A format for describing some Private Use Area glyph usage

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William
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A format for describing some Private Use Area glyph usage

Post by William » Fri Apr 11, 2008 8:00 am

Earlier this morning, in the eighth post in the viewtopic.php?t=2214 thread, I wrote as follows.
It occurs to me that maybe when adding glyphs in the Private Use Area that some form of documentation could be added within the font within the description section. Maybe this could be in a computer readable form by being encoded in a structured format within the description section of the Macintosh Roman platform of a TrueType font, that being because it would then be in a plain text format more easily accessible by a computer program.

If such a structured format could be devised and applied, then TrueType fonts could include information which could potentially be used so that automated conversion of a TrueType font to an OpenType font could be performed at some future time.
This thread is an attempt to produce such a structured format.

Suppose that a use of the format starts with four % characters on a line and ends with four * characters on a line.

Between those two lines are lines which each start with a Unicode Private Use Area codepoint followed by a space followed by the word is followed by a space followed by a string of one or more regular Unicode characters followed by zero, one or more uses of a space followed by a keyword.

For example, suppose that a font contains two characters in the Private Use Area. There is an alternate glyph for g at U+E421 and a glyph for a ct ligature at U+E707.

The use of the format would be as follows.

%%%%
U+E421 is g
U+E707 is ct
****

Suppose that the font also contains a glyph at U+E433 for an alternate version of e, yet useful only for the end of a word. There could be a keyword end_of_word which could be used to characterize that glyph.

The use of the format would be as follows.

%%%%
U+E421 is g
U+E433 is e end_of_word
U+E707 is ct
****

There could be other keywords, such as end_of_line for a glyph such as a very long-tailed e which might be good for the end of a line of poetry yet would bot look too good at the end of a word within a line of text.

Maybe there could be a keyword to indicate if an alternate glyph for a g has a tail which would or might clash with a previous character. Maybe there could be a keyword to indicate if an alternate glyph for a t has a horizontal which would clash with a following character which has an ascender, so that that t might be used in a word such as tomato yet not in a word such as atlantic.

The examples are using some of the glyph codepoints in my Sonnet to a Renaissance Lady font.

http://www.users.globalnet.co.uk/~ngo/SONNETRL.TTF

William Overington

11 April 2008

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