aflatin.c

奇趣公司比较新的qt/emd版本

      }

      /* insert maximum segment */
      if ( max_point )
      {
        /* clear all segment fields */
        error = af_axis_hints_new_segment( axis, memory, &segment );
        if ( error )
          goto Exit;

        segment[0]     = seg0;
        segment->dir   = segment_dir;
        segment->first = max_point;
        segment->last  = max_point;
        segment->pos   = max_pos;

        segment = NULL;
      }
    }
#endif /* AF_HINT_METRICS */

  Exit:
    return error;
  }


  FT_LOCAL_DEF( void )
  af_latin_hints_link_segments( AF_GlyphHints  hints,
                                AF_Dimension   dim )
  {
    AF_AxisHints  axis          = &hints->axis[dim];
    AF_Segment    segments      = axis->segments;
    AF_Segment    segment_limit = segments + axis->num_segments;
    FT_Pos        len_threshold, len_score;
    AF_Segment    seg1, seg2;


    len_threshold = AF_LATIN_CONSTANT( hints->metrics, 8 );
    if ( len_threshold == 0 )
      len_threshold = 1;

    len_score = AF_LATIN_CONSTANT( hints->metrics, 6000 );

    /* now compare each segment to the others */
    for ( seg1 = segments; seg1 < segment_limit; seg1++ )
    {
      /* the fake segments are introduced to hint the metrics -- */
      /* we must never link them to anything                     */
      if ( seg1->first == seg1->last )
        continue;

      for ( seg2 = seg1 + 1; seg2 < segment_limit; seg2++ )
        if ( seg1->dir + seg2->dir == 0 )
        {
          FT_Pos  pos1 = seg1->pos;
          FT_Pos  pos2 = seg2->pos;
          FT_Pos  dist = pos2 - pos1;


          if ( dist < 0 )
            dist = -dist;

          {
            FT_Pos  min = seg1->min_coord;
            FT_Pos  max = seg1->max_coord;
            FT_Pos  len, score;


            if ( min < seg2->min_coord )
              min = seg2->min_coord;

            if ( max > seg2->max_coord )
              max = seg2->max_coord;

            len = max - min;
            if ( len >= len_threshold )
            {
              score = dist + len_score / len;

              if ( score < seg1->score )
              {
                seg1->score = score;
                seg1->link  = seg2;
              }

              if ( score < seg2->score )
              {
                seg2->score = score;
                seg2->link  = seg1;
              }
            }
          }
        }
    }

    /* now, compute the `serif' segments */
    for ( seg1 = segments; seg1 < segment_limit; seg1++ )
    {
      seg2 = seg1->link;

      if ( seg2 )
      {
        if ( seg2->link != seg1 )
        {
          seg1->link  = 0;
          seg1->serif = seg2->link;
        }
      }
    }
  }


  FT_LOCAL_DEF( FT_Error )
  af_latin_hints_compute_edges( AF_GlyphHints  hints,
                                AF_Dimension   dim )
  {
    AF_AxisHints  axis   = &hints->axis[dim];
    FT_Error      error  = AF_Err_Ok;
    FT_Memory     memory = hints->memory;
    AF_LatinAxis  laxis  = &((AF_LatinMetrics)hints->metrics)->axis[dim];

    AF_Segment    segments      = axis->segments;
    AF_Segment    segment_limit = segments + axis->num_segments;
    AF_Segment    seg;

    AF_Direction  up_dir;
    FT_Fixed      scale;
    FT_Pos        edge_distance_threshold;
    FT_Pos        segment_length_threshold;


    axis->num_edges = 0;

    scale = ( dim == AF_DIMENSION_HORZ ) ? hints->x_scale
                                         : hints->y_scale;

    up_dir = ( dim == AF_DIMENSION_HORZ ) ? AF_DIR_UP
                                          : AF_DIR_RIGHT;

    /*
     *  We ignore all segments that are less than 1 pixels in length,
     *  to avoid many problems with serif fonts.  We compute the
     *  corresponding threshold in font units.
     */
    if ( dim == AF_DIMENSION_HORZ )
        segment_length_threshold = FT_DivFix( 64, hints->y_scale );
    else
        segment_length_threshold = 0;

    /*********************************************************************/
    /*                                                                   */
    /* We will begin by generating a sorted table of edges for the       */
    /* current direction.  To do so, we simply scan each segment and try */
    /* to find an edge in our table that corresponds to its position.    */
    /*                                                                   */
    /* If no edge is found, we create and insert a new edge in the       */
    /* sorted table.  Otherwise, we simply add the segment to the edge's */
    /* list which will be processed in the second step to compute the    */
    /* edge's properties.                                                */
    /*                                                                   */
    /* Note that the edges table is sorted along the segment/edge        */
    /* position.                                                         */
    /*                                                                   */
    /*********************************************************************/

    edge_distance_threshold = FT_MulFix( laxis->edge_distance_threshold,
                                         scale );
    if ( edge_distance_threshold > 64 / 4 )
      edge_distance_threshold = 64 / 4;

    edge_distance_threshold = FT_DivFix( edge_distance_threshold,
                                         scale );

    for ( seg = segments; seg < segment_limit; seg++ )
    {
      AF_Edge  found = 0;
      FT_Int   ee;


      if ( seg->height < segment_length_threshold )
        continue;

      /* A special case for serif edges: If they are smaller than */
      /* 1.5 pixels we ignore them.                               */
      if ( seg->serif                                     &&
           2 * seg->height < 3 * segment_length_threshold )
        continue;

      /* look for an edge corresponding to the segment */
      for ( ee = 0; ee < axis->num_edges; ee++ )
      {
        AF_Edge  edge = axis->edges + ee;
        FT_Pos   dist;


        dist = seg->pos - edge->fpos;
        if ( dist < 0 )
          dist = -dist;

        if ( dist < edge_distance_threshold )
        {
          found = edge;
          break;
        }
      }

      if ( !found )
      {
        AF_Edge   edge;


        /* insert a new edge in the list and */
        /* sort according to the position    */
        error = af_axis_hints_new_edge( axis, seg->pos, memory, &edge );
        if ( error )
          goto Exit;

        /* add the segment to the new edge's list */
        FT_ZERO( edge );

        edge->first    = seg;
        edge->last     = seg;
        edge->fpos     = seg->pos;
        edge->opos     = edge->pos = FT_MulFix( seg->pos, scale );
        seg->edge_next = seg;
      }
      else
      {
        /* if an edge was found, simply add the segment to the edge's */
        /* list                                                       */
        seg->edge_next         = found->first;
        found->last->edge_next = seg;
        found->last            = seg;
      }
    }


    /*********************************************************************/
    /*                                                                   */
    /* Good, we will now compute each edge's properties according to     */
    /* segments found on its position.  Basically, these are:            */
    /*                                                                   */
    /*  - edge's main direction                                          */
    /*  - stem edge, serif edge or both (which defaults to stem then)    */
    /*  - rounded edge, straight or both (which defaults to straight)    */
    /*  - link for edge                                                  */
    /*                                                                   */
    /*********************************************************************/

    /* first of all, set the `edge' field in each segment -- this is */
    /* required in order to compute edge links                       */

    /*
     * Note that removing this loop and setting the `edge' field of each
     * segment directly in the code above slows down execution speed for
     * some reasons on platforms like the Sun.
     */
    {
      AF_Edge  edges      = axis->edges;
      AF_Edge  edge_limit = edges + axis->num_edges;
      AF_Edge  edge;


      for ( edge = edges; edge < edge_limit; edge++ )
      {
        seg = edge->first;
        if ( seg )
          do
          {
            seg->edge = edge;
            seg       = seg->edge_next;

          } while ( seg != edge->first );
      }

      /* now, compute each edge properties */
      for ( edge = edges; edge < edge_limit; edge++ )
      {
        FT_Int  is_round    = 0;  /* does it contain round segments?    */
        FT_Int  is_straight = 0;  /* does it contain straight segments? */
        FT_Pos  ups         = 0;  /* number of upwards segments         */
        FT_Pos  downs       = 0;  /* number of downwards segments       */


        seg = edge->first;

        do
        {
          FT_Bool  is_serif;


          /* check for roundness of segment */
          if ( seg->flags & AF_EDGE_ROUND )
            is_round++;
          else
            is_straight++;

          /* check for segment direction */
          if ( seg->dir == up_dir )
            ups   += seg->max_coord-seg->min_coord;
          else
            downs += seg->max_coord-seg->min_coord;

          /* check for links -- if seg->serif is set, then seg->link must */
          /* be ignored                                                   */
          is_serif = (FT_Bool)( seg->serif               &&
                                seg->serif->edge         &&
                                seg->serif->edge != edge );

          if ( ( seg->link && seg->link->edge != NULL ) || is_serif )
          {
            AF_Edge     edge2;
            AF_Segment  seg2;


            edge2 = edge->link;
            seg2  = seg->link;

            if ( is_serif )
            {
              seg2  = seg->serif;
              edge2 = edge->serif;
            }

            if ( edge2 )
            {
              FT_Pos  edge_delta;
              FT_Pos  seg_delta;


              edge_delta = edge->fpos - edge2->fpos;
              if ( edge_delta < 0 )
                edge_delta = -edge_delta;

              seg_delta = seg->pos - seg2->pos;
              if ( seg_delta < 0 )
                seg_delta = -seg_delta;

              if ( seg_delta < edge_delta )
                edge2 = seg2->edge;
            }
            else
              edge2 = seg2->edge;

            if ( is_serif )
            {
              edge->serif   = edge2;
              edge2->flags |= AF_EDGE_SERIF;
            }
            else
              edge->link  = edge2;
          }

          seg = seg->edge_next;

        } while ( seg != edge->first );

        /* set the round/straight flags */
        edge->flags = AF_EDGE_NORMAL;

        if ( is_round > 0 && is_round >= is_straight )
          edge->flags |= AF_EDGE_ROUND;

        /* set the edge's main direction */
        edge->dir = AF_DIR_NONE;

        if ( ups > downs )
          edge->dir = (FT_Char)up_dir;

        else if ( ups < downs )
          edge->dir = (FT_Char)-up_dir;

        else if ( ups == downs )
          edge->dir = 0;  /* both up and down! */

        /* gets rid of serifs if link is set                */
        /* XXX: This gets rid of many unpleasant artefacts! */
        /*      Example: the `c' in cour.pfa at size 13     */

        if ( edge->serif && edge->link )
          edge->serif = 0;
      }
    }

  Exit:
    return error;
  }


  FT_LOCAL_DEF( FT_Error )
  af_latin_hints_detect_features( AF_GlyphHints  hints,
                                  AF_Dimension   dim )
  {
    FT_Error  error;


    error = af_latin_hints_compute_segments( hints, dim );
    if ( !error )
    {
      af_latin_hints_link_segments( hints, dim );

      error = af_latin_hints_compute_edges( hints, dim );
    }
    return error;
  }


  FT_LOCAL_DEF( void )
  af_latin_hints_compute_blue_edges( AF_GlyphHints    hints,
                                     AF_LatinMetrics  metrics )
  {
    AF_AxisHints  axis       = &hints->axis[ AF_DIMENSION_VERT ];
    AF_Edge       edge       = axis->edges;
    AF_Edge       edge_limit = edge + axis->num_edges;
    AF_LatinAxis  latin      = &metrics->axis[ AF_DIMENSION_VERT ];
    FT_Fixed      scale      = latin->scale;


    /* compute which blue zones are active, i.e. have their scaled */
    /* size < 3/4 pixels                                           */

    /* for each horizontal edge search the blue zone which is closest */
    for ( ; edge < edge_limit; edge++ )
    {
      FT_Int    bb;
      AF_Width  best_blue = NULL;
      FT_Pos    best_dist;  /* initial threshold */


      /* compute the initial threshold as a fraction of the EM size */
      best_dist = FT_MulFix( metrics->units_per_em / 40, scale );

      if ( best_dist > 64 / 2 )
        best_dist = 64 / 2;

      for ( bb = 0; bb < AF_LATIN_BLUE_MAX; bb++ )
      {
        AF_LatinBlue  blue = latin->blues + bb;
        FT_Bool       is_top_blue, is_major_dir;


        /* skip inactive blue zones (i.e., those that are too small) */
        if ( !( blue->flags & AF_LATIN_BLUE_ACTIVE ) )
          continue;

        /* if it is a top zone, check for right edges -- if it is a bottom */