From: Asmus Freytag (email@example.com)
Date: Sun Aug 26 2007 - 14:22:30 CDT
imagine you are the programmer writing an editor that, as one of its
features, has a 'Reveal Special Characters' mode. Your users are free to
use this editor with *any* font, but they expect that *all* the special
characters can be shown at all times. Finally, your boss is aware of the
fact that users want the screenshots in the help files to accurately
reflect what they will be seeing, and that any unexplained 'weird'
looking symbols will generate calls to support.
Your choices of how to meet these requirements are very limited. If you
rely on each font to carry visible renditions of all these special
characters, you will face two problems: fonts will not only vary the
symbols based on basic font style (that would be OK), but there will be
no agreement between fonts on how to represent certain special
characters - in the worst case, two fonts might use the same symbol for
two different special characters. Clearly, even if you can trap the use
of the .notdef glyph, your boss will be very concerned with that solution.
You could decide to use as symbols only characters that also occur with
standard semantics, and which are guaranteed to be in each font. Or that
occur in an ever-present suite of system fonts. Many editors do that
when showing spaces, tabs and end of paragraph, but there is the
inevitable risk of confusion when you encounter a legitimate use of one
of these characters, and the repertoire of usable, yet guaranteed to be
available, shapes is limited. The upside is a nice typographic
correspondence between text and special symbols. If your goal was
limited support, you'd be done.
If you want to cover all special characters in Unicode, the easiest
solution is to ship your own font with glyphs for all the special
characters. That way, you are in charge of the choice of representation,
you won't ever get a .notdef glyph, and so forth. You give up having the
symbols match the type style of the surrounding text, but your
user-experience will be predictable, and your boss will be happy.
If the Reveal Special Characters mode is disabled, you would not pass
any of the special character codes to the rendering engine, unless that
engine guarantees not to show it, or would consume it, e.g. in rendering
a variation sequence.
Variation selectors have no business being visible - unless you are in a
special mode. The whole idea behind them is that they can (and should)
be ignored when the resources to act on them (variant glyphs) are not
This archive was generated by hypermail 2.1.5 : Sun Aug 26 2007 - 14:25:05 CDT