harfbuzz/src/hb-aat-layout-kerx-table.hh

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/*
* Copyright © 2018 Ebrahim Byagowi
* Copyright © 2018 Google, Inc.
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*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_AAT_LAYOUT_KERX_TABLE_HH
#define HB_AAT_LAYOUT_KERX_TABLE_HH
#include "hb-open-type-private.hh"
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#include "hb-aat-layout-common-private.hh"
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#include "hb-aat-layout-ankr-table.hh"
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/*
* kerx -- Extended Kerning
* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6kerx.html
*/
#define HB_AAT_TAG_kerx HB_TAG('k','e','r','x')
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namespace AAT {
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using namespace OT;
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struct KerxFormat0Records
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{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this)));
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}
protected:
GlyphID left;
GlyphID right;
FWORD value;
public:
DEFINE_SIZE_STATIC (6);
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};
struct KerxSubTableFormat0
{
// TODO(ebraminio) Enable when we got suitable BinSearchArrayOf
// inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
// {
// hb_glyph_pair_t pair = {left, right};
// int i = pairs.bsearch (pair);
// if (i == -1)
// return 0;
// return pairs[i].get_kerning ();
// }
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inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
recordsZ.sanitize (c, nPairs)));
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}
protected:
// TODO(ebraminio): A custom version of "BinSearchArrayOf<KerxPair> pairs;" is
// needed here to use HBUINT32 instead
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HBUINT32 nPairs; /* The number of kerning pairs in this subtable */
HBUINT32 searchRange; /* The largest power of two less than or equal to the value of nPairs,
* multiplied by the size in bytes of an entry in the subtable. */
HBUINT32 entrySelector; /* This is calculated as log2 of the largest power of two less
* than or equal to the value of nPairs. */
HBUINT32 rangeShift; /* The value of nPairs minus the largest power of two less than or equal to nPairs. */
UnsizedArrayOf<KerxFormat0Records>
recordsZ; /* VAR=nPairs */
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public:
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DEFINE_SIZE_ARRAY (16, recordsZ);
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};
struct KerxSubTableFormat1
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
stateHeader.sanitize (c)));
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}
protected:
StateTable<HBUINT16> stateHeader;
LOffsetTo<ArrayOf<HBUINT16> > valueTable;
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public:
DEFINE_SIZE_STATIC (20);
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};
// TODO(ebraminio): Maybe this can be replaced with Lookup<HBUINT16>?
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struct KerxClassTable
{
inline unsigned int get_class (hb_codepoint_t g) const { return classes[g - firstGlyph]; }
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (firstGlyph.sanitize (c) &&
classes.sanitize (c)));
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}
protected:
HBUINT16 firstGlyph; /* First glyph in class range. */
ArrayOf<HBUINT16> classes; /* Glyph classes. */
public:
DEFINE_SIZE_ARRAY (4, classes);
};
struct KerxSubTableFormat2
{
inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right, const char *end) const
{
unsigned int l = (this+leftClassTable).get_class (left);
unsigned int r = (this+leftClassTable).get_class (left);
unsigned int offset = l * rowWidth + r * sizeof (FWORD);
const FWORD *arr = &(this+array);
if (unlikely ((const void *) arr < (const void *) this || (const void *) arr >= (const void *) end))
return 0;
const FWORD *v = &StructAtOffset<FWORD> (arr, offset);
if (unlikely ((const void *) v < (const void *) arr || (const void *) (v + 1) > (const void *) end))
return 0;
return *v;
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
rowWidth.sanitize (c) &&
leftClassTable.sanitize (c, this) &&
rightClassTable.sanitize (c, this) &&
array.sanitize (c, this)));
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}
protected:
HBUINT32 rowWidth; /* The width, in bytes, of a row in the table. */
LOffsetTo<KerxClassTable>
leftClassTable; /* Offset from beginning of this subtable to
* left-hand class table. */
LOffsetTo<KerxClassTable>
rightClassTable;/* Offset from beginning of this subtable to
* right-hand class table. */
LOffsetTo<FWORD>
array; /* Offset from beginning of this subtable to
* the start of the kerning array. */
public:
DEFINE_SIZE_STATIC (16);
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};
struct KerxSubTableFormat4
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
rowWidth.sanitize (c) &&
leftClassTable.sanitize (c, this) &&
rightClassTable.sanitize (c, this) &&
array.sanitize (c, this)));
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}
protected:
HBUINT32 rowWidth; /* The width, in bytes, of a row in the table. */
LOffsetTo<KerxClassTable>
leftClassTable; /* Offset from beginning of this subtable to
* left-hand class table. */
LOffsetTo<KerxClassTable>
rightClassTable;/* Offset from beginning of this subtable to
* right-hand class table. */
LOffsetTo<FWORD>
array; /* Offset from beginning of this subtable to
* the start of the kerning array. */
public:
DEFINE_SIZE_STATIC (16);
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};
struct KerxSubTableFormat6
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this) &&
rowIndexTable.sanitize (c, this) &&
columnIndexTable.sanitize (c, this) &&
kerningArray.sanitize (c, this) &&
kerningVector.sanitize (c, this)));
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}
protected:
HBUINT32 flags;
HBUINT16 rowCount;
HBUINT16 columnCount;
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LOffsetTo<Lookup<HBUINT16> > rowIndexTable;
LOffsetTo<Lookup<HBUINT16> > columnIndexTable;
LOffsetTo<Lookup<HBUINT16> > kerningArray;
LOffsetTo<Lookup<HBUINT16> > kerningVector;
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public:
DEFINE_SIZE_STATIC (24);
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};
enum coverage_flags_t
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{
COVERAGE_VERTICAL_FLAG = 0x80u,
COVERAGE_CROSSSTREAM_FLAG = 0x40u,
COVERAGE_VARIATION_FLAG = 0x20u,
COVERAGE_PROCESS_DIRECTION = 0x10u,
};
struct KerxTable
{
inline bool apply (hb_aat_apply_context_t *c, const AAT::ankr *ankr) const
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{
TRACE_APPLY (this);
/* TODO */
return_trace (false);
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}
inline unsigned int get_size (void) const { return length; }
inline bool sanitize (hb_sanitize_context_t *c) const
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{
TRACE_SANITIZE (this);
if (unlikely (!c->check_struct (this)))
return_trace (false);
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switch (format) {
case 0: return u.format0.sanitize (c);
case 1: return u.format1.sanitize (c);
case 2: return u.format2.sanitize (c);
case 4: return u.format4.sanitize (c);
case 6: return u.format6.sanitize (c);
default:return_trace (false);
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}
}
protected:
HBUINT32 length;
HBUINT8 coverage;
HBUINT16 unused;
HBUINT8 format;
HBUINT32 tupleIndex;
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union {
KerxSubTableFormat0 format0;
KerxSubTableFormat1 format1;
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KerxSubTableFormat2 format2;
KerxSubTableFormat4 format4;
KerxSubTableFormat6 format6;
} u;
public:
DEFINE_SIZE_MIN (12);
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};
struct SubtableGlyphCoverageArray
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (c->check_struct (this)));
}
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protected:
HBUINT32 length;
HBUINT32 coverage;
HBUINT32 tupleCount;
public:
DEFINE_SIZE_STATIC (12);
};
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struct kerx
{
static const hb_tag_t tableTag = HB_AAT_TAG_kerx;
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inline bool apply (hb_aat_apply_context_t *c, const AAT::ankr *ankr) const
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{
TRACE_APPLY (this);
const KerxTable &table = StructAfter<KerxTable> (*this);
return_trace (table.apply (c, ankr));
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}
inline bool sanitize (hb_sanitize_context_t *c) const
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{
TRACE_SANITIZE (this);
if (unlikely (!(c->check_struct (this))))
return_trace (false);
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/* TODO: Something like `morx`s ChainSubtable should be done here instead */
const KerxTable *table = &StructAfter<KerxTable> (*this);
if (unlikely (!(table->sanitize (c))))
return_trace (false);
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for (unsigned int i = 0; i < nTables - 1; ++i)
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{
table = &StructAfter<KerxTable> (*table);
if (unlikely (!(table->sanitize (c))))
return_trace (false);
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}
// If version is less than 3, we are done here; otherwise better to check footer also
if (version < 3)
return_trace (true);
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// TODO: Investigate why this just work on some fonts no matter of version
// const SubtableGlyphCoverageArray &footer =
// StructAfter<SubtableGlyphCoverageArray> (*table);
// return_trace (footer.sanitize (c));
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return_trace (true);
}
protected:
HBUINT16 version;
HBUINT16 padding;
HBUINT32 nTables;
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/*KerxTable tablesZ[VAR]; XXX ArrayOf??? */
/*SubtableGlyphCoverageArray coverage_array;*/
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public:
DEFINE_SIZE_STATIC (8);
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};
} /* namespace AAT */
#endif /* HB_AAT_LAYOUT_KERX_TABLE_HH */