/*
* 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','i','g','a'),
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('r','c','l','t'),
};
static hb_tag_t vertical_features[] = {
HB_TAG('v','e','r','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;
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
for (unsigned int i = 0; i < ARRAY_LENGTH (vertical_features); i++)
map->add_feature (vertical_features[i], 1, F_GLOBAL |
(vertical_features[i] == HB_TAG('v','k','r','n') ?
F_HAS_FALLBACK : F_NONE));
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_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
*/
struct hb_ot_shaper_font_data_t {};
hb_ot_shaper_font_data_t *
_hb_ot_shaper_font_data_create (hb_font_t *font)
{
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)
{
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);
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 */
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->unicode);
}
static void
hb_insert_dotted_circle (hb_buffer_t *buffer, hb_font_t *font)
{
if (!(buffer->flags & HB_BUFFER_FLAG_BOT) ||
_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;
dottedcircle.codepoint = 0x25CCu;
_hb_glyph_info_set_unicode_props (&dottedcircle, buffer->unicode);
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->next_glyph ();
buffer->swap_buffers ();
}
static void
hb_form_clusters (hb_buffer_t *buffer)
{
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 1; i < count; i++)
if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])))
buffer->merge_clusters (i - 1, i + 1);
}
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))
{
hb_buffer_reverse_clusters (buffer);
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))
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->plan->has_frac)
return;
hb_buffer_t *buffer = c->buffer;
/* TODO look in pre/post context text also. */
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 |= c->plan->numr_mask | c->plan->frac_mask;
info[i].mask |= c->plan->frac_mask;
for (unsigned int j = i + 1; j < end; j++)
info[j].mask |= c->plan->frac_mask | c->plan->dnom_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 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();
}
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_class_mask_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;
if (c->plan->shaper->preprocess_text)
c->plan->shaper->preprocess_text (c->plan, buffer, c->font);
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 (!hb_ot_layout_has_positioning (c->face))
_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);
hb_ot_layout_substitute_finish (c->font, buffer);
return;
}
static inline void
hb_ot_substitute (hb_ot_shape_context_t *c)
{
hb_ot_substitute_default (c);
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_unicode (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_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
{
if (adjust_offsets)
adjust_mark_offsets (&buffer->pos[i]);
zero_mark_width (&buffer->pos[i]);
}
}
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;
for (unsigned int i = 0; i < count; i++)
{
c->font->get_glyph_advance_for_direction (info[i].codepoint,
direction,
&pos[i].x_advance,
&pos[i].y_advance);
c->font->subtract_glyph_origin_for_direction (info[i].codepoint,
direction,
&pos[i].x_offset,
&pos[i].y_offset);
}
}
static inline bool
hb_ot_position_complex (hb_ot_shape_context_t *c)
{
bool ret = false;
unsigned int count = c->buffer->len;
bool has_positioning = hb_ot_layout_has_positioning (c->face);
/* 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 = !(has_positioning || c->plan->shaper->fallback_position ||
HB_DIRECTION_IS_BACKWARD (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;
/* Not currently used for any shaper:
case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_EARLY:
zero_mark_widths_by_unicode (c->buffer, adjust_offsets_when_zeroing);
break;
*/
default:
case HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE:
case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_LATE:
case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE:
break;
}
if (has_positioning)
{
hb_glyph_info_t *info = c->buffer->info;
hb_glyph_position_t *pos = c->buffer->pos;
/* Change glyph origin to what GPOS expects, apply GPOS, change it back. */
for (unsigned int i = 0; i < count; i++) {
c->font->add_glyph_origin_for_direction (info[i].codepoint,
HB_DIRECTION_LTR,
&pos[i].x_offset,
&pos[i].y_offset);
}
c->plan->position (c->font, c->buffer);
for (unsigned int i = 0; i < count; i++) {
c->font->subtract_glyph_origin_for_direction (info[i].codepoint,
HB_DIRECTION_LTR,
&pos[i].x_offset,
&pos[i].y_offset);
}
ret = true;
}
switch (c->plan->shaper->zero_width_marks)
{
case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_LATE:
zero_mark_widths_by_unicode (c->buffer, adjust_offsets_when_zeroing);
break;
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_UNICODE_EARLY:
case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY:
break;
}
return ret;
}
static inline void
hb_ot_position (hb_ot_shape_context_t *c)
{
hb_ot_layout_position_start (c->font, c->buffer);
hb_ot_position_default (c);
hb_bool_t fallback = !hb_ot_position_complex (c);
hb_ot_layout_position_finish (c->font, c->buffer);
if (fallback && 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 (fallback)
_hb_ot_shape_fallback_kern (c->plan, c->font, c->buffer);
}
/* Post-process */
static void
hb_ot_hide_default_ignorables (hb_ot_shape_context_t *c)
{
if (c->buffer->flags & HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES)
return;
hb_codepoint_t space;
enum {
SPACE_DONT_KNOW,
SPACE_AVAILABLE,
SPACE_UNAVAILABLE
} space_status = SPACE_DONT_KNOW;
unsigned int count = c->buffer->len;
hb_glyph_info_t *info = c->buffer->info;
hb_glyph_position_t *pos = c->buffer->pos;
unsigned int j = 0;
for (unsigned int i = 0; i < count; i++)
{
if (unlikely (!_hb_glyph_info_ligated (&info[i]) &&
_hb_glyph_info_is_default_ignorable (&info[i])))
{
if (space_status == SPACE_DONT_KNOW)
space_status = c->font->get_glyph (' ', 0, &space) ? SPACE_AVAILABLE : SPACE_UNAVAILABLE;
if (space_status == SPACE_AVAILABLE)
{
info[i].codepoint = space;
pos[i].x_advance = 0;
pos[i].y_advance = 0;
}
else
continue; /* Delete it. */
}
if (j != i)
{
info[j] = info[i];
pos[j] = pos[i];
}
j++;
}
c->buffer->len = j;
}
/* Pull it all together! */
static void
hb_ot_shape_internal (hb_ot_shape_context_t *c)
{
c->buffer->deallocate_var_all ();
/* 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);
hb_ot_substitute (c);
hb_ot_position (c);
hb_ot_hide_default_ignorables (c);
_hb_buffer_deallocate_unicode_vars (c->buffer);
c->buffer->props.direction = c->target_direction;
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;
}
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_glyph (u, 0, &glyph))
glyphs->add (glyph);
if (mirror)
{
hb_codepoint_t m = unicode->mirroring (u);
if (m != u && font->get_glyph (m, 0, &glyph))
glyphs->add (glyph);
}
}
void
hb_ot_shape_glyphs_closure (hb_font_t *font,
hb_buffer_t *buffer,
const hb_feature_t *features,
unsigned int num_features,
hb_set_t *glyphs)
{
hb_ot_shape_plan_t plan;
const char *shapers[] = {"ot", NULL};
hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached (font->face, &buffer->props,
features, num_features, shapers);
bool mirror = hb_script_get_horizontal_direction (buffer->props.script) == HB_DIRECTION_RTL;
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
add_char (font, buffer->unicode, mirror, info[i].codepoint, glyphs);
hb_set_t lookups;
lookups.init ();
hb_ot_shape_plan_collect_lookups (shape_plan, HB_OT_TAG_GSUB, &lookups);
/* And find transitive closure. */
hb_set_t copy;
copy.init ();
do {
copy.set (glyphs);
for (hb_codepoint_t lookup_index = -1; hb_set_next (&lookups, &lookup_index);)
hb_ot_layout_lookup_substitute_closure (font->face, lookup_index, glyphs);
} while (!copy.is_equal (glyphs));
hb_shape_plan_destroy (shape_plan);
}