[Fwd: Re: Request for review and advice on wqy-bitmap-fonts fontconfig settings]

[Behdad Esfahbod]

On Mon, 2007-12-03 at 21:58 -0500, Qianqian Fang wrote:
> hi Behdad

Hi,

> you may well be right and the behavior of pango is not logically
> flawed. Perhaps this problem should be filed as a feature-request
> rather than a bug.

I'm not stuck at semantic issues like feature-request vs bug.  When I
say it's technically infeasible, I mean it.


>  From Chinese user perspective, Latin scripts and the Common
> scripts are both non-Hanzi or non-CJK characters, therefore,
> they are expecting a similar look-n-feel when rendering these characters.
> For other languages, I guess they more or less share the same
> view: numbers and basic Latin characters (or Basic ASCII, or
> keyboard characters) are the most frequently used, non-local-language
> dependent symbols. As long as their local language does not
> re-define these symbols, they are expected to be rendered with
> similar styles.

Let me repeat what's happening again:  You are setting a Chinese locale,
so when Pango see digits, it assumes that you want to use those digits
with Chinese text, and you have provided a Chinese font that has glyphs
for those digits, so it believes it's found the perfect font for them
(your preferred font indeed) and uses it.  If those digits are not
desired, remove them from the font.


> I don't know the exact definition of PANGO_SCRIPT_COMMON
> and PANGO_SCRIPT_LATIN, but I think it is more natural to
> render the numbers using a Latin font rather than a Chinese
> font, as numbers and Latins are much closer.

Then fix your font.


> Huang Peng provided a patch to get the commonly expected
> behavior for this situation, if it can be implemented, or
> under the condition of Chinese locales, that would be a great
> help. I've seen this report many times on Mandriva, Debian,
> Redhat's bugzilla and almost all Chinese Linux forums.

That's not going to happen.  Pango's core has nothing language or script
specific hardcoded in it except for the data that is computer-generated
from the Unicode Character Database.  In Unicode, ASCII digits are
marked script Common.  There is a very small part of the issue you are
seeing that can be improved in Pango:

  http://bugzilla.gnome.org/show_bug.cgi?id=345386

but other than that, the behavior looks very reasonable to me.  If you
can think of an explanation of the behavior you want, without using
"change character class of digits" and "special-case Chinese", I'm
interested to hear that.

There are a few ways to fix your problem:

  - Remove Latin and ASCII digits from your font.  Why is it there if
it's not desired?  Nicolas suggested that fontconfig adds support for
conditional blacklisting of individual blocks/glyphs in a font.  That
would help too, but it's not in fontconfig yet.

  - If you were doing your font in an OpenType container, you could
split Latin and Chinese parts into two different fonts stuffed into a
single container and having the same name.  Then Pango will not see your
Chinese font having ASCII digits and not use them.

But at the end, it all comes down to real or hacky ways of removing
those glyphs from the font.


> Back to the original topic of this thread, how do you think the
> fontconfig file in my last email? I have heard complains at
> some Chinese forums about font changes due to removing
> the original fontconfig file. Hope I can get something to
> commit to cease their complains.

No idea.


> Qianqian

-- 
behdad
http://behdad.org/

...very few phenomena can pull someone out of Deep Hack Mode, with two
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being struck by lightning.  -- Matt Welsh