On 23/09/2004 00:31, Gerd Schumacher wrote:

Michael Everson wrote:



At 12:13 -0700 2004-09-22, James Kass wrote:


What use is a combining enclosing circle which doesn't combine and


enclose?

The character is an interchangeable data unit. It combines and encloses (nicely at least) only if a font designer has drawn a precomposed glyph for it and its enclosed. And there are a lot of things that could be enclosed.



For example the invisible letter, you proposed ;-)



Of course. <INVISIBLE LETTER, ENCLOSING CIRCLE> should display the enclosing circle glyph with nothing inside it. This may or may not look the same as some non-enclosing circle character. SPACE and NBSP don't work well here because XML may mess them up.


I think, it would make sense to have a tiny database of composable
characters, which are actually used, namely in orthography, and in
dictionaries like the Yorouba letters with dot below, the - 35, if I
remember well - unencoded Lithuanian composites, the underline below vowels,
marking long stressed syllables in German dictionaries, etc.



Do you realise what this database would be like? In Hebrew alone there is an essentially open-ended set of at least tens of thousands of possible grapheme clusters. Even in Latin script, an exhaustive listing of base character and diacritic combinations found in rarely written languages and obsolete orthographies would be a huge task, and one which needs constant revision, as new combinations are discovered or come into use. And then, on your model, fonts need to be constantly revised to track updates to the list.


Not every international font needs to comprise any combination which is
possible. Such a database would be a very valuable guideline for font
designers. Can't it be provided by Unicode, of course, not a as part of the
standard?




If there were such a list, font designers could indeed design precomposed glyphs for each of the tens of thousands of graphemes on it. But I suspect that they would prefer to specify a programmatic way of making most of the combinations, except for rather common ones. And users will prefer this as they won't want huge fonts mostly full of extremely rare precomposed glyphs.

--
Peter Kirk
[EMAIL PROTECTED] (personal)
[EMAIL PROTECTED] (work)
http://www.qaya.org/





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