Re: Looking up fonts and shapers in Pango

[hashao <hashao telebot com>]

Hello Owen,

Friday, January 21, 2000, 5:40:52 AM, you wrote:
...
OT>  - Choosing a font for each character.
OT>  - Choosing a shape engine for each character (handles conversion of 
OT>    characters into font-specifc glyphs)

...
OT> The other approach that I've thought of for handling the font-coverage
OT> problem is to simply punt the procedure to the installation process.

OT> That is, to assume that the person/vendor that is setting up system
OT> fonts, and also the person distributing 3rd party fonts have good
OT> knowledge of what shapers will be available. For instance, somebody
OT> installing an X font encoded as tscii-0 assumes that a Tamil shaper is
OT> available and then claims the coverage range for the font is
OT> U+0B80 - U+0B8F, and installs some appropriate line in a global
OT> configuration file.

OT> The worry I have with the second approach is that it means that the
OT> font installation process has to be very tightly coupled to Pango,
OT> and while I hope that Pango will be very widely used, a high level
OT> installation complexity would hinder that process.

Pango could just maintain a coverage table/database itself. Each time
it is called, it just check if there are new fonts not included in
its database before doing the lookup stuff. If there are new
fonts/shapers or removed fonts/shapers, the database should be
updated. There are normally fewer fonts being added in a system after
installation, so setting up a coverage table for new fonts should not
be too slow. Beside, it is a one time process for each font.

Best regards,
 hashao                            mailto:hashao@telebot.com