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[subset] Allocate same size as source table for GSUB/GPOS/name

This commit is contained in:
Behdad Esfahbod 2022-05-11 13:05:41 -06:00
parent 2e7f1ae48f
commit c78d8ba60b
1 changed files with 11 additions and 5 deletions
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16
src/hb-subset.cc
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@ -79,12 +79,14 @@ using OT::Layout::GSUB::GSUB;
*/
static unsigned
_plan_estimate_subset_table_size (hb_subset_plan_t *plan, unsigned table_len)
_plan_estimate_subset_table_size (hb_subset_plan_t *plan,
unsigned table_len,
bool same_size)
{
unsigned src_glyphs = plan->source->get_num_glyphs ();
unsigned dst_glyphs = plan->glyphset ()->get_population ();
if (unlikely (!src_glyphs))
if (unlikely (!src_glyphs) || same_size)
return 512 + table_len;
return 512 + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs));
@ -167,9 +169,13 @@ _subset (hb_subset_plan_t *plan, hb_vector_t<char> &buf)
return false;
}
/* TODO Not all tables are glyph-related. 'name' table size for example should not be
* affected by number of glyphs. Accommodate that. */
unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob->length);
/* Tables that we want to allocate same space as the source table. For GSUB/GPOS it's
* because those are expensive to subset, so giving them more room is fine. */
bool same_size_table = TableType::tableTag == HB_OT_TAG_GSUB ||
TableType::tableTag == HB_OT_TAG_GPOS ||
TableType::tableTag == HB_OT_TAG_name;
unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob->length, same_size_table);
DEBUG_MSG (SUBSET, nullptr,
"OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size);
if (unlikely (!buf.alloc (buf_size)))