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.hh"
#include "hb-aat-layout-common.hh"
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#include "hb-ot-kern-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 KerxSubTableHeader
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (likely (c->check_struct (this)));
}
public:
HBUINT32 length;
HBUINT32 coverage;
HBUINT32 tupleCount;
public:
DEFINE_SIZE_STATIC (12);
};
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struct KerxSubTableFormat0
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{
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inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
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{
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hb_glyph_pair_t pair = {left, right};
int i = pairs.bsearch (pair);
return i == -1 ? 0 : pairs[i].get_kerning ();
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}
inline bool apply (hb_aat_apply_context_t *c) const
{
TRACE_APPLY (this);
if (!c->plan->requested_kerning)
return false;
hb_kern_machine_t<KerxSubTableFormat0> machine (*this);
machine.kern (c->font, c->buffer, c->plan->kern_mask);
return_trace (true);
}
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inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (pairs.sanitize (c)));
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}
protected:
KerxSubTableHeader header;
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BinSearchArrayOf<KernPair, HBUINT32>
pairs; /* Sorted kern records. */
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public:
DEFINE_SIZE_ARRAY (28, pairs);
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};
struct KerxSubTableFormat1
{
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struct EntryData
{
HBUINT16 ligActionIndex; /* Index to the first ligActionTable entry
* for processing this group, if indicated
* by the flags. */
public:
DEFINE_SIZE_STATIC (2);
};
struct driver_context_t
{
static const bool in_place = true;
enum Flags
{
Push = 0x8000, /* If set, push this glyph on the kerning stack. */
DontAdvance = 0x4000, /* If set, don't advance to the next glyph
* before going to the new state. */
Reset = 0x2000, /* If set, reset the kerning data (clear the stack) */
Reserved = 0x1FFF, /* Not used; set to 0. */
};
inline driver_context_t (const KerxSubTableFormat1 *table)
{}
inline bool is_actionable (StateTableDriver<EntryData> *driver,
const Entry<EntryData> *entry)
{
return false; // XXX return (entry->flags & Verb) && start < end;
}
inline bool transition (StateTableDriver<EntryData> *driver,
const Entry<EntryData> *entry)
{
//hb_buffer_t *buffer = driver->buffer;
//unsigned int flags = entry->flags;
return true;
}
public:
private:
};
inline bool apply (hb_aat_apply_context_t *c) const
{
TRACE_APPLY (this);
if (!c->plan->requested_kerning)
return false;
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driver_context_t dc (this);
StateTableDriver<EntryData> driver (machine, c->buffer, c->font->face);
driver.drive (&dc);
return_trace (true);
}
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inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (machine.sanitize (c)));
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}
protected:
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KerxSubTableHeader header;
StateTable<EntryData> machine;
LOffsetTo<UnsizedArrayOf<FWORD>, false> values;
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public:
DEFINE_SIZE_STATIC (32);
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};
struct KerxSubTableFormat2
{
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inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right,
unsigned int num_glyphs) const
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{
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unsigned int l = (this+leftClassTable).get_value_or_null (left, num_glyphs);
unsigned int r = (this+rightClassTable).get_value_or_null (right, num_glyphs);
unsigned int offset = l + r;
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const FWORD *v = &StructAtOffset<FWORD> (&(this+array), offset);
if (unlikely ((const char *) v < (const char *) &array ||
(const char *) v + v->static_size - (const char *) this <= header.length))
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return 0;
return *v;
}
inline bool apply (hb_aat_apply_context_t *c) const
{
TRACE_APPLY (this);
if (!c->plan->requested_kerning)
return false;
accelerator_t accel (*this,
c->face->get_num_glyphs ());
hb_kern_machine_t<accelerator_t> machine (accel);
machine.kern (c->font, c->buffer, c->plan->kern_mask);
return_trace (true);
}
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inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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return_trace (likely (rowWidth.sanitize (c) &&
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leftClassTable.sanitize (c, this) &&
rightClassTable.sanitize (c, this) &&
array.sanitize (c, this)));
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}
struct accelerator_t
{
const KerxSubTableFormat2 &table;
unsigned int num_glyphs;
inline accelerator_t (const KerxSubTableFormat2 &table_,
unsigned int num_glyphs_)
: table (table_), num_glyphs (num_glyphs_) {}
inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
{
return table.get_kerning (left, right, num_glyphs);
}
};
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protected:
KerxSubTableHeader header;
HBUINT32 rowWidth; /* The width, in bytes, of a row in the table. */
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LOffsetTo<Lookup<HBUINT16> >
leftClassTable; /* Offset from beginning of this subtable to
* left-hand class table. */
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LOffsetTo<Lookup<HBUINT16> >
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. */
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public:
DEFINE_SIZE_STATIC (28);
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};
struct KerxSubTableFormat4
{
inline bool apply (hb_aat_apply_context_t *c) const
{
TRACE_APPLY (this);
/* TODO */
return_trace (true);
}
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inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
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/* TODO */
return_trace (likely (c->check_struct (this)));
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}
protected:
KerxSubTableHeader header;
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public:
DEFINE_SIZE_STATIC (12);
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};
struct KerxSubTableFormat6
{
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enum Flags
{
ValuesAreLong = 0x00000001,
};
inline bool is_long (void) const { return flags & ValuesAreLong; }
inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right,
unsigned int num_glyphs) const
{
if (is_long ())
{
const U::Long &t = u.l;
unsigned int l = (this+t.rowIndexTable).get_value_or_null (left, num_glyphs);
unsigned int r = (this+t.columnIndexTable).get_value_or_null (right, num_glyphs);
unsigned int offset = l + r;
const FWORD32 *v = &StructAtOffset<FWORD32> (&(this+t.array), offset * sizeof (FWORD32));
if (unlikely ((const char *) v < (const char *) &t.array ||
(const char *) v + v->static_size - (const char *) this <= header.length))
return 0;
return *v;
}
else
{
const U::Short &t = u.s;
unsigned int l = (this+t.rowIndexTable).get_value_or_null (left, num_glyphs);
unsigned int r = (this+t.columnIndexTable).get_value_or_null (right, num_glyphs);
unsigned int offset = l + r;
const FWORD *v = &StructAtOffset<FWORD> (&(this+t.array), offset * sizeof (FWORD));
if (unlikely ((const char *) v < (const char *) &t.array ||
(const char *) v + v->static_size - (const char *) this <= header.length))
return 0;
return *v;
}
}
inline bool apply (hb_aat_apply_context_t *c) const
{
TRACE_APPLY (this);
if (!c->plan->requested_kerning)
return false;
accelerator_t accel (*this,
c->face->get_num_glyphs ());
hb_kern_machine_t<accelerator_t> machine (accel);
machine.kern (c->font, c->buffer, c->plan->kern_mask);
return_trace (true);
}
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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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is_long () ?
(
u.l.rowIndexTable.sanitize (c, this) &&
u.l.columnIndexTable.sanitize (c, this) &&
u.l.array.sanitize (c, this)
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) : (
u.s.rowIndexTable.sanitize (c, this) &&
u.s.columnIndexTable.sanitize (c, this) &&
u.s.array.sanitize (c, this)
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)));
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}
struct accelerator_t
{
const KerxSubTableFormat6 &table;
unsigned int num_glyphs;
inline accelerator_t (const KerxSubTableFormat6 &table_,
unsigned int num_glyphs_)
: table (table_), num_glyphs (num_glyphs_) {}
inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
{
return table.get_kerning (left, right, num_glyphs);
}
};
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protected:
KerxSubTableHeader header;
HBUINT32 flags;
HBUINT16 rowCount;
HBUINT16 columnCount;
union U
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{
struct Long
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{
LOffsetTo<Lookup<HBUINT32> > rowIndexTable;
LOffsetTo<Lookup<HBUINT32> > columnIndexTable;
LOffsetTo<FWORD32> array;
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} l;
struct Short
{
LOffsetTo<Lookup<HBUINT16> > rowIndexTable;
LOffsetTo<Lookup<HBUINT16> > columnIndexTable;
LOffsetTo<FWORD> array;
} s;
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} u;
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public:
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DEFINE_SIZE_STATIC (32);
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};
struct KerxTable
{
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friend struct kerx;
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inline unsigned int get_size (void) const { return u.header.length; }
inline unsigned int get_type (void) const { return u.header.coverage & SubtableType; }
enum Coverage
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{
Vertical = 0x80000000, /* Set if table has vertical kerning values. */
CrossStream = 0x40000000, /* Set if table has cross-stream kerning values. */
Variation = 0x20000000, /* Set if table has variation kerning values. */
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Backwards = 0x10000000, /* If clear, process the glyphs forwards, that
* is, from first to last in the glyph stream.
* If we, process them from last to first.
* This flag only applies to state-table based
* 'kerx' subtables (types 1 and 4). */
Reserved = 0x0FFFFF00, /* Reserved, set to zero. */
SubtableType = 0x000000FF, /* Subtable type. */
};
template <typename context_t>
inline typename context_t::return_t dispatch (context_t *c) const
{
unsigned int subtable_type = get_type ();
TRACE_DISPATCH (this, subtable_type);
switch (subtable_type) {
case 0 : return_trace (c->dispatch (u.format0));
case 1 : return_trace (c->dispatch (u.format1));
case 2 : return_trace (c->dispatch (u.format2));
case 4 : return_trace (c->dispatch (u.format4));
case 6 : return_trace (c->dispatch (u.format6));
default: return_trace (c->default_return_value ());
}
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}
inline bool sanitize (hb_sanitize_context_t *c) const
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{
TRACE_SANITIZE (this);
if (!u.header.sanitize (c) ||
!c->check_range (this, u.header.length))
return_trace (false);
return_trace (dispatch (c));
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}
protected:
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union {
KerxSubTableHeader header;
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KerxSubTableFormat0 format0;
KerxSubTableFormat1 format1;
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KerxSubTableFormat2 format2;
KerxSubTableFormat4 format4;
KerxSubTableFormat6 format6;
} u;
public:
DEFINE_SIZE_MIN (12);
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};
/*
* The 'kerx' Table
*/
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struct kerx
{
static const hb_tag_t tableTag = HB_AAT_TAG_kerx;
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inline bool has_data (void) const { return version != 0; }
inline void apply (hb_aat_apply_context_t *c) const
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{
c->set_lookup_index (0);
const KerxTable *table = &firstTable;
unsigned int count = tableCount;
for (unsigned int i = 0; i < count; i++)
{
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bool reverse;
if (table->u.header.coverage & (KerxTable::CrossStream | KerxTable::Variation) ||
table->u.header.tupleCount)
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goto skip; /* We do NOT handle cross-stream or variation kerning. */
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if (HB_DIRECTION_IS_VERTICAL (c->buffer->props.direction) !=
bool (table->u.header.coverage & KerxTable::Vertical))
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goto skip;
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reverse = bool (table->u.header.coverage & KerxTable::Backwards) !=
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HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction);
if (!c->buffer->message (c->font, "start kerx subtable %d", c->lookup_index))
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goto skip;
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if (reverse)
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c->buffer->reverse ();
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c->sanitizer.set_object (*table);
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/* XXX Reverse-kern is not working yet...
* hb_kern_machine_t would need to know that it's reverse-kerning.
* Or better yet, make it work in reverse as well, so we don't have
* to reverse and reverse back? */
table->dispatch (c);
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if (reverse)
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c->buffer->reverse ();
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(void) c->buffer->message (c->font, "end kerx subtable %d", c->lookup_index);
skip:
table = &StructAfter<KerxTable> (*table);
}
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}
inline bool sanitize (hb_sanitize_context_t *c) const
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{
TRACE_SANITIZE (this);
if (!version.sanitize (c) || version < 2 ||
!tableCount.sanitize (c))
return_trace (false);
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const KerxTable *table = &firstTable;
unsigned int count = tableCount;
for (unsigned int i = 0; i < count; i++)
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{
if (!table->sanitize (c))
return_trace (false);
table = &StructAfter<KerxTable> (*table);
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}
return_trace (true);
}
protected:
HBUINT16 version; /* The version number of the extended kerning table
* (currently 2, 3, or 4). */
HBUINT16 unused; /* Set to 0. */
HBUINT32 tableCount; /* The number of subtables included in the extended kerning
* table. */
KerxTable firstTable; /* Subtables. */
/*subtableGlyphCoverageArray*/ /* Only if version >= 3. We don't use. */
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public:
DEFINE_SIZE_MIN (8);
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};
} /* namespace AAT */
#endif /* HB_AAT_LAYOUT_KERX_TABLE_HH */