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[buffer] Optimize _infos_set_glyph_flags to avoid O(n^2) behavior 

85be877925 (commitcomment-99547060)
This commit is contained in:
Behdad Esfahbod 2023-02-06 15:27:13 -07:00
parent 0b97ac39ac
commit 30b84faba7
1 changed files with 38 additions and 6 deletions
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32
src/hb-buffer.hh
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@ -580,6 +580,15 @@ struct hb_buffer_t
unsigned int start, unsigned int end,
unsigned int cluster,
hb_mask_t mask)
{
if (unlikely (start == end))
return;
unsigned cluster_first = info[start].cluster;
unsigned cluster_last = info[end - 1].cluster;
if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_CHARACTERS ||
(cluster != cluster_first && cluster != cluster_last))
{
for (unsigned int i = start; i < end; i++)
if (cluster != infos[i].cluster)
@ -587,6 +596,29 @@ struct hb_buffer_t
scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
infos[i].mask |= mask;
}
return;
}
/* Monotone clusters */
if (cluster == cluster_first)
{
for (unsigned int i = end; start < i && infos[i - 1].cluster != cluster_first; i--)
if (cluster != infos[i - 1].cluster)
{
scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
infos[i - 1].mask |= mask;
}
}
else /* cluster == cluster_last */
{
for (unsigned int i = start; i < end && infos[i].cluster != cluster_last; i++)
if (cluster != infos[i].cluster)
{
scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GLYPH_FLAGS;
infos[i].mask |= mask;
}
}
}
unsigned
_infos_find_min_cluster (const hb_glyph_info_t *infos,