483 lines
14 KiB
C++
483 lines
14 KiB
C++
/*
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* Copyright © 2015 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#ifndef HB_OT_GLYF_TABLE_HH
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#define HB_OT_GLYF_TABLE_HH
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#include "hb-open-type.hh"
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#include "hb-ot-head-table.hh"
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#include "hb-subset-glyf.hh"
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namespace OT {
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/*
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* loca -- Index to Location
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* https://docs.microsoft.com/en-us/typography/opentype/spec/loca
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*/
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#define HB_OT_TAG_loca HB_TAG('l','o','c','a')
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struct loca
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{
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friend struct glyf;
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static constexpr hb_tag_t tableTag = HB_OT_TAG_loca;
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bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
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{
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TRACE_SANITIZE (this);
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return_trace (true);
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}
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protected:
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UnsizedArrayOf<HBUINT8> dataZ; /* Location data. */
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public:
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DEFINE_SIZE_MIN (0); /* In reality, this is UNBOUNDED() type; but since we always
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* check the size externally, allow Null() object of it by
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* defining it _MIN instead. */
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};
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/*
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* glyf -- TrueType Glyph Data
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* https://docs.microsoft.com/en-us/typography/opentype/spec/glyf
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*/
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#define HB_OT_TAG_glyf HB_TAG('g','l','y','f')
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struct glyf
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{
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static constexpr hb_tag_t tableTag = HB_OT_TAG_glyf;
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bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
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{
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TRACE_SANITIZE (this);
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/* We don't check for anything specific here. The users of the
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* struct do all the hard work... */
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return_trace (true);
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}
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bool subset (hb_subset_plan_t *plan) const
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{
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hb_blob_t *glyf_prime = nullptr;
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hb_blob_t *loca_prime = nullptr;
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bool success = true;
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bool use_short_loca = false;
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if (hb_subset_glyf_and_loca (plan, &use_short_loca, &glyf_prime, &loca_prime)) {
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success = success && plan->add_table (HB_OT_TAG_glyf, glyf_prime);
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success = success && plan->add_table (HB_OT_TAG_loca, loca_prime);
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success = success && _add_head_and_set_loca_version (plan, use_short_loca);
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} else {
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success = false;
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}
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hb_blob_destroy (loca_prime);
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hb_blob_destroy (glyf_prime);
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return success;
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}
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static bool
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_add_head_and_set_loca_version (hb_subset_plan_t *plan, bool use_short_loca)
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{
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hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table<head> (plan->source);
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hb_blob_t *head_prime_blob = hb_blob_copy_writable_or_fail (head_blob);
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hb_blob_destroy (head_blob);
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if (unlikely (!head_prime_blob))
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return false;
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head *head_prime = (head *) hb_blob_get_data_writable (head_prime_blob, nullptr);
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head_prime->indexToLocFormat = use_short_loca ? 0 : 1;
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bool success = plan->add_table (HB_OT_TAG_head, head_prime_blob);
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hb_blob_destroy (head_prime_blob);
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return success;
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}
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struct GlyphHeader
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{
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HBINT16 numberOfContours; /* If the number of contours is
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* greater than or equal to zero,
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* this is a simple glyph; if negative,
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* this is a composite glyph. */
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FWORD xMin; /* Minimum x for coordinate data. */
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FWORD yMin; /* Minimum y for coordinate data. */
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FWORD xMax; /* Maximum x for coordinate data. */
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FWORD yMax; /* Maximum y for coordinate data. */
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DEFINE_SIZE_STATIC (10);
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};
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struct CompositeGlyphHeader
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{
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enum composite_glyph_flag_t {
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ARG_1_AND_2_ARE_WORDS = 0x0001,
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ARGS_ARE_XY_VALUES = 0x0002,
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ROUND_XY_TO_GRID = 0x0004,
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WE_HAVE_A_SCALE = 0x0008,
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MORE_COMPONENTS = 0x0020,
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WE_HAVE_AN_X_AND_Y_SCALE = 0x0040,
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WE_HAVE_A_TWO_BY_TWO = 0x0080,
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WE_HAVE_INSTRUCTIONS = 0x0100,
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USE_MY_METRICS = 0x0200,
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OVERLAP_COMPOUND = 0x0400,
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SCALED_COMPONENT_OFFSET = 0x0800,
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UNSCALED_COMPONENT_OFFSET = 0x1000
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};
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HBUINT16 flags;
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GlyphID glyphIndex;
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unsigned int get_size () const
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{
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unsigned int size = min_size;
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// arg1 and 2 are int16
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if (flags & ARG_1_AND_2_ARE_WORDS) size += 4;
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// arg1 and 2 are int8
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else size += 2;
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// One x 16 bit (scale)
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if (flags & WE_HAVE_A_SCALE) size += 2;
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// Two x 16 bit (xscale, yscale)
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else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) size += 4;
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// Four x 16 bit (xscale, scale01, scale10, yscale)
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else if (flags & WE_HAVE_A_TWO_BY_TWO) size += 8;
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return size;
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}
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struct Iterator
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{
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const char *glyph_start;
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const char *glyph_end;
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const CompositeGlyphHeader *current;
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bool move_to_next ()
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{
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if (current->flags & CompositeGlyphHeader::MORE_COMPONENTS)
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{
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const CompositeGlyphHeader *possible =
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&StructAfter<CompositeGlyphHeader, CompositeGlyphHeader> (*current);
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if (!in_range (possible))
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return false;
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current = possible;
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return true;
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}
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return false;
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}
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bool in_range (const CompositeGlyphHeader *composite) const
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{
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return (const char *) composite >= glyph_start
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&& ((const char *) composite + CompositeGlyphHeader::min_size) <= glyph_end
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&& ((const char *) composite + composite->get_size ()) <= glyph_end;
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}
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};
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static bool get_iterator (const char * glyph_data,
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unsigned int length,
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CompositeGlyphHeader::Iterator *iterator /* OUT */)
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{
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if (length < GlyphHeader::static_size)
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return false; /* Empty glyph; zero extents. */
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const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph_data, 0);
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if (glyph_header.numberOfContours < 0)
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{
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const CompositeGlyphHeader *possible =
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&StructAfter<CompositeGlyphHeader, GlyphHeader> (glyph_header);
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iterator->glyph_start = glyph_data;
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iterator->glyph_end = (const char *) glyph_data + length;
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if (!iterator->in_range (possible))
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return false;
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iterator->current = possible;
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return true;
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}
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return false;
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}
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DEFINE_SIZE_MIN (4);
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};
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struct accelerator_t
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{
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void init (hb_face_t *face)
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{
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memset (this, 0, sizeof (accelerator_t));
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const OT::head &head = *face->table.head;
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if (head.indexToLocFormat > 1 || head.glyphDataFormat != 0)
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/* Unknown format. Leave num_glyphs=0, that takes care of disabling us. */
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return;
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short_offset = 0 == head.indexToLocFormat;
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loca_table = hb_sanitize_context_t ().reference_table<loca> (face);
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glyf_table = hb_sanitize_context_t ().reference_table<glyf> (face);
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num_glyphs = hb_max (1u, loca_table.get_length () / (short_offset ? 2 : 4)) - 1;
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}
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void fini ()
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{
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loca_table.destroy ();
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glyf_table.destroy ();
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}
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/*
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* Returns true if the referenced glyph is a valid glyph and a composite glyph.
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* If true is returned a pointer to the composite glyph will be written into
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* composite.
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*/
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bool get_composite (hb_codepoint_t glyph,
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CompositeGlyphHeader::Iterator *composite /* OUT */) const
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{
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if (unlikely (!num_glyphs))
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return false;
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unsigned int start_offset, end_offset;
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if (!get_offsets (glyph, &start_offset, &end_offset))
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return false; /* glyph not found */
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return CompositeGlyphHeader::get_iterator ((const char *) this->glyf_table + start_offset,
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end_offset - start_offset,
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composite);
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}
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enum simple_glyph_flag_t {
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FLAG_ON_CURVE = 0x01,
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FLAG_X_SHORT = 0x02,
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FLAG_Y_SHORT = 0x04,
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FLAG_REPEAT = 0x08,
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FLAG_X_SAME = 0x10,
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FLAG_Y_SAME = 0x20,
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FLAG_RESERVED1 = 0x40,
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FLAG_RESERVED2 = 0x80
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};
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/* based on FontTools _g_l_y_f.py::trim */
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bool remove_padding (unsigned int start_offset,
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unsigned int *end_offset) const
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{
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if (*end_offset - start_offset < GlyphHeader::static_size) return true;
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const char *glyph = ((const char *) glyf_table) + start_offset;
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const char * const glyph_end = glyph + (*end_offset - start_offset);
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const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph, 0);
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int16_t num_contours = (int16_t) glyph_header.numberOfContours;
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if (num_contours < 0)
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/* Trimming for composites not implemented.
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* If removing hints it falls out of that. */
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return true;
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else if (num_contours > 0)
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{
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/* simple glyph w/contours, possibly trimmable */
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glyph += GlyphHeader::static_size + 2 * num_contours;
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if (unlikely (glyph + 2 >= glyph_end)) return false;
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uint16_t nCoordinates = (uint16_t) StructAtOffset<HBUINT16> (glyph - 2, 0) + 1;
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uint16_t nInstructions = (uint16_t) StructAtOffset<HBUINT16> (glyph, 0);
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glyph += 2 + nInstructions;
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if (unlikely (glyph + 2 >= glyph_end)) return false;
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unsigned int coordBytes = 0;
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unsigned int coordsWithFlags = 0;
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while (glyph < glyph_end)
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{
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uint8_t flag = (uint8_t) *glyph;
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glyph++;
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unsigned int repeat = 1;
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if (flag & FLAG_REPEAT)
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{
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if (glyph >= glyph_end)
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{
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DEBUG_MSG(SUBSET, nullptr, "Bad flag");
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return false;
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}
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repeat = ((uint8_t) *glyph) + 1;
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glyph++;
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}
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unsigned int xBytes, yBytes;
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xBytes = yBytes = 0;
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if (flag & FLAG_X_SHORT) xBytes = 1;
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else if ((flag & FLAG_X_SAME) == 0) xBytes = 2;
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if (flag & FLAG_Y_SHORT) yBytes = 1;
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else if ((flag & FLAG_Y_SAME) == 0) yBytes = 2;
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coordBytes += (xBytes + yBytes) * repeat;
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coordsWithFlags += repeat;
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if (coordsWithFlags >= nCoordinates)
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break;
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}
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if (coordsWithFlags != nCoordinates)
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{
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DEBUG_MSG(SUBSET, nullptr, "Expect %d coords to have flags, got flags for %d", nCoordinates, coordsWithFlags);
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return false;
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}
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glyph += coordBytes;
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if (glyph < glyph_end)
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*end_offset -= glyph_end - glyph;
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}
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return true;
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}
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bool get_offsets (hb_codepoint_t glyph,
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unsigned int *start_offset /* OUT */,
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unsigned int *end_offset /* OUT */) const
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{
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if (unlikely (glyph >= num_glyphs))
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return false;
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if (short_offset)
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{
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const HBUINT16 *offsets = (const HBUINT16 *) loca_table->dataZ.arrayZ;
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*start_offset = 2 * offsets[glyph];
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*end_offset = 2 * offsets[glyph + 1];
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}
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else
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{
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const HBUINT32 *offsets = (const HBUINT32 *) loca_table->dataZ.arrayZ;
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*start_offset = offsets[glyph];
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*end_offset = offsets[glyph + 1];
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}
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if (*start_offset > *end_offset || *end_offset > glyf_table.get_length ())
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return false;
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return true;
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}
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bool get_instruction_offsets (unsigned int start_offset,
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unsigned int end_offset,
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unsigned int *instruction_start /* OUT */,
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unsigned int *instruction_end /* OUT */) const
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{
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if (end_offset - start_offset < GlyphHeader::static_size)
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{
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*instruction_start = 0;
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*instruction_end = 0;
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return true; /* Empty glyph; no instructions. */
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}
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const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
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int16_t num_contours = (int16_t) glyph_header.numberOfContours;
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if (num_contours < 0)
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{
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CompositeGlyphHeader::Iterator composite_it;
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if (unlikely (!CompositeGlyphHeader::get_iterator (
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(const char*) this->glyf_table + start_offset,
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end_offset - start_offset, &composite_it))) return false;
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const CompositeGlyphHeader *last;
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do {
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last = composite_it.current;
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} while (composite_it.move_to_next ());
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if ((uint16_t) last->flags & CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS)
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*instruction_start = ((char *) last - (char *) glyf_table->dataZ.arrayZ) + last->get_size ();
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else
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*instruction_start = end_offset;
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*instruction_end = end_offset;
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if (unlikely (*instruction_start > *instruction_end))
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{
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DEBUG_MSG(SUBSET, nullptr, "Invalid instruction offset, %d is outside [%d, %d]", *instruction_start, start_offset, end_offset);
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return false;
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}
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}
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else
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{
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unsigned int instruction_length_offset = start_offset + GlyphHeader::static_size + 2 * num_contours;
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if (unlikely (instruction_length_offset + 2 > end_offset))
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{
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DEBUG_MSG(SUBSET, nullptr, "Glyph size is too short, missing field instructionLength.");
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return false;
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}
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const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (glyf_table, instruction_length_offset);
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unsigned int start = instruction_length_offset + 2;
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unsigned int end = start + (uint16_t) instruction_length;
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if (unlikely (end > end_offset)) // Out of bounds of the current glyph
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{
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DEBUG_MSG(SUBSET, nullptr, "The instructions array overruns the glyph's boundaries.");
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return false;
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}
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*instruction_start = start;
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*instruction_end = end;
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}
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return true;
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}
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bool get_extents (hb_codepoint_t glyph, hb_glyph_extents_t *extents) const
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{
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unsigned int start_offset, end_offset;
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if (!get_offsets (glyph, &start_offset, &end_offset))
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return false;
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if (end_offset - start_offset < GlyphHeader::static_size)
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return true; /* Empty glyph; zero extents. */
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const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
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extents->x_bearing = hb_min (glyph_header.xMin, glyph_header.xMax);
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extents->y_bearing = hb_max (glyph_header.yMin, glyph_header.yMax);
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extents->width = hb_max (glyph_header.xMin, glyph_header.xMax) - extents->x_bearing;
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extents->height = hb_min (glyph_header.yMin, glyph_header.yMax) - extents->y_bearing;
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return true;
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}
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private:
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bool short_offset;
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unsigned int num_glyphs;
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hb_blob_ptr_t<loca> loca_table;
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hb_blob_ptr_t<glyf> glyf_table;
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};
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protected:
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UnsizedArrayOf<HBUINT8> dataZ; /* Glyphs data. */
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public:
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DEFINE_SIZE_MIN (0); /* In reality, this is UNBOUNDED() type; but since we always
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* check the size externally, allow Null() object of it by
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* defining it _MIN instead. */
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};
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struct glyf_accelerator_t : glyf::accelerator_t {};
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} /* namespace OT */
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#endif /* HB_OT_GLYF_TABLE_HH */
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