355 lines
10 KiB
C++
355 lines
10 KiB
C++
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/*
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* Copyright © 2017 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_KERN_TABLE_HH
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#define HB_OT_KERN_TABLE_HH
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#include "hb-aat-layout-kerx-table.hh"
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/*
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* kern -- Kerning
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* https://docs.microsoft.com/en-us/typography/opentype/spec/kern
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* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6kern.html
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*/
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#define HB_OT_TAG_kern HB_TAG('k','e','r','n')
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namespace OT {
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template <typename KernSubTableHeader>
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struct KernSubTableFormat3
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{
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int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
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{
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hb_array_t<const FWORD> kernValue = kernValueZ.as_array (kernValueCount);
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hb_array_t<const HBUINT8> leftClass = StructAfter<const UnsizedArrayOf<HBUINT8>> (kernValue).as_array (glyphCount);
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hb_array_t<const HBUINT8> rightClass = StructAfter<const UnsizedArrayOf<HBUINT8>> (leftClass).as_array (glyphCount);
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hb_array_t<const HBUINT8> kernIndex = StructAfter<const UnsizedArrayOf<HBUINT8>> (rightClass).as_array (leftClassCount * rightClassCount);
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unsigned int leftC = leftClass[left];
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unsigned int rightC = rightClass[right];
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if (unlikely (leftC >= leftClassCount || rightC >= rightClassCount))
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return 0;
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unsigned int i = leftC * rightClassCount + rightC;
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return kernValue[kernIndex[i]];
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}
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bool apply (AAT::hb_aat_apply_context_t *c) const
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{
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TRACE_APPLY (this);
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if (!c->plan->requested_kerning)
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return false;
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if (header.coverage & header.Backwards)
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return false;
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hb_kern_machine_t<KernSubTableFormat3> machine (*this, header.coverage & header.CrossStream);
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machine.kern (c->font, c->buffer, c->plan->kern_mask);
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return_trace (true);
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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 (c->check_struct (this) &&
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c->check_range (kernValueZ,
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kernValueCount * sizeof (FWORD) +
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glyphCount * 2 +
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leftClassCount * rightClassCount));
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}
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protected:
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KernSubTableHeader header;
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HBUINT16 glyphCount; /* The number of glyphs in this font. */
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HBUINT8 kernValueCount; /* The number of kerning values. */
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HBUINT8 leftClassCount; /* The number of left-hand classes. */
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HBUINT8 rightClassCount;/* The number of right-hand classes. */
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HBUINT8 flags; /* Set to zero (reserved for future use). */
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UnsizedArrayOf<FWORD> kernValueZ; /* The kerning values.
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* Length kernValueCount. */
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#if 0
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UnsizedArrayOf<HBUINT8>leftClass; /* The left-hand classes.
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* Length glyphCount. */
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UnsizedArrayOf<HBUINT8>rightClass; /* The right-hand classes.
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* Length glyphCount. */
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UnsizedArrayOf<HBUINT8>kernIndex; /* The indices into the kernValue array.
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* Length leftClassCount * rightClassCount */
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#endif
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public:
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DEFINE_SIZE_ARRAY (KernSubTableHeader::static_size + 6, kernValueZ);
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};
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template <typename KernSubTableHeader>
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struct KernSubTable
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{
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unsigned int get_size () const { return u.header.length; }
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unsigned int get_type () const { return u.header.format; }
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int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
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{
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switch (get_type ()) {
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/* This method hooks up to hb_font_t's get_h_kerning. Only support Format0. */
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case 0: return u.format0.get_kerning (left, right);
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default:return 0;
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}
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}
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template <typename context_t, typename ...Ts>
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typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
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{
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unsigned int subtable_type = get_type ();
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TRACE_DISPATCH (this, subtable_type);
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switch (subtable_type) {
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case 0: return_trace (c->dispatch (u.format0));
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#ifndef HB_NO_AAT_SHAPE
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case 1: return_trace (u.header.apple ? c->dispatch (u.format1, hb_forward<Ts> (ds)...) : c->default_return_value ());
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#endif
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case 2: return_trace (c->dispatch (u.format2));
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#ifndef HB_NO_AAT_SHAPE
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case 3: return_trace (u.header.apple ? c->dispatch (u.format3, hb_forward<Ts> (ds)...) : c->default_return_value ());
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#endif
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default: return_trace (c->default_return_value ());
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}
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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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if (unlikely (!u.header.sanitize (c) ||
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u.header.length < u.header.min_size ||
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!c->check_range (this, u.header.length))) return_trace (false);
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return_trace (dispatch (c));
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}
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public:
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union {
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KernSubTableHeader header;
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AAT::KerxSubTableFormat0<KernSubTableHeader> format0;
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AAT::KerxSubTableFormat1<KernSubTableHeader> format1;
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AAT::KerxSubTableFormat2<KernSubTableHeader> format2;
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KernSubTableFormat3<KernSubTableHeader> format3;
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} u;
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public:
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DEFINE_SIZE_MIN (KernSubTableHeader::static_size);
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};
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struct KernOTSubTableHeader
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{
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static constexpr bool apple = false;
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typedef AAT::ObsoleteTypes Types;
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unsigned tuple_count () const { return 0; }
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bool is_horizontal () const { return (coverage & Horizontal); }
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enum Coverage
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{
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Horizontal = 0x01u,
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Minimum = 0x02u,
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CrossStream = 0x04u,
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Override = 0x08u,
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/* Not supported: */
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Backwards = 0x00u,
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Variation = 0x00u,
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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 (c->check_struct (this));
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}
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public:
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HBUINT16 versionZ; /* Unused. */
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HBUINT16 length; /* Length of the subtable (including this header). */
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HBUINT8 format; /* Subtable format. */
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HBUINT8 coverage; /* Coverage bits. */
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public:
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DEFINE_SIZE_STATIC (6);
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};
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struct KernOT : AAT::KerxTable<KernOT>
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{
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friend struct AAT::KerxTable<KernOT>;
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static constexpr hb_tag_t tableTag = HB_OT_TAG_kern;
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static constexpr unsigned minVersion = 0u;
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typedef KernOTSubTableHeader SubTableHeader;
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typedef SubTableHeader::Types Types;
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typedef KernSubTable<SubTableHeader> SubTable;
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protected:
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HBUINT16 version; /* Version--0x0000u */
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HBUINT16 tableCount; /* Number of subtables in the kerning table. */
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SubTable firstSubTable; /* Subtables. */
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public:
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DEFINE_SIZE_MIN (4);
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};
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struct KernAATSubTableHeader
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{
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static constexpr bool apple = true;
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typedef AAT::ObsoleteTypes Types;
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unsigned tuple_count () const { return 0; }
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bool is_horizontal () const { return !(coverage & Vertical); }
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enum Coverage
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{
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Vertical = 0x80u,
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CrossStream = 0x40u,
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Variation = 0x20u,
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/* Not supported: */
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Backwards = 0x00u,
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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 (c->check_struct (this));
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}
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public:
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HBUINT32 length; /* Length of the subtable (including this header). */
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HBUINT8 coverage; /* Coverage bits. */
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HBUINT8 format; /* Subtable format. */
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HBUINT16 tupleIndex; /* The tuple index (used for variations fonts).
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* This value specifies which tuple this subtable covers.
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* Note: We don't implement. */
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public:
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DEFINE_SIZE_STATIC (8);
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};
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struct KernAAT : AAT::KerxTable<KernAAT>
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{
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friend struct AAT::KerxTable<KernAAT>;
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static constexpr hb_tag_t tableTag = HB_OT_TAG_kern;
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static constexpr unsigned minVersion = 0x00010000u;
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typedef KernAATSubTableHeader SubTableHeader;
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typedef SubTableHeader::Types Types;
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typedef KernSubTable<SubTableHeader> SubTable;
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protected:
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HBUINT32 version; /* Version--0x00010000u */
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HBUINT32 tableCount; /* Number of subtables in the kerning table. */
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SubTable firstSubTable; /* Subtables. */
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public:
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DEFINE_SIZE_MIN (8);
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};
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struct kern
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{
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static constexpr hb_tag_t tableTag = HB_OT_TAG_kern;
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bool has_data () const { return u.version32; }
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unsigned get_type () const { return u.major; }
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bool has_state_machine () const
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{
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switch (get_type ()) {
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case 0: return u.ot.has_state_machine ();
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#ifndef HB_NO_AAT_SHAPE
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case 1: return u.aat.has_state_machine ();
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#endif
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default:return false;
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}
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}
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bool has_cross_stream () const
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{
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switch (get_type ()) {
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case 0: return u.ot.has_cross_stream ();
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#ifndef HB_NO_AAT_SHAPE
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case 1: return u.aat.has_cross_stream ();
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#endif
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default:return false;
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}
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}
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int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
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{
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switch (get_type ()) {
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case 0: return u.ot.get_h_kerning (left, right);
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#ifndef HB_NO_AAT_SHAPE
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case 1: return u.aat.get_h_kerning (left, right);
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#endif
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default:return 0;
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}
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}
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bool apply (AAT::hb_aat_apply_context_t *c) const
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{ return dispatch (c); }
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template <typename context_t, typename ...Ts>
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typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
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{
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unsigned int subtable_type = get_type ();
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TRACE_DISPATCH (this, subtable_type);
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switch (subtable_type) {
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case 0: return_trace (c->dispatch (u.ot, hb_forward<Ts> (ds)...));
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#ifndef HB_NO_AAT_SHAPE
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case 1: return_trace (c->dispatch (u.aat, hb_forward<Ts> (ds)...));
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#endif
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default: return_trace (c->default_return_value ());
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}
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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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if (!u.version32.sanitize (c)) return_trace (false);
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return_trace (dispatch (c));
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}
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protected:
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union {
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HBUINT32 version32;
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HBUINT16 major;
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KernOT ot;
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#ifndef HB_NO_AAT_SHAPE
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KernAAT aat;
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#endif
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} u;
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public:
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DEFINE_SIZE_UNION (4, version32);
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};
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} /* namespace OT */
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#endif /* HB_OT_KERN_TABLE_HH */
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