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[Indic] Reoder pre-base reordering Ra 

Brings down Malayalam failures from 14% down to 3%.
This commit is contained in:
Behdad Esfahbod 2012-07-16 15:49:08 -04:00
parent 1a1dbe9a27
commit 78818124b1
1 changed files with 29 additions and 13 deletions
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42
src/hb-ot-shape-complex-indic.cc
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@ -809,27 +809,43 @@ final_reordering_syllable (hb_buffer_t *buffer,
*
* If a pre-base reordering consonant is found, reorder it according to
* the following rules:
*
* 1. Only reorder a glyph produced by substitution during application
* of the <pref> feature. (Note that a font may shape a Ra consonant with
* the feature generally but block it in certain contexts.)
*
* 2. Try to find a target position the same way as for pre-base matra.
* If it is found, reorder pre-base consonant glyph.
*
* 3. If position is not found, reorder immediately before main
* consonant.
*/
/* XXX */
if (pref_mask && base + 1 < end) /* Otherwise there can't be any pre-base reordering Ra. */
{
/* 1. Only reorder a glyph produced by substitution during application
* of the <pref> feature. (Note that a font may shape a Ra consonant with
* the feature generally but block it in certain contexts.)
*/
if ((info[base + 1].mask & pref_mask) != 0 &&
(base + 2 == end ||
(info[base + 2].mask & pref_mask) == 0))
{
/* Found a pre-base reordering Ra produced by substitution during application of the
* <pref> feature. */
/*
* 2. Try to find a target position the same way as for pre-base matra.
* If it is found, reorder pre-base consonant glyph.
*
* 3. If position is not found, reorder immediately before main
* consonant.
*/
unsigned int new_pos = base;
while (new_pos > start + 1 &&
!(FLAG (info[new_pos - 1].indic_category()) & (FLAG (OT_M) | FLAG (OT_H))))
new_pos--;
if (new_pos > start && info[new_pos - 1].indic_category() == OT_H)
/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
if (new_pos < end && is_joiner (info[new_pos]))
new_pos++;
{
unsigned int old_pos = base + 1;
hb_glyph_info_t tmp = info[old_pos];
memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
info[new_pos] = tmp;
start_of_last_cluster = MIN (new_pos, start_of_last_cluster);
}
}
}