On Sat, 25 Jul 2015 21:05:41 +0300 Eli Zaretskii <e...@gnu.org> wrote:
> > Date: Sat, 25 Jul 2015 18:27:26 +0100 > > From: Richard Wordingham <richard.wording...@ntlworld.com> > > > > > Mirroring is not changing a character's shape. It is a > > > replacement of a character's glyph with a glyph of a different > > > character. > > > > Mirroring is changing a glyph to suitable for reading in the other > > direction. > > Sorry, I disagree. > > > Note the following extract from BidiMirroring.txt in the > > Unicode Character Database: > > > > <quote> > > # The following characters have no appropriate mirroring character. > > # For these characters it is up to the rendering system > > # to provide mirrored glyphs. > > How's that a contradiction to what I said? U+2140 DOUBLE-STRUCK N-ARY SUMMATION gets mirrored, but its glyph is not replaced by any other character's glyph. Or are you claiming that left-to-right U+2140 and right-to-left U+2140 are two different characters? > > > Thus, your reasons make no sense to me, because a character's > > > shape, any character's shape, be it L, R, AL, or anything else, > > > is immutable. > > > > So go back and reread. > > Did that; still no sense. Because you still seem not to understand the concept of mirroring. It isn't just for characters that have a Bidi_Mirroring_Glyph property value other than <none>. > > > > Where we may part company is in our view of Hebrew text (no > > > > Arabic numbers) with parentheses in a right-to-left paragraph. > > > > I think such text is really just as unidirectional as > > > > equivalent Latin text in a left-to-right paragraph. > > My example <snip> is: > > > כרטיס אשראי / דביט (לא אמריקן אקספרס ולא דיינרס) > > > > > However, one needs the UBA to sort out the rendering of the > > > > parentheses in the Hebrew text. > > > > > Not really, you can short-cut it, the same as in strictly > > > left-to-right text. > > > > It's the UBA that mandates that the opening and closing parentheses > > be rendered like right and left parentheses respectively rather > > than like left and right parentheses. > > Mirroring comes after layout in the UBA, as you pointed out, and the > short-cuts I mentioned are about layout, not about mirroring. So irrelevant. I take it we now agree that the right shape for the parentheses for the unidirectional right-to-left example is derived by the UBA. > > > > Indeed, one may rely on the bidi algorithm to declare the Latin > > > > example unidirectional. > > > > > > One might, but to what purpose and goal? > > > > A right-to-left paragraph consisting of the two characters "(a" > > would be bidirectional and have a parenthesis on the right; a > > left-to-right paragraph with the same content would have a > > parenthesis on the left. If there is no higher-level protocol in effect, the 'first strong character' rule (Rules P2 and P3 of the UBA) declares that the paragraph will be a left-to-right paragraph and will look like "(a". Had it been declared a right-to-left paragraph by a higher-level protocol, it would look like "a)". Thus the UBA has a rôle even for unidirectional left-to-right text. Richard.
