On 08/05/2002 12:40:22 PM "James Kass" wrote:
>This indicates that PDF is character rather than glyph based.
Actually, what this indicates in that Acrobat is capable of deriving
character sequences from a PDF document.
>> I may be wrong, but it's my impression that others involved in font
>> technologies would talk about "encoding glyphs" in the sense I used.
>
>Yes, people do. But, not on the Unicode list.
Fair enough, since on this list we're more likely to talk about encoding of
text than about internals of font. If I were talking about documents, I'd
say that characters are encoded in documents. But in the context of fonts,
especially if discussing mapping of presentation forms from the cmap, I
wouldn't consider it out of place for someone to talk of glyphs being
encoded in the cmap.
>And, IIRC, the last
>time I erred in this fashion, you were kind enough to remind me
>that we encode characters, not glyphs.
There you go: proves you shouldn't hesitate to argue with me! :-)
I forget what the context was, but I can imagine me saying "encode a
ligature glyph in the cmap" in one context and saying in another context
(especially the Unicode list) "we encode characters, not glyphs". I only
*seem* inconsistent. Really. :-)
>We map glyphs, we encode characters. In a certain font editor, the
>practice is to first draw the glyph, then map it to a Unicode
>character.
Well, I guess then that glyphs can be mapped to characters in some font
editors. (Actually, we have some tools that do just that, so I quite
agree.) But once the font is made, and when we're talking about what
happens during the rendering process, I think it correct to say that
characters get mapped to glyphs and not vice versa.
>Even though, technically, the cmap is "character-to-glyph mapping
>table", there's nothing to prevent an application from converting
>a GID to a character code.
No, provided it's deterministic.
> Or, in the case of one-to-many, to several
>character codes.
No objection.
><quote>
>The vertical Glyph Display on the left shows a small scale outline of
either
>all glyphs in the current font (optionally including,
>for registered copies of Softy, the kerning pairs for each glyph), or the
>glyphs mapped to the character set for the selected
>platform
>...
></quote>
Well, I just said that I'll buy such usage in the context of font tools, so
I guess I can't object to this.
- Peter
---------------------------------------------------------------------------
Peter Constable
Non-Roman Script Initiative, SIL International
7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA
Tel: +1 972 708 7485
E-mail: <peter_constable@sil.org>
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