Some Unicode characters work everywhere but not on Firefox, why?

Question

I have a problem on Firefox. As it is already said in the title, some Unicode characters are replaced by weird squares with numbers inside. The thing is that it's only the case on Firefox - not on Open Office, not on Opera.

For example, if I look inside the little box at the bottom of this wikipedia page, I have a different outcome with Firefox and Opera.

What should I do ?

I already followed the advices on these two other threads about a similar problem ("Why only some unicode characters are visible on Firefox?" and "Why does Firefox not render some characters?") ; sadly, that wasn't enough : I already have Arial installed on my computer as well as on Firefox itself, and I also installed Code2000 ; that doesn't change anything. My Firefox settings also seem good.

So where's the problem ?

Thank you already for your help !

Update : I also installed DejaVu and DejaVuLGC, that didn't change anything. In fact, I can force Firefox to use only this font, then some (not all) of the missing characters appear ; but that's not a solution, since Opera doesn't have to do this to display correctly these characters (and some others).

For example, consider this page. With my usual Firefox settings, I see this. When I change them to these radical new settings, I see this. Look at the font of the normal text at the top ; obviously, it is DejaVu ; that isn't ideal : Opera does it better.

Solution 1

I update here since I had the same problem. The really simple solution for me is installing the GNU Unifont. It's FOSS and with an enormous range of unicode characters (if you feel like you need it): (with the "standard" version, I can display all the glyphs in the page listed above by the OP)

webpage: http://unifoundry.com/unifont.html

Present in most linux distrib repositories.

in Ubuntu: sudo apt-get install ttf-unifont

Solution 2

If you look closely at your screen shot of Opera, you’ll see that there are problems there, too. The characters that are missing on Firefox are missing on Opera, too, they are just replaced by various empty rectangles instead of rectangles with hex numbers in them. The answer to the question about differences is that the browsers handle the missing glyph problem differently.

Firefox actually handles the situation better by displaying an indication (albeit a technical one) about the identity of the character that cannot be rendered. CSS Fonts Module Level 3 CR recommends that, in section 5.2 Matching font styles: “8. If a particular character cannot be displayed using any font, the user agent should indicate by some means that a character is not being displayed, displaying either a symbolic representation of the missing glyph (e.g. using a Last Resort Font) or using the missing character glyph from a default font.”

As regards to the question why some characters are not rendered on either browser, check out the answers to the questions you mentioned. The general answer is that you simply need suitable fonts. For example, the character U+A78D mentioned by @mgkrebbs in a comment is relatively new (Unicode 5.2), and its font support is therefore rather limited. It has not yet been added to Arial Unicode MS, and it will probably never be added to Code2000 (which appears to be abandonware now). In practice, you would probably want to download and install the DejaVu font family to see it.

Comments

[mgkrebbs]

The "weird squares with numbers" that Firefox is showing are graphic representations which tell you the code of the character that is there. For instance, the first one, in Lettres additionnelles, is a box with A7 over 8D, which tells you the hexadecimal code, A78D, which a Unicode reference will tell you is 'LATIN CAPITAL LETTER TURNED H' (U+A78D).

[Jukka K. Korpela]

You should specify which page is seen in the screen shots (link to it). By Arial, you probably mean Arial Unicode MS. We don’t have threads here, just questions and answers (and comments to them).

[Oneyr]

I couldn't put more than two links in my message because I'm a new superuser member. The page is fr.wikipedia.org/wiki/Alphabet_latin (look in the box called "Alphabet latin" at the bottom).

[Jukka K. Korpela]

The question is much better defined now! I wonder if you have the Unicode BMP Fallback font, from SIL, installed on your computer. It seems to cause problems like this.

[Jukka K. Korpela]

It’s difficult to say exactly what is happening here, and the problems can be different for different characters. Testing with a Wikipedia page with a large repertoire of characters isn’t ideal. The differences seem to depend on different lists of fallback fonts in different browsers; Wikipedia uses just font-family: sans-serif, which is logical in principle but calls for problems in practice.

[Oneyr]

You're right, but what kind of tests should I do instead, then ?

[phuclv]

This is the inverse situation: some characters only work in Firefox (in some OSes)

[Oneyr]

Thank you a lot for your support ! It is true that some characters are also missing on Opera, but most of them are handled correctly by Opera and not by Firefox, for example Ỻ, Ꜯ, and ꜳ ; that's why I don't think your solution is the good one. I tried it anyway ; on dejavu-fonts.org/wiki/Download I downloaded (and installed) 2.34/dejavu-fonts-ttf-2.34.zip and 2.34/dejavu-lgc-fonts-ttf-2.34.zip ; nothing has changed.

[Oneyr]

Look at the original message's update for more details.

[trlkly]

I have both images open. While there are a small number of characters not rendered in the Opera version, the vast majority have been fixed. Furthermore, as the OP said, he had to change the font settings to get it even that good in Firefox. Firefox does not seem to be falling back properly. If it weren't for the fact that you only have one upvote, I'd downvote for saying that they are the same.

[Jukka K. Korpela]

@trlkly, I don’t see your point. I did not write “they are the same”. My answer explains the nature of the font selection problem. Please post your own answer or make some contribution in a comment if you have something to add to the analysis.

[trlkly]

It's not complicated. You said that all the that are missing in Firefox are also missing in Opera. They aren't. The majority are present in Opera. Your answer does not explain this discrepancy but pretends like it doesn't exist. And the discrepancy is what the question is about. Hence you didn't actually answer the question. We still don't know why most glyphs are displaying in Opera but not in Firefox.