Re: Clustering rules (was Re: Adding tis620.2533-0...)

[Chookij Vanatham <chookij vanatham eng sun com>]

Hi Owen,

First of all, thanks so much for giving the direction to sort this out.

] 
] I'm not very happy about any of the solutions that have been proposed
] so far, because they involve separating the font from the clustering
] rules that need to be used for the font.
] 
] This is going to present significant headaches for users, in having
] to create configuration files that describe how each font should
] be clustered and maintain them as they add new fonts.

I agree on this as long as there are other choices to change/adjust
the rules.

] 
] I'm already concerned that the configuration for Pango with the
] pangox-aliases file is not easy enough. I don't want to make this
] worse.
] 
] 
] I think we can do better than this, though it may cause backwards
] compatibility problems with some existing fonts; we need to
] either:
] 
]  - Standardize on one set of clustering rules per encoding
] 
]  - Represent the clustering rules in the encoding field of the
]    XLFD:  (tis620-3.wtt20)

I agree on this and I think this should be done within the scope
that can be controlled for the short term plan and satify everybody
with flexibility.


] 
] Or:
] 
]  - Store the appropriate clustering rules as an additional 
]    property on the font.
] 
]    This could either be an atom representing one of a set 
]    of standard clustering rules or a more complex rule set.

This is an interesting idea as well and, for me, I would like to know
more. For now, I can't say anything more because I don't have experience
much on the font, unless any other related information, let me know,
just in case.

] 
] 
] I think it would be useful if someone could enumerate the clustering
] rules currently in use for Thai on X, so we can see:
] 
]  - How many different rules are in use
]  - Which ones we need to support
]  - How bad the problem is with legacy fonts without identified
]    clustering rules.

I'll be providing the cell-clustering rules for Wtt2.0 and I think,
Thai folks overthere, for sure, K.Theppitak and I should be able
to work all-together or any other Thai folks, so that, we can have, at least,
the standardize on one set of clustering rules per encoding for Thai,
(XLFD: tis620-3.wtt20)

] 
] 
] I hope in the long term we'll be going to font formats like OpenType
] that are rich enough to represent clustering rules natively.
Hopefully, we will have this technology asap.

Thanks again,

Chookij V.

] 
] Regards,
]                                         Owen
]