bugFree UCS Outline Fonts - Bugs: bug #53954, Arabic lam-alef ligature and...

 
 

bug #53954: Arabic lam-alef ligature and diacritics

Submitted by:  Steve White <Stevan_White>
Submitted on:  Mon 21 May 2018 08:27:49 AM UTC  
 
Category:  individual character(s) Severity:  3 - Normal
Item Group:  letter positioning poor Status:  Fixed
Privacy:  Public Assigned to:  Steve White <Stevan_White>
Open/Closed:  Open Release:  development

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Thu 24 May 2018 05:31:56 PM UTC, comment #2:

The main OpenType technology to be applied here is this. When a glyph's OT type is base ligature, it can take multiple marks of a given type. So the first mark following the ligature will be put over mark 0, the second over mark 1, etc.

This way, the text's author decides with which part of a ligature glyph a mark is to be associated.

Steve White <Stevan_White>
Project AdministratorIn charge of this item.
Mon 21 May 2018 05:53:27 PM UTC, comment #1:

As David Corbett pointed out, in Proposal L2/16-056 "Proposal to encode Al-Dani Quranic marks used in Quran published in Libya", comes the remark:

"When marks are placed over Laam Alef ligatures in Al-Dani style, then right side stroke is considered as Alef and left side stroke is considered as Laam"

It goes on to illustrate examples of that style.

However, another reasonable policy would be to place the marks in their proper phonetic order. There is more than one way to accomplish that. But maybe best is just to take the marks in the order they are encoded, with a mark before the letters being placed over the right of the ligature, and a mark between the letters being placed over the left. This is, to ignore the interpretation of the components of the ligature.

I think this explains the way other fonts are placing the marks.

Steve White <Stevan_White>
Project AdministratorIn charge of this item.
Mon 21 May 2018 08:27:49 AM UTC, original submission:

The standard has several entries for the lam-alef ligature with various diacritics already placed: madda, hamza and hamza-below. All of these show the diacritic placed to the left, over the lam component.

I had accordingly placed an anchor for other diacritics over the lam (in fact, I had vacillated on the point). But now I have seen that other fonts place other diacritics over the alef.

The Wikipedia article explains which diacritics appear on what letters -- but it's unclear to me how this relates: madda and hamza are related to the vowel... but evidently in the ligature they go over the consonant. What about other diacritics?

What are the general rules for placement of diacritics over this ligature?

Steve White <Stevan_White>
Project AdministratorIn charge of this item.

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-05-24 Stevan_White StatusNeed info => Fixed

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