1236719 - Firefox for Windows cannot fully display Old Bulgarian (Old Church Slavonic)

Status: UNCONFIRMED

(Core :: Graphics: Text, defect, P3)

Description

[dpldobrev]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:43.0) Gecko/20100101 Firefox/43.0
Build ID: 20151221130713

Steps to reproduce:

I opened https://cu.wikipedia.org/wiki/%D0%A1%D0%BB%D0%BE%D0%B2%D1%A3%D0%BD%D1%8C%D1%81%D0%BA%D1%8A_%D1%A9%EA%99%81%EA%99%91%D0%BA%D1%8A.


Actual results:

Not all characters were displayed.


Expected results:

All characters should've been displayed.

Comment 1

[dpldobrev]

Firefox 43.0.2, Windows 7 64-bit, default encoding: Unicode.

Comment 2

[Loic]

Can you attach a screenshot of what you see, please.

Comment 3

[dpldobrev]

Attachment: A screen-shot of Firefox on Windows displaying Old Bulgarian

Comment 4

[dpldobrev]

Attachment: A screen-shot of Tor Browser displaying Old Bulgarian

Interestingly enough, Tor Browser, which is based on Firefox, manages to recognise a few more characters with the same settings (Unicode). Its version is 5.0.6 (based on FF 38.5.0). Older versions of the Tor Browser were capable of displaying all characters.

Comment 5

[Jonathan Kew [:jfkthame]]

If you go to about:config, find the setting gfx.font_rendering.fallback.always_use_cmaps and toggle it to 'true' (it's false by default), then restart the browser, does that make any difference?

Comment 6

[dpldobrev]

It does, now Firefox displays as many characters as Tor Browser - still not all, that is. The setting was also false in Tor Browser but setting it to true made no difference.

Comment 7

[Jonathan Kew [:jfkthame]]

So part of the issue, at least, is a failure to find the necessary font when using the platform-specific fallback code. cc'ing jdaggett. Turning on always_use_cmaps helps here because it means we'll scan all available fonts looking for something to use, instead of depending on platform APIs.

And if you disable "Use hardware acceleration when available" in Options / Advanced (and again, restart the browser), does that make any difference?

FWIW, the page displays fine for me on both Win8.1 and Win10, but that'll doubtless be because of increased character coverage in the default system fonts on those systems. Win7's system fonts lack some of these characters, but you presumably have additional fonts installed locally that should provide them.

Do other browsers manage to display all the Old Bulgarian letters (running on the same system, with the same available fonts)?

Comment 8

[dpldobrev]

Disabling "Use hardware acceleration when available" makes no difference.
I do not use other browsers but in order to help you, I am going to install Chrome just to check this. I'll let you know about the result in a few minutes.

Comment 9

[dpldobrev]

Chrome fails too, it displays as many characters as Tor Browser (or FF with gfx.font_rendering.fallback.always_use_cmaps true).

Comment 10

[Jonathan Kew [:jfkthame]]

OK, thanks. Are you sure you currently have a font installed that supports the remaining letters? If you copy the problematic text into another application (e.g. WordPad), what font does it indicate is used for the Old Bulgarian letters that don't show in Firefox (or Chrome)?

Comment 11

[dpldobrev]

There's a single letter missing: https://cu.wikipedia.org/wiki/%D0%A1%D0%BB%D0%BE%D0%B2%D1%A3%D0%BD%D1%8C%D1%81%D0%BA%D0%B0_%D0%B0%EA%99%81%D1%8A%D0%B1%D0%BE%D1%83%D0%BA%EA%99%91#/media/File:Early_Cyrillic_letter_Zemlia.png . I cannot get it displayed in any application on Windows, I may be indeed lacking a font for it. Would you know which font I need to install? You could perhaps check which font is used for the character on Windows 8 and 10 since you said all letters are rendered there.

Comment 12

[Jonathan Kew [:jfkthame]]

It's in Segoe UI on Win8.1 and Win10, but I don't know how readily (if at all) that's available for older versions of Windows.

You could check various of the fonts suggested at http://alanwood.net/unicode/cyrillic-extended-b.html to see if they provide what you need.

Comment 13

[dpldobrev]

Thank you. Windows 7 has Segoe UI, by default, but I can see in the Character Map it's missing this particular letter. I guess it's been improved in Windows 8+. I'll just install one of the fonts suggested at your link.

Comment 14

[dpldobrev]

https://en.wikipedia.org/wiki/Segoe#Segoe_UI - "In Windows 8, Segoe UI has undergone a number of changes and stylistic additions:".
I guess this explains it.