Inconsistent kerning in Firefox

[Anders Kaseorg]

Binary package hint: firefox

The attached webpage has two lines of equal length that say AVAVAVAV…AV. The second line has a ™ symbol appended to it. In Firefox, the first line is displayed with greater letter spacing than the second line. It seems that only the second line has kerning applied to it.

[[e-mail] (j.scott.gwin)]

Thank you for reporting your problem, it helps us make Ubuntu better. Does Firefox render other pages properly? I don't think the problem is in Firefox, It looks like the webpage was designed improperly. How can we reproduce the error here?

[Geoffrey Thomas (geofft)]

Confirmed; same issue on Firefox 3.0.6, Intrepid, defaulting to DejaVu Sans, under xmonad with no GNOME or msttcorefonts.

This doesn't seem like a problem with the web page's design to me; it's a very straightforward example. I do wonder if the same kerning issue is present in other programs that render text, though.

[Anders Kaseorg (andersk)]

To reproduce the problem, open the above attachment kerning-test.html in Firefox 3.0 or 3.1 on Intrepid or Jaunty (haven’t tried earlier versions).

The real webpage on which I first noticed this problem is <http://www.ksplice.com/cve-evaluation>, which renders the column of “Yes”s with inconsistent spacing.

[John Vivirito (gnomefreak)]

Maybe i dont understand the problem. If loading the site
http://www.ksplice.com/cve-evaluation
gives a problem or not. See my screenshot.
As for the
http://launchpadlibrarian.net/23892929/kerning-test-screenshot.png
I am unable to reproduce anywhere but in the screenshot.
Can you please give me a screenshot of the page itself showing up wrong?
I am using
gnomefreak@Development:~$ policy firefox-3.1 firefox-3.2 abrowser
firefox-3.1:
  Installed: 3.1~b4~hg20090315r23780+nobinonly-0ubuntu1~umd1
  Candidate: 3.1~b4~hg20090315r23780+nobinonly-0ubuntu1~umd1
  Version table:
 *** 3.1~b4~hg20090315r23780+nobinonly-0ubuntu1~umd1 0
        500 http://ppa.launchpad.net jaunty/main Packages
        100 /var/lib/dpkg/status
     3.1~b3+build2+nobinonly-0ubuntu1 0
        500 http://gb.archive.ubuntu.com jaunty/universe Packages
     3.1~b3+build2+nobinonly-0ubuntu1~fta1 0
        500 http://ppa.launchpad.net jaunty/main Packages
firefox-3.2:
  Installed: 3.2~a1~hg20090315r26208+nobinonly-0ubuntu1~umd1
  Candidate: 3.2~a1~hg20090315r26208+nobinonly-0ubuntu1~umd1
  Version table:
 *** 3.2~a1~hg20090315r26208+nobinonly-0ubuntu1~umd1 0
        500 http://ppa.launchpad.net jaunty/main Packages
        100 /var/lib/dpkg/status
     3.2~a1~hg20090127r24317+nobinonly-0ubuntu1~fta1 0
        500 http://ppa.launchpad.net jaunty/main Packages
abrowser:
  Installed: 3.0.7+nobinonly-0ubuntu1
  Candidate: 3.0.7+nobinonly-0ubuntu1
  Version table:
 *** 3.0.7+nobinonly-0ubuntu1 0
        500 http://gb.archive.ubuntu.com jaunty/main Packages
        100 /var/lib/dpkg/status

and i am unable to reproduce with the info given

[Anders Kaseorg (andersk)]

John: your screenshot bug#343389.png does show the problem. Look carefully at the column of “Yes”s, and you will see that the “Y”s are all aligned, but the “es”s are misaligned: there is a difference of one pixel between the rows that say “Yes” and the rows that say “Yes—with additional code”.

The kerning-test.html is a minimal test case that demonstrates a more extreme version of the problem. In a correct rendering, the two rows of AVAVAVAV…AV would be the same width (excluding the ™); the bug shown in my screenshot is that the first row has greater spacing and is thus wider.

[John Vivirito (gnomefreak)]

Firefox 2.0 will not get this fix since it is EOLS
I am looking closer at it.
What font and theme are you using?

[John Vivirito (gnomefreak)]

What screen res are you using?
I dont see the problem in my screenshot but i'm asking a few others to tell me if they see it (maybe a new set of eyes will help.

[John Vivirito (gnomefreak)]

ok the ones that are not aligned right are the "Yes" with the -- extra wording?
Thats the only thing i can see that would be around what you mean

[brendon (brendon-schu)]

I can help confirm this, as an experience web developer I know these things.

I'm attaching 2 images which demonstrate the problem clearly.

image: webpage.png
This shows the webpage as seen through the browser, and you can see that the first line is MUCH longer than the second line.

image: html.png
This shows the html source for the same webpage in raw text format, and you can see that the 2 lines end in exactly the same place.

It's clear that the browser is processing the first line differently than the second.

My test was done using Firefox 3.0.7 in Hardy.

[brendon (brendon-schu)]

and the 2nd attachment

[Alexander Sack (asac)]

this kind of issue doesn't qualify for the update policy for stable mozilla products; closing firefox-3.0 part won't fix.

Can you please verify that this is still an issue in latest jaunty firefox-3.5?

[Anders Kaseorg (andersk)]

Yes, it’s still an issue in Jaunty firefox-3.5.

I found a workaround, which is to set browser.display.auto_quality_min_font_size=0 in about:config. Apparently this bug is an artifact of a performance hack? I wonder if auto_quality_min_font_size=0 is fast enough to be the default.

[Adolfo Jayme Barrientos (fitojb)]

Can anyone test if this problem still happens in recent versions of Firefox?

[Launchpad Janitor (janitor)]

[Expired for firefox (Ubuntu) because there has been no activity for 60 days.]