src/pshinter/pshglob.c

/****************************************************************************
 *
 * pshglob.c
 *
 *   PostScript hinter global hinting management (body).
 *   Inspired by the new auto-hinter module.
 *
 * Copyright (C) 2001-2022 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 <freetype/freetype.h>
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftcalc.h>
#include "pshglob.h"

#ifdef DEBUG_HINTER
  PSH_Globals  ps_debug_globals = NULL;
#endif


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                       STANDARD WIDTHS                         *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/


  /* scale the widths/heights table */
  static void
  psh_globals_scale_widths( PSH_Globals  globals,
                            FT_UInt      direction )
  {
    PSH_Dimension  dim   = &globals->dimension[direction];
    PSH_Widths     stdw  = &dim->stdw;
    FT_UInt        count = stdw->count;
    PSH_Width      width = stdw->widths;
    PSH_Width      stand = width;               /* standard width/height */
    FT_Fixed       scale = dim->scale_mult;


    if ( count > 0 )
    {
      width->cur = FT_MulFix( width->org, scale );
      width->fit = FT_PIX_ROUND( width->cur );

      width++;
      count--;

      for ( ; count > 0; count--, width++ )
      {
        FT_Pos  w, dist;


        w    = FT_MulFix( width->org, scale );
        dist = w - stand->cur;

        if ( dist < 0 )
          dist = -dist;

        if ( dist < 128 )
          w = stand->cur;

        width->cur = w;
        width->fit = FT_PIX_ROUND( w );
      }
    }
  }


#if 0

  /* org_width is in font units, result in device pixels, 26.6 format */
  FT_LOCAL_DEF( FT_Pos )
  psh_dimension_snap_width( PSH_Dimension  dimension,
                            FT_Int         org_width )
  {
    FT_UInt  n;
    FT_Pos   width     = FT_MulFix( org_width, dimension->scale_mult );
    FT_Pos   best      = 64 + 32 + 2;
    FT_Pos   reference = width;


    for ( n = 0; n < dimension->stdw.count; n++ )
    {
      FT_Pos  w;
      FT_Pos  dist;


      w = dimension->stdw.widths[n].cur;
      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;
  }

#endif /* 0 */


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                       BLUE ZONES                              *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  static void
  psh_blues_set_zones_0( PSH_Blues       target,
                         FT_Bool         is_others,
                         FT_UInt         read_count,
                         FT_Short*       read,
                         PSH_Blue_Table  top_table,
                         PSH_Blue_Table  bot_table )
  {
    FT_UInt  count_top = top_table->count;
    FT_UInt  count_bot = bot_table->count;
    FT_Bool  first     = 1;

    FT_UNUSED( target );


    for ( ; read_count > 1; read_count -= 2 )
    {
      FT_Int         reference, delta;
      FT_UInt        count;
      PSH_Blue_Zone  zones, zone;
      FT_Bool        top;


      /* read blue zone entry, and select target top/bottom zone */
      top = 0;
      if ( first || is_others )
      {
        reference = read[1];
        delta     = read[0] - reference;

        zones = bot_table->zones;
        count = count_bot;
        first = 0;
      }
      else
      {
        reference = read[0];
        delta     = read[1] - reference;

        zones = top_table->zones;
        count = count_top;
        top   = 1;
      }

      /* insert into sorted table */
      zone = zones;
      for ( ; count > 0; count--, zone++ )
      {
        if ( reference < zone->org_ref )
          break;

        if ( reference == zone->org_ref )
        {
          FT_Int  delta0 = zone->org_delta;


          /* we have two zones on the same reference position -- */
          /* only keep the largest one                           */
          if ( delta < 0 )
          {
            if ( delta < delta0 )
              zone->org_delta = delta;
          }
          else
          {
            if ( delta > delta0 )
              zone->org_delta = delta;
          }
          goto Skip;
        }
      }

      for ( ; count > 0; count-- )
        zone[count] = zone[count-1];

      zone->org_ref   = reference;
      zone->org_delta = delta;

      if ( top )
        count_top++;
      else
        count_bot++;

    Skip:
      read += 2;
    }

    top_table->count = count_top;
    bot_table->count = count_bot;
  }


  /* Re-read blue zones from the original fonts and store them into our */
  /* private structure.  This function re-orders, sanitizes, and        */
  /* fuzz-expands the zones as well.                                    */
  static void
  psh_blues_set_zones( PSH_Blues  target,
                       FT_UInt    count,
                       FT_Short*  blues,
                       FT_UInt    count_others,
                       FT_Short*  other_blues,
                       FT_Int     fuzz,
                       FT_Int     family )
  {
    PSH_Blue_Table  top_table, bot_table;
    FT_UInt         count_top, count_bot;


    if ( family )
    {
      top_table = &target->family_top;
      bot_table = &target->family_bottom;
    }
    else
    {
      top_table = &target->normal_top;
      bot_table = &target->normal_bottom;
    }

    /* read the input blue zones, and build two sorted tables  */
    /* (one for the top zones, the other for the bottom zones) */
    top_table->count = 0;
    bot_table->count = 0;

    /* first, the blues */
    psh_blues_set_zones_0( target, 0,
                           count, blues, top_table, bot_table );
    psh_blues_set_zones_0( target, 1,
                           count_others, other_blues, top_table, bot_table );

    count_top = top_table->count;
    count_bot = bot_table->count;

    /* sanitize top table */
    if ( count_top > 0 )
    {
      PSH_Blue_Zone  zone = top_table->zones;


      for ( count = count_top; count > 0; count--, zone++ )
      {
        FT_Int  delta;


        if ( count > 1 )
        {
          delta = zone[1].org_ref - zone[0].org_ref;
          if ( zone->org_delta > delta )
            zone->org_delta = delta;
        }

        zone->org_bottom = zone->org_ref;
        zone->org_top    = zone->org_delta + zone->org_ref;
      }
    }

    /* sanitize bottom table */
    if ( count_bot > 0 )
    {
      PSH_Blue_Zone  zone = bot_table->zones;


      for ( count = count_bot; count > 0; count--, zone++ )
      {
        FT_Int  delta;


        if ( count > 1 )
        {
          delta = zone[0].org_ref - zone[1].org_ref;
          if ( zone->org_delta < delta )
            zone->org_delta = delta;
        }

        zone->org_top    = zone->org_ref;
        zone->org_bottom = zone->org_delta + zone->org_ref;
      }
    }

    /* expand top and bottom tables with blue fuzz */
    {
      FT_Int         dim, top, bot, delta;
      PSH_Blue_Zone  zone;


      zone  = top_table->zones;
      count = count_top;

      for ( dim = 1; dim >= 0; dim-- )
      {
        if ( count > 0 )
        {
          /* expand the bottom of the lowest zone normally */
          zone->org_bottom -= fuzz;

          /* expand the top and bottom of intermediate zones;    */
          /* checking that the interval is smaller than the fuzz */
          top = zone->org_top;

          for ( count--; count > 0; count-- )
          {
            bot   = zone[1].org_bottom;
            delta = bot - top;

            if ( delta / 2 < fuzz )
              zone[0].org_top = zone[1].org_bottom = top + delta / 2;
            else
            {
              zone[0].org_top    = top + fuzz;
              zone[1].org_bottom = bot - fuzz;
            }

            zone++;
            top = zone->org_top;
          }

          /* expand the top of the highest zone normally */
          zone->org_top = top + fuzz;
        }
        zone  = bot_table->zones;
        count = count_bot;
      }
    }
  }


  /* reset the blues table when the device transform changes */
  static void
  psh_blues_scale_zones( PSH_Blues  blues,
                         FT_Fixed   scale,
                         FT_Pos     delta )
  {
    FT_UInt         count;
    FT_UInt         num;
    PSH_Blue_Table  table = NULL;

    /*                                                        */
    /* Determine whether we need to suppress overshoots or    */
    /* not.  We simply need to compare the vertical scale     */
    /* parameter to the raw bluescale value.  Here is why:    */
    /*                                                        */
    /*   We need to suppress overshoots for all pointsizes.   */
    /*   At 300dpi that satisfies:                            */
    /*                                                        */
    /*      pointsize < 240*bluescale + 0.49                  */
    /*                                                        */
    /*   This corresponds to:                                 */
    /*                                                        */
    /*      pixelsize < 1000*bluescale + 49/24                */
    /*                                                        */
    /*      scale*EM_Size < 1000*bluescale + 49/24            */
    /*                                                        */
    /*   However, for normal Type 1 fonts, EM_Size is 1000!   */
    /*   We thus only check:                                  */
    /*                                                        */
    /*      scale < bluescale + 49/24000                      */
    /*                                                        */
    /*   which we shorten to                                  */
    /*                                                        */
    /*      "scale < bluescale"                               */
    /*                                                        */
    /* Note that `blue_scale' is stored 1000 times its real   */
    /* value, and that `scale' converts from font units to    */
    /* fractional pixels.                                     */
    /*                                                        */

    /* 1000 / 64 = 125 / 8 */
    if ( scale >= 0x20C49BAL )
      blues->no_overshoots = FT_BOOL( scale < blues->blue_scale * 8 / 125 );
    else
      blues->no_overshoots = FT_BOOL( scale * 125 < blues->blue_scale * 8 );

    /*                                                        */
    /*  The blue threshold is the font units distance under   */
    /*  which overshoots are suppressed due to the BlueShift  */
    /*  even if the scale is greater than BlueScale.          */
    /*                                                        */
    /*  It is the smallest distance such that                 */
    /*                                                        */
    /*    dist <= BlueShift && dist*scale <= 0.5 pixels       */
    /*                                                        */
    {
      FT_Int  threshold = blues->blue_shift;


      while ( threshold > 0 && FT_MulFix( threshold, scale ) > 32 )
        threshold--;

      blues->blue_threshold = threshold;
    }

    for ( num = 0; num < 4; num++ )
    {
      PSH_Blue_Zone  zone;


      switch ( num )
      {
      case 0:
        table = &blues->normal_top;
        break;
      case 1:
        table = &blues->normal_bottom;
        break;
      case 2:
        table = &blues->family_top;
        break;
      default:
        table = &blues->family_bottom;
        break;
      }

      zone  = table->zones;
      count = table->count;
      for ( ; count > 0; count--, zone++ )
      {
        zone->cur_top    = FT_MulFix( zone->org_top,    scale ) + delta;
        zone->cur_bottom = FT_MulFix( zone->org_bottom, scale ) + delta;
        zone->cur_ref    = FT_MulFix( zone->org_ref,    scale ) + delta;
        zone->cur_delta  = FT_MulFix( zone->org_delta,  scale );

        /* round scaled reference position */
        zone->cur_ref = FT_PIX_ROUND( zone->cur_ref );

#if 0
        if ( zone->cur_ref > zone->cur_top )
          zone->cur_ref -= 64;
        else if ( zone->cur_ref < zone->cur_bottom )
          zone->cur_ref += 64;
#endif
      }
    }

    /* process the families now */

    for ( num = 0; num < 2; num++ )
    {
      PSH_Blue_Zone   zone1, zone2;
      FT_UInt         count1, count2;
      PSH_Blue_Table  normal, family;


      switch ( num )
      {
      case 0:
        normal = &blues->normal_top;
        family = &blues->family_top;
        break;

      default:
        normal = &blues->normal_bottom;
        family = &blues->family_bottom;
      }

      zone1  = normal->zones;
      count1 = normal->count;

      for ( ; count1 > 0; count1--, zone1++ )
      {
        /* try to find a family zone whose reference position is less */
        /* than 1 pixel far from the current zone                     */
        zone2  = family->zones;
        count2 = family->count;

        for ( ; count2 > 0; count2--, zone2++ )
        {
          FT_Pos  Delta;


          Delta = zone1->org_ref - zone2->org_ref;
          if ( Delta < 0 )
            Delta = -Delta;

          if ( FT_MulFix( Delta, scale ) < 64 )
          {
            zone1->cur_top    = zone2->cur_top;
            zone1->cur_bottom = zone2->cur_bottom;
            zone1->cur_ref    = zone2->cur_ref;
            zone1->cur_delta  = zone2->cur_delta;
            break;
          }
        }
      }
    }
  }


  /* calculate the maximum height of given blue zones */
  static FT_Short
  psh_calc_max_height( FT_UInt          num,
                       const FT_Short*  values,
                       FT_Short         cur_max )
  {
    FT_UInt  count;


    for ( count = 0; count < num; count += 2 )
    {
      FT_Short  cur_height = values[count + 1] - values[count];


      if ( cur_height > cur_max )
        cur_max = cur_height;
    }

    return cur_max;
  }


  FT_LOCAL_DEF( void )
  psh_blues_snap_stem( PSH_Blues      blues,
                       FT_Int         stem_top,
                       FT_Int         stem_bot,
                       PSH_Alignment  alignment )
  {
    PSH_Blue_Table  table;
    FT_UInt         count;
    FT_Pos          delta;
    PSH_Blue_Zone   zone;
    FT_Int          no_shoots;


    alignment->align = PSH_BLUE_ALIGN_NONE;

    no_shoots = blues->no_overshoots;

    /* look up stem top in top zones table */
    table = &blues->normal_top;
    count = table->count;
    zone  = table->zones;

    for ( ; count > 0; count--, zone++ )
    {
      delta = SUB_LONG( stem_top, zone->org_bottom );
      if ( delta < -blues->blue_fuzz )
        break;

      if ( stem_top <= zone->org_top + blues->blue_fuzz )
      {
        if ( no_shoots || delta <= blues->blue_threshold )
        {
          alignment->align    |= PSH_BLUE_ALIGN_TOP;
          alignment->align_top = zone->cur_ref;
        }
        break;
      }
    }

    /* look up stem bottom in bottom zones table */
    table = &blues->normal_bottom;
    count = table->count;
    zone  = table->zones + count-1;

    for ( ; count > 0; count--, zone-- )
    {
      delta = SUB_LONG( zone->org_top, stem_bot );
      if ( delta < -blues->blue_fuzz )
        break;

      if ( stem_bot >= zone->org_bottom - blues->blue_fuzz )
      {
        if ( no_shoots || delta < blues->blue_threshold )
        {
          alignment->align    |= PSH_BLUE_ALIGN_BOT;
          alignment->align_bot = zone->cur_ref;
        }
        break;
      }
    }
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                        GLOBAL HINTS                           *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  static void
  psh_globals_destroy( PSH_Globals  globals )
  {
    if ( globals )
    {
      FT_Memory  memory;


      memory = globals->memory;
      globals->dimension[0].stdw.count = 0;
      globals->dimension[1].stdw.count = 0;

      globals->blues.normal_top.count    = 0;
      globals->blues.normal_bottom.count = 0;
      globals->blues.family_top.count    = 0;
      globals->blues.family_bottom.count = 0;

      FT_FREE( globals );

#ifdef DEBUG_HINTER
      ps_debug_globals = NULL;
#endif
    }
  }


  static FT_Error
  psh_globals_new( FT_Memory     memory,
                   T1_Private*   priv,
                   PSH_Globals  *aglobals )
  {
    PSH_Globals  globals;
    FT_Error     error;


    if ( !FT_QNEW( globals ) )
    {
      FT_UInt    count;
      FT_Short*  read;


      globals->memory = memory;

      /* copy standard widths */
      {
        PSH_Dimension  dim   = &globals->dimension[1];
        PSH_Width      write = dim->stdw.widths;


        write->org = priv->standard_width[0];
        write++;

        read = priv->snap_widths;
        for ( count = priv->num_snap_widths; count > 0; count-- )
        {
          write->org = *read;
          write++;
          read++;
        }

        dim->stdw.count = priv->num_snap_widths + 1;
      }

      /* copy standard heights */
      {
        PSH_Dimension  dim = &globals->dimension[0];
        PSH_Width      write = dim->stdw.widths;


        write->org = priv->standard_height[0];
        write++;
        read = priv->snap_heights;
        for ( count = priv->num_snap_heights; count > 0; count-- )
        {
          write->org = *read;
          write++;
          read++;
        }

        dim->stdw.count = priv->num_snap_heights + 1;
      }

      /* copy blue zones */
      psh_blues_set_zones( &globals->blues, priv->num_blue_values,
                           priv->blue_values, priv->num_other_blues,
                           priv->other_blues, priv->blue_fuzz, 0 );

      psh_blues_set_zones( &globals->blues, priv->num_family_blues,
                           priv->family_blues, priv->num_family_other_blues,
                           priv->family_other_blues, priv->blue_fuzz, 1 );

      /* limit the BlueScale value to `1 / max_of_blue_zone_heights' */
      {
        FT_Fixed  max_scale;
        FT_Short  max_height = 1;


        max_height = psh_calc_max_height( priv->num_blue_values,
                                          priv->blue_values,
                                          max_height );
        max_height = psh_calc_max_height( priv->num_other_blues,
                                          priv->other_blues,
                                          max_height );
        max_height = psh_calc_max_height( priv->num_family_blues,
                                          priv->family_blues,
                                          max_height );
        max_height = psh_calc_max_height( priv->num_family_other_blues,
                                          priv->family_other_blues,
                                          max_height );

        /* BlueScale is scaled 1000 times */
        max_scale = FT_DivFix( 1000, max_height );
        globals->blues.blue_scale = priv->blue_scale < max_scale
                                      ? priv->blue_scale
                                      : max_scale;
      }

      globals->blues.blue_shift = priv->blue_shift;
      globals->blues.blue_fuzz  = priv->blue_fuzz;

      globals->dimension[0].scale_mult  = 0;
      globals->dimension[0].scale_delta = 0;
      globals->dimension[1].scale_mult  = 0;
      globals->dimension[1].scale_delta = 0;

#ifdef DEBUG_HINTER
      ps_debug_globals = globals;
#endif
    }

    *aglobals = globals;
    return error;
  }


  FT_LOCAL_DEF( void )
  psh_globals_set_scale( PSH_Globals  globals,
                         FT_Fixed     x_scale,
                         FT_Fixed     y_scale,
                         FT_Fixed     x_delta,
                         FT_Fixed     y_delta )
  {
    PSH_Dimension  dim;


    dim = &globals->dimension[0];
    if ( x_scale != dim->scale_mult  ||
         x_delta != dim->scale_delta )
    {
      dim->scale_mult  = x_scale;
      dim->scale_delta = x_delta;

      psh_globals_scale_widths( globals, 0 );
    }

    dim = &globals->dimension[1];
    if ( y_scale != dim->scale_mult  ||
         y_delta != dim->scale_delta )
    {
      dim->scale_mult  = y_scale;
      dim->scale_delta = y_delta;

      psh_globals_scale_widths( globals, 1 );
      psh_blues_scale_zones( &globals->blues, y_scale, y_delta );
    }
  }


  FT_LOCAL_DEF( void )
  psh_globals_funcs_init( PSH_Globals_FuncsRec*  funcs )
  {
    funcs->create    = psh_globals_new;
    funcs->set_scale = psh_globals_set_scale;
    funcs->destroy   = psh_globals_destroy;
  }


/* END */