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In glyf subsetting add suport for writing out a short loca table when possible.

This commit is contained in:
Garret Rieger 2018-02-09 18:41:21 -08:00
parent 9275bd03ea
commit d18decd201
1 changed files with 33 additions and 9 deletions
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42
src/hb-subset-glyf.cc
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@ -32,7 +32,8 @@
bool
_calculate_glyf_and_loca_prime_size (const OT::glyf::accelerator_t &glyf,
hb_auto_array_t<unsigned int> &glyph_ids,
unsigned int *glyf_size /* OUT */,
bool *use_short_loca, /* OUT */
unsigned int *glyf_size, /* OUT */
unsigned int *loca_size /* OUT */)
{
unsigned int total = 0;
@ -51,23 +52,37 @@ _calculate_glyf_and_loca_prime_size (const OT::glyf::accelerator_t &glyf,
}
*glyf_size = total;
*loca_size = (count + 1) * sizeof(OT::HBUINT32);
*use_short_loca = (total <= 131070);
*loca_size = (count + 1)
* (*use_short_loca ? sizeof(OT::HBUINT16) : sizeof(OT::HBUINT32));
DEBUG_MSG(SUBSET, nullptr, "preparing to subset glyf: final size %d, loca size %d, using %s loca",
total,
*loca_size,
*use_short_loca ? "short" : "long");
return true;
}
void
_write_loca_entry (unsigned int id, unsigned int offset, bool is_short, void *loca_prime) {
if (is_short) {
((OT::HBUINT16*) loca_prime) [id].set (offset / 2);
} else {
((OT::HBUINT32*) loca_prime) [id].set (offset);
}
}
bool
_write_glyf_and_loca_prime (const OT::glyf::accelerator_t &glyf,
const char *glyf_data,
hb_auto_array_t<unsigned int> &glyph_ids,
bool use_short_loca,
int glyf_prime_size,
char *glyf_prime_data /* OUT */,
int loca_prime_size,
char *loca_prime_data /* OUT */)
{
// TODO(grieger): Handle the missing character glyf and outline.
char *glyf_prime_data_next = glyf_prime_data;
OT::HBUINT32 *loca_prime = (OT::HBUINT32*) loca_prime_data;
hb_codepoint_t next_glyph = -1;
hb_codepoint_t new_glyph_id = 0;
@ -81,7 +96,8 @@ _write_glyf_and_loca_prime (const OT::glyf::accelerator_t &glyf,
int length = end_offset - start_offset;
memcpy (glyf_prime_data_next, glyf_data + start_offset, length);
loca_prime[new_glyph_id].set(start_offset);
_write_loca_entry (i, start_offset, use_short_loca, loca_prime_data);
glyf_prime_data_next += length;
new_glyph_id++;
@ -89,7 +105,7 @@ _write_glyf_and_loca_prime (const OT::glyf::accelerator_t &glyf,
// Add the last loca entry which doesn't correspond to a specific glyph
// but identifies the end of the last glyphs data.
loca_prime[new_glyph_id].set(end_offset);
_write_loca_entry (new_glyph_id, end_offset, use_short_loca, loca_prime_data);
return true;
}
@ -98,18 +114,20 @@ bool
_hb_subset_glyf_and_loca (const OT::glyf::accelerator_t &glyf,
const char *glyf_data,
hb_auto_array_t<unsigned int> &glyphs_to_retain,
bool *use_short_loca,
hb_blob_t **glyf_prime /* OUT */,
hb_blob_t **loca_prime /* OUT */)
{
// TODO(grieger): Sanity check writes to make sure they are in-bounds.
// TODO(grieger): Sanity check allocation size for the new table.
// TODO(grieger): Don't fail on bad offsets, just dump them.
// TODO(grieger): Support short loca output.
unsigned int glyf_prime_size;
unsigned int loca_prime_size;
if (unlikely (!_calculate_glyf_and_loca_prime_size (glyf,
glyphs_to_retain,
use_short_loca,
&glyf_prime_size,
&loca_prime_size))) {
return false;
@ -118,6 +136,7 @@ _hb_subset_glyf_and_loca (const OT::glyf::accelerator_t &glyf,
char *glyf_prime_data = (char *) calloc (glyf_prime_size, 1);
char *loca_prime_data = (char *) calloc (loca_prime_size, 1);
if (unlikely (!_write_glyf_and_loca_prime (glyf, glyf_data, glyphs_to_retain,
*use_short_loca,
glyf_prime_size, glyf_prime_data,
loca_prime_size, loca_prime_data))) {
free (glyf_prime_data);
@ -157,7 +176,12 @@ hb_subset_glyf_and_loca (hb_subset_plan_t *plan,
OT::glyf::accelerator_t glyf;
glyf.init(face);
bool result = _hb_subset_glyf_and_loca (glyf, glyf_data, plan->gids_to_retain_sorted, glyf_prime, loca_prime);
bool result = _hb_subset_glyf_and_loca (glyf,
glyf_data,
plan->gids_to_retain_sorted,
use_short_loca,
glyf_prime,
loca_prime);
glyf.fini();
*use_short_loca = false;