aflatin.c

智能设备中PDF阅读器的源码！用于windows mobile2003或者WM5以上

        /* 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 != edge );

          if ( seg->link || 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 */
        /* zone, check for left edges                                      */
        /*                                                                 */
        /* of course, that's for TrueType                                  */
        is_top_blue  = (FT_Byte)( ( blue->flags & AF_LATIN_BLUE_TOP ) != 0 );
        is_major_dir = FT_BOOL( edge->dir == axis->major_dir );

        /* if it is a top zone, the edge must be against the major    */
        /* direction; if it is a bottom zone, it must be in the major */
        /* direction                                                  */
        if ( is_top_blue ^ is_major_dir )
        {
          FT_Pos  dist;


          /* first of all, compare it to the reference position */
          dist = edge->fpos - blue->ref.org;
          if ( dist < 0 )
            dist = -dist;

          dist = FT_MulFix( dist, scale );
          if ( dist < best_dist )
          {
            best_dist = dist;
            best_blue = & blue->ref;
          }

          /* now, compare it to the overshoot position if the edge is     */
          /* rounded, and if the edge is over the reference position of a */
          /* top zone, or under the reference position of a bottom zone   */
          if ( edge->flags & AF_EDGE_ROUND && dist != 0 )
          {
            FT_Bool  is_under_ref = FT_BOOL( edge->fpos < blue->ref.org );


            if ( is_top_blue ^ is_under_ref )
            {
              blue = latin->blues + bb;
              dist = edge->fpos - blue->shoot.org;
              if ( dist < 0 )
                dist = -dist;

              dist = FT_MulFix( dist, scale );
              if ( dist < best_dist )
              {
                best_dist = dist;
                best_blue = & blue->shoot;
              }
            }
          }
        }
      }

      if ( best_blue )
        edge->blue_edge = best_blue;
    }
  }


  static FT_Error
  af_latin_hints_init( AF_GlyphHints    hints,
                       AF_LatinMetrics  metrics )
  {
    FT_Render_Mode  mode;
    FT_UInt32       scaler_flags, other_flags;
    FT_Face         face = metrics->root.scaler.face;


    af_glyph_hints_rescale( hints, (AF_ScriptMetrics)metrics );

    /*
     *  correct x_scale and y_scale when needed, since they may have
     *  been modified af_latin_scale_dim above
     */
    hints->x_scale = metrics->axis[AF_DIMENSION_HORZ].scale;
    hints->x_delta = metrics->axis[AF_DIMENSION_HORZ].delta;
    hints->y_scale = metrics->axis[AF_DIMENSION_VERT].scale;
    hints->y_delta = metrics->axis[AF_DIMENSION_VERT].delta;

    /* compute flags depending on render mode, etc. */
    mode = metrics->root.scaler.render_mode;

#ifdef AF_USE_WARPER
    if ( mode == FT_RENDER_MODE_LCD || mode == FT_RENDER_MODE_LCD_V )
    {
      metrics->root.scaler.render_mode = mode = FT_RENDER_MODE_NORMAL;
    }
#endif

    scaler_flags = hints->scaler_flags;
    other_flags  = 0;

    /*
     *  We snap the width of vertical stems for the monochrome and
     *  horizontal LCD rendering targets only.
     */
    if ( mode == FT_RENDER_MODE_MONO || mode == FT_RENDER_MODE_LCD )
      other_flags |= AF_LATIN_HINTS_HORZ_SNAP;

    /*
     *  We snap the width of horizontal stems for the monochrome and
     *  vertical LCD rendering targets only.
     */
    if ( mode == FT_RENDER_MODE_MONO || mode == FT_RENDER_MODE_LCD_V )
      other_flags |= AF_LATIN_HINTS_VERT_SNAP;

    /*
     *  We adjust stems to full pixels only if we don't use the `light' mode.
     */
    if ( mode != FT_RENDER_MODE_LIGHT )
      other_flags |= AF_LATIN_HINTS_STEM_ADJUST;

    if ( mode == FT_RENDER_MODE_MONO )
      other_flags |= AF_LATIN_HINTS_MONO;

    /*
     *  In `light' hinting mode we disable horizontal hinting completely.
     *  We also do it if the face is italic.
     */
    if ( mode == FT_RENDER_MODE_LIGHT                    ||
         (face->style_flags & FT_STYLE_FLAG_ITALIC) != 0 )
      scaler_flags |= AF_SCALER_FLAG_NO_HORIZONTAL;

    hints->scaler_flags = scaler_flags;
    hints->other_flags  = other_flags;

    return 0;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****        L A T I N   G L Y P H   G R I D - F I T T I N G        *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /* snap a given width in scaled coordinates to one of the */
  /* current standard widths                                */

  static FT_Pos
  af_latin_snap_width( AF_Width  widths,
                       FT_Int    count,
                       FT_Pos    width )
  {
    int     n;
    FT_Pos  best      = 64 + 32 + 2;
    FT_Pos  reference = width;
    FT_Pos  scaled;


    for ( n = 0; n < count; n++ )
    {
      FT_Pos  w;
      FT_Pos  dist;


      w = widths[n].cur;
      dist = width - w;
      if ( dist < 0 )
        dist = -dist;
      if ( dist < best )
      {
        best      = dist;
        reference = w;
      }
    }

    scaled = FT_PIX_ROUND( reference );

    if ( width >= reference )
    {
      if ( width < scaled + 48 )
        width = reference;
    }
    else
    {
      if ( width > scaled - 48 )
        width = reference;
    }

    return width;
  }


  /* compute the snapped width of a given stem */

  static FT_Pos
  af_latin_compute_stem_width( AF_GlyphHints  hints,
                               AF_Dimension   dim,
                               FT_Pos         width,
                               AF_Edge_Flags  base_flags,
                               AF_Edge_Flags  stem_flags )
  {
    AF_LatinMetrics  metrics  = (AF_LatinMetrics) hints->metrics;
    AF_LatinAxis     axis     = & metrics->axis[dim];
    FT_Pos           dist     = width;
    FT_Int           sign     = 0;
    FT_Int           vertical = ( dim == AF_DIMENSION_VERT );


    if ( !AF_LATIN_HINTS_DO_STEM_ADJUST( hints ) )
      return width;

    if ( dist < 0 )
    {
      dist = -width;
      sign = 1;
    }

    if ( (  vertical && !AF_LATIN_HINTS_DO_VERT_SNAP( hints ) ) ||
         ( !vertical && !AF_LATIN_HINTS_DO_HORZ_SNAP( hints ) ) )
    {
      /* smooth hinting process: very lightly quantize the stem width */

      /* leave the widths of serifs alone */

      if ( ( stem_flags & AF_EDGE_SERIF ) && vertical && ( dist < 3 * 64 ) )
        goto Done_Width;

      else if ( ( base_flags & AF_EDGE_ROUND ) )
      {
        if ( dist < 80 )
          dist = 64;
      }
      else if ( dist < 56 )
        dist = 56;

      if ( axis->width_count > 0 )
      {
        FT_Pos  delta;


        /* compare to standard width */
        if ( axis->width_count > 0 )
        {
          delta = dist - axis->widths[0].cur;

          if ( delta < 0 )
            delta = -delta;

          if ( delta < 40 )
          {
            dist = axis->widths[0].cur;
            if ( dist < 48 )
              dist = 48;

            goto Done_Width;
          }
        }

        if ( dist < 3 * 64 )
        {
          delta  = dist & 63;
          dist  &= -64;

          if ( delta < 10 )
            dist += delta;

          else if ( delta < 32 )
            dist += 10;

          else if ( delta < 54 )
            dist += 54;

          else
            dist += delta;
        }
        else
          dist = ( dist + 32 ) & ~63;
      }
    }
    else
    {
      /* strong hinting process: snap the stem width to integer pixels */