ahhint.c

qt-embedded-2.3.8.tar.gz源码

/***************************************************************************/
/*                                                                         */
/*  ahhint.c                                                               */
/*                                                                         */
/*    Glyph hinter (body).                                                 */
/*                                                                         */
/*  Copyright 2000 Catharon Productions Inc.                               */
/*  Author: David Turner                                                   */
/*                                                                         */
/*  This file is part of the Catharon Typography Project and shall only    */
/*  be used, modified, and distributed under the terms of the Catharon     */
/*  Open Source License that should come with this file under the name     */
/*  `CatharonLicense.txt'.  By continuing to use, modify, or distribute    */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/*  Note that this license is compatible with the FreeType license.        */
/*                                                                         */
/***************************************************************************/


#ifdef FT_FLAT_COMPILE

#include "ahhint.h"
#include "ahglyph.h"
#include "ahangles.h"

#else

#include <autohint/ahhint.h>
#include <autohint/ahglyph.h>
#include <autohint/ahangles.h>

#endif

#include <freetype/ftoutln.h>


#define FACE_GLOBALS( face )  ((AH_Face_Globals*)(face)->autohint.data)

#define AH_USE_IUP


  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****   Hinting routines                                              ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/


  static int  disable_horz_edges = 0;
  static int  disable_vert_edges = 0;


  /* snap a given width in scaled coordinates to one of the */
  /* current standard widths                                */
  static
  FT_Pos  ah_snap_width( FT_Pos*  widths,
                         FT_Int   count,
                         FT_Pos   width )
  {
    int     n;
    FT_Pos  best      = 64 + 32 + 2;
    FT_Pos  reference = width;


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


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

    if ( width >= reference )
    {
      width -= 0x21;
      if ( width < reference )
        width = reference;
    }
    else
    {
      width += 0x21;
      if ( width > reference )
        width = reference;
    }

    return width;
  }


  /* align one stem edge relative to the previous stem edge */
  static
  void  ah_align_linked_edge( AH_Hinter*  hinter,
                              AH_Edge*    base_edge,
                              AH_Edge*    stem_edge,
                              int         vertical )
  {
    FT_Pos       dist    = stem_edge->opos - base_edge->opos;
    AH_Globals*  globals = &hinter->globals->scaled;
    FT_Pos       sign    = 1;


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

    if ( vertical )
    {
      dist = ah_snap_width( globals->heights, globals->num_heights, dist );

      /* in the case of vertical hinting, always round */
      /* the stem heights to integer pixels            */
      if ( dist >= 64 )
        dist = ( dist + 16 ) & -64;
      else
        dist = 64;
    }
    else
    {
      dist = ah_snap_width( globals->widths,  globals->num_widths, dist );

      if ( hinter->flags & ah_hinter_monochrome )
      {
        /* monochrome horizontal hinting: snap widths to integer pixels */
        /* with a different threshold                                   */
        if ( dist < 64 )
          dist = 64;
        else
          dist = ( dist + 32 ) & -64;
      }
      else
      {
        /* for horizontal anti-aliased hinting, we adopt a more subtle */
        /* approach: we strengthen small stems, round stems whose size */
        /* is between 1 and 2 pixels to an integer, otherwise nothing  */
        if ( dist < 48 )
          dist = ( dist + 64 ) >> 1;

        else if ( dist < 128 )
          dist = ( dist + 42 ) & -64;
      }
    }

    stem_edge->pos = base_edge->pos + sign * dist;
  }


  static
  void  ah_align_serif_edge( AH_Hinter*  hinter,
                             AH_Edge*    base,
                             AH_Edge*    serif )
  {
    FT_Pos  dist;
    FT_Pos  sign = 1;

    UNUSED( hinter );


    dist = serif->opos - base->opos;
    if ( dist < 0 )
    {
      dist = -dist;
      sign = -1;
    }

    /* do not strengthen serifs */
    if ( base->flags & ah_edge_done )
    {
      if ( dist > 64 )
        dist = ( dist + 16 ) & -64;

      else if ( dist <= 32 )
        dist = ( dist + 33 ) >> 1;
    }

    serif->pos = base->pos + sign * dist;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****       E D G E   H I N T I N G                                   ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


  /* Another alternative edge hinting algorithm */
  static
  void  ah_hint_edges_3( AH_Hinter*  hinter )
  {
    AH_Edge*     edges;
    AH_Edge*     edge_limit;
    AH_Outline*  outline = hinter->glyph;
    FT_Int       dimension;


    edges      = outline->horz_edges;
    edge_limit = edges + outline->num_hedges;

    for ( dimension = 1; dimension >= 0; dimension-- )
    {
      AH_Edge*  edge;
      AH_Edge*  before = 0;
      AH_Edge*  after  = 0;
      AH_Edge*  anchor = 0;
      int       has_serifs = 0;


      if ( disable_vert_edges && !dimension )
        goto Next_Dimension;

      if ( disable_horz_edges && dimension )
        goto Next_Dimension;

      /* we begin by aligning all stems relative to the blue zone */
      /* if needed -- that's only for horizontal edges            */
      if ( dimension )
      {
        for ( edge = edges; edge < edge_limit; edge++ )
        {
          FT_Pos*  blue;
          AH_Edge  *edge1, *edge2;


          if ( edge->flags & ah_edge_done )
            continue;

          blue  = edge->blue_edge;
          edge1 = 0;
          edge2 = edge->link;

          if ( blue )
          {
            edge1 = edge;
          }
          else if (edge2 && edge2->blue_edge)
          {
            blue  = edge2->blue_edge;
            edge1 = edge2;
            edge2 = edge;
          }

          if ( !edge1 )
            continue;

          edge1->pos    = blue[0];
          edge1->flags |= ah_edge_done;

          if ( edge2 && !edge2->blue_edge )
          {
            ah_align_linked_edge( hinter, edge1, edge2, dimension );
            edge2->flags |= ah_edge_done;
          }

          if ( !anchor )
            anchor = edge;
         }
       }

      /* now, we will align all stem edges, trying to maintain the */
      /* relative order of stems in the glyph..                    */
      before = 0;
      after  = 0;
      for ( edge = edges; edge < edge_limit; edge++ )
      {
        AH_Edge  *edge2;


        if ( edge->flags & ah_edge_done )
          continue;

        /* skip all non-stem edges */
        edge2 = edge->link;
        if ( !edge2 )
        {
          has_serifs++;
          continue;
        }

        /* now, align the stem */

        /* this should not happen, but it's better to be safe.. */
        if ( edge2->blue_edge || edge2 < edge )
        {

#if 0
          printf( "strange blue alignement, edge %d to %d\n",
                  edge - edges, edge2 - edges );
#endif

          ah_align_linked_edge( hinter, edge2, edge, dimension );
          edge->flags |= ah_edge_done;
          continue;
        }

        {
          FT_Bool  min = 0;
          FT_Pos   delta;

          if ( !anchor )
          {
            edge->pos = ( edge->opos + 32 ) & -64;
            anchor    = edge;
          }
          else
            edge->pos = anchor->pos +
                        ( ( edge->opos - anchor->opos + 32 ) & -64 );

          edge->flags |= ah_edge_done;

          if ( edge > edges && edge->pos < edge[-1].pos )
          {
            edge->pos = edge[-1].pos;
            min       = 1;
          }

          ah_align_linked_edge( hinter, edge, edge2, dimension );
          delta = 0;
          if ( edge2 + 1 < edge_limit        &&
               edge2[1].flags & ah_edge_done )
            delta = edge2[1].pos - edge2->pos;

          if ( delta < 0 )
          {
            edge2->pos += delta;
            if ( !min )
              edge->pos += delta;
          }
          edge2->flags |= ah_edge_done;
        }
      }

      if ( !has_serifs )
        goto Next_Dimension;

      /* now, hint the remaining edges (serifs and single) in order */
      /* to complete our processing                                 */
      for ( edge = edges; edge < edge_limit; edge++ )
      {
        if ( edge->flags & ah_edge_done )
          continue;

        if ( edge->serif )
        {
          ah_align_serif_edge( hinter, edge->serif, edge );
        }
        else if ( !anchor )
        {
          edge->pos = ( edge->opos + 32 ) & -64;
          anchor    = edge;
        }
        else
          edge->pos = anchor->pos +
                      ( ( edge->opos-anchor->opos + 32 ) & -64 );

        edge->flags |= ah_edge_done;

        if ( edge > edges && edge->pos < edge[-1].pos )
          edge->pos = edge[-1].pos;

        if ( edge + 1 < edge_limit        &&
             edge[1].flags & ah_edge_done &&
             edge->pos > edge[1].pos      )
          edge->pos = edge[1].pos;
      }

    Next_Dimension:
      edges      = outline->vert_edges;
      edge_limit = edges + outline->num_vedges;
    }
  }


  FT_LOCAL_DEF
  void  ah_hinter_hint_edges( AH_Hinter*  hinter,
                              int         no_horz_edges,
                              int         no_vert_edges )
  {
    disable_horz_edges = no_horz_edges;
    disable_vert_edges = no_vert_edges;

    /* AH_Interpolate_Blue_Edges( hinter ); -- doesn't seem to help      */
    /* reduce the problem of the disappearing eye in the `e' of Times... */
    /* also, creates some artifacts near the blue zones?                 */
    {
      ah_hint_edges_3( hinter );

#if 0
      /* outline optimizer removed temporarily */
      if ( hinter->flags & ah_hinter_optimize )
      {
        AH_Optimizer  opt;


        if ( !AH_Optimizer_Init( &opt, hinter->glyph, hinter->memory ) )
        {
          AH_Optimizer_Compute( &opt );
          AH_Optimizer_Done( &opt );
        }
      }
#endif

    }
  }


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****       P O I N T   H I N T I N G                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/

  static
  void  ah_hinter_align_edge_points( AH_Hinter*  hinter )
  {
    AH_Outline*  outline = hinter->glyph;
    AH_Edge*     edges;
    AH_Edge*     edge_limit;
    FT_Int       dimension;


    edges      = outline->horz_edges;
    edge_limit = edges + outline->num_hedges;

    for ( dimension = 1; dimension >= 0; dimension-- )
    {
      AH_Edge*   edge;
      AH_Edge*   before;
      AH_Edge*   after;


      before = 0;
      after  = 0;

      edge = edges;
      for ( ; edge < edge_limit; edge++ )
      {
        /* move the points of each segment     */
        /* in each edge to the edge's position */
        AH_Segment*  seg = edge->first;


        do
        {
          AH_Point*  point = seg->first;


          for (;;)
          {
            if ( dimension )
            {
              point->y      = edge->pos;
              point->flags |= ah_flah_touch_y;
            }
            else
            {
              point->x      = edge->pos;
              point->flags |= ah_flah_touch_x;
            }