From: Peter Kirk (peterkirk@qaya.org)
Date: Wed Aug 24 2005 - 18:19:56 CDT
On 24/08/2005 23:27, Philippe Verdy wrote:
> ...
>
> Unfortunately, browsers are not prepared for that: even MSIE will not
> allow you to select font preferences for new scripts, because it seems
> to use an hardwired list of scripts, instead of consulting a registry
> of font capabilities, and the capabilities of the OTLS shaping engine
> (if a script requires to activate some OT features within some complex
> sequence before or after reordering...)
MSIE (on Windows XP) seems to have a specific problem with web pages
using the non-core parts of a script. For example, when viewing a web
page including Greek Extended characters and/or Hebrew accents (see
http://englishbibles.blogspot.com/2005/08/unicode-hebrew-and-greek.html
for an example - but the original problem on this page with Greek
Extended has been fixed by specifying the font Tahoma), where the
default font for the page (in the case of this blog posting provided by
a template) does not support those characters, MSIE apparently
substitutes the default font with a font which is registered as
supporting "Greek" or "Hebrew" but does not in fact support the extended
characters or accents. So the unsupported characters end up replaced by
empty boxes.
Mozilla Firefox does somewhat better, as instead of giving empty boxes
it finds a suitable glyph from any available font, which is usually
legible even if it doesn't match the rest of the word properly.
This is quite a serious problem because it comes close to making certain
characters, e.g. Greek Extended characters and Hebrew accents, unusable
on the Internet. Browsers need somehow to ensure that their font
substitution mechanisms actually find a glyph for each character. One
way to do this would be to choose as substitutes only fonts which are
guaranteed to cover the whole of a particular Unicode block. If there is
"a registry of font capabilities", it must be accurate, and not allow
claims to support the whole of Hebrew when certain characters are not
supported at all - nor interpret a claim to support Greek as applicable
also to the Greek Extended range.
-- Peter Kirk peter@qaya.org (personal) peterkirk@qaya.org (work) http://www.qaya.org/ -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.338 / Virus Database: 267.10.15/80 - Release Date: 23/08/2005
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