Font Technology for Pango

[Chookij Vanatham <chookij vanatham eng sun com>]

Hi Owen,

Seems to be that all the shaping rules for complex text scripts, particulary,
Devanagai, should be in the font.

I guess that, in the industry now, OpenType font would be the best font
technology. I don't know much about this technology yet. Just curious if
Pango is having the plan to use this technology and how soon would that be
possible ? or any other clue ?

Thanks,

Chookij V.

] 
] X provides a mechanism where extra properties can be attached to
] an X font and accessed by a client using the font. 
] 
] The data is basically, a string, though it is transferred to the
] client in a rather inefficient form for representing arbitrary string
] data: an atom interned on the X server.
] 
] We will be using this for representing ligaturing rules for Indic
] fonts in Pango, where:
] 
]  - There is no standard for Indic glyph encodings in common use
]    currently.
]  - The set of ligatures can depend quite a bit on the font.
] 
] In this case, since the set of ligature rules is not at all
] fixed, we actually store the rules in the property.
] 
] 
] I don't think that we really need that much flexibility for
] Thai, since there is no reason for every font to have a different
] clustering rule. So, if we wanted to use a font property, 
] it would be more efficient to use a single atom as an enumeration.
] 
] 
] However, there are problems with this approach.
] 
]  - It seems to be limited to BFD (bitmap) fonts, since I don't think
]    there is any way to attach font properties to TrueType or Type1
]    fonts in X.
] 
]  - Using it for existing fonts would require modifying the font 
]    data, unlike the approach of representing it in the encoding
]    field, which can be done with simple X font aliases.
] 
] 
] Regards,
]                                         Owen