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Add implementation of glyf subsetting.

This commit is contained in:
Garret Rieger 2018-02-07 13:09:54 -08:00 committed by Behdad Esfahbod
parent 05d65baa1b
commit 0a5d1440f8
1 changed files with 76 additions and 5 deletions
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81
src/hb-subset-glyf.cc
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@ -24,9 +24,56 @@
* Google Author(s): Garret Rieger
*/
#include "hb-open-type-private.hh"
#include "hb-ot-glyf-table.hh"
#include "hb-set.h"
#include "hb-subset-glyf.hh"
bool
calculate_glyf_prime_size (const OT::glyf::accelerator_t &glyf,
hb_set_t *glyph_ids,
unsigned int *size /* OUT */)
{
unsigned int total = 0;
hb_codepoint_t next_glyph = -1;
while (hb_set_next(glyph_ids, &next_glyph)) {
unsigned int start_offset, end_offset;
if (!glyf.get_offsets (next_glyph, &start_offset, &end_offset)) {
*size = 0;
return false;
}
total += end_offset - start_offset;
}
*size = total;
return true;
}
bool
write_glyf_prime (const OT::glyf::accelerator_t &glyf,
const char *glyf_data,
hb_set_t *glyph_ids,
int glyf_prime_size,
char *glyf_prime_data /* OUT */)
{
char *glyf_prime_data_next = glyf_prime_data;
hb_codepoint_t next_glyph = -1;
while (hb_set_next(glyph_ids, &next_glyph)) {
unsigned int start_offset, end_offset;
if (!glyf.get_offsets (next_glyph, &start_offset, &end_offset)) {
return false;
}
int length = end_offset - start_offset;
memcpy (glyf_prime_data_next, glyf_data + start_offset, length);
glyf_prime_data_next += length;
}
return true;
}
/**
* hb_subset_glyf:
* Subsets the glyph table according to a provided plan.
@ -40,13 +87,37 @@ hb_subset_glyf (hb_subset_plan_t *plan,
hb_face_t *face,
hb_blob_t **glyf_prime /* OUT */)
{
OT::glyf::accelerator_t glyf_accelerator;
glyf_accelerator.init(face);
// TODO(grieger): Sanity check writes to make sure they are in-bounds.
// TODO(grieger): Sanity check allocation size for the new table.
// TODO(grieger): Subset loca simultaneously.
// TODO
hb_blob_t *glyf_blob = OT::Sanitizer<OT::glyf>().sanitize (face->reference_table (HB_OT_TAG_glyf));
const char *glyf_data = hb_blob_get_data(glyf_blob, nullptr);
glyf_accelerator.fini();
OT::glyf::accelerator_t glyf;
glyf.init(face);
*glyf_prime = hb_blob_get_empty ();
unsigned int glyf_prime_size;
if (!calculate_glyf_prime_size (glyf,
plan->glyphs_to_retain,
&glyf_prime_size)) {
glyf.fini();
return false;
}
char *glyf_prime_data = (char *) calloc (glyf_prime_size, 1);
if (!write_glyf_prime (glyf, glyf_data, plan->glyphs_to_retain, glyf_prime_size,
glyf_prime_data)) {
glyf.fini();
free (glyf_prime_data);
return false;
}
glyf.fini();
*glyf_prime = hb_blob_create (glyf_prime_data,
glyf_prime_size,
HB_MEMORY_MODE_READONLY,
glyf_prime_data,
free);
return true;
}