/*

 * Copyright © 2009,2010  Red Hat, Inc.

 * Copyright © 2010,2011,2012  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.

 *

 * Red Hat Author(s): Behdad Esfahbod

 * Google Author(s): Behdad Esfahbod

 */

#define HB_SHAPER ot

#define hb_ot_shaper_face_data_t hb_ot_layout_t

#define hb_ot_shaper_shape_plan_data_t hb_ot_shape_plan_t

#include "hb-shaper-impl-private.hh"

#include "hb-ot-shape-private.hh"

#include "hb-ot-shape-complex-private.hh"

#include "hb-ot-shape-fallback-private.hh"

#include "hb-ot-shape-normalize-private.hh"

#include "hb-ot-layout-private.hh"

#include "hb-unicode-private.hh"

#include "hb-set-private.hh"

static hb_tag_t common_features[] = {

  HB_TAG('c','c','m','p'),

  HB_TAG('l','o','c','l'),

  HB_TAG('m','a','r','k'),

  HB_TAG('m','k','m','k'),

  HB_TAG('r','l','i','g'),

};

static hb_tag_t horizontal_features[] = {

  HB_TAG('c','a','l','t'),

  HB_TAG('c','l','i','g'),

  HB_TAG('c','u','r','s'),

  HB_TAG('k','e','r','n'),

  HB_TAG('l','i','g','a'),

  HB_TAG('r','c','l','t'),

};

static void

hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,

			      const hb_segment_properties_t  *props,

			      const hb_feature_t             *user_features,

			      unsigned int                    num_user_features)

{

  hb_ot_map_builder_t *map = &planner->map;

  map->add_global_bool_feature (HB_TAG('r','v','r','n'));

  map->add_gsub_pause (NULL);

  switch (props->direction) {

    case HB_DIRECTION_LTR:

      map->add_global_bool_feature (HB_TAG ('l','t','r','a'));

      map->add_global_bool_feature (HB_TAG ('l','t','r','m'));

      break;

    case HB_DIRECTION_RTL:

      map->add_global_bool_feature (HB_TAG ('r','t','l','a'));

      map->add_feature (HB_TAG ('r','t','l','m'), 1, F_NONE);

      break;

    case HB_DIRECTION_TTB:

    case HB_DIRECTION_BTT:

    case HB_DIRECTION_INVALID:

    default:

      break;

  }

  map->add_feature (HB_TAG ('f','r','a','c'), 1, F_NONE);

  map->add_feature (HB_TAG ('n','u','m','r'), 1, F_NONE);

  map->add_feature (HB_TAG ('d','n','o','m'), 1, F_NONE);

  if (planner->shaper->collect_features)

    planner->shaper->collect_features (planner);

  for (unsigned int i = 0; i < ARRAY_LENGTH (common_features); i++)

    map->add_global_bool_feature (common_features[i]);

  if (HB_DIRECTION_IS_HORIZONTAL (props->direction))

    for (unsigned int i = 0; i < ARRAY_LENGTH (horizontal_features); i++)

      map->add_feature (horizontal_features[i], 1, F_GLOBAL |

			(horizontal_features[i] == HB_TAG('k','e','r','n') ?

			 F_HAS_FALLBACK : F_NONE));

  else

  {

    /* We really want to find a 'vert' feature if there's any in the font, no

     * matter which script/langsys it is listed (or not) under.

     * See various bugs referenced from:

     * https://github.com/behdad/harfbuzz/issues/63 */

    map->add_feature (HB_TAG ('v','e','r','t'), 1, F_GLOBAL | F_GLOBAL_SEARCH);

  }

  if (planner->shaper->override_features)

    planner->shaper->override_features (planner);

  for (unsigned int i = 0; i < num_user_features; i++) {

    const hb_feature_t *feature = &user_features[i];

    map->add_feature (feature->tag, feature->value,

		      (feature->start == 0 && feature->end == (unsigned int) -1) ?

		       F_GLOBAL : F_NONE);

  }

}

/*

 * shaper face data

 */

HB_SHAPER_DATA_ENSURE_DEFINE(ot, face)

hb_ot_shaper_face_data_t *

_hb_ot_shaper_face_data_create (hb_face_t *face)

{

  return _hb_ot_layout_create (face);

}

void

_hb_ot_shaper_face_data_destroy (hb_ot_shaper_face_data_t *data)

{

  _hb_ot_layout_destroy (data);

}

/*

 * shaper font data

 */

HB_SHAPER_DATA_ENSURE_DEFINE(ot, font)

struct hb_ot_shaper_font_data_t {};

hb_ot_shaper_font_data_t *

_hb_ot_shaper_font_data_create (hb_font_t *font HB_UNUSED)

{

  return (hb_ot_shaper_font_data_t *) HB_SHAPER_DATA_SUCCEEDED;

}

void

_hb_ot_shaper_font_data_destroy (hb_ot_shaper_font_data_t *data)

{

}

/*

 * shaper shape_plan data

 */

hb_ot_shaper_shape_plan_data_t *

_hb_ot_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan,

				      const hb_feature_t *user_features,

				      unsigned int        num_user_features,

				      const int          *coords,

				      unsigned int        num_coords)

{

  hb_ot_shape_plan_t *plan = (hb_ot_shape_plan_t *) calloc (1, sizeof (hb_ot_shape_plan_t));

  if (unlikely (!plan))

    return NULL;

  hb_ot_shape_planner_t planner (shape_plan);

  planner.shaper = hb_ot_shape_complex_categorize (&planner);

  hb_ot_shape_collect_features (&planner, &shape_plan->props,

				user_features, num_user_features);

  planner.compile (*plan, coords, num_coords);

  if (plan->shaper->data_create) {

    plan->data = plan->shaper->data_create (plan);

    if (unlikely (!plan->data))

      return NULL;

  }

  return plan;

}

void

_hb_ot_shaper_shape_plan_data_destroy (hb_ot_shaper_shape_plan_data_t *plan)

{

  if (plan->shaper->data_destroy)

    plan->shaper->data_destroy (const_cast<void *> (plan->data));

  plan->finish ();

  free (plan);

}

/*

 * shaper

 */

struct hb_ot_shape_context_t

{

  hb_ot_shape_plan_t *plan;

  hb_font_t *font;

  hb_face_t *face;

  hb_buffer_t  *buffer;

  const hb_feature_t *user_features;

  unsigned int        num_user_features;

  /* Transient stuff */

  bool fallback_positioning;

  bool fallback_glyph_classes;

  hb_direction_t target_direction;

};

/* Main shaper */

/* Prepare */

static void

hb_set_unicode_props (hb_buffer_t *buffer)

{

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 0; i < count; i++)

    _hb_glyph_info_set_unicode_props (&info[i], buffer);

}

static void

hb_insert_dotted_circle (hb_buffer_t *buffer, hb_font_t *font)

{

  if (!(buffer->flags & HB_BUFFER_FLAG_BOT) ||

      buffer->context_len[0] ||

      _hb_glyph_info_get_general_category (&buffer->info[0]) !=

      HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)

    return;

  if (!font->has_glyph (0x25CCu))

    return;

  hb_glyph_info_t dottedcircle = {0};

  dottedcircle.codepoint = 0x25CCu;

  _hb_glyph_info_set_unicode_props (&dottedcircle, buffer);

  buffer->clear_output ();

  buffer->idx = 0;

  hb_glyph_info_t info = dottedcircle;

  info.cluster = buffer->cur().cluster;

  info.mask = buffer->cur().mask;

  buffer->output_info (info);

  while (buffer->idx < buffer->len && !buffer->in_error)

    buffer->next_glyph ();

  buffer->swap_buffers ();

}

static void

hb_form_clusters (hb_buffer_t *buffer)

{

  if (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_NON_ASCII) ||

      buffer->cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)

    return;

  /* Loop duplicated in hb_ensure_native_direction(), and in _hb-coretext.cc */

  unsigned int base = 0;

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 1; i < count; i++)

  {

    if (likely (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])) &&

		!_hb_glyph_info_is_joiner (&info[i])))

    {

      buffer->merge_clusters (base, i);

      base = i;

    }

  }

  buffer->merge_clusters (base, count);

}

static void

hb_ensure_native_direction (hb_buffer_t *buffer)

{

  hb_direction_t direction = buffer->props.direction;

  /* TODO vertical:

   * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType

   * Ogham fonts are supposed to be implemented BTT or not.  Need to research that

   * first. */

  if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (buffer->props.script)) ||

      (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))

  {

    /* Same loop as hb_form_clusters().

     * Since form_clusters() merged clusters already, we don't merge. */

    unsigned int base = 0;

    unsigned int count = buffer->len;

    hb_glyph_info_t *info = buffer->info;

    for (unsigned int i = 1; i < count; i++)

    {

      if (likely (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i]))))

      {

	if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)

	  buffer->merge_clusters (base, i);

	buffer->reverse_range (base, i);

	base = i;

      }

    }

    if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)

      buffer->merge_clusters (base, count);

    buffer->reverse_range (base, count);

    buffer->reverse ();

    buffer->props.direction = HB_DIRECTION_REVERSE (buffer->props.direction);

  }

}

/* Substitute */

static inline void

hb_ot_mirror_chars (hb_ot_shape_context_t *c)

{

  if (HB_DIRECTION_IS_FORWARD (c->target_direction))

    return;

  hb_buffer_t *buffer = c->buffer;

  hb_unicode_funcs_t *unicode = buffer->unicode;

  hb_mask_t rtlm_mask = c->plan->rtlm_mask;

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 0; i < count; i++) {

    hb_codepoint_t codepoint = unicode->mirroring (info[i].codepoint);

    if (likely (codepoint == info[i].codepoint || !c->font->has_glyph (codepoint)))

      info[i].mask |= rtlm_mask;

    else

      info[i].codepoint = codepoint;

  }

}

static inline void

hb_ot_shape_setup_masks_fraction (hb_ot_shape_context_t *c)

{

  if (!(c->buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_NON_ASCII) ||

      !c->plan->has_frac)

    return;

  hb_buffer_t *buffer = c->buffer;

  hb_mask_t pre_mask, post_mask;

  if (HB_DIRECTION_IS_FORWARD (buffer->props.direction))

  {

    pre_mask = c->plan->numr_mask | c->plan->frac_mask;

    post_mask = c->plan->frac_mask | c->plan->dnom_mask;

  }

  else

  {

    pre_mask = c->plan->frac_mask | c->plan->dnom_mask;

    post_mask = c->plan->numr_mask | c->plan->frac_mask;

  }

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 0; i < count; i++)

  {

    if (info[i].codepoint == 0x2044u) /* FRACTION SLASH */

    {

      unsigned int start = i, end = i + 1;

      while (start &&

	     _hb_glyph_info_get_general_category (&info[start - 1]) ==

	     HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER)

        start--;

      while (end < count &&

	     _hb_glyph_info_get_general_category (&info[end]) ==

	     HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER)

        end++;

      for (unsigned int j = start; j < i; j++)

        info[j].mask |= pre_mask;

      info[i].mask |= c->plan->frac_mask;

      for (unsigned int j = i + 1; j < end; j++)

        info[j].mask |= post_mask;

      i = end - 1;

    }

  }

}

static inline void

hb_ot_shape_initialize_masks (hb_ot_shape_context_t *c)

{

  hb_ot_map_t *map = &c->plan->map;

  hb_buffer_t *buffer = c->buffer;

  hb_mask_t global_mask = map->get_global_mask ();

  buffer->reset_masks (global_mask);

}

static inline void

hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)

{

  hb_ot_map_t *map = &c->plan->map;

  hb_buffer_t *buffer = c->buffer;

  hb_ot_shape_setup_masks_fraction (c);

  if (c->plan->shaper->setup_masks)

    c->plan->shaper->setup_masks (c->plan, buffer, c->font);

  for (unsigned int i = 0; i < c->num_user_features; i++)

  {

    const hb_feature_t *feature = &c->user_features[i];

    if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {

      unsigned int shift;

      hb_mask_t mask = map->get_mask (feature->tag, &shift);

      buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);

    }

  }

}

static void

hb_ot_zero_width_default_ignorables (hb_ot_shape_context_t *c)

{

  hb_buffer_t *buffer = c->buffer;

  if (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES) ||

      (buffer->flags & HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES))

    return;

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  hb_glyph_position_t *pos = buffer->pos;

  unsigned int i = 0;

  for (i = 0; i < count; i++)

    if (unlikely (_hb_glyph_info_is_default_ignorable (&info[i])))

      pos[i].x_advance = pos[i].y_advance = pos[i].x_offset = pos[i].y_offset = 0;

}

static void

hb_ot_hide_default_ignorables (hb_ot_shape_context_t *c)

{

  hb_buffer_t *buffer = c->buffer;

  if (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES) ||

      (buffer->flags & HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES))

    return;

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  hb_glyph_position_t *pos = buffer->pos;

  unsigned int i = 0;

  for (i = 0; i < count; i++)

  {

    if (unlikely (_hb_glyph_info_is_default_ignorable (&info[i])))

      break;

  }

  /* No default-ignorables found; return. */

  if (i == count)

    return;

  hb_codepoint_t space;

  if (c->font->get_nominal_glyph (' ', &space))

  {

    /* Replace default-ignorables with a zero-advance space glyph. */

    for (/*continue*/; i < count; i++)

    {

      if (_hb_glyph_info_is_default_ignorable (&info[i]))

	info[i].codepoint = space;

    }

  }

  else

  {

    /* Merge clusters and delete default-ignorables.

     * NOTE! We can't use out-buffer as we have positioning data. */

    unsigned int j = i;

    for (; i < count; i++)

    {

      if (_hb_glyph_info_is_default_ignorable (&info[i]))

      {

	/* Merge clusters.

	 * Same logic as buffer->delete_glyph(), but for in-place removal. */

	unsigned int cluster = info[i].cluster;

	if (i + 1 < count && cluster == info[i + 1].cluster)

	  continue; /* Cluster survives; do nothing. */

	if (j)

	{

	  /* Merge cluster backward. */

	  if (cluster < info[j - 1].cluster)

	  {

	    unsigned int old_cluster = info[j - 1].cluster;

	    for (unsigned k = j; k && info[k - 1].cluster == old_cluster; k--)

	      info[k - 1].cluster = cluster;

	  }

	  continue;

	}

	if (i + 1 < count)

	  buffer->merge_clusters (i, i + 2); /* Merge cluster forward. */

	continue;

      }

      if (j != i)

      {

	info[j] = info[i];

	pos[j] = pos[i];

      }

      j++;

    }

    buffer->len = j;

  }

}

static inline void

hb_ot_map_glyphs_fast (hb_buffer_t  *buffer)

{

  /* Normalization process sets up glyph_index(), we just copy it. */

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 0; i < count; i++)

    info[i].codepoint = info[i].glyph_index();

  buffer->content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;

}

static inline void

hb_synthesize_glyph_classes (hb_ot_shape_context_t *c)

{

  unsigned int count = c->buffer->len;

  hb_glyph_info_t *info = c->buffer->info;

  for (unsigned int i = 0; i < count; i++)

  {

    hb_ot_layout_glyph_props_flags_t klass;

    /* Never mark default-ignorables as marks.

     * They won't get in the way of lookups anyway,

     * but having them as mark will cause them to be skipped

     * over if the lookup-flag says so, but at least for the

     * Mongolian variation selectors, looks like Uniscribe

     * marks them as non-mark.  Some Mongolian fonts without

     * GDEF rely on this.  Another notable character that

     * this applies to is COMBINING GRAPHEME JOINER. */

    klass = (_hb_glyph_info_get_general_category (&info[i]) !=

	     HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK ||

	     _hb_glyph_info_is_default_ignorable (&info[i])) ?

	    HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH :

	    HB_OT_LAYOUT_GLYPH_PROPS_MARK;

    _hb_glyph_info_set_glyph_props (&info[i], klass);

  }

}

static inline void

hb_ot_substitute_default (hb_ot_shape_context_t *c)

{

  hb_buffer_t *buffer = c->buffer;

  hb_ot_shape_initialize_masks (c);

  hb_ot_mirror_chars (c);

  HB_BUFFER_ALLOCATE_VAR (buffer, glyph_index);

  _hb_ot_shape_normalize (c->plan, buffer, c->font);

  hb_ot_shape_setup_masks (c);

  /* This is unfortunate to go here, but necessary... */

  if (c->fallback_positioning)

    _hb_ot_shape_fallback_position_recategorize_marks (c->plan, c->font, buffer);

  hb_ot_map_glyphs_fast (buffer);

  HB_BUFFER_DEALLOCATE_VAR (buffer, glyph_index);

}

static inline void

hb_ot_substitute_complex (hb_ot_shape_context_t *c)

{

  hb_buffer_t *buffer = c->buffer;

  hb_ot_layout_substitute_start (c->font, buffer);

  if (!hb_ot_layout_has_glyph_classes (c->face))

    hb_synthesize_glyph_classes (c);

  c->plan->substitute (c->font, buffer);

  return;

}

static inline void

hb_ot_substitute (hb_ot_shape_context_t *c)

{

  hb_ot_substitute_default (c);

  _hb_buffer_allocate_gsubgpos_vars (c->buffer);

  hb_ot_substitute_complex (c);

}

/* Position */

static inline void

adjust_mark_offsets (hb_glyph_position_t *pos)

{

  pos->x_offset -= pos->x_advance;

  pos->y_offset -= pos->y_advance;

}

static inline void

zero_mark_width (hb_glyph_position_t *pos)

{

  pos->x_advance = 0;

  pos->y_advance = 0;

}

static inline void

zero_mark_widths_by_gdef (hb_buffer_t *buffer, bool adjust_offsets)

{

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 0; i < count; i++)

    if (_hb_glyph_info_is_mark (&info[i]))

    {

      if (adjust_offsets)

        adjust_mark_offsets (&buffer->pos[i]);

      zero_mark_width (&buffer->pos[i]);

    }

}

static inline void

hb_ot_position_default (hb_ot_shape_context_t *c)

{

  hb_direction_t direction = c->buffer->props.direction;

  unsigned int count = c->buffer->len;

  hb_glyph_info_t *info = c->buffer->info;

  hb_glyph_position_t *pos = c->buffer->pos;

  if (HB_DIRECTION_IS_HORIZONTAL (direction))

  {

    for (unsigned int i = 0; i < count; i++)

      pos[i].x_advance = c->font->get_glyph_h_advance (info[i].codepoint);

    /* The nil glyph_h_origin() func returns 0, so no need to apply it. */

    if (c->font->has_glyph_h_origin_func ())

      for (unsigned int i = 0; i < count; i++)

	c->font->subtract_glyph_h_origin (info[i].codepoint,

					  &pos[i].x_offset,

					  &pos[i].y_offset);

  }

  else

  {

    for (unsigned int i = 0; i < count; i++)

    {

      pos[i].y_advance = c->font->get_glyph_v_advance (info[i].codepoint);

      c->font->subtract_glyph_v_origin (info[i].codepoint,

					&pos[i].x_offset,

					&pos[i].y_offset);

    }

  }

  if (c->buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_SPACE_FALLBACK)

    _hb_ot_shape_fallback_spaces (c->plan, c->font, c->buffer);

}

static inline void

hb_ot_position_complex (hb_ot_shape_context_t *c)

{

  hb_ot_layout_position_start (c->font, c->buffer);

  unsigned int count = c->buffer->len;

  /* If the font has no GPOS, AND, no fallback positioning will

   * happen, AND, direction is forward, then when zeroing mark

   * widths, we shift the mark with it, such that the mark

   * is positioned hanging over the previous glyph.  When

   * direction is backward we don't shift and it will end up

   * hanging over the next glyph after the final reordering.

   * If fallback positinoing happens or GPOS is present, we don't

   * care.

   */

  bool adjust_offsets_when_zeroing = c->fallback_positioning &&

				     !c->plan->shaper->fallback_position &&

				     HB_DIRECTION_IS_FORWARD (c->buffer->props.direction);

  switch (c->plan->shaper->zero_width_marks)

  {

    case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY:

      zero_mark_widths_by_gdef (c->buffer, adjust_offsets_when_zeroing);

      break;

    default:

    case HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE:

    case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE:

      break;

  }

  if (likely (!c->fallback_positioning))

  {

    hb_glyph_info_t *info = c->buffer->info;

    hb_glyph_position_t *pos = c->buffer->pos;

    /* Change glyph origin to what GPOS expects (horizontal), apply GPOS, change it back. */

    /* The nil glyph_h_origin() func returns 0, so no need to apply it. */

    if (c->font->has_glyph_h_origin_func ())

      for (unsigned int i = 0; i < count; i++)

	c->font->add_glyph_h_origin (info[i].codepoint,

				     &pos[i].x_offset,

				     &pos[i].y_offset);

    c->plan->position (c->font, c->buffer);

    /* The nil glyph_h_origin() func returns 0, so no need to apply it. */

    if (c->font->has_glyph_h_origin_func ())

      for (unsigned int i = 0; i < count; i++)

	c->font->subtract_glyph_h_origin (info[i].codepoint,

					  &pos[i].x_offset,

					  &pos[i].y_offset);

  }

  switch (c->plan->shaper->zero_width_marks)

  {

    case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE:

      zero_mark_widths_by_gdef (c->buffer, adjust_offsets_when_zeroing);

      break;

    default:

    case HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE:

    case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY:

      break;

  }

  /* Finishing off GPOS has to follow a certain order. */

  hb_ot_layout_position_finish_advances (c->font, c->buffer);

  hb_ot_zero_width_default_ignorables (c);

  hb_ot_layout_position_finish_offsets (c->font, c->buffer);

}

static inline void

hb_ot_position (hb_ot_shape_context_t *c)

{

  c->buffer->clear_positions ();

  hb_ot_position_default (c);

  hb_ot_position_complex (c);

  if (c->fallback_positioning && c->plan->shaper->fallback_position)

    _hb_ot_shape_fallback_position (c->plan, c->font, c->buffer);

  if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))

    hb_buffer_reverse (c->buffer);

  /* Visual fallback goes here. */

  if (c->fallback_positioning)

    _hb_ot_shape_fallback_kern (c->plan, c->font, c->buffer);

  _hb_buffer_deallocate_gsubgpos_vars (c->buffer);

}

/* Pull it all together! */

static void

hb_ot_shape_internal (hb_ot_shape_context_t *c)

{

  c->buffer->deallocate_var_all ();

  c->buffer->scratch_flags = HB_BUFFER_SCRATCH_FLAG_DEFAULT;

  if (likely (!_hb_unsigned_int_mul_overflows (c->buffer->len, HB_BUFFER_MAX_EXPANSION_FACTOR)))

  {

    c->buffer->max_len = MAX (c->buffer->len * HB_BUFFER_MAX_EXPANSION_FACTOR,

			      (unsigned) HB_BUFFER_MAX_LEN_MIN);

  }

  bool disable_otl = c->plan->shaper->disable_otl && c->plan->shaper->disable_otl (c->plan);

  //c->fallback_substitute     = disable_otl || !hb_ot_layout_has_substitution (c->face);

  c->fallback_positioning    = disable_otl || !hb_ot_layout_has_positioning (c->face);

  c->fallback_glyph_classes  = disable_otl || !hb_ot_layout_has_glyph_classes (c->face);

  /* Save the original direction, we use it later. */

  c->target_direction = c->buffer->props.direction;

  _hb_buffer_allocate_unicode_vars (c->buffer);

  c->buffer->clear_output ();

  hb_set_unicode_props (c->buffer);

  hb_insert_dotted_circle (c->buffer, c->font);

  hb_form_clusters (c->buffer);

  hb_ensure_native_direction (c->buffer);

  if (c->plan->shaper->preprocess_text)

    c->plan->shaper->preprocess_text (c->plan, c->buffer, c->font);

  hb_ot_substitute (c);

  hb_ot_position (c);

  hb_ot_hide_default_ignorables (c);

  if (c->plan->shaper->postprocess_glyphs)

    c->plan->shaper->postprocess_glyphs (c->plan, c->buffer, c->font);

  _hb_buffer_deallocate_unicode_vars (c->buffer);

  c->buffer->props.direction = c->target_direction;

  c->buffer->max_len = HB_BUFFER_MAX_LEN_DEFAULT;

  c->buffer->deallocate_var_all ();

}

hb_bool_t

_hb_ot_shape (hb_shape_plan_t    *shape_plan,

	      hb_font_t          *font,

	      hb_buffer_t        *buffer,

	      const hb_feature_t *features,

	      unsigned int        num_features)

{

  hb_ot_shape_context_t c = {HB_SHAPER_DATA_GET (shape_plan), font, font->face, buffer, features, num_features};

  hb_ot_shape_internal (&c);

  return true;

}

/**

 * hb_ot_shape_plan_collect_lookups:

 *

 * Since: 0.9.7

 **/

void

hb_ot_shape_plan_collect_lookups (hb_shape_plan_t *shape_plan,

				  hb_tag_t         table_tag,

				  hb_set_t        *lookup_indexes /* OUT */)

{

  /* XXX Does the first part always succeed? */

  HB_SHAPER_DATA_GET (shape_plan)->collect_lookups (table_tag, lookup_indexes);

}

/* TODO Move this to hb-ot-shape-normalize, make it do decompose, and make it public. */

static void

add_char (hb_font_t          *font,

	  hb_unicode_funcs_t *unicode,

	  hb_bool_t           mirror,

	  hb_codepoint_t      u,

	  hb_set_t           *glyphs)

{

  hb_codepoint_t glyph;

  if (font->get_nominal_glyph (u, &glyph))

    glyphs->add (glyph);

  if (mirror)

  {

    hb_codepoint_t m = unicode->mirroring (u);

    if (m != u && font->get_nominal_glyph (m, &glyph))