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[subset] Limit the iterations of the closure algorithm. 

Prevents O(n^2) run times.
This commit is contained in:
Garret Rieger 2018-07-23 15:37:18 -07:00
parent 94759d4cf8
commit 85646fdadb
2 changed files with 11 additions and 1 deletions
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7
src/hb-ot-layout-common-private.hh
View File

@ -41,6 +41,13 @@
#ifndef HB_MAX_CONTEXT_LENGTH
#define HB_MAX_CONTEXT_LENGTH 64
#endif
#ifndef HB_CLOSURE_MAX_STAGES
/*
* The maximum number of times a lookup can be applied during shaping.
* Used to limit the number of iterations of the closure algorithm.
*/
#define HB_CLOSURE_MAX_STAGES 8
#endif
namespace OT {

5
src/hb-ot-layout.cc
View File

@ -971,6 +971,7 @@ hb_ot_layout_lookups_substitute_closure (hb_face_t *face,
OT::hb_closure_context_t c (face, glyphs, &done_lookups);
const OT::GSUB& gsub = _get_gsub (face);
unsigned int iteration_count = 0;
unsigned int glyphs_length;
do
{
@ -985,7 +986,9 @@ hb_ot_layout_lookups_substitute_closure (hb_face_t *face,
for (unsigned int i = 0; i < gsub.get_lookup_count (); i++)
gsub.get_lookup (i).closure (&c, i);
}
} while (glyphs_length != glyphs->get_population ());
iteration_count++;
} while (iteration_count <= HB_CLOSURE_MAX_STAGES
&& glyphs_length != glyphs->get_population ());
}
/*