michael@0: /*
michael@0:  * Copyright © 2011,2012  Google, Inc.
michael@0:  *
michael@0:  *  This is part of HarfBuzz, a text shaping library.
michael@0:  *
michael@0:  * Permission is hereby granted, without written agreement and without
michael@0:  * license or royalty fees, to use, copy, modify, and distribute this
michael@0:  * software and its documentation for any purpose, provided that the
michael@0:  * above copyright notice and the following two paragraphs appear in
michael@0:  * all copies of this software.
michael@0:  *
michael@0:  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
michael@0:  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
michael@0:  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
michael@0:  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
michael@0:  * DAMAGE.
michael@0:  *
michael@0:  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
michael@0:  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
michael@0:  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
michael@0:  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
michael@0:  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
michael@0:  *
michael@0:  * Google Author(s): Behdad Esfahbod
michael@0:  */
michael@0: 
michael@0: #include "hb-ot-shape-fallback-private.hh"
michael@0: #include "hb-ot-layout-gsubgpos-private.hh"
michael@0: 
michael@0: static unsigned int
michael@0: recategorize_combining_class (hb_codepoint_t u,
michael@0: 			      unsigned int klass)
michael@0: {
michael@0:   if (klass >= 200)
michael@0:     return klass;
michael@0: 
michael@0:   /* Thai / Lao need some per-character work. */
michael@0:   if ((u & ~0xFF) == 0x0E00)
michael@0:   {
michael@0:     if (unlikely (klass == 0))
michael@0:     {
michael@0:       switch (u)
michael@0:       {
michael@0:         case 0x0E31:
michael@0:         case 0x0E34:
michael@0:         case 0x0E35:
michael@0:         case 0x0E36:
michael@0:         case 0x0E37:
michael@0:         case 0x0E47:
michael@0:         case 0x0E4C:
michael@0:         case 0x0E4D:
michael@0:         case 0x0E4E:
michael@0: 	  klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
michael@0: 	  break;
michael@0: 
michael@0:         case 0x0EB1:
michael@0:         case 0x0EB4:
michael@0:         case 0x0EB5:
michael@0:         case 0x0EB6:
michael@0:         case 0x0EB7:
michael@0:         case 0x0EBB:
michael@0:         case 0x0ECC:
michael@0:         case 0x0ECD:
michael@0: 	  klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
michael@0: 	  break;
michael@0: 
michael@0:         case 0x0EBC:
michael@0: 	  klass = HB_UNICODE_COMBINING_CLASS_BELOW;
michael@0: 	  break;
michael@0:       }
michael@0:     } else {
michael@0:       /* Thai virama is below-right */
michael@0:       if (u == 0x0E3A)
michael@0: 	klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   switch (klass)
michael@0:   {
michael@0: 
michael@0:     /* Hebrew */
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */
michael@0:       return HB_UNICODE_COMBINING_CLASS_BELOW;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */
michael@0:       break;
michael@0: 
michael@0: 
michael@0:     /* Arabic and Syriac */
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */
michael@0:       return HB_UNICODE_COMBINING_CLASS_BELOW;
michael@0: 
michael@0: 
michael@0:     /* Thai */
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */
michael@0:       return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
michael@0: 
michael@0: 
michael@0:     /* Lao */
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */
michael@0:       return HB_UNICODE_COMBINING_CLASS_BELOW;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE;
michael@0: 
michael@0: 
michael@0:     /* Tibetan */
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */
michael@0:       return HB_UNICODE_COMBINING_CLASS_BELOW;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/
michael@0:       return HB_UNICODE_COMBINING_CLASS_ABOVE;
michael@0: 
michael@0:     case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */
michael@0:       return HB_UNICODE_COMBINING_CLASS_BELOW;
michael@0: 
michael@0:   }
michael@0: 
michael@0:   return klass;
michael@0: }
michael@0: 
michael@0: void
michael@0: _hb_ot_shape_fallback_position_recategorize_marks (const hb_ot_shape_plan_t *plan HB_UNUSED,
michael@0: 						   hb_font_t *font HB_UNUSED,
michael@0: 						   hb_buffer_t  *buffer)
michael@0: {
michael@0:   unsigned int count = buffer->len;
michael@0:   for (unsigned int i = 0; i < count; i++)
michael@0:     if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
michael@0:       unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
michael@0:       combining_class = recategorize_combining_class (buffer->info[i].codepoint, combining_class);
michael@0:       _hb_glyph_info_set_modified_combining_class (&buffer->info[i], combining_class);
michael@0:     }
michael@0: }
michael@0: 
michael@0: 
michael@0: static void
michael@0: zero_mark_advances (hb_buffer_t *buffer,
michael@0: 		    unsigned int start,
michael@0: 		    unsigned int end)
michael@0: {
michael@0:   for (unsigned int i = start; i < end; i++)
michael@0:     if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
michael@0:     {
michael@0:       buffer->pos[i].x_advance = 0;
michael@0:       buffer->pos[i].y_advance = 0;
michael@0:     }
michael@0: }
michael@0: 
michael@0: static inline void
michael@0: position_mark (const hb_ot_shape_plan_t *plan,
michael@0: 	       hb_font_t *font,
michael@0: 	       hb_buffer_t  *buffer,
michael@0: 	       hb_glyph_extents_t &base_extents,
michael@0: 	       unsigned int i,
michael@0: 	       unsigned int combining_class)
michael@0: {
michael@0:   hb_glyph_extents_t mark_extents;
michael@0:   if (!font->get_glyph_extents (buffer->info[i].codepoint,
michael@0: 				&mark_extents))
michael@0:     return;
michael@0: 
michael@0:   hb_position_t y_gap = font->y_scale / 16;
michael@0: 
michael@0:   hb_glyph_position_t &pos = buffer->pos[i];
michael@0:   pos.x_offset = pos.y_offset = 0;
michael@0: 
michael@0: 
michael@0:   /* We dont position LEFT and RIGHT marks. */
michael@0: 
michael@0:   /* X positioning */
michael@0:   switch (combining_class)
michael@0:   {
michael@0:     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
michael@0:     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
michael@0:       if (buffer->props.direction == HB_DIRECTION_LTR) {
michael@0: 	pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
michael@0:         break;
michael@0:       } else if (buffer->props.direction == HB_DIRECTION_RTL) {
michael@0: 	pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
michael@0:         break;
michael@0:       }
michael@0:       /* Fall through */
michael@0: 
michael@0:     default:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
michael@0:     case HB_UNICODE_COMBINING_CLASS_BELOW:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ABOVE:
michael@0:       /* Center align. */
michael@0:       pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
michael@0:       break;
michael@0: 
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
michael@0:       /* Left align. */
michael@0:       pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
michael@0:       break;
michael@0: 
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
michael@0:       /* Right align. */
michael@0:       pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
michael@0:       break;
michael@0:   }
michael@0: 
michael@0:   /* Y positioning */
michael@0:   switch (combining_class)
michael@0:   {
michael@0:     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
michael@0:     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_BELOW:
michael@0:     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
michael@0:       /* Add gap, fall-through. */
michael@0:       base_extents.height -= y_gap;
michael@0: 
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
michael@0:       pos.y_offset = base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
michael@0:       /* Never shift up "below" marks. */
michael@0:       if ((y_gap > 0) == (pos.y_offset > 0))
michael@0:       {
michael@0: 	base_extents.height -= pos.y_offset;
michael@0: 	pos.y_offset = 0;
michael@0:       }
michael@0:       base_extents.height += mark_extents.height;
michael@0:       break;
michael@0: 
michael@0:     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ABOVE:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
michael@0:       /* Add gap, fall-through. */
michael@0:       base_extents.y_bearing += y_gap;
michael@0:       base_extents.height -= y_gap;
michael@0: 
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
michael@0:     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
michael@0:       pos.y_offset = base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
michael@0:       /* Don't shift down "above" marks too much. */
michael@0:       if ((y_gap > 0) != (pos.y_offset > 0))
michael@0:       {
michael@0: 	unsigned int correction = -pos.y_offset / 2;
michael@0: 	base_extents.y_bearing += correction;
michael@0: 	base_extents.height -= correction;
michael@0: 	pos.y_offset += correction;
michael@0:       }
michael@0:       base_extents.y_bearing -= mark_extents.height;
michael@0:       base_extents.height += mark_extents.height;
michael@0:       break;
michael@0:   }
michael@0: }
michael@0: 
michael@0: static inline void
michael@0: position_around_base (const hb_ot_shape_plan_t *plan,
michael@0: 		      hb_font_t *font,
michael@0: 		      hb_buffer_t  *buffer,
michael@0: 		      unsigned int base,
michael@0: 		      unsigned int end)
michael@0: {
michael@0:   hb_direction_t horiz_dir = HB_DIRECTION_INVALID;
michael@0:   hb_glyph_extents_t base_extents;
michael@0:   if (!font->get_glyph_extents (buffer->info[base].codepoint,
michael@0: 				&base_extents))
michael@0:   {
michael@0:     /* If extents don't work, zero marks and go home. */
michael@0:     zero_mark_advances (buffer, base + 1, end);
michael@0:     return;
michael@0:   }
michael@0:   base_extents.x_bearing += buffer->pos[base].x_offset;
michael@0:   base_extents.y_bearing += buffer->pos[base].y_offset;
michael@0: 
michael@0:   unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[base]);
michael@0:   unsigned int num_lig_components = _hb_glyph_info_get_lig_num_comps (&buffer->info[base]);
michael@0: 
michael@0:   hb_position_t x_offset = 0, y_offset = 0;
michael@0:   if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
michael@0:     x_offset -= buffer->pos[base].x_advance;
michael@0:     y_offset -= buffer->pos[base].y_advance;
michael@0:   }
michael@0: 
michael@0:   hb_glyph_extents_t component_extents = base_extents;
michael@0:   unsigned int last_lig_component = (unsigned int) -1;
michael@0:   unsigned int last_combining_class = 255;
michael@0:   hb_glyph_extents_t cluster_extents = base_extents; /* Initialization is just to shut gcc up. */
michael@0:   for (unsigned int i = base + 1; i < end; i++)
michael@0:     if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]))
michael@0:     {
michael@0:       if (num_lig_components > 1) {
michael@0: 	unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&buffer->info[i]);
michael@0: 	unsigned int this_lig_component = _hb_glyph_info_get_lig_comp (&buffer->info[i]) - 1;
michael@0: 	/* Conditions for attaching to the last component. */
michael@0: 	if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)
michael@0: 	  this_lig_component = num_lig_components - 1;
michael@0: 	if (last_lig_component != this_lig_component)
michael@0: 	{
michael@0: 	  last_lig_component = this_lig_component;
michael@0: 	  last_combining_class = 255;
michael@0: 	  component_extents = base_extents;
michael@0: 	  if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {
michael@0: 	    if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))
michael@0: 	      horiz_dir = plan->props.direction;
michael@0: 	    else
michael@0: 	      horiz_dir = hb_script_get_horizontal_direction (plan->props.script);
michael@0: 	  }
michael@0: 	  if (horiz_dir == HB_DIRECTION_LTR)
michael@0: 	    component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;
michael@0: 	  else
michael@0: 	    component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;
michael@0: 	  component_extents.width /= num_lig_components;
michael@0: 	}
michael@0:       }
michael@0: 
michael@0:       unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
michael@0:       if (last_combining_class != this_combining_class)
michael@0:       {
michael@0: 	last_combining_class = this_combining_class;
michael@0:         cluster_extents = component_extents;
michael@0:       }
michael@0: 
michael@0:       position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
michael@0: 
michael@0:       buffer->pos[i].x_advance = 0;
michael@0:       buffer->pos[i].y_advance = 0;
michael@0:       buffer->pos[i].x_offset += x_offset;
michael@0:       buffer->pos[i].y_offset += y_offset;
michael@0: 
michael@0:     } else {
michael@0:       if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
michael@0: 	x_offset -= buffer->pos[i].x_advance;
michael@0: 	y_offset -= buffer->pos[i].y_advance;
michael@0:       } else {
michael@0: 	x_offset += buffer->pos[i].x_advance;
michael@0: 	y_offset += buffer->pos[i].y_advance;
michael@0:       }
michael@0:     }
michael@0: }
michael@0: 
michael@0: static inline void
michael@0: position_cluster (const hb_ot_shape_plan_t *plan,
michael@0: 		  hb_font_t *font,
michael@0: 		  hb_buffer_t  *buffer,
michael@0: 		  unsigned int start,
michael@0: 		  unsigned int end)
michael@0: {
michael@0:   if (end - start < 2)
michael@0:     return;
michael@0: 
michael@0:   /* Find the base glyph */
michael@0:   for (unsigned int i = start; i < end; i++)
michael@0:     if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[i])))
michael@0:     {
michael@0:       /* Find mark glyphs */
michael@0:       unsigned int j;
michael@0:       for (j = i + 1; j < end; j++)
michael@0: 	if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[j])))
michael@0: 	  break;
michael@0: 
michael@0:       position_around_base (plan, font, buffer, i, j);
michael@0: 
michael@0:       i = j - 1;
michael@0:     }
michael@0: }
michael@0: 
michael@0: void
michael@0: _hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,
michael@0: 				hb_font_t *font,
michael@0: 				hb_buffer_t  *buffer)
michael@0: {
michael@0:   unsigned int start = 0;
michael@0:   unsigned int last_cluster = buffer->info[0].cluster;
michael@0:   unsigned int count = buffer->len;
michael@0:   for (unsigned int i = 1; i < count; i++)
michael@0:     if (buffer->info[i].cluster != last_cluster) {
michael@0:       position_cluster (plan, font, buffer, start, i);
michael@0:       start = i;
michael@0:       last_cluster = buffer->info[i].cluster;
michael@0:     }
michael@0:   position_cluster (plan, font, buffer, start, count);
michael@0: }
michael@0: 
michael@0: 
michael@0: /* Performs old-style TrueType kerning. */
michael@0: void
michael@0: _hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
michael@0: 			    hb_font_t *font,
michael@0: 			    hb_buffer_t  *buffer)
michael@0: {
michael@0:   if (!plan->has_kern) return;
michael@0: 
michael@0:   unsigned int count = buffer->len;
michael@0: 
michael@0:   OT::hb_apply_context_t c (1, font, buffer);
michael@0:   c.set_lookup_mask (plan->kern_mask);
michael@0:   c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
michael@0: 
michael@0:   hb_glyph_info_t *info = buffer->info;
michael@0:   hb_glyph_position_t *pos = buffer->pos;
michael@0: 
michael@0:   for (unsigned int idx = 0; idx < count;)
michael@0:   {
michael@0:     OT::hb_apply_context_t::skipping_forward_iterator_t skippy_iter (&c, idx, 1);
michael@0:     if (!skippy_iter.next ())
michael@0:     {
michael@0:       idx++;
michael@0:       continue;
michael@0:     }
michael@0: 
michael@0:     hb_position_t x_kern, y_kern;
michael@0:     font->get_glyph_kerning_for_direction (info[idx].codepoint,
michael@0: 					   info[skippy_iter.idx].codepoint,
michael@0: 					   buffer->props.direction,
michael@0: 					   &x_kern, &y_kern);
michael@0: 
michael@0:     if (x_kern)
michael@0:     {
michael@0:       hb_position_t kern1 = x_kern >> 1;
michael@0:       hb_position_t kern2 = x_kern - kern1;
michael@0:       pos[idx].x_advance += kern1;
michael@0:       pos[skippy_iter.idx].x_advance += kern2;
michael@0:       pos[skippy_iter.idx].x_offset += kern2;
michael@0:     }
michael@0: 
michael@0:     if (y_kern)
michael@0:     {
michael@0:       hb_position_t kern1 = y_kern >> 1;
michael@0:       hb_position_t kern2 = y_kern - kern1;
michael@0:       pos[idx].y_advance += kern1;
michael@0:       pos[skippy_iter.idx].y_advance += kern2;
michael@0:       pos[skippy_iter.idx].y_offset += kern2;
michael@0:     }
michael@0: 
michael@0:     idx = skippy_iter.idx;
michael@0:   }
michael@0: }