<html> <head> <style></style></head> <body class='hmmessage'><div dir='ltr'> Hi JK: Thanks your reply. But, in windows 7, the <U+0628,U+06C2,U+06C2> and <U+0628,U+06C1, U+0654,U+06C2> will be rendered as different glyphs, refer to the attachment. I use the "msuighur.ttf" font file of win 7 to display such text, there is no medial glyph for U+06C2 in the font file. It seems win7 shape engine will treat U+062C as single joining. I also check other open source font file, example: DroidSansArabic.ttf, there is no medial glyph for U+06C2. So it seems most of font not include medial glyph for U+062C. I think it better that treat U+062C as a single joining same as win7 shape engine. Br, Dean <DIV> <DIV id=SkyDrivePlaceholder></DIV>> Date: Thu, 12 Jul 2012 08:45:31 +0100 > From: jfkthame@googlemail.com > To: harfbuzz@lists.freedesktop.org > Subject: Re: [HarfBuzz] HEH GOAL WITH HAMZA ABOVE(0x06C2) error in arabic > > On 12/7/12 04:12, datao zhang wrote: > > Hi Behdad: > > When i try to draw the text "U+0628,U+06C2,U+06C2,U+0020" with harfbuzz, > > i find it is rendered differently in windows 7. please see attachment > > file. After checking the hb-ot-shape-complex-arabic-table.hh, I found > > U+06C2 joining type was JOINING_TYPE_D (double joining). I don’t know > > why Unicode specifies it double joining, it really does not make any > > sense. At least, when render the text, it should be treated as single > > joining type. > > U+06C2 is classified as double-joining because it has a canonical > decomposition to <U+06C1, U+0654>, and U+06C1 is double-joining. If > U+06C2 were right-joining, we'd have a situation where equivalent text > sequences would have different joining behaviors, so that a canonical > normalization process might unexpectedly alter the rendering. > > While I agree that the various HEH-related characters in Unicode are a > confusing mess, the various compatibility and stability requirements, as > well as the different usage patterns needed for various languages and > regions, make it difficult to see how we could "fix" them. > > The broken-looking result you're getting from harfbuzz happens because > the font used does not have a 'medi' glyph for the U+06C2 character. > This is a font bug. > > To reliably produce the "windows 7" result shown in your attachment, I > believe the correct text sequence would be <U+0628, U+06C2, U+200C, U+06C2>. > > JK > _______________________________________________ > HarfBuzz mailing list > HarfBuzz@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/harfbuzz </DIV> </div></body> </html>