents also include a description of

[normalization](opentype-shaping-normalization.md) in the OpenType

shaping context, which differs from Unicode normalization in several

respects.



Various [notes](notes/README.md) about the document set and the details

of its scope, limitations, and quirks are also provided.



Some [errata](errata.md) about the "upstream" specifications and

reference documents are noted separately. 



In its final form, this repository will hold documentation describing

the shaping behavior used for layout of OpenType text. In particular,

it will focus on complex scripts.



In addition to the primary, per-script documents, implementers and

other interesteed readers are encouraged to check the

[character tables](character-tables/README.md) for correctness and to

examine the [image-generation logs](/images/README.md) to identify

issues seen in the inline images.



### References



These documents cite the following informative references:



1. The Microsoft [Script development

   specifications](https://docs.microsoft.com/en-us/typography/script-development/standard),

   which document the behaviors expected for OpenType Layout fonts and

   provide guidance & examples for type designers. OpenType is a

   registered trademark of Microsoft Corporation. 

2. Related portions of the Microsoft OpenType specification, such as the

   [OpenType Layout tag

   registry](https://docs.microsoft.com/en-us/typography/opentype/spec/ttoreg)

   and [OpenType Layout common table

   formats](https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2),

   which list and define feature tags, script & language tags, and

   other internals of compliant OpenType font binaries. OpenType is a

   registered trademark of Microsoft Corporation. 

3. The [HarfBuzz](https://github.com/harfbuzz/harfbuzz) project, which

   includes a free-software/open-source implementation of OpenType

   Layout shaping with full source code and documentation. 

4. The [AllSorts](https://github.com/yeslogic/allsorts) project, which

   includes a free-software/open-source implementation of OpenType

   Layout shaping with full source code and documentation.

5. The [Unicode

   Standard](http://www.unicode.org/standard/standard.html) and

   related Unicode Consortium projects such as the [Unicode Character

   Database](http://www.unicode.org/reports/tr44/), which defines

   Unicode code points and formal character properties used in

   shaping. Unicode and the Unicode Logo are registered trademarks of

   Unicode, Inc. in the United States and other countries.

6. The YesLogic [text corpus](https://github.com/yeslogic/corpus),

   which includes real-world text data for several Indic scripts,

   scraped from Wikipedia, Reddit, and multiple online news

   sources. This data is used to test shaping in AllSorts and Prince.

7. Known but unofficial information about other shaping-engine

   projects. Primarily this includes tests and reproducible issues

   found via [HarfBuzz](https://github.com/harfbuzz/harfbuzz), because

   HarfBuzz intentionally aims to produce results that will 100% match

   the output of Microsoft Uniscribe (not counting cases where

   Uniscribe's output is known to be incorrect, of course).

   > Note: occasionally, tests or issues documenting the behavior of

   > Apple CoreText are also included, but CoreText compatibility is

   > not an explicit goal for HarfBuzz.