pshalgo.c

一个类似windows

/***************************************************************************/
/*                                                                         */
/*  pshalgo.c                                                              */
/*                                                                         */
/*    PostScript hinting algorithm (body).                                 */
/*                                                                         */
/*  Copyright 2001, 2002, 2003, 2004, 2005 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.                                        */
/*                                                                         */
/***************************************************************************/


#include <ft2build.h>
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_DEBUG_H
#include "pshalgo.h"

#include "pshnterr.h"


#undef  FT_COMPONENT
#define FT_COMPONENT  trace_pshalgo2


#ifdef DEBUG_HINTER
  PSH_Hint_Table  ps_debug_hint_table = 0;
  PSH_HintFunc    ps_debug_hint_func  = 0;
  PSH_Glyph       ps_debug_glyph      = 0;
#endif


#define  COMPUTE_INFLEXS  /* compute inflection points to optimize `S' */
                          /* and similar glyphs                        */
#define  STRONGER         /* slightly increase the contrast of smooth  */
                          /* hinting                                   */


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                  BASIC HINTS RECORDINGS                       *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /* return true if two stem hints overlap */
  static FT_Int
  psh_hint_overlap( PSH_Hint  hint1,
                    PSH_Hint  hint2 )
  {
    return hint1->org_pos + hint1->org_len >= hint2->org_pos &&
           hint2->org_pos + hint2->org_len >= hint1->org_pos;
  }


  /* destroy hints table */
  static void
  psh_hint_table_done( PSH_Hint_Table  table,
                       FT_Memory       memory )
  {
    FT_FREE( table->zones );
    table->num_zones = 0;
    table->zone      = 0;

    FT_FREE( table->sort );
    FT_FREE( table->hints );
    table->num_hints   = 0;
    table->max_hints   = 0;
    table->sort_global = 0;
  }


  /* deactivate all hints in a table */
  static void
  psh_hint_table_deactivate( PSH_Hint_Table  table )
  {
    FT_UInt   count = table->max_hints;
    PSH_Hint  hint  = table->hints;


    for ( ; count > 0; count--, hint++ )
    {
      psh_hint_deactivate( hint );
      hint->order = -1;
    }
  }


  /* internal function to record a new hint */
  static void
  psh_hint_table_record( PSH_Hint_Table  table,
                         FT_UInt         idx )
  {
    PSH_Hint  hint = table->hints + idx;


    if ( idx >= table->max_hints )
    {
      FT_ERROR(( "psh_hint_table_record: invalid hint index %d\n", idx ));
      return;
    }

    /* ignore active hints */
    if ( psh_hint_is_active( hint ) )
      return;

    psh_hint_activate( hint );

    /* now scan the current active hint set to check */
    /* whether `hint' overlaps with another hint     */
    {
      PSH_Hint*  sorted = table->sort_global;
      FT_UInt    count  = table->num_hints;
      PSH_Hint   hint2;


      hint->parent = 0;
      for ( ; count > 0; count--, sorted++ )
      {
        hint2 = sorted[0];

        if ( psh_hint_overlap( hint, hint2 ) )
        {
          hint->parent = hint2;
          break;
        }
      }
    }

    if ( table->num_hints < table->max_hints )
      table->sort_global[table->num_hints++] = hint;
    else
      FT_ERROR(( "psh_hint_table_record: too many sorted hints!  BUG!\n" ));
  }


  static void
  psh_hint_table_record_mask( PSH_Hint_Table  table,
                              PS_Mask         hint_mask )
  {
    FT_Int    mask = 0, val = 0;
    FT_Byte*  cursor = hint_mask->bytes;
    FT_UInt   idx, limit;


    limit = hint_mask->num_bits;

    for ( idx = 0; idx < limit; idx++ )
    {
      if ( mask == 0 )
      {
        val  = *cursor++;
        mask = 0x80;
      }

      if ( val & mask )
        psh_hint_table_record( table, idx );

      mask >>= 1;
    }
  }


  /* create hints table */
  static FT_Error
  psh_hint_table_init( PSH_Hint_Table  table,
                       PS_Hint_Table   hints,
                       PS_Mask_Table   hint_masks,
                       PS_Mask_Table   counter_masks,
                       FT_Memory       memory )
  {
    FT_UInt   count;
    FT_Error  error;

    FT_UNUSED( counter_masks );


    count = hints->num_hints;

    /* allocate our tables */
    if ( FT_NEW_ARRAY( table->sort,  2 * count     ) ||
         FT_NEW_ARRAY( table->hints,     count     ) ||
         FT_NEW_ARRAY( table->zones, 2 * count + 1 ) )
      goto Exit;

    table->max_hints   = count;
    table->sort_global = table->sort + count;
    table->num_hints   = 0;
    table->num_zones   = 0;
    table->zone        = 0;

    /* initialize the `table->hints' array */
    {
      PSH_Hint  write = table->hints;
      PS_Hint   read  = hints->hints;


      for ( ; count > 0; count--, write++, read++ )
      {
        write->org_pos = read->pos;
        write->org_len = read->len;
        write->flags   = read->flags;
      }
    }

    /* we now need to determine the initial `parent' stems; first  */
    /* activate the hints that are given by the initial hint masks */
    if ( hint_masks )
    {
      PS_Mask  mask = hint_masks->masks;


      count             = hint_masks->num_masks;
      table->hint_masks = hint_masks;

      for ( ; count > 0; count--, mask++ )
        psh_hint_table_record_mask( table, mask );
    }

    /* finally, do a linear parse in case some hints were left alone */
    if ( table->num_hints != table->max_hints )
    {
      FT_UInt  idx;


      FT_ERROR(( "psh_hint_table_init: missing/incorrect hint masks!\n" ));

      count = table->max_hints;
      for ( idx = 0; idx < count; idx++ )
        psh_hint_table_record( table, idx );
    }

  Exit:
    return error;
  }


  static void
  psh_hint_table_activate_mask( PSH_Hint_Table  table,
                                PS_Mask         hint_mask )
  {
    FT_Int    mask = 0, val = 0;
    FT_Byte*  cursor = hint_mask->bytes;
    FT_UInt   idx, limit, count;


    limit = hint_mask->num_bits;
    count = 0;

    psh_hint_table_deactivate( table );

    for ( idx = 0; idx < limit; idx++ )
    {
      if ( mask == 0 )
      {
        val  = *cursor++;
        mask = 0x80;
      }

      if ( val & mask )
      {
        PSH_Hint  hint = &table->hints[idx];


        if ( !psh_hint_is_active( hint ) )
        {
          FT_UInt     count2;

#if 0
          PSH_Hint*  sort = table->sort;
          PSH_Hint   hint2;


          for ( count2 = count; count2 > 0; count2--, sort++ )
          {
            hint2 = sort[0];
            if ( psh_hint_overlap( hint, hint2 ) )
              FT_ERROR(( "psh_hint_table_activate_mask:"
                         " found overlapping hints\n" ))
          }
#else
          count2 = 0;
#endif

          if ( count2 == 0 )
          {
            psh_hint_activate( hint );
            if ( count < table->max_hints )
              table->sort[count++] = hint;
            else
              FT_ERROR(( "psh_hint_tableactivate_mask:"
                         " too many active hints\n" ));
          }
        }
      }

      mask >>= 1;
    }
    table->num_hints = count;

    /* now, sort the hints; they are guaranteed to not overlap */
    /* so we can compare their "org_pos" field directly        */
    {
      FT_Int     i1, i2;
      PSH_Hint   hint1, hint2;
      PSH_Hint*  sort = table->sort;


      /* a simple bubble sort will do, since in 99% of cases, the hints */
      /* will be already sorted -- and the sort will be linear          */
      for ( i1 = 1; i1 < (FT_Int)count; i1++ )
      {
        hint1 = sort[i1];
        for ( i2 = i1 - 1; i2 >= 0; i2-- )
        {
          hint2 = sort[i2];

          if ( hint2->org_pos < hint1->org_pos )
            break;

          sort[i2 + 1] = hint2;
          sort[i2]     = hint1;
        }
      }
    }
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****               HINTS GRID-FITTING AND OPTIMIZATION             *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

#if 1
  static FT_Pos
  psh_dimension_quantize_len( PSH_Dimension  dim,
                              FT_Pos         len,
                              FT_Bool        do_snapping )
  {
    if ( len <= 64 )
      len = 64;
    else
    {
      FT_Pos  delta = len - dim->stdw.widths[0].cur;


      if ( delta < 0 )
        delta = -delta;

      if ( delta < 40 )
      {
        len = dim->stdw.widths[0].cur;
        if ( len < 48 )
          len = 48;
      }

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

        if ( delta < 10 )
          len += delta;

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

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

        else
          len += delta;
      }
      else
        len = FT_PIX_ROUND( len );
    }

    if ( do_snapping )
      len = FT_PIX_ROUND( len );

    return  len;
  }
#endif /* 0 */


#ifdef DEBUG_HINTER

  static void
  ps_simple_scale( PSH_Hint_Table  table,
                   FT_Fixed        scale,
                   FT_Fixed        delta,
                   FT_Int          dimension )
  {
    PSH_Hint  hint;
    FT_UInt   count;


    for ( count = 0; count < table->max_hints; count++ )
    {
      hint = table->hints + count;

      hint->cur_pos = FT_MulFix( hint->org_pos, scale ) + delta;
      hint->cur_len = FT_MulFix( hint->org_len, scale );

      if ( ps_debug_hint_func )
        ps_debug_hint_func( hint, dimension );
    }
  }

#endif /* DEBUG_HINTER */


  static FT_Fixed
  psh_hint_snap_stem_side_delta( FT_Fixed  pos,
                                 FT_Fixed  len )
  {
    FT_Fixed  delta1 = FT_PIX_ROUND( pos ) - pos;
    FT_Fixed  delta2 = FT_PIX_ROUND( pos + len ) - pos - len;


    if ( FT_ABS( delta1 ) <= FT_ABS( delta2 ) )
      return delta1;
    else
      return delta2;
  }


  static void
  psh_hint_align( PSH_Hint     hint,
                  PSH_Globals  globals,
                  FT_Int       dimension,
                  PSH_Glyph    glyph )
  {
    PSH_Dimension  dim   = &globals->dimension[dimension];
    FT_Fixed       scale = dim->scale_mult;
    FT_Fixed       delta = dim->scale_delta;


    if ( !psh_hint_is_fitted( hint ) )
    {
      FT_Pos  pos = FT_MulFix( hint->org_pos, scale ) + delta;
      FT_Pos  len = FT_MulFix( hint->org_len, scale );

      FT_Int            do_snapping;
      FT_Pos            fit_len;
      PSH_AlignmentRec  align;


      /* ignore stem alignments when requested through the hint flags */
      if ( ( dimension == 0 && !glyph->do_horz_hints ) ||
           ( dimension == 1 && !glyph->do_vert_hints ) )
      {
        hint->cur_pos = pos;
        hint->cur_len = len;

        psh_hint_set_fitted( hint );
        return;
      }

      /* perform stem snapping when requested - this is necessary
       * for monochrome and LCD hinting modes only
       */
      do_snapping = ( dimension == 0 && glyph->do_horz_snapping ) ||
                    ( dimension == 1 && glyph->do_vert_snapping );

      hint->cur_len = fit_len = len;

      /* check blue zones for horizontal stems */
      align.align     = PSH_BLUE_ALIGN_NONE;
      align.align_bot = align.align_top = 0;

      if ( dimension == 1 )
        psh_blues_snap_stem( &globals->blues,
                             hint->org_pos + hint->org_len,
                             hint->org_pos,
                             &align );

      switch ( align.align )
      {
      case PSH_BLUE_ALIGN_TOP:
        /* the top of the stem is aligned against a blue zone */
        hint->cur_pos = align.align_top - fit_len;
        break;

      case PSH_BLUE_ALIGN_BOT:
        /* the bottom of the stem is aligned against a blue zone */
        hint->cur_pos = align.align_bot;
        break;

      case PSH_BLUE_ALIGN_TOP | PSH_BLUE_ALIGN_BOT:
        /* both edges of the stem are aligned against blue zones */
        hint->cur_pos = align.align_bot;
        hint->cur_len = align.align_top - align.align_bot;
        break;

      default:
        {
          PSH_Hint  parent = hint->parent;


          if ( parent )
          {
            FT_Pos  par_org_center, par_cur_center;
            FT_Pos  cur_org_center, cur_delta;


            /* ensure that parent is already fitted */
            if ( !psh_hint_is_fitted( parent ) )
              psh_hint_align( parent, globals, dimension, glyph );

            /* keep original relation between hints, this is, use the */
            /* scaled distance between the centers of the hints to    */
            /* compute the new position                               */
            par_org_center = parent->org_pos + ( parent->org_len >> 1 );
            par_cur_center = parent->cur_pos + ( parent->cur_len >> 1 );