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[subset] Tweak hint stripping

This commit is contained in:
rsheeter 2019-05-11 23:16:40 -07:00 committed by Rod Sheeter
parent 3a4c928fcf
commit 9d09ac13a1
1 changed files with 33 additions and 13 deletions
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46
src/hb-ot-glyf-table.hh
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@ -107,7 +107,7 @@ struct glyf
const hb_subset_plan_t *plan)
{
TRACE_SERIALIZE (this);
// pad glyphs to 2-byte boundaries to permit short loca
HBUINT8 pad;
pad = 0;
+ it
@ -124,10 +124,14 @@ struct glyf
}
_fix_component_gids (plan, dest_glyph);
if (plan->drop_hints)
{
// we copied the glyph w/o instructions, just need to zero instruction length
_zero_instruction_length (dest_glyph);
}
});
// Things old impl did we now don't:
// TODO set instruction length to 0 where appropriate
// TODO _remove_composite_instruction_flag
return_trace (true);
@ -145,6 +149,9 @@ struct glyf
// make an iterator of per-glyph hb_bytes_t.
// unpadded, hints removed if that was requested.
// TODO log shows we redo a bunch of the work here; should sink this at end?
auto glyphs =
+ hb_range (c->plan->num_output_glyphs ())
| hb_map ([&] (hb_codepoint_t new_gid) {
@ -163,15 +170,16 @@ struct glyf
}
hb_bytes_t glyph (((const char *) this) + start_offset, end_offset - start_offset);
// if dropping hints, find hints region and subtract it
unsigned int instruction_length = 0;
// if dropping hints, find hints region and chop it off the end
if (c->plan->drop_hints) {
unsigned int instruction_length = 0;
if (!glyf.get_instruction_length (glyph, &instruction_length))
{
// TODO signal fatal error
DEBUG_MSG(SUBSET, nullptr, "Unable to read instruction length for new_gid %d", new_gid);
return hb_bytes_t ();
}
DEBUG_MSG(SUBSET, nullptr, "new_gid %d drop %d instruction bytes from %d byte glyph", new_gid, instruction_length, glyph.length);
glyph = hb_bytes_t (&glyph, glyph.length - instruction_length);
}
@ -233,6 +241,18 @@ struct glyf
}
}
static void
_zero_instruction_length (hb_bytes_t glyph)
{
const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (&glyph, 0);
int16_t num_contours = (int16_t) glyph_header.numberOfContours;
if (num_contours > 0)
{
const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (&glyph, GlyphHeader::static_size + 2 * num_contours);
(HBUINT16 &) instruction_length = 0;
}
}
static bool
_add_head_and_set_loca_version (hb_subset_plan_t *plan, bool use_short_loca)
{
@ -517,17 +537,18 @@ struct glyf
unsigned int * length /* OUT */) const
{
/* Empty glyph; no instructions. */
if (glyph.get_size() < GlyphHeader::static_size)
if (glyph.length < GlyphHeader::static_size)
{
*length = 0;
return true;
// only 0 byte glyphs are healthy when missing GlyphHeader
return glyph.length == 0;
}
unsigned int start = glyph.length;
unsigned int end = glyph.length;
const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (&glyph, 0);
int16_t num_contours = (int16_t) glyph_header.numberOfContours;
if (num_contours < 0)
{
unsigned int start = glyph.length;
unsigned int end = glyph.length;
CompositeGlyphHeader::Iterator composite_it;
if (unlikely (!CompositeGlyphHeader::get_iterator (&glyph, glyph.length, &composite_it))) return false;
const CompositeGlyphHeader *last;
@ -542,6 +563,7 @@ struct glyf
DEBUG_MSG(SUBSET, nullptr, "Invalid instruction offset, %d is outside %d byte buffer", start, glyph.length);
return false;
}
*length = end - start;
}
else
{
@ -552,16 +574,14 @@ struct glyf
return false;
}
const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (glyf_table, instruction_length_offset);
unsigned int start = instruction_length_offset + 2;
unsigned int end = start + (uint16_t) instruction_length;
if (unlikely (end > glyph.length)) // Out of bounds of the current glyph
const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (&glyph, instruction_length_offset);
if (unlikely (instruction_length_offset + instruction_length > glyph.length)) // Out of bounds of the current glyph
{
DEBUG_MSG(SUBSET, nullptr, "The instructions array overruns the glyph's boundaries.");
return false;
}
*length = (uint16_t) instruction_length;
}
*length = end - start;
return true;
}