[just] Initial table implementation (#1364)
A starting point, its sanitization is not tested however
This commit is contained in:
Ebrahim Byagowi
GitHub
parent
b8b00fb3c6
commit
f90423847b
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@ -100,6 +100,7 @@ HB_OT_sources = \
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hb-aat-layout-ankr-table.hh \
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hb-aat-layout-bsln-table.hh \
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hb-aat-layout-feat-table.hh \
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hb-aat-layout-just-table.hh \
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hb-aat-layout-kerx-table.hh \
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hb-aat-layout-morx-table.hh \
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hb-aat-layout-trak-table.hh \
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@ -0,0 +1,416 @@
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/*
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* Copyright © 2018 Ebrahim Byagowi
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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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#ifndef HB_AAT_LAYOUT_JUST_TABLE_HH
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#define HB_AAT_LAYOUT_JUST_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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#include "hb-aat-layout-morx-table.hh"
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/*
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* just -- Justification
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* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6just.html
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*/
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#define HB_AAT_TAG_just HB_TAG('j','u','s','t')
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namespace AAT {
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using namespace OT;
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struct ActionSubrecordHeader
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{
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inline 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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}
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HBUINT16 actionClass; /* The JustClass value associated with this
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* ActionSubrecord. */
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HBUINT16 actionType; /* The type of postcompensation action. */
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HBUINT16 actionLength; /* Length of this ActionSubrecord record, which
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* must be a multiple of 4. */
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public:
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DEFINE_SIZE_STATIC (6);
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};
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struct DecompositionAction
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{
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inline 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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}
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ActionSubrecordHeader
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header;
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Fixed lowerLimit; /* If the distance factor is less than this value,
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* then the ligature is decomposed. */
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Fixed upperLimit; /* If the distance factor is greater than this value,
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* then the ligature is decomposed. */
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HBUINT16 order; /* Numerical order in which this ligature will
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* be decomposed; you may want infrequent ligatures
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* to decompose before more frequent ones. The ligatures
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* on the line of text will decompose in increasing
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* value of this field. */
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ArrayOf<HBUINT16>
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decomposedglyphs;
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/* Number of 16-bit glyph indexes that follow;
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* the ligature will be decomposed into these glyphs.
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*
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* Array of decomposed glyphs. */
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public:
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DEFINE_SIZE_ARRAY (18, decomposedglyphs);
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};
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struct UnconditionalAddGlyphAction
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{
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inline 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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protected:
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ActionSubrecordHeader
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header;
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GlyphID addGlyph; /* Glyph that should be added if the distance factor
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* is growing. */
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public:
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DEFINE_SIZE_STATIC (8);
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};
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struct ConditionalAddGlyphAction
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{
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inline 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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}
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protected:
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ActionSubrecordHeader
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header;
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Fixed substThreshold; /* Distance growth factor (in ems) at which
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* this glyph is replaced and the growth factor
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* recalculated. */
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GlyphID addGlyph; /* Glyph to be added as kashida. If this value is
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* 0xFFFF, no extra glyph will be added. Note that
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* generally when a glyph is added, justification
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* will need to be redone. */
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GlyphID substGlyph; /* Glyph to be substituted for this glyph if the
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* growth factor equals or exceeds the value of
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* substThreshold. */
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public:
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DEFINE_SIZE_STATIC (14);
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};
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struct DuctileGlyphAction
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{
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inline 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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}
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protected:
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ActionSubrecordHeader
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header;
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HBUINT32 variationAxis; /* The 4-byte tag identifying the ductile axis.
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* This would normally be 0x64756374 ('duct'),
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* but you may use any axis the font contains. */
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Fixed minimumLimit; /* The lowest value for the ductility axis tha
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* still yields an acceptable appearance. Normally
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* this will be 1.0. */
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Fixed noStretchValue; /* This is the default value that corresponds to
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* no change in appearance. Normally, this will
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* be 1.0. */
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Fixed maximumLimit; /* The highest value for the ductility axis that
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* still yields an acceptable appearance. */
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public:
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DEFINE_SIZE_STATIC (22);
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};
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struct RepeatedAddGlyphAction
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{
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inline 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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}
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protected:
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ActionSubrecordHeader
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header;
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HBUINT16 flags; /* Currently unused; set to 0. */
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GlyphID glyph; /* Glyph that should be added if the distance factor
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* is growing. */
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public:
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DEFINE_SIZE_STATIC (10);
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};
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struct ActionSubrecord
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{
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inline 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 (!c->check_struct (this)))
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return_trace (false);
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switch (u.header.actionType)
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{
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case 0: return_trace (u.decompositionAction.sanitize (c));
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case 1: return_trace (u.unconditionalAddGlyphAction.sanitize (c));
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case 2: return_trace (u.conditionalAddGlyphAction.sanitize (c));
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// case 3: return_trace (u.stretchGlyphAction.sanitize (c));
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case 4: return_trace (u.decompositionAction.sanitize (c));
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case 5: return_trace (u.decompositionAction.sanitize (c));
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default: return_trace (true);
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}
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}
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inline unsigned int get_length () const { return u.header.actionLength; }
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protected:
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union {
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ActionSubrecordHeader header;
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DecompositionAction decompositionAction;
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UnconditionalAddGlyphAction unconditionalAddGlyphAction;
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ConditionalAddGlyphAction conditionalAddGlyphAction;
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/* StretchGlyphAction stretchGlyphAction; -- Not supported by CoreText */
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DuctileGlyphAction ductileGlyphAction;
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RepeatedAddGlyphAction repeatedAddGlyphAction;
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} u; /* Data. The format of this data depends on
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* the value of the actionType field. */
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public:
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DEFINE_SIZE_UNION (6, header);
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};
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struct PostcompensationActionChain
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{
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inline 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 (!c->check_struct (this)))
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return_trace (false);
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unsigned int offset = min_size;
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for (unsigned int i = 0; i < count; i++)
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{
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const ActionSubrecord& subrecord = StructAtOffset<ActionSubrecord> (this, offset);
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if (unlikely (!subrecord.sanitize (c))) return_trace (false);
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offset += subrecord.get_length ();
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}
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return_trace (true);
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}
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protected:
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HBUINT32 count;
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public:
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DEFINE_SIZE_STATIC (4);
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};
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struct JustWidthDeltaEntry
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{
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enum Flags
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{
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Reserved1 =0xE000,/* Reserved. You should set these bits to zero. */
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UnlimiteGap =0x1000,/* The glyph can take unlimited gap. When this
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* glyph participates in the justification process,
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* it and any other glyphs on the line having this
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* bit set absorb all the remaining gap. */
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Reserved2 =0x0FF0,/* Reserved. You should set these bits to zero. */
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Priority =0x000F /* The justification priority of the glyph. */
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};
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enum Priority
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{
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Kashida = 0, /* Kashida priority. This is the highest priority
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* during justification. */
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Whitespace = 1, /* Whitespace priority. Any whitespace glyphs (as
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* identified in the glyph properties table) will
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* get this priority. */
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InterCharacter = 2, /* Inter-character priority. Give this to any
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* remaining glyphs. */
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NullPriority = 3 /* Null priority. You should set this priority for
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* glyphs that only participate in justification
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* after the above priorities. Normally all glyphs
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* have one of the previous three values. If you
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* don't want a glyph to participate in justification,
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* and you don't want to set its factors to zero,
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* you may instead assign it to the null priority. */
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};
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protected:
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Fixed beforeGrowLimit;/* The ratio by which the advance width of the
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* glyph is permitted to grow on the left or top side. */
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Fixed beforeShrinkLimit;
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/* The ratio by which the advance width of the
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* glyph is permitted to shrink on the left or top side. */
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Fixed afterGrowLimit; /* The ratio by which the advance width of the glyph
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* is permitted to shrink on the left or top side. */
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Fixed afterShrinkLimit;
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/* The ratio by which the advance width of the glyph
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* is at most permitted to shrink on the right or
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* bottom side. */
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HBUINT16 growFlags; /* Flags controlling the grow case. */
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HBUINT16 shrinkFlags; /* Flags controlling the shrink case. */
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public:
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DEFINE_SIZE_STATIC (20);
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};
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struct WidthDeltaPair
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{
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inline 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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}
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protected:
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HBUINT32 justClass; /* The justification category associated
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* with the wdRecord field. Only 7 bits of
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* this field are used. (The other bits are
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* used as padding to guarantee longword
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* alignment of the following record). */
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JustWidthDeltaEntry
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wdRecord; /* The actual width delta record. */
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public:
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DEFINE_SIZE_STATIC (24);
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};
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struct WidthDeltaCluster : OT::LArrayOf<WidthDeltaPair> {};
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struct JustificationCategory
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{
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typedef void EntryData;
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enum Flags
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{
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SetMark =0x8000,/* If set, make the current glyph the marked
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* glyph. */
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DontAdvance =0x4000,/* If set, don't advance to the next glyph before
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* going to the new state. */
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MarkCategory =0x3F80,/* The justification category for the marked
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* glyph if nonzero. */
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CurrentCategory =0x007F /* The justification category for the current
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* glyph if nonzero. */
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};
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inline 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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morphHeader.sanitize (c) &&
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stHeader.sanitize (c)));
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}
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protected:
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ChainSubtable<ObsoleteTypes>
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morphHeader; /* Metamorphosis-style subtable header. */
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StateTable<ObsoleteTypes, EntryData>
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stHeader; /* The justification insertion state table header */
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public:
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DEFINE_SIZE_STATIC (30);
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};
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struct JustificationHeader
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{
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inline 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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justClassTable.sanitize (c, base, base) &&
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wdcTable.sanitize (c, base) &&
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pcTable.sanitize (c, base) &&
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lookupTable.sanitize (c, base)));
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}
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protected:
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OffsetTo<JustificationCategory>
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justClassTable; /* Offset to the justification category state table. */
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OffsetTo<WidthDeltaCluster>
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wdcTable; /* Offset from start of justification table to start
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* of the subtable containing the width delta factors
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* for the glyphs in your font.
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*
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* The width delta clusters table. */
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OffsetTo<PostcompensationActionChain>
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pcTable; /* Offset from start of justification table to start
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* of postcompensation subtable (set to zero if none).
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*
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* The postcompensation subtable, if present in the font. */
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Lookup<OffsetTo<WidthDeltaCluster> >
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lookupTable; /* Lookup table associating glyphs with width delta
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* clusters. See the description of Width Delta Clusters
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* table for details on how to interpret the lookup values. */
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public:
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DEFINE_SIZE_MIN (8);
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};
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struct just
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{
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static const hb_tag_t tableTag = HB_AAT_TAG_just;
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inline 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 (unlikely (c->check_struct (this) &&
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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 justification table
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* (0x00010000u for version 1.0). */
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HBUINT16 format; /* Format of the justification table (set to 0). */
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OffsetTo<JustificationHeader>
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horizData; /* Byte offset from the start of the justification table
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* to the header for tables that contain justification
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* information for horizontal text.
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* If you are not including this information,
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* store 0. */
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OffsetTo<JustificationHeader>
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vertData; /* ditto, vertical */
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public:
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DEFINE_SIZE_STATIC (10);
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};
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} /* namespace AAT */
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#endif /* HB_AAT_LAYOUT_JUST_TABLE_HH */
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@ -31,6 +31,7 @@
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#include "hb-aat-layout-ankr-table.hh"
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#include "hb-aat-layout-bsln-table.hh" // Just so we compile it; unused otherwise.
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#include "hb-aat-layout-feat-table.hh" // Just so we compile it; unused otherwise.
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#include "hb-aat-layout-just-table.hh" // Just so we compile it; unused otherwise.
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#include "hb-aat-layout-kerx-table.hh"
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#include "hb-aat-layout-morx-table.hh"
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#include "hb-aat-layout-trak-table.hh"
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