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Reorder combining-class to better suit Arabic shadda mark-mark positioning 

As reported by Khaled on the list:

"After the introduction of canonical reordering of combining marks
(commit 34c22f8), I'm no longer able to do mark/mark substitution or
positioning for mark sequences that involve shadda as a first mark (or
most interesting sequences at least).

"After some digging, it turned out that shadda have a ccc=33 while most
Arabic marks that combine with it have a lower ccc value, which results
in the shadda being reordered after the other mark which,
unsurprisingly, breaks my contextual substitution and mkmk anchors."

See:

http://unicode.org/faq/normalization.html#8
http://unicode.org/faq/normalization.html#9
This commit is contained in:
Behdad Esfahbod 2011-08-25 09:08:53 +02:00
parent 74ef81a0b0
commit 3007ffa9e5
1 changed files with 17 additions and 1 deletions
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18
src/hb-ot-shape-private.hh
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@ -98,11 +98,27 @@ is_variation_selector (hb_codepoint_t unicode)
(unicode >= 0xE0100 && unicode <= 0xE01EF)); /* VARIATION SELECTOR-17..256 */
}
static inline unsigned int
_hb_unicode_modified_combining_class (hb_unicode_funcs_t *ufuncs,
hb_codepoint_t unicode)
{
int c = hb_unicode_combining_class (ufuncs, unicode);
/* Modify the combining-class to suit Arabic better. See:
* http://unicode.org/faq/normalization.html#8
* http://unicode.org/faq/normalization.html#9
*/
if (unlikely (hb_in_range<int> (c, 27, 33)))
c = c == 33 ? 27 : c + 1;
return c;
}
static inline void
hb_glyph_info_set_unicode_props (hb_glyph_info_t *info, hb_unicode_funcs_t *unicode)
{
info->general_category() = hb_unicode_general_category (unicode, info->codepoint);
info->combining_class() = hb_unicode_combining_class (unicode, info->codepoint);
info->combining_class() = _hb_unicode_modified_combining_class (unicode, info->codepoint);
}
HB_INTERNAL void _hb_set_unicode_props (hb_buffer_t *buffer);