afcjk.c

奇趣公司比较新的qt/emd版本

/***************************************************************************/
/*                                                                         */
/*  afcjk.c                                                                */
/*                                                                         */
/*    Auto-fitter hinting routines for CJK script (body).                  */
/*                                                                         */
/*  Copyright 2006 by                                                      */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/

  /*
   *  The algorithm is based on akito's autohint patch, available here:
   *
   *  http://www.kde.gr.jp/~akito/patch/freetype2/
   *
   */

#include "aftypes.h"
#include "aflatin.h"


#ifdef AF_CONFIG_OPTION_CJK

#include "afcjk.h"
#include "aferrors.h"


#ifdef AF_USE_WARPER
#include "afwarp.h"
#endif


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****              C J K   G L O B A L   M E T R I C S              *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  static FT_Error
  af_cjk_metrics_init( AF_LatinMetrics  metrics,
                       FT_Face          face )
  {
    FT_CharMap  oldmap = face->charmap;


    metrics->units_per_em = face->units_per_EM;

    /* TODO are there blues? */

    if ( FT_Select_Charmap( face, FT_ENCODING_UNICODE ) )
      face->charmap = NULL;

    /* latin's version would suffice */
    af_latin_metrics_init_widths( metrics, face, 0x7530 );

    FT_Set_Charmap( face, oldmap );

    return AF_Err_Ok;
  }


  static void
  af_cjk_metrics_scale_dim( AF_LatinMetrics  metrics,
                            AF_Scaler        scaler,
                            AF_Dimension     dim )
  {
    AF_LatinAxis  axis;


    axis = &metrics->axis[dim];

    if ( dim == AF_DIMENSION_HORZ )
    {
      axis->scale = scaler->x_scale;
      axis->delta = scaler->x_delta;
    }
    else
    {
      axis->scale = scaler->y_scale;
      axis->delta = scaler->y_delta;
    }
  }


  static void
  af_cjk_metrics_scale( AF_LatinMetrics  metrics,
                        AF_Scaler        scaler )
  {
    metrics->root.scaler = *scaler;

    af_cjk_metrics_scale_dim( metrics, scaler, AF_DIMENSION_HORZ );
    af_cjk_metrics_scale_dim( metrics, scaler, AF_DIMENSION_VERT );
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****              C J K   G L Y P H   A N A L Y S I S              *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  static FT_Error
  af_cjk_hints_compute_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_Error      error;
    AF_Segment    seg;


    error = af_latin_hints_compute_segments( hints, dim );
    if ( error )
      return error;

    /* a segment is round if it doesn't have successive */
    /* on-curve points.                                 */
    for ( seg = segments; seg < segment_limit; seg++ )
    {
      AF_Point  pt   = seg->first;
      AF_Point  last = seg->last;
      AF_Flags  f0   = (AF_Flags)(pt->flags & AF_FLAG_CONTROL);
      AF_Flags  f1;


      seg->flags &= ~AF_EDGE_ROUND;

      for ( ; pt != last; f0 = f1 )
      {
        pt = pt->next;
        f1 = (AF_Flags)(pt->flags & AF_FLAG_CONTROL);

        if ( !f0 && !f1 )
          break;

        if ( pt == last )
          seg->flags |= AF_EDGE_ROUND;
      }
    }

    return AF_Err_Ok;
  }


  static void
  af_cjk_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;
    AF_Direction  major_dir     = axis->major_dir;
    AF_Segment    seg1, seg2;
    FT_Pos        len_threshold;
    FT_Pos        dist_threshold;


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

    dist_threshold = ( dim == AF_DIMENSION_HORZ ) ? hints->x_scale
                                                  : hints->y_scale;
    dist_threshold = FT_DivFix( 64 * 3, dist_threshold );

    /* now compare each segment to the others */
    for ( seg1 = segments; seg1 < segment_limit; seg1++ )
    {
      /* the fake segments are for metrics hinting only */
      if ( seg1->first == seg1->last )
        continue;

      if ( seg1->dir != major_dir )
        continue;

      for ( seg2 = segments; seg2 < segment_limit; seg2++ )
        if ( seg2 != seg1 && seg1->dir + seg2->dir == 0 )
        {
          FT_Pos  dist = seg2->pos - seg1->pos;


          if ( dist < 0 )
            continue;

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


            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 )
            {
              if ( dist * 8 < seg1->score * 9                        &&
                   ( dist * 8 < seg1->score * 7 || seg1->len < len ) )
              {
                seg1->score = dist;
                seg1->len   = len;
                seg1->link  = seg2;
              }

              if ( dist * 8 < seg2->score * 9                        &&
                   ( dist * 8 < seg2->score * 7 || seg2->len < len ) )
              {
                seg2->score = dist;
                seg2->len   = len;
                seg2->link  = seg1;
              }
            }
          }
        }
    }

    /*
     *  now compute the `serif' segments
     *
     *  In Hanzi, some strokes are wider on one or both of the ends.
     *  We either identify the stems on the ends as serifs or remove
     *  the linkage, depending on the length of the stems.
     *
     */

    {
      AF_Segment  link1, link2;


      for ( seg1 = segments; seg1 < segment_limit; seg1++ )
      {
        link1 = seg1->link;
        if ( !link1 || link1->link != seg1 || link1->pos <= seg1->pos )
          continue;

        if ( seg1->score >= dist_threshold )
          continue;

        for ( seg2 = segments; seg2 < segment_limit; seg2++ )
        {
          if ( seg2->pos > seg1->pos || seg1 == seg2 )
            continue;

          link2 = seg2->link;
          if ( !link2 || link2->link != seg2 || link2->pos < link1->pos )
            continue;

          if ( seg1->pos == seg2->pos && link1->pos == link2->pos )
            continue;

          if ( seg2->score <= seg1->score || seg1->score * 4 <= seg2->score )
            continue;

          /* seg2 < seg1 < link1 < link2 */

          if ( seg1->len >= seg2->len * 3 )
          {
            AF_Segment  seg;


            for ( seg = segments; seg < segment_limit; seg++ )
            {
              AF_Segment  link = seg->link;


              if ( link == seg2 )
              {
                seg->link  = 0;
                seg->serif = link1;
              }
              else if ( link == link2 )
              {
                seg->link  = 0;
                seg->serif = seg1;
              }
            }
          }
          else
          {
            seg1->link = link1->link = 0;

            break;
          }
        }
      }
    }

    for ( seg1 = segments; seg1 < segment_limit; seg1++ )
    {
      seg2 = seg1->link;

      if ( seg2 )
      {
        seg2->num_linked++;
        if ( seg2->link != seg1 )
        {
          seg1->link = 0;

          if ( seg2->score < dist_threshold || seg1->score < seg2->score * 4 )
            seg1->serif = seg2->link;
          else
            seg2->num_linked--;
        }
      }
    }
  }


  static FT_Error
  af_cjk_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;


    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 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 is then 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 = FT_DivFix( 64 / 4, scale );
    else
      edge_distance_threshold = laxis->edge_distance_threshold;

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


      /* 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;


        if ( edge->dir != seg->dir )
          continue;

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

        if ( dist < edge_distance_threshold && dist < best )
        {
          AF_Segment  link = seg->link;


          /* check whether all linked segments of the candidate edge */
          /* can make a single edge.                                 */
          if ( link )
          {
            AF_Segment  seg1 = edge->first;
            AF_Segment  link1;
            FT_Pos      dist2 = 0;


            do
            {
              link1 = seg1->link;
              if ( link1 )
              {
                dist2 = AF_SEGMENT_DIST( link, link1 );
                if ( dist2 >= edge_distance_threshold )
                  break;
              }

            } while ( ( seg1 = seg1->edge_next ) != edge->first );

            if ( dist2 >= edge_distance_threshold )
              continue;
          }

          best  = dist;
          found = edge;
        }
      }

      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;
        edge->dir      = seg->dir;
      }
      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 now compute each edge's properties according to segments */
    /* found on its position.  Basically, these are as follows.          */
    /*                                                                   */
    /*  - 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? */


        seg = edge->first;

        do