harfbuzz/src/hb-subset-glyf.cc

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/*
* Copyright © 2018 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Garret Rieger, Roderick Sheeter
*/
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#include "hb-open-type-private.hh"
#include "hb-ot-glyf-table.hh"
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#include "hb-set.h"
#include "hb-subset-glyf.hh"
#include "hb-subset-plan.hh"
static bool
_calculate_glyf_and_loca_prime_size (const OT::glyf::accelerator_t &glyf,
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hb_prealloced_array_t<hb_codepoint_t> &glyph_ids,
hb_bool_t drop_hints,
bool *use_short_loca /* OUT */,
unsigned int *glyf_size /* OUT */,
unsigned int *loca_size /* OUT */,
hb_prealloced_array_t<unsigned int> *instruction_ranges /* OUT */)
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{
unsigned int total = 0;
for (unsigned int i = 0; i < glyph_ids.len; i++)
{
hb_codepoint_t next_glyph = glyph_ids[i];
*(instruction_ranges->push()) = 0;
*(instruction_ranges->push()) = 0;
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unsigned int start_offset, end_offset;
if (unlikely (!glyf.get_offsets(next_glyph, /* trim */ true, &start_offset, &end_offset)))
{
DEBUG_MSG(SUBSET, nullptr, "Invalid gid %d", next_glyph);
continue;
}
if (end_offset - start_offset < OT::glyf::GlyphHeader::static_size)
continue; /* 0-length glyph */
unsigned int instruction_start = 0, instruction_end = 0;
if (drop_hints)
{
if (unlikely (!glyf.get_instruction_offsets(start_offset, end_offset,
&instruction_start, &instruction_end)))
{
DEBUG_MSG(SUBSET, nullptr, "Unable to get instruction offsets for %d", next_glyph);
return false;
}
instruction_ranges->array[i * 2] = instruction_start;
instruction_ranges->array[i * 2 + 1] = instruction_end;
}
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total += end_offset - start_offset - (instruction_end - instruction_start);
/* round2 so short loca will work */
total += total % 2;
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}
*glyf_size = total;
*use_short_loca = (total <= 131070);
*loca_size = (glyph_ids.len + 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");
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return true;
}
static bool
_write_loca_entry (unsigned int id,
unsigned int offset,
bool is_short,
void *loca_prime,
unsigned int loca_size)
{
unsigned int entry_size = is_short ? sizeof (OT::HBUINT16) : sizeof (OT::HBUINT32);
if ((id + 1) * entry_size <= loca_size)
{
if (is_short) {
((OT::HBUINT16*) loca_prime) [id].set (offset / 2);
} else {
((OT::HBUINT32*) loca_prime) [id].set (offset);
}
return true;
}
// Offset was not written because the write is out of bounds.
DEBUG_MSG (SUBSET,
nullptr,
"WARNING: Attempted to write an out of bounds loca entry at index %d. Loca size is %d.",
id,
loca_size);
return false;
}
static void
_update_components (hb_subset_plan_t * plan,
char * glyph_start,
unsigned int length)
{
OT::glyf::CompositeGlyphHeader::Iterator iterator;
if (OT::glyf::CompositeGlyphHeader::get_iterator (glyph_start,
length,
&iterator))
{
do
{
hb_codepoint_t new_gid;
if (!hb_subset_plan_new_gid_for_old_id (plan,
iterator.current->glyphIndex,
&new_gid))
continue;
((OT::glyf::CompositeGlyphHeader *) iterator.current)->glyphIndex.set (new_gid);
} while (iterator.move_to_next());
}
}
static bool
_write_glyf_and_loca_prime (hb_subset_plan_t *plan,
const OT::glyf::accelerator_t &glyf,
const char *glyf_data,
bool use_short_loca,
hb_prealloced_array_t<unsigned int> &instruction_ranges,
unsigned int glyf_prime_size,
char *glyf_prime_data /* OUT */,
unsigned int loca_prime_size,
char *loca_prime_data /* OUT */)
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{
hb_prealloced_array_t<hb_codepoint_t> &glyph_ids = plan->gids_to_retain_sorted;
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char *glyf_prime_data_next = glyf_prime_data;
bool success = true;
for (unsigned int i = 0; i < glyph_ids.len; i++)
{
unsigned int start_offset, end_offset;
if (unlikely (!glyf.get_offsets (glyph_ids[i], /* trim */ true, &start_offset, &end_offset)))
end_offset = start_offset = 0;
unsigned int instruction_start = instruction_ranges[i * 2];
unsigned int instruction_end = instruction_ranges[i * 2 + 1];
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int length = end_offset - start_offset - (instruction_end - instruction_start);
length += length % 2;
if (glyf_prime_data_next + length > glyf_prime_data + glyf_prime_size)
{
DEBUG_MSG (SUBSET,
nullptr,
"WARNING: Attempted to write an out of bounds glyph entry for gid %d (length %d)",
i, length);
return false;
}
if (instruction_start == instruction_end)
memcpy (glyf_prime_data_next, glyf_data + start_offset, length);
else
{
memcpy (glyf_prime_data_next, glyf_data + start_offset, instruction_start - start_offset);
memcpy (glyf_prime_data_next + instruction_start - start_offset, glyf_data + instruction_end, end_offset - instruction_end);
/* if the instructions end at the end this was a composite glyph */
if (instruction_end == end_offset)
; // TODO(rsheeter) remove WE_HAVE_INSTRUCTIONS from last flags
else
/* zero instruction length, which is just before instruction_start */
memset (glyf_prime_data_next + instruction_start - start_offset - 2, 0, 2);
}
success = success && _write_loca_entry (i,
glyf_prime_data_next - glyf_prime_data,
use_short_loca,
loca_prime_data,
loca_prime_size);
_update_components (plan, glyf_prime_data_next, length);
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glyf_prime_data_next += length;
}
success = success && _write_loca_entry (glyph_ids.len,
glyf_prime_data_next - glyf_prime_data,
use_short_loca,
loca_prime_data,
loca_prime_size);
return success;
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}
static bool
_hb_subset_glyf_and_loca (const OT::glyf::accelerator_t &glyf,
const char *glyf_data,
hb_subset_plan_t *plan,
bool *use_short_loca,
hb_blob_t **glyf_prime /* OUT */,
hb_blob_t **loca_prime /* OUT */)
{
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// TODO(grieger): Sanity check allocation size for the new table.
hb_prealloced_array_t<hb_codepoint_t> &glyphs_to_retain = plan->gids_to_retain_sorted;
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unsigned int glyf_prime_size;
unsigned int loca_prime_size;
hb_prealloced_array_t<unsigned int> instruction_ranges;
instruction_ranges.init();
if (unlikely (!_calculate_glyf_and_loca_prime_size (glyf,
glyphs_to_retain,
plan->drop_hints,
use_short_loca,
&glyf_prime_size,
&loca_prime_size,
&instruction_ranges))) {
instruction_ranges.finish();
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return false;
}
char *glyf_prime_data = (char *) calloc (1, glyf_prime_size);
char *loca_prime_data = (char *) calloc (1, loca_prime_size);
if (unlikely (!_write_glyf_and_loca_prime (plan, glyf, glyf_data,
*use_short_loca,
instruction_ranges,
glyf_prime_size, glyf_prime_data,
loca_prime_size, loca_prime_data))) {
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free (glyf_prime_data);
free (loca_prime_data);
instruction_ranges.finish();
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return false;
}
instruction_ranges.finish();
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*glyf_prime = hb_blob_create (glyf_prime_data,
glyf_prime_size,
HB_MEMORY_MODE_READONLY,
glyf_prime_data,
free);
*loca_prime = hb_blob_create (loca_prime_data,
loca_prime_size,
HB_MEMORY_MODE_READONLY,
loca_prime_data,
free);
return true;
}
/**
* hb_subset_glyf:
* Subsets the glyph table according to a provided plan.
*
* Return value: subsetted glyf table.
*
* Since: 1.7.5
**/
bool
hb_subset_glyf_and_loca (hb_subset_plan_t *plan,
bool *use_short_loca, /* OUT */
hb_blob_t **glyf_prime, /* OUT */
hb_blob_t **loca_prime /* OUT */)
{
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hb_blob_t *glyf_blob = OT::Sanitizer<OT::glyf>().sanitize (plan->source->reference_table (HB_OT_TAG_glyf));
const char *glyf_data = hb_blob_get_data(glyf_blob, nullptr);
OT::glyf::accelerator_t glyf;
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glyf.init(plan->source);
bool result = _hb_subset_glyf_and_loca (glyf,
glyf_data,
plan,
use_short_loca,
glyf_prime,
loca_prime);
glyf.fini();
return result;
}