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

[Qianqian Fang]

hi

I respect your philosophy of structuring the style propagations
based on the context and script natures. I think it is indeed an elegant
solution to use a COMMON charset to represent the language-independent
symbols and render them based on the context.

IMHO, the confusion comes from the fact that "language-neutrality"
and "local-language dependent" are not distinguished for the COMMON 
scripts.
In another word, the charset of COMMON is a mixture of the characters
that are essentially not tied to any specific language (such as digits),
and those are re-defined by local languages (such as some punctuations,
geometric shapes U2500-U25FF). For the former case, I think they
should not be influenced by local language preferences, rather,
using system fall-back setup (likely Latin-preferred) should be the
best solution; for the later case, using local font preference is
the best, as in your current COMMON charset handling.

In short, I think the current COMMON set should be further
refined into a NEUTRAL and a LOCAL_DEPENDENT char sets,
and use system fall-back configuation for NEUTRAL set, and
use local-language preferences for the LOCAL_DEPENDENT set.
Specifically, for digits, they are language neutral and should
be rendered by system fall-back settings rather than a local
language settings.

Qianqian


Behdad Esfahbod wrote:
> 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
>>     
>
>