"G. Adam Stanislav" <adam@whizkidtech.net> writes:
GAS> The situation is made more complicated with TrueType expecting a
GAS> one-on-one mapping of glyphs to characters.
I believe what the honourable gentleman has said to be untrue.
TrueType, as we know it now, assumes a functional (many-to-one) map
from character codes to glyphs, defined by the `cmap' data structure;
a single font file may contain multiple `cmap's (for various coded
character sets). This map does not need to be either onto/surjective
(not all glyphs need to be assigned character codes), or
one-to-one/injective (multiple codes may point to the same glyph),
although injective maps are recommended by the spec. The only
exception to the many-to-one nature of `cmap's is the ability to
encode ligature information in the font file.
OpenType (formerly know as TrueType Open) is a compatible extension to
TrueType [1] defined by Microsoft and Adobe, which Microsoft claims
will be supported in Windows 1901. OpenType defines a number of new
data structures that may (optionally) be included into TrueType fonts,
in order to allow for complex mappings between sequences of character
codes and sequences of glyphs. This includes glyph variants
(language-dependent, contextual, and user-selected), as well as a host
of other features.
I am not currently able to judge whether OpenType is any good, as I
still haven't got my hands on a useful OpenType font. However, the
specification seems to imply that most of the needed features are
there; it remains to be seen whether font manufacturers will make the
effort to include useful and exhaustive data in font files. This, in
turn, will be dependent on the quality of the support for OpenType
fonts that Microsoft and Adobe will provide.
More information on OpenType (including the font format specification)
is available from
http://partners.adobe.com/asn/developer/typeforum/fontinfo.html
Sincerely,
J.
[1] Actually, this is not quite true. There are two formats defined
for OpenType fonts: OpenType/TFF, which use TrueType outlines, and are
compatible with systems with support for TrueType, and OpenType/CFF,
which contain outlines in `CFF', or `Type 2' format (a format similar
to Type 1), and will only be usable on systems with explicit support
for CFF outlines.
This archive was generated by hypermail 2.1.2 : Tue Jul 10 2001 - 17:20:48 EDT