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Diffstat (limited to 'gfx/harfbuzz/src/hb-aat-layout-kerx-table.hh')
| -rw-r--r-- | gfx/harfbuzz/src/hb-aat-layout-kerx-table.hh | 999 |
1 files changed, 999 insertions, 0 deletions
diff --git a/gfx/harfbuzz/src/hb-aat-layout-kerx-table.hh b/gfx/harfbuzz/src/hb-aat-layout-kerx-table.hh new file mode 100644 index 0000000000..995492cd5a --- /dev/null +++ b/gfx/harfbuzz/src/hb-aat-layout-kerx-table.hh @@ -0,0 +1,999 @@ +/* + * Copyright © 2018 Ebrahim Byagowi + * Copyright © 2018 Google, Inc. + * + * 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-kern.hh" +#include "hb-aat-layout-ankr-table.hh" + +/* + * 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') + + +namespace AAT { + +using namespace OT; + + +static inline int +kerxTupleKern (int value, + unsigned int tupleCount, + const void *base, + hb_aat_apply_context_t *c) +{ + if (likely (!tupleCount || !c)) return value; + + unsigned int offset = value; + const FWORD *pv = &StructAtOffset<FWORD> (base, offset); + if (unlikely (!c->sanitizer.check_array (pv, tupleCount))) return 0; + return *pv; +} + + +struct hb_glyph_pair_t +{ + hb_codepoint_t left; + hb_codepoint_t right; +}; + +struct KernPair +{ + int get_kerning () const { return value; } + + int cmp (const hb_glyph_pair_t &o) const + { + int ret = left.cmp (o.left); + if (ret) return ret; + return right.cmp (o.right); + } + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + return_trace (c->check_struct (this)); + } + + protected: + HBGlyphID16 left; + HBGlyphID16 right; + FWORD value; + public: + DEFINE_SIZE_STATIC (6); +}; + +template <typename KernSubTableHeader> +struct KerxSubTableFormat0 +{ + int get_kerning (hb_codepoint_t left, hb_codepoint_t right, + hb_aat_apply_context_t *c = nullptr) const + { + hb_glyph_pair_t pair = {left, right}; + int v = pairs.bsearch (pair).get_kerning (); + return kerxTupleKern (v, header.tuple_count (), this, c); + } + + bool apply (hb_aat_apply_context_t *c) const + { + TRACE_APPLY (this); + + if (!c->plan->requested_kerning) + return false; + + if (header.coverage & header.Backwards) + return false; + + accelerator_t accel (*this, c); + hb_kern_machine_t<accelerator_t> machine (accel, header.coverage & header.CrossStream); + machine.kern (c->font, c->buffer, c->plan->kern_mask); + + return_trace (true); + } + + struct accelerator_t + { + const KerxSubTableFormat0 &table; + hb_aat_apply_context_t *c; + + accelerator_t (const KerxSubTableFormat0 &table_, + hb_aat_apply_context_t *c_) : + table (table_), c (c_) {} + + int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const + { return table.get_kerning (left, right, c); } + }; + + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + return_trace (likely (pairs.sanitize (c))); + } + + protected: + KernSubTableHeader header; + BinSearchArrayOf<KernPair, typename KernSubTableHeader::Types::HBUINT> + pairs; /* Sorted kern records. */ + public: + DEFINE_SIZE_ARRAY (KernSubTableHeader::static_size + 16, pairs); +}; + + +template <bool extended> +struct Format1Entry; + +template <> +struct Format1Entry<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. */ + }; + + struct EntryData + { + HBUINT16 kernActionIndex;/* Index into the kerning value array. If + * this index is 0xFFFF, then no kerning + * is to be performed. */ + public: + DEFINE_SIZE_STATIC (2); + }; + + static bool performAction (const Entry<EntryData> &entry) + { return entry.data.kernActionIndex != 0xFFFF; } + + static unsigned int kernActionIndex (const Entry<EntryData> &entry) + { return entry.data.kernActionIndex; } +}; +template <> +struct Format1Entry<false> +{ + 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. */ + Offset = 0x3FFF, /* Byte offset from beginning of subtable to the + * value table for the glyphs on the kerning stack. */ + + Reset = 0x0000, /* Not supported? */ + }; + + typedef void EntryData; + + static bool performAction (const Entry<EntryData> &entry) + { return entry.flags & Offset; } + + static unsigned int kernActionIndex (const Entry<EntryData> &entry) + { return entry.flags & Offset; } +}; + +template <typename KernSubTableHeader> +struct KerxSubTableFormat1 +{ + typedef typename KernSubTableHeader::Types Types; + typedef typename Types::HBUINT HBUINT; + + typedef Format1Entry<Types::extended> Format1EntryT; + typedef typename Format1EntryT::EntryData EntryData; + + struct driver_context_t + { + static constexpr bool in_place = true; + enum + { + DontAdvance = Format1EntryT::DontAdvance, + }; + + driver_context_t (const KerxSubTableFormat1 *table_, + hb_aat_apply_context_t *c_) : + c (c_), + table (table_), + /* Apparently the offset kernAction is from the beginning of the state-machine, + * similar to offsets in morx table, NOT from beginning of this table, like + * other subtables in kerx. Discovered via testing. */ + kernAction (&table->machine + table->kernAction), + depth (0), + crossStream (table->header.coverage & table->header.CrossStream) {} + + bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED, + const Entry<EntryData> &entry) + { return Format1EntryT::performAction (entry); } + void transition (StateTableDriver<Types, EntryData> *driver, + const Entry<EntryData> &entry) + { + hb_buffer_t *buffer = driver->buffer; + unsigned int flags = entry.flags; + + if (flags & Format1EntryT::Reset) + depth = 0; + + if (flags & Format1EntryT::Push) + { + if (likely (depth < ARRAY_LENGTH (stack))) + stack[depth++] = buffer->idx; + else + depth = 0; /* Probably not what CoreText does, but better? */ + } + + if (Format1EntryT::performAction (entry) && depth) + { + unsigned int tuple_count = hb_max (1u, table->header.tuple_count ()); + + unsigned int kern_idx = Format1EntryT::kernActionIndex (entry); + kern_idx = Types::byteOffsetToIndex (kern_idx, &table->machine, kernAction.arrayZ); + const FWORD *actions = &kernAction[kern_idx]; + if (!c->sanitizer.check_array (actions, depth, tuple_count)) + { + depth = 0; + return; + } + + hb_mask_t kern_mask = c->plan->kern_mask; + + /* From Apple 'kern' spec: + * "Each pops one glyph from the kerning stack and applies the kerning value to it. + * The end of the list is marked by an odd value... */ + bool last = false; + while (!last && depth) + { + unsigned int idx = stack[--depth]; + int v = *actions; + actions += tuple_count; + if (idx >= buffer->len) continue; + + /* "The end of the list is marked by an odd value..." */ + last = v & 1; + v &= ~1; + + hb_glyph_position_t &o = buffer->pos[idx]; + + if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction)) + { + if (crossStream) + { + /* The following flag is undocumented in the spec, but described + * in the 'kern' table example. */ + if (v == -0x8000) + { + o.attach_type() = OT::Layout::GPOS_impl::ATTACH_TYPE_NONE; + o.attach_chain() = 0; + o.y_offset = 0; + } + else if (o.attach_type()) + { + o.y_offset += c->font->em_scale_y (v); + buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT; + } + } + else if (buffer->info[idx].mask & kern_mask) + { + o.x_advance += c->font->em_scale_x (v); + o.x_offset += c->font->em_scale_x (v); + } + } + else + { + if (crossStream) + { + /* CoreText doesn't do crossStream kerning in vertical. We do. */ + if (v == -0x8000) + { + o.attach_type() = OT::Layout::GPOS_impl::ATTACH_TYPE_NONE; + o.attach_chain() = 0; + o.x_offset = 0; + } + else if (o.attach_type()) + { + o.x_offset += c->font->em_scale_x (v); + buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT; + } + } + else if (buffer->info[idx].mask & kern_mask) + { + o.y_advance += c->font->em_scale_y (v); + o.y_offset += c->font->em_scale_y (v); + } + } + } + } + } + + private: + hb_aat_apply_context_t *c; + const KerxSubTableFormat1 *table; + const UnsizedArrayOf<FWORD> &kernAction; + unsigned int stack[8]; + unsigned int depth; + bool crossStream; + }; + + bool apply (hb_aat_apply_context_t *c) const + { + TRACE_APPLY (this); + + if (!c->plan->requested_kerning && + !(header.coverage & header.CrossStream)) + return false; + + driver_context_t dc (this, c); + + StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->font->face); + driver.drive (&dc); + + return_trace (true); + } + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + /* The rest of array sanitizations are done at run-time. */ + return_trace (likely (c->check_struct (this) && + machine.sanitize (c))); + } + + protected: + KernSubTableHeader header; + StateTable<Types, EntryData> machine; + NNOffsetTo<UnsizedArrayOf<FWORD>, HBUINT> kernAction; + public: + DEFINE_SIZE_STATIC (KernSubTableHeader::static_size + 5 * sizeof (HBUINT)); +}; + +template <typename KernSubTableHeader> +struct KerxSubTableFormat2 +{ + typedef typename KernSubTableHeader::Types Types; + typedef typename Types::HBUINT HBUINT; + + int get_kerning (hb_codepoint_t left, hb_codepoint_t right, + hb_aat_apply_context_t *c) const + { + unsigned int num_glyphs = c->sanitizer.get_num_glyphs (); + unsigned int l = (this+leftClassTable).get_class (left, num_glyphs, 0); + unsigned int r = (this+rightClassTable).get_class (right, num_glyphs, 0); + + const UnsizedArrayOf<FWORD> &arrayZ = this+array; + unsigned int kern_idx = l + r; + kern_idx = Types::offsetToIndex (kern_idx, this, arrayZ.arrayZ); + const FWORD *v = &arrayZ[kern_idx]; + if (unlikely (!v->sanitize (&c->sanitizer))) return 0; + + return kerxTupleKern (*v, header.tuple_count (), this, c); + } + + bool apply (hb_aat_apply_context_t *c) const + { + TRACE_APPLY (this); + + if (!c->plan->requested_kerning) + return false; + + if (header.coverage & header.Backwards) + return false; + + accelerator_t accel (*this, c); + hb_kern_machine_t<accelerator_t> machine (accel, header.coverage & header.CrossStream); + machine.kern (c->font, c->buffer, c->plan->kern_mask); + + return_trace (true); + } + + struct accelerator_t + { + const KerxSubTableFormat2 &table; + hb_aat_apply_context_t *c; + + accelerator_t (const KerxSubTableFormat2 &table_, + hb_aat_apply_context_t *c_) : + table (table_), c (c_) {} + + int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const + { return table.get_kerning (left, right, c); } + }; + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + return_trace (likely (c->check_struct (this) && + leftClassTable.sanitize (c, this) && + rightClassTable.sanitize (c, this) && + c->check_range (this, array))); + } + + protected: + KernSubTableHeader header; + HBUINT rowWidth; /* The width, in bytes, of a row in the table. */ + NNOffsetTo<typename Types::ClassTypeWide, HBUINT> + leftClassTable; /* Offset from beginning of this subtable to + * left-hand class table. */ + NNOffsetTo<typename Types::ClassTypeWide, HBUINT> + rightClassTable;/* Offset from beginning of this subtable to + * right-hand class table. */ + NNOffsetTo<UnsizedArrayOf<FWORD>, HBUINT> + array; /* Offset from beginning of this subtable to + * the start of the kerning array. */ + public: + DEFINE_SIZE_STATIC (KernSubTableHeader::static_size + 4 * sizeof (HBUINT)); +}; + +template <typename KernSubTableHeader> +struct KerxSubTableFormat4 +{ + typedef ExtendedTypes Types; + + struct EntryData + { + HBUINT16 ankrActionIndex;/* Either 0xFFFF (for no action) or the index of + * the action to perform. */ + public: + DEFINE_SIZE_STATIC (2); + }; + + struct driver_context_t + { + static constexpr bool in_place = true; + enum Flags + { + Mark = 0x8000, /* If set, remember this glyph as the marked glyph. */ + DontAdvance = 0x4000, /* If set, don't advance to the next glyph before + * going to the new state. */ + Reserved = 0x3FFF, /* Not used; set to 0. */ + }; + + enum SubTableFlags + { + ActionType = 0xC0000000, /* A two-bit field containing the action type. */ + Unused = 0x3F000000, /* Unused - must be zero. */ + Offset = 0x00FFFFFF, /* Masks the offset in bytes from the beginning + * of the subtable to the beginning of the control + * point table. */ + }; + + driver_context_t (const KerxSubTableFormat4 *table, + hb_aat_apply_context_t *c_) : + c (c_), + action_type ((table->flags & ActionType) >> 30), + ankrData ((HBUINT16 *) ((const char *) &table->machine + (table->flags & Offset))), + mark_set (false), + mark (0) {} + + bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED, + const Entry<EntryData> &entry) + { return entry.data.ankrActionIndex != 0xFFFF; } + void transition (StateTableDriver<Types, EntryData> *driver, + const Entry<EntryData> &entry) + { + hb_buffer_t *buffer = driver->buffer; + + if (mark_set && entry.data.ankrActionIndex != 0xFFFF && buffer->idx < buffer->len) + { + hb_glyph_position_t &o = buffer->cur_pos(); + switch (action_type) + { + case 0: /* Control Point Actions.*/ + { + /* Indexed into glyph outline. */ + /* Each action (record in ankrData) contains two 16-bit fields, so we must + double the ankrActionIndex to get the correct offset here. */ + const HBUINT16 *data = &ankrData[entry.data.ankrActionIndex * 2]; + if (!c->sanitizer.check_array (data, 2)) return; + unsigned int markControlPoint = *data++; + unsigned int currControlPoint = *data++; + hb_position_t markX = 0; + hb_position_t markY = 0; + hb_position_t currX = 0; + hb_position_t currY = 0; + if (!c->font->get_glyph_contour_point_for_origin (c->buffer->info[mark].codepoint, + markControlPoint, + HB_DIRECTION_LTR /*XXX*/, + &markX, &markY) || + !c->font->get_glyph_contour_point_for_origin (c->buffer->cur ().codepoint, + currControlPoint, + HB_DIRECTION_LTR /*XXX*/, + &currX, &currY)) + return; + + o.x_offset = markX - currX; + o.y_offset = markY - currY; + } + break; + + case 1: /* Anchor Point Actions. */ + { + /* Indexed into 'ankr' table. */ + /* Each action (record in ankrData) contains two 16-bit fields, so we must + double the ankrActionIndex to get the correct offset here. */ + const HBUINT16 *data = &ankrData[entry.data.ankrActionIndex * 2]; + if (!c->sanitizer.check_array (data, 2)) return; + unsigned int markAnchorPoint = *data++; + unsigned int currAnchorPoint = *data++; + const Anchor &markAnchor = c->ankr_table->get_anchor (c->buffer->info[mark].codepoint, + markAnchorPoint, + c->sanitizer.get_num_glyphs ()); + const Anchor &currAnchor = c->ankr_table->get_anchor (c->buffer->cur ().codepoint, + currAnchorPoint, + c->sanitizer.get_num_glyphs ()); + + o.x_offset = c->font->em_scale_x (markAnchor.xCoordinate) - c->font->em_scale_x (currAnchor.xCoordinate); + o.y_offset = c->font->em_scale_y (markAnchor.yCoordinate) - c->font->em_scale_y (currAnchor.yCoordinate); + } + break; + + case 2: /* Control Point Coordinate Actions. */ + { + /* Each action contains four 16-bit fields, so we multiply the ankrActionIndex + by 4 to get the correct offset for the given action. */ + const FWORD *data = (const FWORD *) &ankrData[entry.data.ankrActionIndex * 4]; + if (!c->sanitizer.check_array (data, 4)) return; + int markX = *data++; + int markY = *data++; + int currX = *data++; + int currY = *data++; + + o.x_offset = c->font->em_scale_x (markX) - c->font->em_scale_x (currX); + o.y_offset = c->font->em_scale_y (markY) - c->font->em_scale_y (currY); + } + break; + } + o.attach_type() = OT::Layout::GPOS_impl::ATTACH_TYPE_MARK; + o.attach_chain() = (int) mark - (int) buffer->idx; + buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT; + } + + if (entry.flags & Mark) + { + mark_set = true; + mark = buffer->idx; + } + } + + private: + hb_aat_apply_context_t *c; + unsigned int action_type; + const HBUINT16 *ankrData; + bool mark_set; + unsigned int mark; + }; + + bool apply (hb_aat_apply_context_t *c) const + { + TRACE_APPLY (this); + + driver_context_t dc (this, c); + + StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->font->face); + driver.drive (&dc); + + return_trace (true); + } + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + /* The rest of array sanitizations are done at run-time. */ + return_trace (likely (c->check_struct (this) && + machine.sanitize (c))); + } + + protected: + KernSubTableHeader header; + StateTable<Types, EntryData> machine; + HBUINT32 flags; + public: + DEFINE_SIZE_STATIC (KernSubTableHeader::static_size + 20); +}; + +template <typename KernSubTableHeader> +struct KerxSubTableFormat6 +{ + enum Flags + { + ValuesAreLong = 0x00000001, + }; + + bool is_long () const { return flags & ValuesAreLong; } + + int get_kerning (hb_codepoint_t left, hb_codepoint_t right, + hb_aat_apply_context_t *c) const + { + unsigned int num_glyphs = c->sanitizer.get_num_glyphs (); + if (is_long ()) + { + const typename 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; + if (unlikely (offset < l)) return 0; /* Addition overflow. */ + if (unlikely (hb_unsigned_mul_overflows (offset, sizeof (FWORD32)))) return 0; + const FWORD32 *v = &StructAtOffset<FWORD32> (&(this+t.array), offset * sizeof (FWORD32)); + if (unlikely (!v->sanitize (&c->sanitizer))) return 0; + return kerxTupleKern (*v, header.tuple_count (), &(this+vector), c); + } + else + { + const typename 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 (!v->sanitize (&c->sanitizer))) return 0; + return kerxTupleKern (*v, header.tuple_count (), &(this+vector), c); + } + } + + bool apply (hb_aat_apply_context_t *c) const + { + TRACE_APPLY (this); + + if (!c->plan->requested_kerning) + return false; + + if (header.coverage & header.Backwards) + return false; + + accelerator_t accel (*this, c); + hb_kern_machine_t<accelerator_t> machine (accel, header.coverage & header.CrossStream); + machine.kern (c->font, c->buffer, c->plan->kern_mask); + + return_trace (true); + } + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + return_trace (likely (c->check_struct (this) && + (is_long () ? + ( + u.l.rowIndexTable.sanitize (c, this) && + u.l.columnIndexTable.sanitize (c, this) && + c->check_range (this, u.l.array) + ) : ( + u.s.rowIndexTable.sanitize (c, this) && + u.s.columnIndexTable.sanitize (c, this) && + c->check_range (this, u.s.array) + )) && + (header.tuple_count () == 0 || + c->check_range (this, vector)))); + } + + struct accelerator_t + { + const KerxSubTableFormat6 &table; + hb_aat_apply_context_t *c; + + accelerator_t (const KerxSubTableFormat6 &table_, + hb_aat_apply_context_t *c_) : + table (table_), c (c_) {} + + int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const + { return table.get_kerning (left, right, c); } + }; + + protected: + KernSubTableHeader header; + HBUINT32 flags; + HBUINT16 rowCount; + HBUINT16 columnCount; + union U + { + struct Long + { + NNOffset32To<Lookup<HBUINT32>> rowIndexTable; + NNOffset32To<Lookup<HBUINT32>> columnIndexTable; + NNOffset32To<UnsizedArrayOf<FWORD32>> array; + } l; + struct Short + { + NNOffset32To<Lookup<HBUINT16>> rowIndexTable; + NNOffset32To<Lookup<HBUINT16>> columnIndexTable; + NNOffset32To<UnsizedArrayOf<FWORD>> array; + } s; + } u; + NNOffset32To<UnsizedArrayOf<FWORD>> vector; + public: + DEFINE_SIZE_STATIC (KernSubTableHeader::static_size + 24); +}; + + +struct KerxSubTableHeader +{ + typedef ExtendedTypes Types; + + unsigned tuple_count () const { return tupleCount; } + bool is_horizontal () const { return !(coverage & Vertical); } + + enum Coverage + { + Vertical = 0x80000000u, /* Set if table has vertical kerning values. */ + CrossStream = 0x40000000u, /* Set if table has cross-stream kerning values. */ + Variation = 0x20000000u, /* Set if table has variation kerning values. */ + Backwards = 0x10000000u, /* 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 = 0x0FFFFF00u, /* Reserved, set to zero. */ + SubtableType= 0x000000FFu, /* Subtable type. */ + }; + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + return_trace (c->check_struct (this)); + } + + public: + HBUINT32 length; + HBUINT32 coverage; + HBUINT32 tupleCount; + public: + DEFINE_SIZE_STATIC (12); +}; + +struct KerxSubTable +{ + friend struct kerx; + + unsigned int get_size () const { return u.header.length; } + unsigned int get_type () const { return u.header.coverage & u.header.SubtableType; } + + template <typename context_t, typename ...Ts> + typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const + { + unsigned int subtable_type = get_type (); + TRACE_DISPATCH (this, subtable_type); + switch (subtable_type) { + case 0: return_trace (c->dispatch (u.format0, std::forward<Ts> (ds)...)); + case 1: return_trace (c->dispatch (u.format1, std::forward<Ts> (ds)...)); + case 2: return_trace (c->dispatch (u.format2, std::forward<Ts> (ds)...)); + case 4: return_trace (c->dispatch (u.format4, std::forward<Ts> (ds)...)); + case 6: return_trace (c->dispatch (u.format6, std::forward<Ts> (ds)...)); + default: return_trace (c->default_return_value ()); + } + } + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + if (!u.header.sanitize (c) || + u.header.length <= u.header.static_size || + !c->check_range (this, u.header.length)) + return_trace (false); + + return_trace (dispatch (c)); + } + + public: + union { + KerxSubTableHeader header; + KerxSubTableFormat0<KerxSubTableHeader> format0; + KerxSubTableFormat1<KerxSubTableHeader> format1; + KerxSubTableFormat2<KerxSubTableHeader> format2; + KerxSubTableFormat4<KerxSubTableHeader> format4; + KerxSubTableFormat6<KerxSubTableHeader> format6; + } u; + public: + DEFINE_SIZE_MIN (12); +}; + + +/* + * The 'kerx' Table + */ + +template <typename T> +struct KerxTable +{ + /* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */ + const T* thiz () const { return static_cast<const T *> (this); } + + bool has_state_machine () const + { + typedef typename T::SubTable SubTable; + + const SubTable *st = &thiz()->firstSubTable; + unsigned int count = thiz()->tableCount; + for (unsigned int i = 0; i < count; i++) + { + if (st->get_type () == 1) + return true; + st = &StructAfter<SubTable> (*st); + } + return false; + } + + bool has_cross_stream () const + { + typedef typename T::SubTable SubTable; + + const SubTable *st = &thiz()->firstSubTable; + unsigned int count = thiz()->tableCount; + for (unsigned int i = 0; i < count; i++) + { + if (st->u.header.coverage & st->u.header.CrossStream) + return true; + st = &StructAfter<SubTable> (*st); + } + return false; + } + + int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const + { + typedef typename T::SubTable SubTable; + + int v = 0; + const SubTable *st = &thiz()->firstSubTable; + unsigned int count = thiz()->tableCount; + for (unsigned int i = 0; i < count; i++) + { + if ((st->u.header.coverage & (st->u.header.Variation | st->u.header.CrossStream)) || + !st->u.header.is_horizontal ()) + continue; + v += st->get_kerning (left, right); + st = &StructAfter<SubTable> (*st); + } + return v; + } + + bool apply (AAT::hb_aat_apply_context_t *c) const + { + typedef typename T::SubTable SubTable; + + bool ret = false; + bool seenCrossStream = false; + c->set_lookup_index (0); + const SubTable *st = &thiz()->firstSubTable; + unsigned int count = thiz()->tableCount; + for (unsigned int i = 0; i < count; i++) + { + bool reverse; + + if (!T::Types::extended && (st->u.header.coverage & st->u.header.Variation)) + goto skip; + + if (HB_DIRECTION_IS_HORIZONTAL (c->buffer->props.direction) != st->u.header.is_horizontal ()) + goto skip; + + reverse = bool (st->u.header.coverage & st->u.header.Backwards) != + HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction); + + if (!c->buffer->message (c->font, "start subtable %d", c->lookup_index)) + goto skip; + + if (!seenCrossStream && + (st->u.header.coverage & st->u.header.CrossStream)) + { + /* Attach all glyphs into a chain. */ + seenCrossStream = true; + hb_glyph_position_t *pos = c->buffer->pos; + unsigned int count = c->buffer->len; + for (unsigned int i = 0; i < count; i++) + { + pos[i].attach_type() = OT::Layout::GPOS_impl::ATTACH_TYPE_CURSIVE; + pos[i].attach_chain() = HB_DIRECTION_IS_FORWARD (c->buffer->props.direction) ? -1 : +1; + /* We intentionally don't set HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT, + * since there needs to be a non-zero attachment for post-positioning to + * be needed. */ + } + } + + if (reverse) + c->buffer->reverse (); + + { + /* See comment in sanitize() for conditional here. */ + hb_sanitize_with_object_t with (&c->sanitizer, i < count - 1 ? st : (const SubTable *) nullptr); + ret |= st->dispatch (c); + } + + if (reverse) + c->buffer->reverse (); + + (void) c->buffer->message (c->font, "end subtable %d", c->lookup_index); + + skip: + st = &StructAfter<SubTable> (*st); + c->set_lookup_index (c->lookup_index + 1); + } + + return ret; + } + + bool sanitize (hb_sanitize_context_t *c) const + { + TRACE_SANITIZE (this); + if (unlikely (!thiz()->version.sanitize (c) || + (unsigned) thiz()->version < (unsigned) T::minVersion || + !thiz()->tableCount.sanitize (c))) + return_trace (false); + + typedef typename T::SubTable SubTable; + + const SubTable *st = &thiz()->firstSubTable; + unsigned int count = thiz()->tableCount; + for (unsigned int i = 0; i < count; i++) + { + if (unlikely (!st->u.header.sanitize (c))) + return_trace (false); + /* OpenType kern table has 2-byte subtable lengths. That's limiting. + * MS implementation also only supports one subtable, of format 0, + * anyway. Certain versions of some fonts, like Calibry, contain + * kern subtable that exceeds 64kb. Looks like, the subtable length + * is simply ignored. Which makes sense. It's only needed if you + * have multiple subtables. To handle such fonts, we just ignore + * the length for the last subtable. */ + hb_sanitize_with_object_t with (c, i < count - 1 ? st : (const SubTable *) nullptr); + + if (unlikely (!st->sanitize (c))) + return_trace (false); + + st = &StructAfter<SubTable> (*st); + } + + return_trace (true); + } +}; + +struct kerx : KerxTable<kerx> +{ + friend struct KerxTable<kerx>; + + static constexpr hb_tag_t tableTag = HB_AAT_TAG_kerx; + static constexpr unsigned minVersion = 2u; + + typedef KerxSubTableHeader SubTableHeader; + typedef SubTableHeader::Types Types; + typedef KerxSubTable SubTable; + + bool has_data () const { return version; } + + 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. */ + SubTable firstSubTable; /* Subtables. */ +/*subtableGlyphCoverageArray*/ /* Only if version >= 3. We don't use. */ + + public: + DEFINE_SIZE_MIN (8); +}; + + +} /* namespace AAT */ + + +#endif /* HB_AAT_LAYOUT_KERX_TABLE_HH */ |