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

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/*
 * Copyright © 2017  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_MORX_TABLE_HH
#define HB_AAT_LAYOUT_MORX_TABLE_HH

#include "hb-open-type.hh"
#include "hb-aat-layout-common.hh"
#include "hb-ot-layout-common.hh"
#include "hb-ot-layout-gdef-table.hh"
#include "hb-aat-map.hh"

/*
 * morx -- Extended Glyph Metamorphosis
 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6morx.html
 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6mort.html
 */
#define HB_AAT_TAG_morx HB_TAG('m','o','r','x')
#define HB_AAT_TAG_mort HB_TAG('m','o','r','t')


namespace AAT {

using namespace OT;

template <typename Types>
struct RearrangementSubtable
{
  typedef typename Types::HBUINT HBUINT;

  typedef void EntryData;

  struct driver_context_t
  {
    static constexpr bool in_place = true;
    enum Flags
    {
      MarkFirst   = 0x8000, /* If set, make the current glyph the first
           * glyph to be rearranged. */
      DontAdvance = 0x4000, /* If set, don't advance to the next glyph
           * before going to the new state. This means
           * that the glyph index doesn't change, even
           * if the glyph at that index has changed. */
      MarkLast    = 0x2000, /* If set, make the current glyph the last
           * glyph to be rearranged. */
      Reserved    = 0x1FF0, /* These bits are reserved and should be set to 0. */
      Verb    = 0x000F, /* The type of rearrangement specified. */
    };

    driver_context_t (const RearrangementSubtable *table HB_UNUSED) :
  ret (false),
  start (0), end (0) {}

    bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
      const Entry<EntryData> &entry)
    {
      return (entry.flags & Verb) && start < end;
    }
    void transition (StateTableDriver<Types, EntryData> *driver,
         const Entry<EntryData> &entry)
    {
      hb_buffer_t *buffer = driver->buffer;
      unsigned int flags = entry.flags;

      if (flags & MarkFirst)
  start = buffer->idx;

      if (flags & MarkLast)
  end = hb_min (buffer->idx + 1, buffer->len);

      if ((flags & Verb) && start < end)
      {
  /* The following map has two nibbles, for start-side
   * and end-side. Values of 0,1,2 mean move that many
   * to the other side. Value of 3 means move 2 and
   * flip them. */
  const unsigned char map[16] =
  {
    0x00, /* 0  no change */
    0x10, /* 1  Ax => xA */
    0x01, /* 2  xD => Dx */
    0x11, /* 3  AxD => DxA */
    0x20, /* 4  ABx => xAB */
    0x30, /* 5  ABx => xBA */
    0x02, /* 6  xCD => CDx */
    0x03, /* 7  xCD => DCx */
    0x12, /* 8  AxCD => CDxA */
    0x13, /* 9  AxCD => DCxA */
    0x21, /* 10 ABxD => DxAB */
    0x31, /* 11 ABxD => DxBA */
    0x22, /* 12 ABxCD => CDxAB */
    0x32, /* 13 ABxCD => CDxBA */
    0x23, /* 14 ABxCD => DCxAB */
    0x33, /* 15 ABxCD => DCxBA */
  };

  unsigned int m = map[flags & Verb];
  unsigned int l = hb_min (2u, m >> 4);
  unsigned int r = hb_min (2u, m & 0x0F);
  bool reverse_l = 3 == (m >> 4);
  bool reverse_r = 3 == (m & 0x0F);

  if (end - start >= l + r && end-start <= HB_MAX_CONTEXT_LENGTH)
  {
    buffer->merge_clusters (start, hb_min (buffer->idx + 1, buffer->len));
    buffer->merge_clusters (start, end);

    hb_glyph_info_t *info = buffer->info;
    hb_glyph_info_t buf[4];

    hb_memcpy (buf, info + start, l * sizeof (buf[0]));
    hb_memcpy (buf + 2, info + end - r, r * sizeof (buf[0]));

    if (l != r)
      memmove (info + start + r, info + start + l, (end - start - l - r) * sizeof (buf[0]));

    hb_memcpy (info + start, buf + 2, r * sizeof (buf[0]));
    hb_memcpy (info + end - l, buf, l * sizeof (buf[0]));
    if (reverse_l)
    {
      buf[0] = info[end - 1];
      info[end - 1] = info[end - 2];
      info[end - 2] = buf[0];
    }
    if (reverse_r)
    {
      buf[0] = info[start];
      info[start] = info[start + 1];
      info[start + 1] = buf[0];
    }
  }
      }
    }

    public:
    bool ret;
    private:
    unsigned int start;
    unsigned int end;
  };

  bool apply (hb_aat_apply_context_t *c) const
  {
    TRACE_APPLY (this);

    driver_context_t dc (this);

    StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->face);
    driver.drive (&dc, c);

    return_trace (dc.ret);
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    return_trace (machine.sanitize (c));
  }

  protected:
  StateTable<Types, EntryData>  machine;
  public:
  DEFINE_SIZE_STATIC (16);
};

template <typename Types>
struct ContextualSubtable
{
  typedef typename Types::HBUINT HBUINT;

  struct EntryData
  {
    HBUINT16  markIndex;  /* Index of the substitution table for the
         * marked glyph (use 0xFFFF for none). */
    HBUINT16  currentIndex; /* Index of the substitution table for the
         * current glyph (use 0xFFFF for none). */
    public:
    DEFINE_SIZE_STATIC (4);
  };

  struct driver_context_t
  {
    static constexpr bool in_place = true;
    enum Flags
    {
      SetMark   = 0x8000, /* If set, make the current glyph the marked glyph. */
      DontAdvance = 0x4000, /* If set, don't advance to the next glyph before
           * going to the new state. */
      Reserved    = 0x3FFF, /* These bits are reserved and should be set to 0. */
    };

    driver_context_t (const ContextualSubtable *table_,
           hb_aat_apply_context_t *c_) :
  ret (false),
  c (c_),
  gdef (*c->gdef_table),
  mark_set (false),
  has_glyph_classes (gdef.has_glyph_classes ()),
  mark (0),
  table (table_),
  subs (table+table->substitutionTables) {}

    bool is_actionable (StateTableDriver<Types, EntryData> *driver,
      const Entry<EntryData> &entry)
    {
      hb_buffer_t *buffer = driver->buffer;

      if (buffer->idx == buffer->len && !mark_set)
  return false;

      return entry.data.markIndex != 0xFFFF || entry.data.currentIndex != 0xFFFF;
    }
    void transition (StateTableDriver<Types, EntryData> *driver,
         const Entry<EntryData> &entry)
    {
      hb_buffer_t *buffer = driver->buffer;

      /* Looks like CoreText applies neither mark nor current substitution for
       * end-of-text if mark was not explicitly set. */
      if (buffer->idx == buffer->len && !mark_set)
  return;

      const HBGlyphID16 *replacement;

      replacement = nullptr;
      if (Types::extended)
      {
  if (entry.data.markIndex != 0xFFFF)
  {
    const Lookup<HBGlyphID16> &lookup = subs[entry.data.markIndex];
    replacement = lookup.get_value (buffer->info[mark].codepoint, driver->num_glyphs);
  }
      }
      else
      {
  unsigned int offset = entry.data.markIndex + buffer->info[mark].codepoint;
  const UnsizedArrayOf<HBGlyphID16> &subs_old = (const UnsizedArrayOf<HBGlyphID16> &) subs;
  replacement = &subs_old[Types::wordOffsetToIndex (offset, table, subs_old.arrayZ)];
  if (!replacement->sanitize (&c->sanitizer) || !*replacement)
    replacement = nullptr;
      }
      if (replacement)
      {
  buffer->unsafe_to_break (mark, hb_min (buffer->idx + 1, buffer->len));
  buffer->info[mark].codepoint = *replacement;
  if (has_glyph_classes)
    _hb_glyph_info_set_glyph_props (&buffer->info[mark],
            gdef.get_glyph_props (*replacement));
  ret = true;
      }

      replacement = nullptr;
      unsigned int idx = hb_min (buffer->idx, buffer->len - 1);
      if (Types::extended)
      {
  if (entry.data.currentIndex != 0xFFFF)
  {
    const Lookup<HBGlyphID16> &lookup = subs[entry.data.currentIndex];
    replacement = lookup.get_value (buffer->info[idx].codepoint, driver->num_glyphs);
  }
      }
      else
      {
  unsigned int offset = entry.data.currentIndex + buffer->info[idx].codepoint;
  const UnsizedArrayOf<HBGlyphID16> &subs_old = (const UnsizedArrayOf<HBGlyphID16> &) subs;
  replacement = &subs_old[Types::wordOffsetToIndex (offset, table, subs_old.arrayZ)];
  if (!replacement->sanitize (&c->sanitizer) || !*replacement)
    replacement = nullptr;
      }
      if (replacement)
      {
  buffer->info[idx].codepoint = *replacement;
  if (has_glyph_classes)
    _hb_glyph_info_set_glyph_props (&buffer->info[idx],
            gdef.get_glyph_props (*replacement));
  ret = true;
      }

      if (entry.flags & SetMark)
      {
  mark_set = true;
  mark = buffer->idx;
      }
    }

    public:
    bool ret;
    private:
    hb_aat_apply_context_t *c;
    const OT::GDEF &gdef;
    bool mark_set;
    bool has_glyph_classes;
    unsigned int mark;
    const ContextualSubtable *table;
    const UnsizedListOfOffset16To<Lookup<HBGlyphID16>, HBUINT, false> &subs;
  };

  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->face);
    driver.drive (&dc, c);

    return_trace (dc.ret);
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);

    unsigned int num_entries = 0;
    if (unlikely (!machine.sanitize (c, &num_entries))) return_trace (false);

    if (!Types::extended)
      return_trace (substitutionTables.sanitize (c, this, 0));

    unsigned int num_lookups = 0;

    const Entry<EntryData> *entries = machine.get_entries ();
    for (unsigned int i = 0; i < num_entries; i++)
    {
      const EntryData &data = entries[i].data;

      if (data.markIndex != 0xFFFF)
  num_lookups = hb_max (num_lookups, 1u + data.markIndex);
      if (data.currentIndex != 0xFFFF)
  num_lookups = hb_max (num_lookups, 1u + data.currentIndex);
    }

    return_trace (substitutionTables.sanitize (c, this, num_lookups));
  }

  protected:
  StateTable<Types, EntryData>
    machine;
  NNOffsetTo<UnsizedListOfOffset16To<Lookup<HBGlyphID16>, HBUINT, false>, HBUINT>
    substitutionTables;
  public:
  DEFINE_SIZE_STATIC (20);
};


template <bool extended>
struct LigatureEntry;

template <>
struct LigatureEntry<true>
{
  enum Flags
  {
    SetComponent  = 0x8000, /* Push this glyph onto the component stack for
           * eventual processing. */
    DontAdvance   = 0x4000, /* Leave the glyph pointer at this glyph for the
             next iteration. */
    PerformAction = 0x2000, /* Use the ligActionIndex to process a ligature
           * group. */
    Reserved    = 0x1FFF, /* These bits are reserved and should be set to 0. */
  };

  struct EntryData
  {
    HBUINT16  ligActionIndex; /* Index to the first ligActionTable entry
         * for processing this group, if indicated
         * by the flags. */
    public:
    DEFINE_SIZE_STATIC (2);
  };

  static bool performAction (const Entry<EntryData> &entry)
  { return entry.flags & PerformAction; }

  static unsigned int ligActionIndex (const Entry<EntryData> &entry)
  { return entry.data.ligActionIndex; }
};
template <>
struct LigatureEntry<false>
{
  enum Flags
  {
    SetComponent  = 0x8000, /* Push this glyph onto the component stack for
           * eventual processing. */
    DontAdvance   = 0x4000, /* Leave the glyph pointer at this glyph for the
             next iteration. */
    Offset    = 0x3FFF, /* Byte offset from beginning of subtable to the
           * ligature action list. This value must be a
           * multiple of 4. */
  };

  typedef void EntryData;

  static bool performAction (const Entry<EntryData> &entry)
  { return entry.flags & Offset; }

  static unsigned int ligActionIndex (const Entry<EntryData> &entry)
  { return entry.flags & Offset; }
};


template <typename Types>
struct LigatureSubtable
{
  typedef typename Types::HBUINT HBUINT;

  typedef LigatureEntry<Types::extended> LigatureEntryT;
  typedef typename LigatureEntryT::EntryData EntryData;

  struct driver_context_t
  {
    static constexpr bool in_place = false;
    enum
    {
      DontAdvance = LigatureEntryT::DontAdvance,
    };
    enum LigActionFlags
    {
      LigActionLast = 0x80000000, /* This is the last action in the list. This also
           * implies storage. */
      LigActionStore  = 0x40000000, /* Store the ligature at the current cumulated index
           * in the ligature table in place of the marked
           * (i.e. currently-popped) glyph. */
      LigActionOffset = 0x3FFFFFFF, /* A 30-bit value which is sign-extended to 32-bits
           * and added to the glyph ID, resulting in an index
           * into the component table. */
    };

    driver_context_t (const LigatureSubtable *table_,
          hb_aat_apply_context_t *c_) :
  ret (false),
  c (c_),
  table (table_),
  ligAction (table+table->ligAction),
  component (table+table->component),
  ligature (table+table->ligature),
  match_length (0) {}

    bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
      const Entry<EntryData> &entry)
    {
      return LigatureEntryT::performAction (entry);
    }
    void transition (StateTableDriver<Types, EntryData> *driver,
         const Entry<EntryData> &entry)
    {
      hb_buffer_t *buffer = driver->buffer;

      DEBUG_MSG (APPLY, nullptr, "Ligature transition at %u", buffer->idx);
      if (entry.flags & LigatureEntryT::SetComponent)
      {
  /* Never mark same index twice, in case DontAdvance was used... */
  if (match_length && match_positions[(match_length - 1u) % ARRAY_LENGTH (match_positions)] == buffer->out_len)
    match_length--;

  match_positions[match_length++ % ARRAY_LENGTH (match_positions)] = buffer->out_len;
  DEBUG_MSG (APPLY, nullptr, "Set component at %u", buffer->out_len);
      }

      if (LigatureEntryT::performAction (entry))
      {
  DEBUG_MSG (APPLY, nullptr, "Perform action with %u", match_length);
  unsigned int end = buffer->out_len;

  if (unlikely (!match_length))
    return;

  if (buffer->idx >= buffer->len)
    return; /* TODO Work on previous instead? */

  unsigned int cursor = match_length;

  unsigned int action_idx = LigatureEntryT::ligActionIndex (entry);
  action_idx = Types::offsetToIndex (action_idx, table, ligAction.arrayZ);
  const HBUINT32 *actionData = &ligAction[action_idx];

  unsigned int ligature_idx = 0;
  unsigned int action;
  do
  {
    if (unlikely (!cursor))
    {
      /* Stack underflow.  Clear the stack. */
      DEBUG_MSG (APPLY, nullptr, "Stack underflow");
      match_length = 0;
      break;
    }

    DEBUG_MSG (APPLY, nullptr, "Moving to stack position %u", cursor - 1);
    if (unlikely (!buffer->move_to (match_positions[--cursor % ARRAY_LENGTH (match_positions)]))) return;

    if (unlikely (!actionData->sanitize (&c->sanitizer))) break;
    action = *actionData;

    uint32_t uoffset = action & LigActionOffset;
    if (uoffset & 0x20000000)
      uoffset |= 0xC0000000; /* Sign-extend. */
    int32_t offset = (int32_t) uoffset;
    unsigned int component_idx = buffer->cur().codepoint + offset;
    component_idx = Types::wordOffsetToIndex (component_idx, table, component.arrayZ);
    const HBUINT16 &componentData = component[component_idx];
    if (unlikely (!componentData.sanitize (&c->sanitizer))) break;
    ligature_idx += componentData;

    DEBUG_MSG (APPLY, nullptr, "Action store %d last %d",
         bool (action & LigActionStore),
         bool (action & LigActionLast));
    if (action & (LigActionStore | LigActionLast))
    {
      ligature_idx = Types::offsetToIndex (ligature_idx, table, ligature.arrayZ);
      const HBGlyphID16 &ligatureData = ligature[ligature_idx];
      if (unlikely (!ligatureData.sanitize (&c->sanitizer))) break;
      hb_codepoint_t lig = ligatureData;

      DEBUG_MSG (APPLY, nullptr, "Produced ligature %u", lig);
      if (unlikely (!buffer->replace_glyph (lig))) return;

      unsigned int lig_end = match_positions[(match_length - 1u) % ARRAY_LENGTH (match_positions)] + 1u;
      /* Now go and delete all subsequent components. */
      while (match_length - 1u > cursor)
      {
        DEBUG_MSG (APPLY, nullptr, "Skipping ligature component");
        if (unlikely (!buffer->move_to (match_positions[--match_length % ARRAY_LENGTH (match_positions)]))) return;
        if (unlikely (!buffer->replace_glyph (DELETED_GLYPH))) return;
      }

      if (unlikely (!buffer->move_to (lig_end))) return;
      buffer->merge_out_clusters (match_positions[cursor % ARRAY_LENGTH (match_positions)], buffer->out_len);
    }

    actionData++;
  }
  while (!(action & LigActionLast));
  if (unlikely (!buffer->move_to (end))) return;
      }
    }

    public:
    bool ret;
    private:
    hb_aat_apply_context_t *c;
    const LigatureSubtable *table;
    const UnsizedArrayOf<HBUINT32> &ligAction;
    const UnsizedArrayOf<HBUINT16> &component;
    const UnsizedArrayOf<HBGlyphID16> &ligature;
    unsigned int match_length;
    unsigned int match_positions[HB_MAX_CONTEXT_LENGTH];
  };

  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->face);
    driver.drive (&dc, c);

    return_trace (dc.ret);
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    /* The rest of array sanitizations are done at run-time. */
    return_trace (c->check_struct (this) && machine.sanitize (c) &&
      ligAction && component && ligature);
  }

  protected:
  StateTable<Types, EntryData>
    machine;
  NNOffsetTo<UnsizedArrayOf<HBUINT32>, HBUINT>
    ligAction;  /* Offset to the ligature action table. */
  NNOffsetTo<UnsizedArrayOf<HBUINT16>, HBUINT>
    component;  /* Offset to the component table. */
  NNOffsetTo<UnsizedArrayOf<HBGlyphID16>, HBUINT>
    ligature; /* Offset to the actual ligature lists. */
  public:
  DEFINE_SIZE_STATIC (28);
};

template <typename Types>
struct NoncontextualSubtable
{
  bool apply (hb_aat_apply_context_t *c) const
  {
    TRACE_APPLY (this);

    const OT::GDEF &gdef (*c->gdef_table);
    bool has_glyph_classes = gdef.has_glyph_classes ();

    bool ret = false;
    unsigned int num_glyphs = c->face->get_num_glyphs ();

    hb_glyph_info_t *info = c->buffer->info;
    unsigned int count = c->buffer->len;
    // If there's only one range, we already checked the flag.
    auto *last_range = c->range_flags && (c->range_flags->length > 1) ? &(*c->range_flags)[0] : nullptr;
    for (unsigned int i = 0; i < count; i++)
    {
      /* This block copied from StateTableDriver::drive. Keep in sync. */
      if (last_range)
      {
  auto *range = last_range;
  {
    unsigned cluster = info[i].cluster;
    while (cluster < range->cluster_first)
      range--;
    while (cluster > range->cluster_last)
      range++;

    last_range = range;
  }
  if (!(range->flags & c->subtable_flags))
    continue;
      }

      const HBGlyphID16 *replacement = substitute.get_value (info[i].codepoint, num_glyphs);
      if (replacement)
      {
  info[i].codepoint = *replacement;
  if (has_glyph_classes)
    _hb_glyph_info_set_glyph_props (&info[i],
            gdef.get_glyph_props (*replacement));
  ret = true;
      }
    }

    return_trace (ret);
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    return_trace (substitute.sanitize (c));
  }

  protected:
  Lookup<HBGlyphID16> substitute;
  public:
  DEFINE_SIZE_MIN (2);
};

template <typename Types>
struct InsertionSubtable
{
  typedef typename Types::HBUINT HBUINT;

  struct EntryData
  {
    HBUINT16  currentInsertIndex; /* Zero-based index into the insertion glyph table.
           * The number of glyphs to be inserted is contained
           * in the currentInsertCount field in the flags.
           * A value of 0xFFFF indicates no insertion is to
           * be done. */
    HBUINT16  markedInsertIndex;  /* Zero-based index into the insertion glyph table.
           * The number of glyphs to be inserted is contained
           * in the markedInsertCount field in the flags.
           * A value of 0xFFFF indicates no insertion is to
           * be done. */
    public:
    DEFINE_SIZE_STATIC (4);
  };

  struct driver_context_t
  {
    static constexpr bool in_place = false;
    enum Flags
    {
      SetMark   = 0x8000, /* If set, mark the current glyph. */
      DontAdvance = 0x4000, /* If set, don't advance to the next glyph before
           * going to the new state.  This does not mean
           * that the glyph pointed to is the same one as
           * before. If you've made insertions immediately
           * downstream of the current glyph, the next glyph
           * processed would in fact be the first one
           * inserted. */
      CurrentIsKashidaLike= 0x2000, /* If set, and the currentInsertList is nonzero,
           * then the specified glyph list will be inserted
           * as a kashida-like insertion, either before or
           * after the current glyph (depending on the state
           * of the currentInsertBefore flag). If clear, and
           * the currentInsertList is nonzero, then the
           * specified glyph list will be inserted as a
           * split-vowel-like insertion, either before or
           * after the current glyph (depending on the state
           * of the currentInsertBefore flag). */
      MarkedIsKashidaLike= 0x1000,  /* If set, and the markedInsertList is nonzero,
           * then the specified glyph list will be inserted
           * as a kashida-like insertion, either before or
           * after the marked glyph (depending on the state
           * of the markedInsertBefore flag). If clear, and
           * the markedInsertList is nonzero, then the
           * specified glyph list will be inserted as a
           * split-vowel-like insertion, either before or
           * after the marked glyph (depending on the state
           * of the markedInsertBefore flag). */
      CurrentInsertBefore= 0x0800,  /* If set, specifies that insertions are to be made
           * to the left of the current glyph. If clear,
           * they're made to the right of the current glyph. */
      MarkedInsertBefore= 0x0400, /* If set, specifies that insertions are to be
           * made to the left of the marked glyph. If clear,
           * they're made to the right of the marked glyph. */
      CurrentInsertCount= 0x3E0,  /* This 5-bit field is treated as a count of the
           * number of glyphs to insert at the current
           * position. Since zero means no insertions, the
           * largest number of insertions at any given
           * current location is 31 glyphs. */
      MarkedInsertCount= 0x001F,  /* This 5-bit field is treated as a count of the
           * number of glyphs to insert at the marked
           * position. Since zero means no insertions, the
           * largest number of insertions at any given
           * marked location is 31 glyphs. */
    };

    driver_context_t (const InsertionSubtable *table,
          hb_aat_apply_context_t *c_) :
  ret (false),
  c (c_),
  mark (0),
  insertionAction (table+table->insertionAction) {}

    bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
      const Entry<EntryData> &entry)
    {
      return (entry.flags & (CurrentInsertCount | MarkedInsertCount)) &&
       (entry.data.currentInsertIndex != 0xFFFF ||entry.data.markedInsertIndex != 0xFFFF);
    }
    void transition (StateTableDriver<Types, EntryData> *driver,
         const Entry<EntryData> &entry)
    {
      hb_buffer_t *buffer = driver->buffer;
      unsigned int flags = entry.flags;

      unsigned mark_loc = buffer->out_len;

      if (entry.data.markedInsertIndex != 0xFFFF)
      {
  unsigned int count = (flags & MarkedInsertCount);
  if (unlikely ((buffer->max_ops -= count) <= 0)) return;
  unsigned int start = entry.data.markedInsertIndex;
  const HBGlyphID16 *glyphs = &insertionAction[start];
  if (unlikely (!c->sanitizer.check_array (glyphs, count))) count = 0;

  bool before = flags & MarkedInsertBefore;

  unsigned int end = buffer->out_len;
  if (unlikely (!buffer->move_to (mark))) return;

  if (buffer->idx < buffer->len && !before)
    if (unlikely (!buffer->copy_glyph ())) return;
  /* TODO We ignore KashidaLike setting. */
  if (unlikely (!buffer->replace_glyphs (0, count, glyphs))) return;
  if (buffer->idx < buffer->len && !before)
    buffer->skip_glyph ();

  if (unlikely (!buffer->move_to (end + count))) return;

  buffer->unsafe_to_break_from_outbuffer (mark, hb_min (buffer->idx + 1, buffer->len));
      }

      if (flags & SetMark)
  mark = mark_loc;

      if (entry.data.currentInsertIndex != 0xFFFF)
      {
  unsigned int count = (flags & CurrentInsertCount) >> 5;
  if (unlikely ((buffer->max_ops -= count) <= 0)) return;
  unsigned int start = entry.data.currentInsertIndex;
  const HBGlyphID16 *glyphs = &insertionAction[start];
  if (unlikely (!c->sanitizer.check_array (glyphs, count))) count = 0;

  bool before = flags & CurrentInsertBefore;

  unsigned int end = buffer->out_len;

  if (buffer->idx < buffer->len && !before)
    if (unlikely (!buffer->copy_glyph ())) return;
  /* TODO We ignore KashidaLike setting. */
  if (unlikely (!buffer->replace_glyphs (0, count, glyphs))) return;
  if (buffer->idx < buffer->len && !before)
    buffer->skip_glyph ();

  /* Humm. Not sure where to move to.  There's this wording under
   * DontAdvance flag:
   *
   * "If set, don't update the glyph index before going to the new state.
   * This does not mean that the glyph pointed to is the same one as
   * before. If you've made insertions immediately downstream of the
   * current glyph, the next glyph processed would in fact be the first
   * one inserted."
   *
   * This suggests that if DontAdvance is NOT set, we should move to
   * end+count.  If it *was*, then move to end, such that newly inserted
   * glyphs are now visible.
   *
   * https://github.com/harfbuzz/harfbuzz/issues/1224#issuecomment-427691417
   */
  if (unlikely (!buffer->move_to ((flags & DontAdvance) ? end : end + count))) return;
      }
    }

    public:
    bool ret;
    private:
    hb_aat_apply_context_t *c;
    unsigned int mark;
    const UnsizedArrayOf<HBGlyphID16> &insertionAction;
  };

  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->face);
    driver.drive (&dc, c);

    return_trace (dc.ret);
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    /* The rest of array sanitizations are done at run-time. */
    return_trace (c->check_struct (this) && machine.sanitize (c) &&
      insertionAction);
  }

  protected:
  StateTable<Types, EntryData>
    machine;
  NNOffsetTo<UnsizedArrayOf<HBGlyphID16>, HBUINT>
    insertionAction;  /* Byte offset from stateHeader to the start of
           * the insertion glyph table. */
  public:
  DEFINE_SIZE_STATIC (20);
};


struct Feature
{
  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    return_trace (c->check_struct (this));
  }

  public:
  HBUINT16  featureType;  /* The type of feature. */
  HBUINT16  featureSetting; /* The feature's setting (aka selector). */
  HBUINT32  enableFlags;  /* Flags for the settings that this feature
         * and setting enables. */
  HBUINT32  disableFlags; /* Complement of flags for the settings that this
         * feature and setting disable. */

  public:
  DEFINE_SIZE_STATIC (12);
};

template <typename Types>
struct ChainSubtable
{
  typedef typename Types::HBUINT HBUINT;

  template <typename T>
  friend struct Chain;

  unsigned int get_size () const     { return length; }
  unsigned int get_type () const     { return coverage & 0xFF; }
  unsigned int get_coverage () const { return coverage >> (sizeof (HBUINT) * 8 - 8); }

  enum Coverage
  {
    Vertical    = 0x80, /* If set, this subtable will only be applied
         * to vertical text. If clear, this subtable
         * will only be applied to horizontal text. */
    Backwards   = 0x40, /* If set, this subtable will process glyphs
         * in descending order. If clear, it will
         * process the glyphs in ascending order. */
    AllDirections = 0x20, /* If set, this subtable will be applied to
         * both horizontal and vertical text (i.e.
         * the state of bit 0x80000000 is ignored). */
    Logical   = 0x10, /* If set, this subtable will process glyphs
         * in logical order (or reverse logical order,
         * depending on the value of bit 0x80000000). */
  };
  enum Type
  {
    Rearrangement = 0,
    Contextual    = 1,
    Ligature    = 2,
    Noncontextual = 4,
    Insertion   = 5
  };

  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 Rearrangement:   return_trace (c->dispatch (u.rearrangement, std::forward<Ts> (ds)...));
    case Contextual:    return_trace (c->dispatch (u.contextual, std::forward<Ts> (ds)...));
    case Ligature:    return_trace (c->dispatch (u.ligature, std::forward<Ts> (ds)...));
    case Noncontextual:   return_trace (c->dispatch (u.noncontextual, std::forward<Ts> (ds)...));
    case Insertion:   return_trace (c->dispatch (u.insertion, std::forward<Ts> (ds)...));
    default:      return_trace (c->default_return_value ());
    }
  }

  bool apply (hb_aat_apply_context_t *c) const
  {
    TRACE_APPLY (this);
    hb_sanitize_with_object_t with (&c->sanitizer, this);
    return_trace (dispatch (c));
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    if (!length.sanitize (c) ||
  length <= min_size ||
  !c->check_range (this, length))
      return_trace (false);

    hb_sanitize_with_object_t with (c, this);
    return_trace (dispatch (c));
  }

  protected:
  HBUINT  length;   /* Total subtable length, including this header. */
  HBUINT  coverage; /* Coverage flags and subtable type. */
  HBUINT32  subFeatureFlags;/* The 32-bit mask identifying which subtable this is. */
  union {
  RearrangementSubtable<Types>  rearrangement;
  ContextualSubtable<Types> contextual;
  LigatureSubtable<Types> ligature;
  NoncontextualSubtable<Types>  noncontextual;
  InsertionSubtable<Types>  insertion;
  } u;
  public:
  DEFINE_SIZE_MIN (2 * sizeof (HBUINT) + 4);
};

template <typename Types>
struct Chain
{
  typedef typename Types::HBUINT HBUINT;

  hb_mask_t compile_flags (const hb_aat_map_builder_t *map) const
  {
    hb_mask_t flags = defaultFlags;
    {
      unsigned int count = featureCount;
      for (unsigned i = 0; i < count; i++)
      {
  const Feature &feature = featureZ[i];
  hb_aat_layout_feature_type_t type = (hb_aat_layout_feature_type_t) (unsigned int) feature.featureType;
  hb_aat_layout_feature_selector_t setting = (hb_aat_layout_feature_selector_t) (unsigned int) feature.featureSetting;
      retry:
  // Check whether this type/setting pair was requested in the map, and if so, apply its flags.
  // (The search here only looks at the type and setting fields of feature_info_t.)
  hb_aat_map_builder_t::feature_info_t info = { type, setting, false, 0 };
  if (map->current_features.bsearch (info))
  {
    flags &= feature.disableFlags;
    flags |= feature.enableFlags;
  }
  else if (type == HB_AAT_LAYOUT_FEATURE_TYPE_LETTER_CASE && setting == HB_AAT_LAYOUT_FEATURE_SELECTOR_SMALL_CAPS)
  {
    /* Deprecated. https://github.com/harfbuzz/harfbuzz/issues/1342 */
    type = HB_AAT_LAYOUT_FEATURE_TYPE_LOWER_CASE;
    setting = HB_AAT_LAYOUT_FEATURE_SELECTOR_LOWER_CASE_SMALL_CAPS;
    goto retry;
  }
#ifndef HB_NO_AAT
  else if (type == HB_AAT_LAYOUT_FEATURE_TYPE_LANGUAGE_TAG_TYPE && setting &&
     /* TODO: Rudimentary language matching. */
     hb_language_matches (map->face->table.ltag->get_language (setting - 1), map->props.language))
  {
    flags &= feature.disableFlags;
    flags |= feature.enableFlags;
  }
#endif
      }
    }
    return flags;
  }

  void apply (hb_aat_apply_context_t *c) const
  {
    const ChainSubtable<Types> *subtable = &StructAfter<ChainSubtable<Types>> (featureZ.as_array (featureCount));
    unsigned int count = subtableCount;
    for (unsigned int i = 0; i < count; i++)
    {
      bool reverse;

      if (hb_none (hb_iter (c->range_flags) |
       hb_map ([&subtable] (const hb_aat_map_t::range_flags_t _) -> bool { return subtable->subFeatureFlags & (_.flags); })))
  goto skip;
      c->subtable_flags = subtable->subFeatureFlags;

      if (!(subtable->get_coverage() & ChainSubtable<Types>::AllDirections) &&
    HB_DIRECTION_IS_VERTICAL (c->buffer->props.direction) !=
    bool (subtable->get_coverage() & ChainSubtable<Types>::Vertical))
  goto skip;

      /* Buffer contents is always in logical direction.  Determine if
       * we need to reverse before applying this subtable.  We reverse
       * back after if we did reverse indeed.
       *
       * Quoting the spac:
       * """
       * Bits 28 and 30 of the coverage field control the order in which
       * glyphs are processed when the subtable is run by the layout engine.
       * Bit 28 is used to indicate if the glyph processing direction is
       * the same as logical order or layout order. Bit 30 is used to
       * indicate whether glyphs are processed forwards or backwards within
       * that order.

    Bit 30  Bit 28  Interpretation for Horizontal Text
    0 0 The subtable is processed in layout order
        (the same order as the glyphs, which is
        always left-to-right).
    1 0 The subtable is processed in reverse layout order
        (the order opposite that of the glyphs, which is
        always right-to-left).
    0 1 The subtable is processed in logical order
        (the same order as the characters, which may be
        left-to-right or right-to-left).
    1 1 The subtable is processed in reverse logical order
        (the order opposite that of the characters, which
        may be right-to-left or left-to-right).
       */
      reverse = subtable->get_coverage () & ChainSubtable<Types>::Logical ?
    bool (subtable->get_coverage () & ChainSubtable<Types>::Backwards) :
    bool (subtable->get_coverage () & ChainSubtable<Types>::Backwards) !=
    HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction);

      if (!c->buffer->message (c->font, "start chainsubtable %u", c->lookup_index))
  goto skip;

      if (reverse)
  c->buffer->reverse ();

      subtable->apply (c);

      if (reverse)
  c->buffer->reverse ();

      (void) c->buffer->message (c->font, "end chainsubtable %u", c->lookup_index);

      if (unlikely (!c->buffer->successful)) return;

    skip:
      subtable = &StructAfter<ChainSubtable<Types>> (*subtable);
      c->set_lookup_index (c->lookup_index + 1);
    }
  }

  unsigned int get_size () const { return length; }

  bool sanitize (hb_sanitize_context_t *c, unsigned int version HB_UNUSED) const
  {
    TRACE_SANITIZE (this);
    if (!length.sanitize (c) ||
  length < min_size ||
  !c->check_range (this, length))
      return_trace (false);

    if (!c->check_array (featureZ.arrayZ, featureCount))
      return_trace (false);

    const ChainSubtable<Types> *subtable = &StructAfter<ChainSubtable<Types>> (featureZ.as_array (featureCount));
    unsigned int count = subtableCount;
    for (unsigned int i = 0; i < count; i++)
    {
      if (!subtable->sanitize (c))
  return_trace (false);
      subtable = &StructAfter<ChainSubtable<Types>> (*subtable);
    }

    return_trace (true);
  }

  protected:
  HBUINT32  defaultFlags; /* The default specification for subtables. */
  HBUINT32  length;   /* Total byte count, including this header. */
  HBUINT  featureCount; /* Number of feature subtable entries. */
  HBUINT  subtableCount;  /* The number of subtables in the chain. */

  UnsizedArrayOf<Feature> featureZ; /* Features. */
/*ChainSubtable firstSubtable;*//* Subtables. */
/*subtableGlyphCoverageArray*/  /* Only if version >= 3. We don't use. */

  public:
  DEFINE_SIZE_MIN (8 + 2 * sizeof (HBUINT));
};


/*
 * The 'mort'/'morx' Table
 */

template <typename Types, hb_tag_t TAG>
struct mortmorx
{
  static constexpr hb_tag_t tableTag = TAG;

  bool has_data () const { return version != 0; }

  void compile_flags (const hb_aat_map_builder_t *mapper,
          hb_aat_map_t *map) const
  {
    const Chain<Types> *chain = &firstChain;
    unsigned int count = chainCount;
    if (unlikely (!map->chain_flags.resize (count)))
      return;
    for (unsigned int i = 0; i < count; i++)
    {
      map->chain_flags[i].push (hb_aat_map_t::range_flags_t {chain->compile_flags (mapper),
                   mapper->range_first,
                   mapper->range_last});
      chain = &StructAfter<Chain<Types>> (*chain);
    }
  }

  void apply (hb_aat_apply_context_t *c,
        const hb_aat_map_t &map) const
  {
    if (unlikely (!c->buffer->successful)) return;

    c->buffer->unsafe_to_concat ();

    c->set_lookup_index (0);
    const Chain<Types> *chain = &firstChain;
    unsigned int count = chainCount;
    for (unsigned int i = 0; i < count; i++)
    {
      c->range_flags = &map.chain_flags[i];
      chain->apply (c);
      if (unlikely (!c->buffer->successful)) return;
      chain = &StructAfter<Chain<Types>> (*chain);
    }
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    if (!version.sanitize (c) || !version || !chainCount.sanitize (c))
      return_trace (false);

    const Chain<Types> *chain = &firstChain;
    unsigned int count = chainCount;
    for (unsigned int i = 0; i < count; i++)
    {
      if (!chain->sanitize (c, version))
  return_trace (false);
      chain = &StructAfter<Chain<Types>> (*chain);
    }

    return_trace (true);
  }

  protected:
  HBUINT16  version;  /* Version number of the glyph metamorphosis table.
         * 1, 2, or 3. */
  HBUINT16  unused;   /* Set to 0. */
  HBUINT32  chainCount; /* Number of metamorphosis chains contained in this
         * table. */
  Chain<Types>  firstChain; /* Chains. */

  public:
  DEFINE_SIZE_MIN (8);
};

struct morx : mortmorx<ExtendedTypes, HB_AAT_TAG_morx> {};
struct mort : mortmorx<ObsoleteTypes, HB_AAT_TAG_mort> {};


} /* namespace AAT */


#endif /* HB_AAT_LAYOUT_MORX_TABLE_HH */

Coverage Report

Created: 2025-01-16 12:48