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Respect user's wish if they set rand feature manually 

Except if the set it to 1, which would mean "randomize"... Ugly.
This commit is contained in:
Behdad Esfahbod 2018-09-10 16:36:05 +02:00
parent 80de4bcd26
commit cc1c4fdf88
1 changed files with 16 additions and 14 deletions
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30
src/hb-ot-layout-gsub-table.hh
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@ -534,24 +534,26 @@ struct AlternateSet
if (unlikely (!count)) return_trace (false);
if (c->random)
hb_mask_t glyph_mask = c->buffer->cur().mask;
hb_mask_t lookup_mask = c->lookup_mask;
/* Note: This breaks badly if two features enabled this lookup together. */
unsigned int shift = hb_ctz (lookup_mask);
unsigned int alt_index = ((lookup_mask & glyph_mask) >> shift);
if (unlikely (alt_index > count || alt_index == 0)) return_trace (false);
/* This is ugly... If alt_index is 1, we take it as "on", and randomize
* feature if it is the rand feature. If it's > 1, it's a user-set value
* for sure, so respect it. So, user cannot set rand=1 and expect it to
* choose the first alternate... */
if (alt_index == 1 && c->random)
{
c->random_state = (0x5DEECE66Dull * c->random_state + 11) & (((uint64_t) 1 << 48) - 1);
c->replace_glyph (alternates[(c->random_state >> 32) % count]);
alt_index = (c->random_state >> 32) % count + 1;
}
else
{
hb_mask_t glyph_mask = c->buffer->cur().mask;
hb_mask_t lookup_mask = c->lookup_mask;
/* Note: This breaks badly if two features enabled this lookup together. */
unsigned int shift = hb_ctz (lookup_mask);
unsigned int alt_index = ((lookup_mask & glyph_mask) >> shift);
if (unlikely (alt_index > count || alt_index == 0)) return_trace (false);
c->replace_glyph (alternates[alt_index - 1]);
}
c->replace_glyph (alternates[alt_index - 1]);
return_trace (true);
}