- From: Najib Tounsi <ntounsi@gmail.com>
- Date: Fri, 20 Jun 2014 18:34:56 +0100
- To: "Phillips, Addison" <addison@lab126.com>, Asmus Freytag <asmusf@ix.netcom.com>, Matitiahu Allouche <matitiahu.allouche@gmail.com>, "www-international@w3.org" <www-international@w3.org>
On 6/19/14 8:44 PM, Phillips, Addison wrote: >> On 6/19/2014 11:27 AM, Najib Tounsi wrote: >>> On 6/19/14 2:51 PM, Matitiahu Allouche wrote: >>>> 11) In 2.2 table of Compatibility Equivalence, the third example is >>>> labelled "Cursive forms". I think that this would be better labelled >>>> "character shapes". Rationale: the example shows various shapes of an >>>> Arabic letter. But similar examples could be taken from final versus >>>> non-final shapes of some Hebrew letters, or from the final versus >>>> non-final shapes of the Greek sigma letter. Hebrew and Greek are not >>>> cursive scripts, so the issue here is having position-dependent >>>> shapes, not cursiveness. >> The Greek final sigma uses a different character code which is not a >> compatibility equivalent. >> >> The reason is that, unlike Arabic positional shaping, the selection of the final >> form cannot be determined algorithmically at rendering time and would >> otherwise introduce the need to use ZWNJ with Greek; not a good tradeoff. >> >> Whatever example is used needs to be limited to cases of automatic shape >> selection at rendering. >> > Context matters here. The table is not merely one containing characters that use contextual shaping. These are *specifically* characters with compatibility decompositions in Unicode and the table is illustrating the various kinds of compatibility decomposition. I tend to agree with Mati's comment that "cursive forms" is not that accurate a label. In practice only Arabic uses <initial>, <medial>, <final>, and <isolated> decompositions, though, so the other offered examples are not what the table is meant to illustrate. The items in the table are the four compatibility variations of ARABIC LETTER NOON (U+0646). Actually, you use codepoints in the zone "Arabic presentation Form B" to have the desired shape (isolated, final, initial and medial) for the Arabic characters (e.g. U+FEE5, U+FEE6, U+FEE7 and U+FEE8 for the ARABIC LETTER NOON). But for some characters (Beh U+0628, teh U+062A, noon U+0646,…) some fonts in some browsers don't render the difference between isolated and final forms and between initial and medial forms. I suggest to use the ARABIC LETTER HEH (U+FEE9, U+FEEA, U+FEEB and U+FEEC) for example. Or ARBIC LETTER AIN (U+FEC9, U+FECA, U+FECB and U+FECC) in stead of NOON. > Note that this table is identical to Figure 2 in UAX#15. Seems they use the Tahoma font. It renders correctly the shapes of the ARABIC LETTER NOON Regards, Najib > > Addison
Received on Friday, 20 June 2014 17:27:36 UTC