234 lines
6.7 KiB
C++
234 lines
6.7 KiB
C++
/*
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* Copyright © 2018 Ebrahim Byagowi
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* Copyright © 2018 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_AAT_LAYOUT_TRAK_TABLE_HH
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#define HB_AAT_LAYOUT_TRAK_TABLE_HH
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#include "hb-aat-layout-common.hh"
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#include "hb-ot-layout.hh"
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#include "hb-open-type.hh"
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/*
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* trak -- Tracking
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* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6trak.html
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*/
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#define HB_AAT_TAG_trak HB_TAG('t','r','a','k')
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namespace AAT {
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struct TrackTableEntry
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{
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friend struct TrackData;
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float get_track_value () const { return track.to_float (); }
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float interpolate_at (unsigned int idx,
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float ptem,
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const void *base,
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hb_array_t<const F16DOT16> size_table) const
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{
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const FWORD *values = (base+valuesZ).arrayZ;
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float s0 = size_table[idx].to_float ();
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float s1 = size_table[idx + 1].to_float ();
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int v0 = values[idx];
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int v1 = values[idx + 1];
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// Deal with font bugs.
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if (unlikely (s1 < s0))
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{ hb_swap (s0, s1); hb_swap (v0, v1); }
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if (unlikely (ptem < s0)) return v0;
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if (unlikely (ptem > s1)) return v1;
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if (unlikely (s0 == s1)) return (v0 + v1) * 0.5f;
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float t = (ptem - s0) / (s1 - s0);
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return v0 + t * (v1 - v0);
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}
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float get_value (float ptem,
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const void *base,
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hb_array_t<const F16DOT16> size_table) const
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{
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const FWORD *values = (base+valuesZ).arrayZ;
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unsigned int n_sizes = size_table.length;
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/*
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* Choose size.
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*/
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if (!n_sizes) return 0.f;
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if (n_sizes == 1) return values[0];
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// At least two entries.
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unsigned i;
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for (i = 0; i < n_sizes; i++)
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if (size_table[i].to_float () >= ptem)
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break;
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// Boundary conditions.
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if (i == 0) return values[0];
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if (i == n_sizes) return values[n_sizes - 1];
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// Exact match.
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if (size_table[i].to_float () == ptem) return values[i];
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// Interpolate.
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return interpolate_at (i - 1, ptem, base, size_table);
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}
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public:
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bool sanitize (hb_sanitize_context_t *c,
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const void *base,
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unsigned int n_sizes) const
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{
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TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
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(valuesZ.sanitize (c, base, n_sizes))));
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}
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protected:
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F16DOT16 track; /* Track value for this record. */
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NameID trackNameID; /* The 'name' table index for this track.
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* (a short word or phrase like "loose"
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* or "very tight") */
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NNOffset16To<UnsizedArrayOf<FWORD>>
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valuesZ; /* Offset from start of tracking table to
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* per-size tracking values for this track. */
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public:
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DEFINE_SIZE_STATIC (8);
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};
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struct TrackData
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{
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float get_tracking (const void *base, float ptem, float track = 0.f) const
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{
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unsigned count = nTracks;
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hb_array_t<const F16DOT16> size_table = (base+sizeTable).as_array (nSizes);
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if (!count) return 0.f;
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if (count == 1) return trackTable[0].get_value (ptem, base, size_table);
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// At least two entries.
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unsigned i = 0;
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unsigned j = count - 1;
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// Find the two entries that track is between.
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while (i + 1 < count && trackTable[i + 1].get_track_value () < track)
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i++;
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while (j > 0 && trackTable[j - 1].get_track_value () > track)
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j--;
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// Exact match.
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if (i == j) return trackTable[i].get_value (ptem, base, size_table);
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// Interpolate.
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float t0 = trackTable[i].get_track_value ();
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float t1 = trackTable[j].get_track_value ();
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float t = (track - t0) / (t1 - t0);
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float a = trackTable[i].get_value (ptem, base, size_table);
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float b = trackTable[j].get_value (ptem, base, size_table);
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return a + t * (b - a);
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}
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bool sanitize (hb_sanitize_context_t *c, const void *base) const
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{
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TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
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hb_barrier () &&
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sizeTable.sanitize (c, base, nSizes) &&
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trackTable.sanitize (c, nTracks, base, nSizes)));
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}
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protected:
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HBUINT16 nTracks; /* Number of separate tracks included in this table. */
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HBUINT16 nSizes; /* Number of point sizes included in this table. */
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NNOffset32To<UnsizedArrayOf<F16DOT16>>
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sizeTable; /* Offset from start of the tracking table to
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* Array[nSizes] of size values.. */
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UnsizedArrayOf<TrackTableEntry>
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trackTable; /* Array[nTracks] of TrackTableEntry records. */
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public:
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DEFINE_SIZE_ARRAY (8, trackTable);
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};
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struct trak
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{
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static constexpr hb_tag_t tableTag = HB_AAT_TAG_trak;
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bool has_data () const { return version.to_int (); }
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hb_position_t get_h_tracking (hb_font_t *font, float track = 0.f) const
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{
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float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;
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return font->em_scalef_x ((this+horizData).get_tracking (this, ptem, track));
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}
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hb_position_t get_v_tracking (hb_font_t *font, float track = 0.f) const
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{
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float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;
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return font->em_scalef_y ((this+vertData).get_tracking (this, ptem, track));
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}
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bool sanitize (hb_sanitize_context_t *c) const
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{
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TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
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hb_barrier () &&
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version.major == 1 &&
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horizData.sanitize (c, this, this) &&
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vertData.sanitize (c, this, this)));
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}
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protected:
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FixedVersion<>version; /* Version of the tracking table
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* (0x00010000u for version 1.0). */
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HBUINT16 format; /* Format of the tracking table (set to 0). */
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Offset16To<TrackData>
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horizData; /* Offset from start of tracking table to TrackData
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* for horizontal text (or 0 if none). */
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Offset16To<TrackData>
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vertData; /* Offset from start of tracking table to TrackData
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* for vertical text (or 0 if none). */
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HBUINT16 reserved; /* Reserved. Set to 0. */
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public:
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DEFINE_SIZE_STATIC (12);
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};
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} /* namespace AAT */
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#endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */
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