GNOME Bugzilla – Bug 327907
Ligatures rendered wrong with DejaVu
Last modified: 2006-04-16 19:24:06 UTC
With pango-enabled gecko applications like Yelp, ligatures are rendered wrong if you use a DejaVu font. I will attach screenshots to show the problem. See also the discussion on the dejavu mailing list: http://sourceforge.net/mailarchive/forum.php?thread_id=9487746&forum_id=40874
Created attachment 57751 [details] rendering of 'bladwijzer' in Yelp
Created attachment 57752 [details] Rendering of 'effort' in Epiphany
chpe suggested to try starting epiphany with MOZ_DISABLE_PANGO=1. With this variable set, the problem does not occur.
Can you reproduce this in any non-Mozilla-using applications? Like gedit for example? If not, it may as well be a problem in Mozilla. The behavior is very weird, and I like to blame DejaVu fonts in the first place. :) Just to make sure, it only happens with 1.11, right? That's because we switched to using OpenType engine for Latin. So it's expected that ftstring doesn't show this problem.
- Yes, it only happens with 1.11 - When I try it under gedit, the spacing for ligatures is *slightly* off on the bare eye, but not nearly as much as observed in Mozilla.
Then I really think there's nothing wrong with Pango. CC'ing Chris Blizzard.
Hmm, it might be related to a patch we have which use pango more than standard mozilla/firefox does which fixes issues with CJK : http://cvs.mandriva.com/cgi-bin/cvsweb.cgi/SPECS/mozilla-firefox/mozilla-firefox-1.5-pango-underline.patch?rev=1.1&content-type=text/x-cvsweb-markup This patch is from MagicLinux, a chinese distro (but unfortunately, I don't have more info about it).
The patch seems to deal with ascent and descent mostly, not horizontal alignment, but yes, it may be the Chinese stuff biting again... Reinout, cano you test with a package without this patch?
(Just FYI, the mozilla patch is from https://bugzilla.mozilla.org/show_bug.cgi?id=218032 .)
I haven't tested without the patch yet (sorry) but the strange thing is now that I can't reproduce the problem in Epiphany 1.9.7 any more, but I do still see it in Yelp 2.13.5.
Epiphany doesn't use moz-pango anymore unless you run it with export MOZ_ENABLE_PANGO=1, while yelp doesn't do that (yet).
IMO, it is a mistake to disable pango rendering in gecko, since it is becoming the default in many linux distros for firefox and is required for some languages. This means people will get a different rendering between firefox and epiphany.
Frederic: in fact, distributions do disable pango rendering in gecko by default (.e.g ubuntu).
Yelp now disabled moz-pango by default too.
Hmm, one distro disables it (Ubuntu), two distros enable it (Fedora, Mandriva). Take your chance ;)
Forward progress will only be made if people stop running in circles.
Christian highlighted one problem when trying to render mathml with pango enabled firefox : http://www.mozilla.org/projects/mathml/demo/texvsmml.xhtml According to Christopher Blizzard on https://bugzilla.mozilla.org/show_bug.cgi?id=214715 pango code in mozilla is not yet finished for mathml..
Turn on Pango, fix various languages, break MathML. Turn off Pango, fix MathML, break various languages. Repeat ad infinitum. (Don't wait for Chris to get around to fixing MathML ... someone else will have to take the initiative there.)
Yeah, I have zero time. Someone else is going to have to figure it out. Try rbs@maths.uq.edu.au - he might be able to help at least diagnose the problem. My biggest problem with figuring out the MathML problems with pango was that it wasn't clear how MathML was _supposed_ to be rendering.
I have rebuilt pango 1.11.6 without the slighthint patch and cannot reproduce the problem, so indeed that patch is probably the culprit. I've also sent a polite mail to the MathML maintainer that Chris Blizzard suggested, but haven't heard back from him.
Ok Thanks. If I understand it correctly it's not Pango then.
Well, I'm not so sure any more. The problem has resurfaced and I'm quite sure I'm still using the "unpatched" pango 1.11.6. :( Will do some more testing.
https://launchpad.net/distros/ubuntu/+source/firefox/+bug/37828 reports the same (or a very similar) problem.
DejaVu 2.5 has just been released, http://dejavu.sourceforge.net/ and it solves the ligature/justified bug. For more, see http://sourceforge.net/mailarchive/forum.php?thread_id=10152634&forum_id=40874 I verified with Ubuntu Dapper Flight 6 (+all updates), viewing the page http://www.gnome.org/~jamesh/firefox-ligature.html