From: Philippe Verdy (firstname.lastname@example.org)
Date: Sat Nov 03 2007 - 22:10:02 CST
James Kass wrote:
> ZWJ requests a more joined form from the rendering system
> if one is available.
> Consider "ASSOCIATED PRESS SYMBOL", which is essentially a
> typographic ligature of "A" and "P".
> Would inserting a ZWJ between an "A" and a "P" in order to
> get a ligature of "AP" to use for representing that symbol
> in plain text be a Bad Thing?
There's a big difference between your example and a true ligature: ligatures
when they are enabled in a font style, do not change the semantic of the
characters they are representing; they can also be used freely almost every
where, independently of the context of surrounding letters. And they don't
prohibit a line break between the letters, if this ligature is joining two
syllables (for example the ligature of "ffi" or "ffl" does not prohibit the
syllable break between the two f; the linebreak does not occur between "f"
and "i" or "l", just because there's no syllable break.
In the "AP" symbol, it will be inappropriate for use in any word also
containing the two letters "AP". This is in fact an unbreakable logo that is
formed from the initials of the organization. So this is not a ligature; if
it was encoded, it should be usable for any words, not just by Associated
Press that has registered it as a logographic trademark. So as long as this
is protected by Associated Press, and there's no other legal occurrence of
this ligature in actual texts without any forced link to Associated Press,
there's NO chance it will be encoded.
A font that would be designed to contain the ligature would propably violate
the Associated Press copyright and trademark on its logo; that's the same
issue with the Apple logo, despite it is used in its legacy 8-bit charset
encodings: it is then mapped to a PUA, and the implementation of the glyph
in a font requires a permission by Apple.
The same would be said about the Windows logo used on PC keyboards and in
documentations, however there's an Unicode-encoded glyph that is very close
to it (the Unicode version is a black diamond with a thin white cross
splitting it into 4 equal squares). The Windows logo is not even present in
any font shipped with Windows.
On the opposite, the glyphs found in the "Marlett" font for Windows (used to
build GUI interface decorations and elements like: radio buttons,
checkboxes, or slider buttons, or icon buttons at the corner of GUI windows
and dialogs) are quite generic, and could be encoded as generic symbols, as
they are not trademarks (some of them are already encoded, but the "Marlett"
font is not Unicode encoded, but just mapped on a specific 8-bit symbol
charset. They were inserted in a font, just because it's a convenient
distribution format for resizable vectorized glyphs, and they can be
rendered with the existing OpenType renderer, including for creating 3D
effects like shadows; they allow these control buttons of the GUI to be
easily resized, without requiring many bitmaps at various resolutions.
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