[Bug 492510] Regression: wqy-bitmap-fonts preferred font over truetype fonts

[bugzilla at redhat.com]

Please do not reply directly to this email. All additional
comments should be made in the comments box of this bug.


https://bugzilla.redhat.com/show_bug.cgi?id=492510





--- Comment #6 from Qianqian Fang <fangqq at gmail.com>  2009-03-27 10:10:01 EDT ---
(In reply to comment #0)
> Failure Case 1: gramps PDF generation

This looks to me really should be a cairo bug, as Behdad reported in his
upstream bug. Bitmaps are only preferred when rendering on-screen font sizes,
i.e. 11px~16px, as defined in 61-wqy-bitmapfont.conf. But for printing, the
font sizes should be way bigger than that, and should by-pass bitmap rendering.


> 
> Failure Case 2: pango-view
> ==========================
> Here is a similar way to reproduce this bug:
> LANG=en_US.utf8 pango-view --text "日本語 test" --font "100"
> LANG=zh_CN.utf8 pango-view --text "日本語 test" --font "100"
> 
> English pango renders the Chinese characters as ugly bitmap.
> Chinese pango renders the Chinese characters as truetype.


Again, I think this is not an issue for wqy-bitmap-fonts, rather, this is an
old problem associated with the absence of preferred language (i.e.
PANGO_LANGUAGE) when rendering CJK characters under non-CJK locales.

Indeed, there are two issues tangled together: 

First, pango can not tell if "日本語" are Japanese Kanji or Chinese Hanzi, while
PANGU_LANGUAGE is not defined under non-CJK language, so, pango will not mark
the character with the proper language tags, and some CJK specific fontconfig
rules will be bypassed.

Second, as a result of the above, the font rendering is now handled to
fontconfig without proper language tag, while the default font orders in
fontconfig 65-non-latin is very outdated. Mixed with proprietary fonts with
free fonts, low quality fonts with small Unicode coverage were placed in front
of more complete and polished fonts. In this case, the rendering of Chinese is
horrible, mixed by Japanese Gothic, Mincho and Chinese Song/Kai glyphs, see

http://wenq.org/gallery/albums/userpics/10002/confopt_F8_no_wqy-bitmap_en-us.png

In order to display Chinese properly under non-CJK fonts, I proposed using
wqy-bitmap-fonts as the default CJK fonts for en locales, (many friends and I
myself work under en_US locales but want to use Chinese):

http://markmail.org/message/waeyjb3hqkpglfgk


To solve this issue, I suggest to correct two things:

1. define default PANGO_LANGUAGE definition for non-CJK locales, preferably
"zh". Because zh contains more complete unicode coverage (20000 characters vs.
6000 for ja and ko) which will give a more uniform look of the rendering; and
there are several default Chinese fonts support large char set, such as
wqy-bitmap-fonts (>27000 Hanzi), wqy-unibit-fonts(>27000 Hanzi),
wqy-zenhei-fonts (=20932), and all the Arphic fonts (>20000 Hanzi). In
comparison, Japanese fonts contains too little Han glyphs, and the quality is
not impressive.

2. update 65-non-latin.conf. it is too old and only makes more troubles if it
stay the way it is.

-- 
Configure bugmail: https://bugzilla.redhat.com/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.