kc3-lang/harfbuzz/src/hb-ot-shape-fallback.cc

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• Hash : 1d581ec3
  Author :
  Date : 2012-09-01T20:06:26
  

  [OT] Fallback-position ccc=0 Thai / Lao marks
  
  Not perfect, but so is fallback positioning in 2012...
  

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• src/hb-ot-shape-fallback.cc

• /*
   * 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
   */
  
  #include "hb-ot-shape-fallback-private.hh"
  
  static unsigned int
  recategorize_combining_class (hb_codepoint_t u,
  			      unsigned int klass)
  {
    if (klass >= 200)
      return klass;
  
    /* Thai / Lao need some per-character work. */
    if ((u & ~0xFF) == 0x0E00)
    {
      if (unlikely (klass == 0))
      {
        switch (u)
        {
          case 0x0E31:
          case 0x0E34:
          case 0x0E35:
          case 0x0E36:
          case 0x0E37:
          case 0x0E47:
          case 0x0E4C:
          case 0x0E4D:
          case 0x0E4E:
  	  klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
  	  break;
  
          case 0x0EB1:
          case 0x0EB4:
          case 0x0EB5:
          case 0x0EB6:
          case 0x0EB7:
          case 0x0EBB:
          case 0x0ECC:
          case 0x0ECD:
  	  klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
  	  break;
  
          case 0x0EBC:
  	  klass = HB_UNICODE_COMBINING_CLASS_BELOW;
  	  break;
        }
      } else {
        /* Thai virama is below-right */
        if (u == 0x0E3A)
  	klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
      }
    }
  
    switch (klass)
    {
  
      /* Hebrew */
  
      case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */
      case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */
      case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */
      case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */
      case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */
      case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */
      case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */
      case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */
      case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats */
      case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */
      case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */
        return HB_UNICODE_COMBINING_CLASS_BELOW;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */
        return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */
        return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */
      case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam */
        return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */
        return HB_UNICODE_COMBINING_CLASS_ABOVE;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */
        break;
  
  
      /* Arabic and Syriac */
  
      case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */
      case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */
      case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */
      case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */
      case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */
      case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */
      case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */
      case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */
        return HB_UNICODE_COMBINING_CLASS_ABOVE;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */
      case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */
        return HB_UNICODE_COMBINING_CLASS_BELOW;
  
  
      /* Thai */
  
      case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */
        return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */
        return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
  
  
      /* Lao */
  
      case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */
        return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */
        return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
  
  
      /* Tibetan */
  
      case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */
        return HB_UNICODE_COMBINING_CLASS_BELOW;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/
        return HB_UNICODE_COMBINING_CLASS_ABOVE;
  
      case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */
        return HB_UNICODE_COMBINING_CLASS_BELOW;
  
    }
  
    return klass;
  }
  
  void
  _hb_ot_shape_fallback_position_recategorize_marks (const hb_ot_shape_plan_t *plan,
  						   hb_font_t *font,
  						   hb_buffer_t  *buffer)
  {
    unsigned int count = buffer->len;
    for (unsigned int i = 0; i < count; i++)
      if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
        unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
        combining_class = recategorize_combining_class (buffer->info[i].codepoint, combining_class);
        _hb_glyph_info_set_modified_combining_class (&buffer->info[i], combining_class);
      }
  }
  
  
  static void
  zero_mark_advances (hb_buffer_t *buffer,
  		    unsigned int start,
  		    unsigned int end)
  {
    for (unsigned int i = start; i < end; i++)
      if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
      {
        buffer->pos[i].x_advance = 0;
        buffer->pos[i].y_advance = 0;
      }
  }
  
  static inline void
  position_mark (const hb_ot_shape_plan_t *plan,
  	       hb_font_t *font,
  	       hb_buffer_t  *buffer,
  	       hb_glyph_extents_t &base_extents,
  	       unsigned int i,
  	       unsigned int combining_class)
  {
    hb_glyph_extents_t mark_extents;
    if (!font->get_glyph_extents (buffer->info[i].codepoint,
  				&mark_extents))
      return;
  
    hb_position_t y_gap = font->y_scale / 16;
  
    hb_glyph_position_t &pos = buffer->pos[i];
    pos.x_offset = pos.y_offset = 0;
  
  
    /* We dont position LEFT and RIGHT marks. */
  
    /* X positioning */
    switch (combining_class)
    {
      case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
      case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
        if (buffer->props.direction == HB_DIRECTION_LTR) {
  	pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
          break;
        } else if (buffer->props.direction == HB_DIRECTION_RTL) {
  	pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
          break;
        }
        /* Fall through */
  
      default:
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
      case HB_UNICODE_COMBINING_CLASS_BELOW:
      case HB_UNICODE_COMBINING_CLASS_ABOVE:
        /* Center align. */
        pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
        break;
  
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
      case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
      case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
        /* Left align. */
        pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
        break;
  
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
      case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
      case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
        /* Right align. */
        pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
        break;
    }
  
    /* Y positioning */
    switch (combining_class)
    {
      case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
      case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
      case HB_UNICODE_COMBINING_CLASS_BELOW:
      case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
        /* Add gap, fall-through. */
        base_extents.height -= y_gap;
  
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
        pos.y_offset += base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
        base_extents.height += mark_extents.height;
        break;
  
      case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
      case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
      case HB_UNICODE_COMBINING_CLASS_ABOVE:
      case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
        /* Add gap, fall-through. */
        base_extents.y_bearing += y_gap;
        base_extents.height -= y_gap;
  
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
      case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
        pos.y_offset += base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
        base_extents.y_bearing -= mark_extents.height;
        base_extents.height += mark_extents.height;
        break;
    }
  }
  
  static inline void
  position_around_base (const hb_ot_shape_plan_t *plan,
  		      hb_font_t *font,
  		      hb_buffer_t  *buffer,
  		      unsigned int base,
  		      unsigned int end)
  {
    hb_glyph_extents_t base_extents;
    if (!font->get_glyph_extents (buffer->info[base].codepoint,
  				&base_extents))
    {
      /* If extents don't work, zero marks and go home. */
      zero_mark_advances (buffer, base + 1, end);
      return;
    }
    base_extents.x_bearing += buffer->pos[base].x_offset;
    base_extents.y_bearing += buffer->pos[base].y_offset;
  
    /* XXX Handle ligature component positioning... */
    HB_UNUSED bool is_ligature = is_a_ligature (buffer->info[base]);
  
    hb_position_t x_offset = 0, y_offset = 0;
    if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
      x_offset -= buffer->pos[base].x_advance;
      y_offset -= buffer->pos[base].y_advance;
    }
    unsigned int last_combining_class = 255;
    hb_glyph_extents_t cluster_extents;
    for (unsigned int i = base + 1; i < end; i++)
      if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]))
      {
        unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
        if (this_combining_class != last_combining_class)
          cluster_extents = base_extents;
  
        position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
  
        buffer->pos[i].x_advance = 0;
        buffer->pos[i].y_advance = 0;
        buffer->pos[i].x_offset += x_offset;
        buffer->pos[i].y_offset += y_offset;
  
        last_combining_class = this_combining_class;
      } else {
        if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
  	x_offset -= buffer->pos[i].x_advance;
  	y_offset -= buffer->pos[i].y_advance;
        } else {
  	x_offset += buffer->pos[i].x_advance;
  	y_offset += buffer->pos[i].y_advance;
        }
      }
  
  
  }
  
  static inline void
  position_cluster (const hb_ot_shape_plan_t *plan,
  		  hb_font_t *font,
  		  hb_buffer_t  *buffer,
  		  unsigned int start,
  		  unsigned int end)
  {
    if (end - start < 2)
      return;
  
    /* Find the base glyph */
    for (unsigned int i = start; i < end; i++)
      if (is_a_ligature (buffer->info[i]) ||
          !(FLAG (_hb_glyph_info_get_general_category (&buffer->info[i])) &
  	  (FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
  	   FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
  	   FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK))))
      {
        position_around_base (plan, font, buffer, i, end);
        break;
      }
  }
  
  void
  _hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,
  				hb_font_t *font,
  				hb_buffer_t  *buffer)
  {
    unsigned int start = 0;
    unsigned int last_cluster = buffer->info[0].cluster;
    unsigned int count = buffer->len;
    for (unsigned int i = 1; i < count; i++)
      if (buffer->info[i].cluster != last_cluster) {
        position_cluster (plan, font, buffer, start, i);
        start = i;
        last_cluster = buffer->info[i].cluster;
      }
    position_cluster (plan, font, buffer, start, count);
  }
  

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