src/hb-graphite2.cc - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2011  Martin Hosken
  * Copyright © 2011  SIL International
  * Copyright © 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.
  *
  * Google Author(s): Behdad Esfahbod
  */

 #define HB_SHAPER graphite2
 #define hb_graphite2_shaper_font_data_t gr_font
 #include "hb-shaper-impl-private.hh"

 #include "hb-graphite2.h"

 #include <graphite2/Segment.h>


 HB_SHAPER_DATA_ENSURE_DECLARE(graphite2, face)
 HB_SHAPER_DATA_ENSURE_DECLARE(graphite2, font)


 /*
  * shaper face data
  */

 typedef struct hb_graphite2_tablelist_t {
   struct hb_graphite2_tablelist_t *next;
   hb_blob_t *blob;
   unsigned int tag;
 } hb_graphite2_tablelist_t;

 struct hb_graphite2_shaper_face_data_t {
   hb_face_t *face;
   gr_face   *grface;
   hb_graphite2_tablelist_t *tlist;
 };

 static const void *hb_graphite2_get_table (const void *data, unsigned int tag, size_t *len)
 {
   hb_graphite2_shaper_face_data_t *face_data = (hb_graphite2_shaper_face_data_t *) data;
   hb_graphite2_tablelist_t *tlist = face_data->tlist;

   hb_blob_t *blob = NULL;

   for (hb_graphite2_tablelist_t *p = tlist; p; p = p->next)
     if (p->tag == tag) {
       blob = p->blob;
       break;
     }

   if (unlikely (!blob))
   {
     blob = face_data->face->reference_table (tag);

     hb_graphite2_tablelist_t *p = (hb_graphite2_tablelist_t *) calloc (1, sizeof (hb_graphite2_tablelist_t));
     if (unlikely (!p)) {
       hb_blob_destroy (blob);
       return NULL;
     }
     p->blob = blob;
     p->tag = tag;

     /* TODO Not thread-safe, but fairly harmless.
      * We can do the double-chcked pointer cmpexch thing here. */
     p->next = face_data->tlist;
     face_data->tlist = p;
   }

   unsigned int tlen;
   const char *d = hb_blob_get_data (blob, &tlen);
   *len = tlen;
   return d;
 }

 hb_graphite2_shaper_face_data_t *
 _hb_graphite2_shaper_face_data_create (hb_face_t *face)
 {
   hb_blob_t *silf_blob = face->reference_table (HB_GRAPHITE2_TAG_SILF);
   /* Umm, we just reference the table to check whether it exists.
    * Maybe add better API for this? */
   if (!hb_blob_get_length (silf_blob))
   {
     hb_blob_destroy (silf_blob);
     return NULL;
   }
   hb_blob_destroy (silf_blob);

   hb_graphite2_shaper_face_data_t *data = (hb_graphite2_shaper_face_data_t *) calloc (1, sizeof (hb_graphite2_shaper_face_data_t));
   if (unlikely (!data))
     return NULL;

   data->face = face;
   data->grface = gr_make_face (data, &hb_graphite2_get_table, gr_face_preloadAll);

   if (unlikely (!data->grface)) {
     free (data);
     return NULL;
   }

   return data;
 }

 void
 _hb_graphite2_shaper_face_data_destroy (hb_graphite2_shaper_face_data_t *data)
 {
   hb_graphite2_tablelist_t *tlist = data->tlist;

   while (tlist)
   {
     hb_graphite2_tablelist_t *old = tlist;
     hb_blob_destroy (tlist->blob);
     tlist = tlist->next;
     free (old);
   }

   gr_face_destroy (data->grface);

   free (data);
 }

 gr_face *
 hb_graphite2_face_get_gr_face (hb_face_t *face)
 {
   if (unlikely (!hb_graphite2_shaper_face_data_ensure (face))) return NULL;
   return HB_SHAPER_DATA_GET (face)->grface;
 }


 /*
  * shaper font data
  */

 static float hb_graphite2_get_advance (const void *hb_font, unsigned short gid)
 {
   return ((hb_font_t *) hb_font)->get_glyph_h_advance (gid);
 }

 hb_graphite2_shaper_font_data_t *
 _hb_graphite2_shaper_font_data_create (hb_font_t *font)
 {
   if (unlikely (!hb_graphite2_shaper_face_data_ensure (font->face))) return NULL;

   hb_face_t *face = font->face;
   hb_graphite2_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);

   return gr_make_font_with_advance_fn (font->x_scale, font, &hb_graphite2_get_advance, face_data->grface);
 }

 void
 _hb_graphite2_shaper_font_data_destroy (hb_graphite2_shaper_font_data_t *data)
 {
   gr_font_destroy (data);
 }

 gr_font *
 hb_graphite2_font_get_gr_font (hb_font_t *font)
 {
   if (unlikely (!hb_graphite2_shaper_font_data_ensure (font))) return NULL;
   return HB_SHAPER_DATA_GET (font);
 }


 /*
  * shaper shape_plan data
  */

 struct hb_graphite2_shaper_shape_plan_data_t {};

 hb_graphite2_shaper_shape_plan_data_t *
 _hb_graphite2_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
 					     const hb_feature_t *user_features HB_UNUSED,
 					     unsigned int        num_user_features HB_UNUSED)
 {
   return (hb_graphite2_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
 }

 void
 _hb_graphite2_shaper_shape_plan_data_destroy (hb_graphite2_shaper_shape_plan_data_t *data HB_UNUSED)
 {
 }


 /*
  * shaper
  */

 struct hb_graphite2_cluster_t {
   unsigned int base_char;
   unsigned int num_chars;
   unsigned int base_glyph;
   unsigned int num_glyphs;
   unsigned int cluster;
 };

 hb_bool_t
 _hb_graphite2_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_face_t *face = font->face;
   gr_face *grface = HB_SHAPER_DATA_GET (face)->grface;
   gr_font *grfont = HB_SHAPER_DATA_GET (font);

   const char *lang = hb_language_to_string (hb_buffer_get_language (buffer));
   const char *lang_end = lang ? strchr (lang, '-') : NULL;
   int lang_len = lang_end ? lang_end - lang : -1;
   gr_feature_val *feats = gr_face_featureval_for_lang (grface, lang ? hb_tag_from_string (lang, lang_len) : 0);

   for (unsigned int i = 0; i < num_features; i++)
   {
     const gr_feature_ref *fref = gr_face_find_fref (grface, features[i].tag);
     if (fref)
       gr_fref_set_feature_value (fref, features[i].value, feats);
   }

   gr_segment *seg = NULL;
   const gr_slot *is;
   unsigned int ci = 0, ic = 0;
   float curradvx = 0., curradvy = 0.;

   unsigned int scratch_size;
   hb_buffer_t::scratch_buffer_t *scratch = buffer->get_scratch_buffer (&scratch_size);

   uint32_t *chars = (uint32_t *) scratch;

   for (unsigned int i = 0; i < buffer->len; ++i)
     chars[i] = buffer->info[i].codepoint;

   /* TODO ensure_native_direction. */

   hb_tag_t script_tag[2];
   hb_ot_tags_from_script (hb_buffer_get_script (buffer), &script_tag[0], &script_tag[1]);

   seg = gr_make_seg (grfont, grface,
 		     script_tag[1] == HB_TAG_NONE ? script_tag[0] : script_tag[1],
 		     feats,
 		     gr_utf32, chars, buffer->len,
 		     2 | (hb_buffer_get_direction (buffer) == HB_DIRECTION_RTL ? 1 : 0));

   if (unlikely (!seg)) {
     if (feats) gr_featureval_destroy (feats);
     return false;
   }

   unsigned int glyph_count = gr_seg_n_slots (seg);
   if (unlikely (!glyph_count)) {
     if (feats) gr_featureval_destroy (feats);
     gr_seg_destroy (seg);
     buffer->len = 0;
     return true;
   }

   buffer->ensure (glyph_count);
   scratch = buffer->get_scratch_buffer (&scratch_size);
   while ((DIV_CEIL (sizeof (hb_graphite2_cluster_t) * buffer->len, sizeof (*scratch)) +
 	  DIV_CEIL (sizeof (hb_codepoint_t) * glyph_count, sizeof (*scratch))) > scratch_size)
   {
     if (unlikely (!buffer->ensure (buffer->allocated * 2)))
     {
       if (feats) gr_featureval_destroy (feats);
       gr_seg_destroy (seg);
       return false;
     }
     scratch = buffer->get_scratch_buffer (&scratch_size);
   }

 #define ALLOCATE_ARRAY(Type, name, len) \
   Type *name = (Type *) scratch; \
   { \
     unsigned int _consumed = DIV_CEIL ((len) * sizeof (Type), sizeof (*scratch)); \
     assert (_consumed <= scratch_size); \
     scratch += _consumed; \
     scratch_size -= _consumed; \
   }

   ALLOCATE_ARRAY (hb_graphite2_cluster_t, clusters, buffer->len);
   ALLOCATE_ARRAY (hb_codepoint_t, gids, glyph_count);

 #undef ALLOCATE_ARRAY

   memset (clusters, 0, sizeof (clusters[0]) * buffer->len);

   hb_codepoint_t *pg = gids;
   clusters[0].cluster = buffer->info[0].cluster;
   for (is = gr_seg_first_slot (seg), ic = 0; is; is = gr_slot_next_in_segment (is), ic++)
   {
     unsigned int before = gr_slot_before (is);
     unsigned int after = gr_slot_after (is);
     *pg = gr_slot_gid (is);
     pg++;
     while (clusters[ci].base_char > before && ci)
     {
       clusters[ci-1].num_chars += clusters[ci].num_chars;
       clusters[ci-1].num_glyphs += clusters[ci].num_glyphs;
       ci--;
     }

     if (gr_slot_can_insert_before (is) && clusters[ci].num_chars && before >= clusters[ci].base_char + clusters[ci].num_chars)
     {
       hb_graphite2_cluster_t *c = clusters + ci + 1;
       c->base_char = clusters[ci].base_char + clusters[ci].num_chars;
       c->cluster = buffer->info[c->base_char].cluster;
       c->num_chars = before - c->base_char;
       c->base_glyph = ic;
       c->num_glyphs = 0;
       ci++;
     }
     clusters[ci].num_glyphs++;

     if (clusters[ci].base_char + clusters[ci].num_chars < after + 1)
 	clusters[ci].num_chars = after + 1 - clusters[ci].base_char;
   }
   ci++;

   for (unsigned int i = 0; i < ci; ++i)
   {
     for (unsigned int j = 0; j < clusters[i].num_glyphs; ++j)
     {
       hb_glyph_info_t *info = &buffer->info[clusters[i].base_glyph + j];
       info->codepoint = gids[clusters[i].base_glyph + j];
       info->cluster = clusters[i].cluster;
     }
   }
   buffer->len = glyph_count;

   /* Positioning. */
   if (!HB_DIRECTION_IS_BACKWARD(buffer->props.direction))
   {
     hb_glyph_position_t *pPos;
     for (pPos = hb_buffer_get_glyph_positions (buffer, NULL), is = gr_seg_first_slot (seg);
          is; pPos++, is = gr_slot_next_in_segment (is))
     {
       pPos->x_offset = gr_slot_origin_X (is) - curradvx;
       pPos->y_offset = gr_slot_origin_Y (is) - curradvy;
       pPos->x_advance = gr_slot_advance_X (is, grface, grfont);
       pPos->y_advance = gr_slot_advance_Y (is, grface, grfont);
       curradvx += pPos->x_advance;
       curradvy += pPos->y_advance;
     }
     pPos[-1].x_advance += gr_seg_advance_X(seg) - curradvx;
   }
   else
   {
     hb_glyph_position_t *pPos = hb_buffer_get_glyph_positions (buffer, NULL) + buffer->len - 1;
     const hb_glyph_info_t *info = buffer->info + buffer->len - 1;
     const hb_glyph_info_t *tinfo;
     const gr_slot *tis;
     int currclus = -1;
     float clusx = 0., clusy = 0.;
     for (is = gr_seg_last_slot (seg); is; pPos--, info--, is = gr_slot_prev_in_segment (is))
     {
       if (info->cluster != currclus)
       {
         curradvx += clusx;
         curradvy += clusy;
         currclus = info->cluster;
         clusx = 0.;
         clusy = 0.;
         for (tis = is, tinfo = info; tis && tinfo->cluster == currclus; tis = gr_slot_prev_in_segment (tis), tinfo--)
         {
           clusx += gr_slot_advance_X (tis, grface, grfont);
           clusy += gr_slot_advance_Y (tis, grface, grfont);
         }
         curradvx += clusx;
         curradvy += clusy;
       }
       pPos->x_advance = gr_slot_advance_X (is, grface, grfont);
       pPos->y_advance = gr_slot_advance_Y (is, grface, grfont);
       curradvx -= pPos->x_advance;
       curradvy -= pPos->y_advance;
       pPos->x_offset = gr_slot_origin_X (is) - curradvx;
       pPos->y_offset = gr_slot_origin_Y (is) - curradvy;
     }
     hb_buffer_reverse_clusters (buffer);
   }

   if (feats) gr_featureval_destroy (feats);
   gr_seg_destroy (seg);

   return true;
 }
	/*
	* Copyright © 2011 Martin Hosken
	* Copyright © 2011 SIL International
	* Copyright © 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.
	*
	* Google Author(s): Behdad Esfahbod
	*/

	#define HB_SHAPER graphite2
	#define hb_graphite2_shaper_font_data_t gr_font
	#include "hb-shaper-impl-private.hh"

	#include "hb-graphite2.h"

	#include <graphite2/Segment.h>


	HB_SHAPER_DATA_ENSURE_DECLARE(graphite2, face)
	HB_SHAPER_DATA_ENSURE_DECLARE(graphite2, font)


	/*
	* shaper face data
	*/

	typedef struct hb_graphite2_tablelist_t {
	struct hb_graphite2_tablelist_t *next;
	hb_blob_t *blob;
	unsigned int tag;
	} hb_graphite2_tablelist_t;

	struct hb_graphite2_shaper_face_data_t {
	hb_face_t *face;
	gr_face *grface;
	hb_graphite2_tablelist_t *tlist;
	};

	static const void hb_graphite2_get_table (const void data, unsigned int tag, size_t *len)
	{
	hb_graphite2_shaper_face_data_t face_data = (hb_graphite2_shaper_face_data_t ) data;
	hb_graphite2_tablelist_t *tlist = face_data->tlist;

	hb_blob_t *blob = NULL;

	for (hb_graphite2_tablelist_t *p = tlist; p; p = p->next)
	if (p->tag == tag) {
	blob = p->blob;
	break;
	}

	if (unlikely (!blob))
	{
	blob = face_data->face->reference_table (tag);

	hb_graphite2_tablelist_t p = (hb_graphite2_tablelist_t ) calloc (1, sizeof (hb_graphite2_tablelist_t));
	if (unlikely (!p)) {
	hb_blob_destroy (blob);
	return NULL;
	}
	p->blob = blob;
	p->tag = tag;

	/* TODO Not thread-safe, but fairly harmless.
	* We can do the double-chcked pointer cmpexch thing here. */
	p->next = face_data->tlist;
	face_data->tlist = p;
	}

	unsigned int tlen;
	const char *d = hb_blob_get_data (blob, &tlen);
	*len = tlen;
	return d;
	}

	hb_graphite2_shaper_face_data_t *
	_hb_graphite2_shaper_face_data_create (hb_face_t *face)
	{
	hb_blob_t *silf_blob = face->reference_table (HB_GRAPHITE2_TAG_SILF);
	/* Umm, we just reference the table to check whether it exists.
	* Maybe add better API for this? */
	if (!hb_blob_get_length (silf_blob))
	{
	hb_blob_destroy (silf_blob);
	return NULL;
	}
	hb_blob_destroy (silf_blob);

	hb_graphite2_shaper_face_data_t data = (hb_graphite2_shaper_face_data_t ) calloc (1, sizeof (hb_graphite2_shaper_face_data_t));
	if (unlikely (!data))
	return NULL;

	data->face = face;
	data->grface = gr_make_face (data, &hb_graphite2_get_table, gr_face_preloadAll);

	if (unlikely (!data->grface)) {
	free (data);
	return NULL;
	}

	return data;
	}

	void
	_hb_graphite2_shaper_face_data_destroy (hb_graphite2_shaper_face_data_t *data)
	{
	hb_graphite2_tablelist_t *tlist = data->tlist;

	while (tlist)
	{
	hb_graphite2_tablelist_t *old = tlist;
	hb_blob_destroy (tlist->blob);
	tlist = tlist->next;
	free (old);
	}

	gr_face_destroy (data->grface);

	free (data);
	}

	gr_face *
	hb_graphite2_face_get_gr_face (hb_face_t *face)
	{
	if (unlikely (!hb_graphite2_shaper_face_data_ensure (face))) return NULL;
	return HB_SHAPER_DATA_GET (face)->grface;
	}


	/*
	* shaper font data
	*/

	static float hb_graphite2_get_advance (const void *hb_font, unsigned short gid)
	{
	return ((hb_font_t *) hb_font)->get_glyph_h_advance (gid);
	}

	hb_graphite2_shaper_font_data_t *
	_hb_graphite2_shaper_font_data_create (hb_font_t *font)
	{
	if (unlikely (!hb_graphite2_shaper_face_data_ensure (font->face))) return NULL;

	hb_face_t *face = font->face;
	hb_graphite2_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);

	return gr_make_font_with_advance_fn (font->x_scale, font, &hb_graphite2_get_advance, face_data->grface);
	}

	void
	_hb_graphite2_shaper_font_data_destroy (hb_graphite2_shaper_font_data_t *data)
	{
	gr_font_destroy (data);
	}

	gr_font *
	hb_graphite2_font_get_gr_font (hb_font_t *font)
	{
	if (unlikely (!hb_graphite2_shaper_font_data_ensure (font))) return NULL;
	return HB_SHAPER_DATA_GET (font);
	}


	/*
	* shaper shape_plan data
	*/

	struct hb_graphite2_shaper_shape_plan_data_t {};

	hb_graphite2_shaper_shape_plan_data_t *
	_hb_graphite2_shaper_shape_plan_data_create (hb_shape_plan_t *shape_plan HB_UNUSED,
	const hb_feature_t *user_features HB_UNUSED,
	unsigned int num_user_features HB_UNUSED)
	{
	return (hb_graphite2_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
	}

	void
	_hb_graphite2_shaper_shape_plan_data_destroy (hb_graphite2_shaper_shape_plan_data_t *data HB_UNUSED)
	{
	}


	/*
	* shaper
	*/

	struct hb_graphite2_cluster_t {
	unsigned int base_char;
	unsigned int num_chars;
	unsigned int base_glyph;
	unsigned int num_glyphs;
	unsigned int cluster;
	};

	hb_bool_t
	_hb_graphite2_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_face_t *face = font->face;
	gr_face *grface = HB_SHAPER_DATA_GET (face)->grface;
	gr_font *grfont = HB_SHAPER_DATA_GET (font);

	const char *lang = hb_language_to_string (hb_buffer_get_language (buffer));
	const char *lang_end = lang ? strchr (lang, '-') : NULL;
	int lang_len = lang_end ? lang_end - lang : -1;
	gr_feature_val *feats = gr_face_featureval_for_lang (grface, lang ? hb_tag_from_string (lang, lang_len) : 0);

	for (unsigned int i = 0; i < num_features; i++)
	{
	const gr_feature_ref *fref = gr_face_find_fref (grface, features[i].tag);
	if (fref)
	gr_fref_set_feature_value (fref, features[i].value, feats);
	}

	gr_segment *seg = NULL;
	const gr_slot *is;
	unsigned int ci = 0, ic = 0;
	float curradvx = 0., curradvy = 0.;

	unsigned int scratch_size;
	hb_buffer_t::scratch_buffer_t *scratch = buffer->get_scratch_buffer (&scratch_size);

	uint32_t chars = (uint32_t ) scratch;

	for (unsigned int i = 0; i < buffer->len; ++i)
	chars[i] = buffer->info[i].codepoint;

	/* TODO ensure_native_direction. */

	hb_tag_t script_tag[2];
	hb_ot_tags_from_script (hb_buffer_get_script (buffer), &script_tag[0], &script_tag[1]);

	seg = gr_make_seg (grfont, grface,
	script_tag[1] == HB_TAG_NONE ? script_tag[0] : script_tag[1],
	feats,
	gr_utf32, chars, buffer->len,
	2 \| (hb_buffer_get_direction (buffer) == HB_DIRECTION_RTL ? 1 : 0));

	if (unlikely (!seg)) {
	if (feats) gr_featureval_destroy (feats);
	return false;
	}

	unsigned int glyph_count = gr_seg_n_slots (seg);
	if (unlikely (!glyph_count)) {
	if (feats) gr_featureval_destroy (feats);
	gr_seg_destroy (seg);
	buffer->len = 0;
	return true;
	}

	buffer->ensure (glyph_count);
	scratch = buffer->get_scratch_buffer (&scratch_size);
	while ((DIV_CEIL (sizeof (hb_graphite2_cluster_t) * buffer->len, sizeof (*scratch)) +
	DIV_CEIL (sizeof (hb_codepoint_t) * glyph_count, sizeof (*scratch))) > scratch_size)
	{
	if (unlikely (!buffer->ensure (buffer->allocated * 2)))
	{
	if (feats) gr_featureval_destroy (feats);
	gr_seg_destroy (seg);
	return false;
	}
	scratch = buffer->get_scratch_buffer (&scratch_size);
	}

	#define ALLOCATE_ARRAY(Type, name, len) \
	Type name = (Type ) scratch; \
	{ \
	unsigned int _consumed = DIV_CEIL ((len) * sizeof (Type), sizeof (*scratch)); \
	assert (_consumed <= scratch_size); \
	scratch += _consumed; \
	scratch_size -= _consumed; \
	}

	ALLOCATE_ARRAY (hb_graphite2_cluster_t, clusters, buffer->len);
	ALLOCATE_ARRAY (hb_codepoint_t, gids, glyph_count);

	#undef ALLOCATE_ARRAY

	memset (clusters, 0, sizeof (clusters[0]) * buffer->len);

	hb_codepoint_t *pg = gids;
	clusters[0].cluster = buffer->info[0].cluster;
	for (is = gr_seg_first_slot (seg), ic = 0; is; is = gr_slot_next_in_segment (is), ic++)
	{
	unsigned int before = gr_slot_before (is);
	unsigned int after = gr_slot_after (is);
	*pg = gr_slot_gid (is);
	pg++;
	while (clusters[ci].base_char > before && ci)
	{
	clusters[ci-1].num_chars += clusters[ci].num_chars;
	clusters[ci-1].num_glyphs += clusters[ci].num_glyphs;
	ci--;
	}

	if (gr_slot_can_insert_before (is) && clusters[ci].num_chars && before >= clusters[ci].base_char + clusters[ci].num_chars)
	{
	hb_graphite2_cluster_t *c = clusters + ci + 1;
	c->base_char = clusters[ci].base_char + clusters[ci].num_chars;
	c->cluster = buffer->info[c->base_char].cluster;
	c->num_chars = before - c->base_char;
	c->base_glyph = ic;
	c->num_glyphs = 0;
	ci++;
	}
	clusters[ci].num_glyphs++;

	if (clusters[ci].base_char + clusters[ci].num_chars < after + 1)
	clusters[ci].num_chars = after + 1 - clusters[ci].base_char;
	}
	ci++;

	for (unsigned int i = 0; i < ci; ++i)
	{
	for (unsigned int j = 0; j < clusters[i].num_glyphs; ++j)
	{
	hb_glyph_info_t *info = &buffer->info[clusters[i].base_glyph + j];
	info->codepoint = gids[clusters[i].base_glyph + j];
	info->cluster = clusters[i].cluster;
	}
	}
	buffer->len = glyph_count;

	/* Positioning. */
	if (!HB_DIRECTION_IS_BACKWARD(buffer->props.direction))
	{
	hb_glyph_position_t *pPos;
	for (pPos = hb_buffer_get_glyph_positions (buffer, NULL), is = gr_seg_first_slot (seg);
	is; pPos++, is = gr_slot_next_in_segment (is))
	{
	pPos->x_offset = gr_slot_origin_X (is) - curradvx;
	pPos->y_offset = gr_slot_origin_Y (is) - curradvy;
	pPos->x_advance = gr_slot_advance_X (is, grface, grfont);
	pPos->y_advance = gr_slot_advance_Y (is, grface, grfont);
	curradvx += pPos->x_advance;
	curradvy += pPos->y_advance;
	}
	pPos[-1].x_advance += gr_seg_advance_X(seg) - curradvx;
	}
	else
	{
	hb_glyph_position_t *pPos = hb_buffer_get_glyph_positions (buffer, NULL) + buffer->len - 1;
	const hb_glyph_info_t *info = buffer->info + buffer->len - 1;
	const hb_glyph_info_t *tinfo;
	const gr_slot *tis;
	int currclus = -1;
	float clusx = 0., clusy = 0.;
	for (is = gr_seg_last_slot (seg); is; pPos--, info--, is = gr_slot_prev_in_segment (is))
	{
	if (info->cluster != currclus)
	{
	curradvx += clusx;
	curradvy += clusy;
	currclus = info->cluster;
	clusx = 0.;
	clusy = 0.;
	for (tis = is, tinfo = info; tis && tinfo->cluster == currclus; tis = gr_slot_prev_in_segment (tis), tinfo--)
	{
	clusx += gr_slot_advance_X (tis, grface, grfont);
	clusy += gr_slot_advance_Y (tis, grface, grfont);
	}
	curradvx += clusx;
	curradvy += clusy;
	}
	pPos->x_advance = gr_slot_advance_X (is, grface, grfont);
	pPos->y_advance = gr_slot_advance_Y (is, grface, grfont);
	curradvx -= pPos->x_advance;
	curradvy -= pPos->y_advance;
	pPos->x_offset = gr_slot_origin_X (is) - curradvx;
	pPos->y_offset = gr_slot_origin_Y (is) - curradvy;
	}
	hb_buffer_reverse_clusters (buffer);
	}

	if (feats) gr_featureval_destroy (feats);
	gr_seg_destroy (seg);

	return true;
	}