972859 - Armenian letters incorrectly rendered as ligatures

Status: NEW

(Core :: Graphics: Text, defect)

Description

[Aram Palian]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:25.0) Gecko/20100101 Firefox/25.0 (Beta/Release)
Build ID: 20131115110315

Steps to reproduce:

Please look at this testing page.  http://lezu.am/test/armligaturetesting.html



Actual results:

The Armenian letters "m","n" and some others. are transformed by the browser engine in to Armenian medieval ligatures that have no place in modern texts and sites.  There is no need for such a automatic transformation. If someone want to use this ligatures he can do it directly by entering from keyboard the Unicode values of this symbols.  Please remove this feature from Firefox. 


Expected results:

This problem happens in many Armenian websites.  It happens only in Firefox. Chrome/IE has no this problem. It is not a catastrophe, but it is very uncomfortable to see these ligatures in modern Armenian texts.

Comment 1

[Aram Palian]

Excuse me I didn't finish the "Expected results".  The expected result is this, if You have armenian letters "m" and "n" side by side (other examples also) they should be rendered as a normal letters, they should not be merged into ligatures by the engine.

Comment 2

[Aram Palian]

The problem occurs in Sylfaen and GNU Freefont but not in DejaVu.

Comment 3

[Manuela Muntean [Away]]

I can reproduce this issue with the latest Nightly on Ubuntu 13.10 32-bit: the first/top Sylfaen row from the .html page is indeed rendered differently than with Chrome

Comment 4

[Jonathan Kew [:jfkthame]]

I looked at sylfaen.ttf, and in this case, at least, it's a feature of the font: these ligatures are included in the OpenType 'liga' feature, which is enabled by default. To suppress them, you could use
  -moz-font-feature-settings:"liga" off;
in CSS.

If the use of these ligatures is not appropriate for most Armenian text, they should have been implemented as 'dlig' (discretionary ligatures) rather than 'liga' (common ligatures); then the feature would not be applied by default but only when explicitly requested. So I'd consider that a font bug.

I don't see the problem in FreeSans here; please confirm exactly what version of the font you have, as it's possible the OpenType features have been modified. (I tested Version 0412.2268.)

Comment 5

[Aram Palian]

Thank You Jonathan
I added the CSS line and it resolved the problem.  
I am using Ubuntu 12.04 so perhaps my FreeSans is older version. I will check now what version I have.

Comment 6

[Aram Palian]

Jonathan
I have FreeSans version (Revision: 1.344), I downloaded the latest version and the problem in FreeSans was fixed. 

The problem in Sylfaen remains. Now I understand that it is related to the font, but what is the correct way of ligature handling?  The Firefox way or Chrome way? Or there is no specific correctness in this situation?

p.s. By the way it seems that CSS command that helped me, is not documented.