Bug 241551

Created attachment 155532 [details]
experimental fontconfig file

on FC6, under zh_* locales, uses vector latin fonts for latin, and wqy for
9/10/11/12pt CJK char on-screen rendering; however, under en_*, wqy did not get
sufficient priority for CJK rendering.

This is a known "feature" of the font, designed mostly in the considerations for
Chinese users.

What I want to achieve with this current setup is:

when users specify a general font family class, such as Sans/Serif/Monospace,
WQY bitmap fonts are only preferred for displaying CJK glyphs at 9,10,11,12pt;
the CJK glyphs at other sizes will be rendered by installed vector CJK fonts on
the system; if no other CJK vector font exist, use WQY font instead (smaller
than 9pt will use 9pt, greater than 12pt will use 12pt).

when users specify "WenQuanYi bitmap Song" as font name, use this font for all
glyphs, no matter which size.

my test results with the current configuration on FC6 under en_US locale is
shown here (click the figure to enlarge):

http://wenq.org/gallery/displayimage.php?album=7&pos=11

in this case, the Latin were not overridden. 

However, I did notice, also reported by other users, under zh_CN/zh_TW/zh_SG,
the Latin characters for Sans/Serif/Mono were actually assigned to wqy bitmap
font. something like this

http://wenq.org/gallery/displayimage.php?album=7&pos=0

We think this is a "bug" of fontconfig, which seems not consistent for
lang-specific font selection, and giving fonts which covers the current locale
much higher priority than those do not. In this case, because wqy covers most
char. for zh_CN, so it overrides Dejavu/Bitstream Vera because they do not cover
these zones. 

Language/locale-specific font selection is an known issue for fontconfig, see
http://osdir.com/ml/fonts.fontconfig/2006-06/msg00007.html
and I know there are patches available, but not incorporated in the main branch. 

I came up with an experimental fontconfig file, see Attachment #155532 [details] 
(you need to override /etc/fonts/conf.d/85-wqy-bitmapsong.conf)

I found that under zh_* locale, this seems eliminates the above problem (tested
on FC6), however, under en_*, WQY fonts do not function at all for CJK
characters. I need more test to see the problem and decide if this works
consistently or just by chance. I would be glad to know the behavior of this
file on your system.

From the feedbacks from most Chinese user communities, I did not hear much
complain about this though. Most of them think it is worthwhile to keep this
font on the system for displaying CJK text; and in case they don't like wqy as
sans/serif, they will chose specific font to override sans/seif.

My locale is de_AT.UTF-8 and I did end up with overridden latin fonts. It's 
interesting that it apparently doesn't happen for you under en_US.

I ran a quick test on a FC6 virtual machine, under de locales, I found no
overbidding of Latin on this system, the screen shot for de_DE.UTF-8 is here: 

http://wenq.org/gallery/displayimage.php?album=7&pos=9

for de_AT.UTF-8, the screen is identical. the fontconfig is 2.4.1, the testing
page URL is

http://wqy.sourceforge.net/cgi-bin/index.cgi?WQYTest

I am curious what does this page look like on your system, and what's your
fontconfig version. Does other people have similar problem under non-zh locales?

*** This bug has been marked as a duplicate of 381311 ***