misc/libfreetype/src/pshinter/pshalgo.c
changeset 5172 88f2e05288ba
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/misc/libfreetype/src/pshinter/pshalgo.c	Mon Apr 25 01:46:54 2011 +0200
@@ -0,0 +1,2306 @@
+/***************************************************************************/
+/*                                                                         */
+/*  pshalgo.c                                                              */
+/*                                                                         */
+/*    PostScript hinting algorithm (body).                                 */
+/*                                                                         */
+/*  Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010   */
+/*            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 FT_INTERNAL_CALC_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_TRACE0(( "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_TRACE0(( "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_TRACE0(( "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_TRACE0(( "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_TRACE0(( "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 );
+            cur_org_center = hint->org_pos   + ( hint->org_len   >> 1 );
+
+            cur_delta = FT_MulFix( cur_org_center - par_org_center, scale );
+            pos       = par_cur_center + cur_delta - ( len >> 1 );
+          }
+
+          hint->cur_pos = pos;
+          hint->cur_len = fit_len;
+
+          /* Stem adjustment tries to snap stem widths to standard
+           * ones.  This is important to prevent unpleasant rounding
+           * artefacts.
+           */
+          if ( glyph->do_stem_adjust )
+          {
+            if ( len <= 64 )
+            {
+              /* the stem is less than one pixel; we will center it
+               * around the nearest pixel center
+               */
+              if ( len >= 32 )
+              {
+                /* This is a special case where we also widen the stem
+                 * and align it to the pixel grid.
+                 *
+                 *   stem_center          = pos + (len/2)
+                 *   nearest_pixel_center = FT_ROUND(stem_center-32)+32
+                 *   new_pos              = nearest_pixel_center-32
+                 *                        = FT_ROUND(stem_center-32)
+                 *                        = FT_FLOOR(stem_center-32+32)
+                 *                        = FT_FLOOR(stem_center)
+                 *   new_len              = 64
+                 */
+                pos = FT_PIX_FLOOR( pos + ( len >> 1 ) );
+                len = 64;
+              }
+              else if ( len > 0 )
+              {
+                /* This is a very small stem; we simply align it to the
+                 * pixel grid, trying to find the minimal displacement.
+                 *
+                 * left               = pos
+                 * right              = pos + len
+                 * left_nearest_edge  = ROUND(pos)
+                 * right_nearest_edge = ROUND(right)
+                 *
+                 * if ( ABS(left_nearest_edge - left) <=
+                 *      ABS(right_nearest_edge - right) )
+                 *    new_pos = left
+                 * else
+                 *    new_pos = right
+                 */
+                FT_Pos  left_nearest  = FT_PIX_ROUND( pos );
+                FT_Pos  right_nearest = FT_PIX_ROUND( pos + len );
+                FT_Pos  left_disp     = left_nearest - pos;
+                FT_Pos  right_disp    = right_nearest - ( pos + len );
+
+
+                if ( left_disp < 0 )
+                  left_disp = -left_disp;
+                if ( right_disp < 0 )
+                  right_disp = -right_disp;
+                if ( left_disp <= right_disp )
+                  pos = left_nearest;
+                else
+                  pos = right_nearest;
+              }
+              else
+              {
+                /* this is a ghost stem; we simply round it */
+                pos = FT_PIX_ROUND( pos );
+              }
+            }
+            else
+            {
+              len = psh_dimension_quantize_len( dim, len, 0 );
+            }
+          }
+
+          /* now that we have a good hinted stem width, try to position */
+          /* the stem along a pixel grid integer coordinate             */
+          hint->cur_pos = pos + psh_hint_snap_stem_side_delta( pos, len );
+          hint->cur_len = len;
+        }
+      }
+
+      if ( do_snapping )
+      {
+        pos = hint->cur_pos;
+        len = hint->cur_len;
+
+        if ( len < 64 )
+          len = 64;
+        else
+          len = FT_PIX_ROUND( len );
+
+        switch ( align.align )
+        {
+          case PSH_BLUE_ALIGN_TOP:
+            hint->cur_pos = align.align_top - len;
+            hint->cur_len = len;
+            break;
+
+          case PSH_BLUE_ALIGN_BOT:
+            hint->cur_len = len;
+            break;
+
+          case PSH_BLUE_ALIGN_BOT | PSH_BLUE_ALIGN_TOP:
+            /* don't touch */
+            break;
+
+
+          default:
+            hint->cur_len = len;
+            if ( len & 64 )
+              pos = FT_PIX_FLOOR( pos + ( len >> 1 ) ) + 32;
+            else
+              pos = FT_PIX_ROUND( pos + ( len >> 1 ) );
+
+            hint->cur_pos = pos - ( len >> 1 );
+            hint->cur_len = len;
+        }
+      }
+
+      psh_hint_set_fitted( hint );
+
+#ifdef DEBUG_HINTER
+      if ( ps_debug_hint_func )
+        ps_debug_hint_func( hint, dimension );
+#endif
+    }
+  }
+
+
+#if 0  /* not used for now, experimental */
+
+ /*
+  *  A variant to perform "light" hinting (i.e. FT_RENDER_MODE_LIGHT)
+  *  of stems
+  */
+  static void
+  psh_hint_align_light( 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_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;
+      }
+
+      fit_len = len;
+
+      hint->cur_len = fit_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_light( parent, globals, dimension, glyph );
+
+            par_org_center = parent->org_pos + ( parent->org_len / 2 );
+            par_cur_center = parent->cur_pos + ( parent->cur_len / 2 );
+            cur_org_center = hint->org_pos   + ( hint->org_len   / 2 );
+
+            cur_delta = FT_MulFix( cur_org_center - par_org_center, scale );
+            pos       = par_cur_center + cur_delta - ( len >> 1 );
+          }
+
+          /* Stems less than one pixel wide are easy -- we want to
+           * make them as dark as possible, so they must fall within
+           * one pixel.  If the stem is split between two pixels
+           * then snap the edge that is nearer to the pixel boundary
+           * to the pixel boundary.
+           */
+          if ( len <= 64 )
+          {
+            if ( ( pos + len + 63 ) / 64  != pos / 64 + 1 )
+              pos += psh_hint_snap_stem_side_delta ( pos, len );
+          }
+
+          /* Position stems other to minimize the amount of mid-grays.
+           * There are, in general, two positions that do this,
+           * illustrated as A) and B) below.
+           *
+           *   +                   +                   +                   +
+           *
+           * A)             |--------------------------------|
+           * B)   |--------------------------------|
+           * C)       |--------------------------------|
+           *
+           * Position A) (split the excess stem equally) should be better
+           * for stems of width N + f where f < 0.5.
+           *
+           * Position B) (split the deficiency equally) should be better
+           * for stems of width N + f where f > 0.5.
+           *
+           * It turns out though that minimizing the total number of lit
+           * pixels is also important, so position C), with one edge
+           * aligned with a pixel boundary is actually preferable
+           * to A).  There are also more possibile positions for C) than
+           * for A) or B), so it involves less distortion of the overall
+           * character shape.
+           */
+          else /* len > 64 */
+          {
+            FT_Fixed  frac_len = len & 63;
+            FT_Fixed  center = pos + ( len >> 1 );
+            FT_Fixed  delta_a, delta_b;
+
+
+            if ( ( len / 64 ) & 1 )
+            {
+              delta_a = FT_PIX_FLOOR( center ) + 32 - center;
+              delta_b = FT_PIX_ROUND( center ) - center;
+            }
+            else
+            {
+              delta_a = FT_PIX_ROUND( center ) - center;
+              delta_b = FT_PIX_FLOOR( center ) + 32 - center;
+            }
+
+            /* We choose between B) and C) above based on the amount
+             * of fractinal stem width; for small amounts, choose
+             * C) always, for large amounts, B) always, and inbetween,
+             * pick whichever one involves less stem movement.
+             */
+            if ( frac_len < 32 )
+            {
+              pos += psh_hint_snap_stem_side_delta ( pos, len );
+            }
+            else if ( frac_len < 48 )
+            {
+              FT_Fixed  side_delta = psh_hint_snap_stem_side_delta ( pos,
+                                                                     len );
+
+              if ( FT_ABS( side_delta ) < FT_ABS( delta_b ) )
+                pos += side_delta;
+              else
+                pos += delta_b;
+            }
+            else
+            {
+              pos += delta_b;
+            }
+          }
+
+          hint->cur_pos = pos;
+        }
+      }  /* switch */
+
+      psh_hint_set_fitted( hint );
+
+#ifdef DEBUG_HINTER
+      if ( ps_debug_hint_func )
+        ps_debug_hint_func( hint, dimension );
+#endif
+    }
+  }
+
+#endif /* 0 */
+
+
+  static void
+  psh_hint_table_align_hints( PSH_Hint_Table  table,
+                              PSH_Globals     globals,
+                              FT_Int          dimension,
+                              PSH_Glyph       glyph )
+  {
+    PSH_Hint       hint;
+    FT_UInt        count;
+
+#ifdef DEBUG_HINTER
+
+    PSH_Dimension  dim   = &globals->dimension[dimension];
+    FT_Fixed       scale = dim->scale_mult;
+    FT_Fixed       delta = dim->scale_delta;
+
+
+    if ( ps_debug_no_vert_hints && dimension == 0 )
+    {
+      ps_simple_scale( table, scale, delta, dimension );
+      return;
+    }
+
+    if ( ps_debug_no_horz_hints && dimension == 1 )
+    {
+      ps_simple_scale( table, scale, delta, dimension );
+      return;
+    }
+
+#endif /* DEBUG_HINTER*/
+
+    hint  = table->hints;
+    count = table->max_hints;
+
+    for ( ; count > 0; count--, hint++ )
+      psh_hint_align( hint, globals, dimension, glyph );
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                POINTS INTERPOLATION ROUTINES                  *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+#define PSH_ZONE_MIN  -3200000L
+#define PSH_ZONE_MAX  +3200000L
+
+#define xxDEBUG_ZONES
+
+
+#ifdef DEBUG_ZONES
+
+#include FT_CONFIG_STANDARD_LIBRARY_H
+
+  static void
+  psh_print_zone( PSH_Zone  zone )
+  {
+    printf( "zone [scale,delta,min,max] = [%.3f,%.3f,%d,%d]\n",
+             zone->scale / 65536.0,
+             zone->delta / 64.0,
+             zone->min,
+             zone->max );
+  }
+
+#else
+
+#define psh_print_zone( x )  do { } while ( 0 )
+
+#endif /* DEBUG_ZONES */
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                    HINTER GLYPH MANAGEMENT                    *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+#if 1
+
+#define  psh_corner_is_flat      ft_corner_is_flat
+#define  psh_corner_orientation  ft_corner_orientation
+
+#else
+
+  FT_LOCAL_DEF( FT_Int )
+  psh_corner_is_flat( FT_Pos  x_in,
+                      FT_Pos  y_in,
+                      FT_Pos  x_out,
+                      FT_Pos  y_out )
+  {
+    FT_Pos  ax = x_in;
+    FT_Pos  ay = y_in;
+
+    FT_Pos  d_in, d_out, d_corner;
+
+
+    if ( ax < 0 )
+      ax = -ax;
+    if ( ay < 0 )
+      ay = -ay;
+    d_in = ax + ay;
+
+    ax = x_out;
+    if ( ax < 0 )
+      ax = -ax;
+    ay = y_out;
+    if ( ay < 0 )
+      ay = -ay;
+    d_out = ax + ay;
+
+    ax = x_out + x_in;
+    if ( ax < 0 )
+      ax = -ax;
+    ay = y_out + y_in;
+    if ( ay < 0 )
+      ay = -ay;
+    d_corner = ax + ay;
+
+    return ( d_in + d_out - d_corner ) < ( d_corner >> 4 );
+  }
+
+  static FT_Int
+  psh_corner_orientation( FT_Pos  in_x,
+                          FT_Pos  in_y,
+                          FT_Pos  out_x,
+                          FT_Pos  out_y )
+  {
+    FT_Int  result;
+
+
+    /* deal with the trivial cases quickly */
+    if ( in_y == 0 )
+    {
+      if ( in_x >= 0 )
+        result = out_y;
+      else
+        result = -out_y;
+    }
+    else if ( in_x == 0 )
+    {
+      if ( in_y >= 0 )
+        result = -out_x;
+      else
+        result = out_x;
+    }
+    else if ( out_y == 0 )
+    {
+      if ( out_x >= 0 )
+        result = in_y;
+      else
+        result = -in_y;
+    }
+    else if ( out_x == 0 )
+    {
+      if ( out_y >= 0 )
+        result = -in_x;
+      else
+        result =  in_x;
+    }
+    else /* general case */
+    {
+      long long  delta = (long long)in_x * out_y - (long long)in_y * out_x;
+
+      if ( delta == 0 )
+        result = 0;
+      else
+        result = 1 - 2 * ( delta < 0 );
+    }
+
+    return result;
+  }
+
+#endif /* !1 */
+
+
+#ifdef COMPUTE_INFLEXS
+
+  /* compute all inflex points in a given glyph */
+  static void
+  psh_glyph_compute_inflections( PSH_Glyph  glyph )
+  {
+    FT_UInt  n;
+
+
+    for ( n = 0; n < glyph->num_contours; n++ )
+    {
+      PSH_Point  first, start, end, before, after;
+      FT_Pos     in_x, in_y, out_x, out_y;
+      FT_Int     orient_prev, orient_cur;
+      FT_Int     finished = 0;
+
+
+      /* we need at least 4 points to create an inflection point */
+      if ( glyph->contours[n].count < 4 )
+        continue;
+
+      /* compute first segment in contour */
+      first = glyph->contours[n].start;
+
+      start = end = first;
+      do
+      {
+        end = end->next;
+        if ( end == first )
+          goto Skip;
+
+        in_x = end->org_u - start->org_u;
+        in_y = end->org_v - start->org_v;
+
+      } while ( in_x == 0 && in_y == 0 );
+
+      /* extend the segment start whenever possible */
+      before = start;
+      do
+      {
+        do
+        {
+          start  = before;
+          before = before->prev;
+          if ( before == first )
+            goto Skip;
+
+          out_x = start->org_u - before->org_u;
+          out_y = start->org_v - before->org_v;
+
+        } while ( out_x == 0 && out_y == 0 );
+
+        orient_prev = psh_corner_orientation( in_x, in_y, out_x, out_y );
+
+      } while ( orient_prev == 0 );
+
+      first = start;
+      in_x  = out_x;
+      in_y  = out_y;
+
+      /* now, process all segments in the contour */
+      do
+      {
+        /* first, extend current segment's end whenever possible */
+        after = end;
+        do
+        {
+          do
+          {
+            end   = after;
+            after = after->next;
+            if ( after == first )
+              finished = 1;
+
+            out_x = after->org_u - end->org_u;
+            out_y = after->org_v - end->org_v;
+
+          } while ( out_x == 0 && out_y == 0 );
+
+          orient_cur = psh_corner_orientation( in_x, in_y, out_x, out_y );
+
+        } while ( orient_cur == 0 );
+
+        if ( ( orient_cur ^ orient_prev ) < 0 )
+        {
+          do
+          {
+            psh_point_set_inflex( start );
+            start = start->next;
+          }
+          while ( start != end );
+
+          psh_point_set_inflex( start );
+        }
+
+        start       = end;
+        end         = after;
+        orient_prev = orient_cur;
+        in_x        = out_x;
+        in_y        = out_y;
+
+      } while ( !finished );
+
+    Skip:
+      ;
+    }
+  }
+
+#endif /* COMPUTE_INFLEXS */
+
+
+  static void
+  psh_glyph_done( PSH_Glyph  glyph )
+  {
+    FT_Memory  memory = glyph->memory;
+
+
+    psh_hint_table_done( &glyph->hint_tables[1], memory );
+    psh_hint_table_done( &glyph->hint_tables[0], memory );
+
+    FT_FREE( glyph->points );
+    FT_FREE( glyph->contours );
+
+    glyph->num_points   = 0;
+    glyph->num_contours = 0;
+
+    glyph->memory = 0;
+  }
+
+
+  static int
+  psh_compute_dir( FT_Pos  dx,
+                   FT_Pos  dy )
+  {
+    FT_Pos  ax, ay;
+    int     result = PSH_DIR_NONE;
+
+
+    ax = ( dx >= 0 ) ? dx : -dx;
+    ay = ( dy >= 0 ) ? dy : -dy;
+
+    if ( ay * 12 < ax )
+    {
+      /* |dy| <<< |dx|  means a near-horizontal segment */
+      result = ( dx >= 0 ) ? PSH_DIR_RIGHT : PSH_DIR_LEFT;
+    }
+    else if ( ax * 12 < ay )
+    {
+      /* |dx| <<< |dy|  means a near-vertical segment */
+      result = ( dy >= 0 ) ? PSH_DIR_UP : PSH_DIR_DOWN;
+    }
+
+    return result;
+  }
+
+
+  /* load outline point coordinates into hinter glyph */
+  static void
+  psh_glyph_load_points( PSH_Glyph  glyph,
+                         FT_Int     dimension )
+  {
+    FT_Vector*  vec   = glyph->outline->points;
+    PSH_Point   point = glyph->points;
+    FT_UInt     count = glyph->num_points;
+
+
+    for ( ; count > 0; count--, point++, vec++ )
+    {
+      point->flags2 = 0;
+      point->hint   = NULL;
+      if ( dimension == 0 )
+      {
+        point->org_u = vec->x;
+        point->org_v = vec->y;
+      }
+      else
+      {
+        point->org_u = vec->y;
+        point->org_v = vec->x;
+      }
+
+#ifdef DEBUG_HINTER
+      point->org_x = vec->x;
+      point->org_y = vec->y;
+#endif
+
+    }
+  }
+
+
+  /* save hinted point coordinates back to outline */
+  static void
+  psh_glyph_save_points( PSH_Glyph  glyph,
+                         FT_Int     dimension )
+  {
+    FT_UInt     n;
+    PSH_Point   point = glyph->points;
+    FT_Vector*  vec   = glyph->outline->points;
+    char*       tags  = glyph->outline->tags;
+
+
+    for ( n = 0; n < glyph->num_points; n++ )
+    {
+      if ( dimension == 0 )
+        vec[n].x = point->cur_u;
+      else
+        vec[n].y = point->cur_u;
+
+      if ( psh_point_is_strong( point ) )
+        tags[n] |= (char)( ( dimension == 0 ) ? 32 : 64 );
+
+#ifdef DEBUG_HINTER
+
+      if ( dimension == 0 )
+      {
+        point->cur_x   = point->cur_u;
+        point->flags_x = point->flags2 | point->flags;
+      }
+      else
+      {
+        point->cur_y   = point->cur_u;
+        point->flags_y = point->flags2 | point->flags;
+      }
+
+#endif
+
+      point++;
+    }
+  }
+
+
+  static FT_Error
+  psh_glyph_init( PSH_Glyph    glyph,
+                  FT_Outline*  outline,
+                  PS_Hints     ps_hints,
+                  PSH_Globals  globals )
+  {
+    FT_Error   error;
+    FT_Memory  memory;
+
+
+    /* clear all fields */
+    FT_MEM_ZERO( glyph, sizeof ( *glyph ) );
+
+    memory = glyph->memory = globals->memory;
+
+    /* allocate and setup points + contours arrays */
+    if ( FT_NEW_ARRAY( glyph->points,   outline->n_points   ) ||
+         FT_NEW_ARRAY( glyph->contours, outline->n_contours ) )
+      goto Exit;
+
+    glyph->num_points   = outline->n_points;
+    glyph->num_contours = outline->n_contours;
+
+    {
+      FT_UInt      first = 0, next, n;
+      PSH_Point    points  = glyph->points;
+      PSH_Contour  contour = glyph->contours;
+
+
+      for ( n = 0; n < glyph->num_contours; n++ )
+      {
+        FT_Int     count;
+        PSH_Point  point;
+
+
+        next  = outline->contours[n] + 1;
+        count = next - first;
+
+        contour->start = points + first;
+        contour->count = (FT_UInt)count;
+
+        if ( count > 0 )
+        {
+          point = points + first;
+
+          point->prev    = points + next - 1;
+          point->contour = contour;
+
+          for ( ; count > 1; count-- )
+          {
+            point[0].next = point + 1;
+            point[1].prev = point;
+            point++;
+            point->contour = contour;
+          }
+          point->next = points + first;
+        }
+
+        contour++;
+        first = next;
+      }
+    }
+
+    {
+      PSH_Point   points = glyph->points;
+      PSH_Point   point  = points;
+      FT_Vector*  vec    = outline->points;
+      FT_UInt     n;
+
+
+      for ( n = 0; n < glyph->num_points; n++, point++ )
+      {
+        FT_Int  n_prev = (FT_Int)( point->prev - points );
+        FT_Int  n_next = (FT_Int)( point->next - points );
+        FT_Pos  dxi, dyi, dxo, dyo;
+
+
+        if ( !( outline->tags[n] & FT_CURVE_TAG_ON ) )
+          point->flags = PSH_POINT_OFF;
+
+        dxi = vec[n].x - vec[n_prev].x;
+        dyi = vec[n].y - vec[n_prev].y;
+
+        point->dir_in = (FT_Char)psh_compute_dir( dxi, dyi );
+
+        dxo = vec[n_next].x - vec[n].x;
+        dyo = vec[n_next].y - vec[n].y;
+
+        point->dir_out = (FT_Char)psh_compute_dir( dxo, dyo );
+
+        /* detect smooth points */
+        if ( point->flags & PSH_POINT_OFF )
+          point->flags |= PSH_POINT_SMOOTH;
+
+        else if ( point->dir_in == point->dir_out )
+        {
+          if ( point->dir_out != PSH_DIR_NONE           ||
+               psh_corner_is_flat( dxi, dyi, dxo, dyo ) )
+            point->flags |= PSH_POINT_SMOOTH;
+        }
+      }
+    }
+
+    glyph->outline = outline;
+    glyph->globals = globals;
+
+#ifdef COMPUTE_INFLEXS
+    psh_glyph_load_points( glyph, 0 );
+    psh_glyph_compute_inflections( glyph );
+#endif /* COMPUTE_INFLEXS */
+
+    /* now deal with hints tables */
+    error = psh_hint_table_init( &glyph->hint_tables [0],
+                                 &ps_hints->dimension[0].hints,
+                                 &ps_hints->dimension[0].masks,
+                                 &ps_hints->dimension[0].counters,
+                                 memory );
+    if ( error )
+      goto Exit;
+
+    error = psh_hint_table_init( &glyph->hint_tables [1],
+                                 &ps_hints->dimension[1].hints,
+                                 &ps_hints->dimension[1].masks,
+                                 &ps_hints->dimension[1].counters,
+                                 memory );
+    if ( error )
+      goto Exit;
+
+  Exit:
+    return error;
+  }
+
+
+  /* compute all extrema in a glyph for a given dimension */
+  static void
+  psh_glyph_compute_extrema( PSH_Glyph  glyph )
+  {
+    FT_UInt  n;
+
+
+    /* first of all, compute all local extrema */
+    for ( n = 0; n < glyph->num_contours; n++ )
+    {
+      PSH_Point  first = glyph->contours[n].start;
+      PSH_Point  point, before, after;
+
+
+      if ( glyph->contours[n].count == 0 )
+        continue;
+
+      point  = first;
+      before = point;
+      after  = point;
+
+      do
+      {
+        before = before->prev;
+        if ( before == first )
+          goto Skip;
+
+      } while ( before->org_u == point->org_u );
+
+      first = point = before->next;
+
+      for (;;)
+      {
+        after = point;
+        do
+        {
+          after = after->next;
+          if ( after == first )
+            goto Next;
+
+        } while ( after->org_u == point->org_u );
+
+        if ( before->org_u < point->org_u )
+        {
+          if ( after->org_u < point->org_u )
+          {
+            /* local maximum */
+            goto Extremum;
+          }
+        }
+        else /* before->org_u > point->org_u */
+        {
+          if ( after->org_u > point->org_u )
+          {
+            /* local minimum */
+          Extremum:
+            do
+            {
+              psh_point_set_extremum( point );
+              point = point->next;
+
+            } while ( point != after );
+          }
+        }
+
+        before = after->prev;
+        point  = after;
+
+      } /* for  */
+
+    Next:
+      ;
+    }
+
+    /* for each extremum, determine its direction along the */
+    /* orthogonal axis                                      */
+    for ( n = 0; n < glyph->num_points; n++ )
+    {
+      PSH_Point  point, before, after;
+
+
+      point  = &glyph->points[n];
+      before = point;
+      after  = point;
+
+      if ( psh_point_is_extremum( point ) )
+      {
+        do
+        {
+          before = before->prev;
+          if ( before == point )
+            goto Skip;
+
+        } while ( before->org_v == point->org_v );
+
+        do
+        {
+          after = after->next;
+          if ( after == point )
+            goto Skip;
+
+        } while ( after->org_v == point->org_v );
+      }
+
+      if ( before->org_v < point->org_v &&
+           after->org_v  > point->org_v )
+      {
+        psh_point_set_positive( point );
+      }
+      else if ( before->org_v > point->org_v &&
+                after->org_v  < point->org_v )
+      {
+        psh_point_set_negative( point );
+      }
+
+    Skip:
+      ;
+    }
+  }
+
+
+  /* major_dir is the direction for points on the bottom/left of the stem; */
+  /* Points on the top/right of the stem will have a direction of          */
+  /* -major_dir.                                                           */
+
+  static void
+  psh_hint_table_find_strong_points( PSH_Hint_Table  table,
+                                     PSH_Point       point,
+                                     FT_UInt         count,
+                                     FT_Int          threshold,
+                                     FT_Int          major_dir )
+  {
+    PSH_Hint*  sort      = table->sort;
+    FT_UInt    num_hints = table->num_hints;
+
+
+    for ( ; count > 0; count--, point++ )
+    {
+      FT_Int  point_dir = 0;
+      FT_Pos  org_u     = point->org_u;
+
+
+      if ( psh_point_is_strong( point ) )
+        continue;
+
+      if ( PSH_DIR_COMPARE( point->dir_in, major_dir ) )
+        point_dir = point->dir_in;
+
+      else if ( PSH_DIR_COMPARE( point->dir_out, major_dir ) )
+        point_dir = point->dir_out;
+
+      if ( point_dir )
+      {
+        if ( point_dir == major_dir )
+        {
+          FT_UInt  nn;
+
+
+          for ( nn = 0; nn < num_hints; nn++ )
+          {
+            PSH_Hint  hint = sort[nn];
+            FT_Pos    d    = org_u - hint->org_pos;
+
+
+            if ( d < threshold && -d < threshold )
+            {
+              psh_point_set_strong( point );
+              point->flags2 |= PSH_POINT_EDGE_MIN;
+              point->hint    = hint;
+              break;
+            }
+          }
+        }
+        else if ( point_dir == -major_dir )
+        {
+          FT_UInt  nn;
+
+
+          for ( nn = 0; nn < num_hints; nn++ )
+          {
+            PSH_Hint  hint = sort[nn];
+            FT_Pos    d    = org_u - hint->org_pos - hint->org_len;
+
+
+            if ( d < threshold && -d < threshold )
+            {
+              psh_point_set_strong( point );
+              point->flags2 |= PSH_POINT_EDGE_MAX;
+              point->hint    = hint;
+              break;
+            }
+          }
+        }
+      }
+
+#if 1
+      else if ( psh_point_is_extremum( point ) )
+      {
+        /* treat extrema as special cases for stem edge alignment */
+        FT_UInt  nn, min_flag, max_flag;
+
+
+        if ( major_dir == PSH_DIR_HORIZONTAL )
+        {
+          min_flag = PSH_POINT_POSITIVE;
+          max_flag = PSH_POINT_NEGATIVE;
+        }
+        else
+        {
+          min_flag = PSH_POINT_NEGATIVE;
+          max_flag = PSH_POINT_POSITIVE;
+        }
+
+        if ( point->flags2 & min_flag )
+        {
+          for ( nn = 0; nn < num_hints; nn++ )
+          {
+            PSH_Hint  hint = sort[nn];
+            FT_Pos    d    = org_u - hint->org_pos;
+
+
+            if ( d < threshold && -d < threshold )
+            {
+              point->flags2 |= PSH_POINT_EDGE_MIN;
+              point->hint    = hint;
+              psh_point_set_strong( point );
+              break;
+            }
+          }
+        }
+        else if ( point->flags2 & max_flag )
+        {
+          for ( nn = 0; nn < num_hints; nn++ )
+          {
+            PSH_Hint  hint = sort[nn];
+            FT_Pos    d    = org_u - hint->org_pos - hint->org_len;
+
+
+            if ( d < threshold && -d < threshold )
+            {
+              point->flags2 |= PSH_POINT_EDGE_MAX;
+              point->hint    = hint;
+              psh_point_set_strong( point );
+              break;
+            }
+          }
+        }
+
+        if ( point->hint == NULL )
+        {
+          for ( nn = 0; nn < num_hints; nn++ )
+          {
+            PSH_Hint  hint = sort[nn];
+
+
+            if ( org_u >= hint->org_pos                 &&
+                org_u <= hint->org_pos + hint->org_len )
+            {
+              point->hint = hint;
+              break;
+            }
+          }
+        }
+      }
+
+#endif /* 1 */
+    }
+  }
+
+
+  /* the accepted shift for strong points in fractional pixels */
+#define PSH_STRONG_THRESHOLD  32
+
+  /* the maximum shift value in font units */
+#define PSH_STRONG_THRESHOLD_MAXIMUM  30
+
+
+  /* find strong points in a glyph */
+  static void
+  psh_glyph_find_strong_points( PSH_Glyph  glyph,
+                                FT_Int     dimension )
+  {
+    /* a point is `strong' if it is located on a stem edge and       */
+    /* has an `in' or `out' tangent parallel to the hint's direction */
+
+    PSH_Hint_Table  table     = &glyph->hint_tables[dimension];
+    PS_Mask         mask      = table->hint_masks->masks;
+    FT_UInt         num_masks = table->hint_masks->num_masks;
+    FT_UInt         first     = 0;
+    FT_Int          major_dir = dimension == 0 ? PSH_DIR_VERTICAL
+                                               : PSH_DIR_HORIZONTAL;
+    PSH_Dimension   dim       = &glyph->globals->dimension[dimension];
+    FT_Fixed        scale     = dim->scale_mult;
+    FT_Int          threshold;
+
+
+    threshold = (FT_Int)FT_DivFix( PSH_STRONG_THRESHOLD, scale );
+    if ( threshold > PSH_STRONG_THRESHOLD_MAXIMUM )
+      threshold = PSH_STRONG_THRESHOLD_MAXIMUM;
+
+    /* process secondary hints to `selected' points */
+    if ( num_masks > 1 && glyph->num_points > 0 )
+    {
+      /* the `endchar' op can reduce the number of points */
+      first = mask->end_point > glyph->num_points
+                ? glyph->num_points
+                : mask->end_point;
+      mask++;
+      for ( ; num_masks > 1; num_masks--, mask++ )
+      {
+        FT_UInt  next;
+        FT_Int   count;
+
+
+        next  = mask->end_point > glyph->num_points
+                  ? glyph->num_points
+                  : mask->end_point;
+        count = next - first;
+        if ( count > 0 )
+        {
+          PSH_Point  point = glyph->points + first;
+
+
+          psh_hint_table_activate_mask( table, mask );
+
+          psh_hint_table_find_strong_points( table, point, count,
+                                             threshold, major_dir );
+        }
+        first = next;
+      }
+    }
+
+    /* process primary hints for all points */
+    if ( num_masks == 1 )
+    {
+      FT_UInt    count = glyph->num_points;
+      PSH_Point  point = glyph->points;
+
+
+      psh_hint_table_activate_mask( table, table->hint_masks->masks );
+
+      psh_hint_table_find_strong_points( table, point, count,
+                                         threshold, major_dir );
+    }
+
+    /* now, certain points may have been attached to a hint and */
+    /* not marked as strong; update their flags then            */
+    {
+      FT_UInt    count = glyph->num_points;
+      PSH_Point  point = glyph->points;
+
+
+      for ( ; count > 0; count--, point++ )
+        if ( point->hint && !psh_point_is_strong( point ) )
+          psh_point_set_strong( point );
+    }
+  }
+
+
+  /* find points in a glyph which are in a blue zone and have `in' or */
+  /* `out' tangents parallel to the horizontal axis                   */
+  static void
+  psh_glyph_find_blue_points( PSH_Blues  blues,
+                              PSH_Glyph  glyph )
+  {
+    PSH_Blue_Table  table;
+    PSH_Blue_Zone   zone;
+    FT_UInt         glyph_count = glyph->num_points;
+    FT_UInt         blue_count;
+    PSH_Point       point = glyph->points;
+
+
+    for ( ; glyph_count > 0; glyph_count--, point++ )
+    {
+      FT_Pos  y;
+
+
+      /* check tangents */
+      if ( !PSH_DIR_COMPARE( point->dir_in,  PSH_DIR_HORIZONTAL ) &&
+           !PSH_DIR_COMPARE( point->dir_out, PSH_DIR_HORIZONTAL ) )
+        continue;
+
+      /* skip strong points */
+      if ( psh_point_is_strong( point ) )
+        continue;
+
+      y = point->org_u;
+
+      /* look up top zones */
+      table      = &blues->normal_top;
+      blue_count = table->count;
+      zone       = table->zones;
+
+      for ( ; blue_count > 0; blue_count--, zone++ )
+      {
+        FT_Pos  delta = y - zone->org_bottom;
+
+
+        if ( delta < -blues->blue_fuzz )
+          break;
+
+        if ( y <= zone->org_top + blues->blue_fuzz )
+          if ( blues->no_overshoots || delta <= blues->blue_threshold )
+          {
+            point->cur_u = zone->cur_bottom;
+            psh_point_set_strong( point );
+            psh_point_set_fitted( point );
+          }
+      }
+
+      /* look up bottom zones */
+      table      = &blues->normal_bottom;
+      blue_count = table->count;
+      zone       = table->zones + blue_count - 1;
+
+      for ( ; blue_count > 0; blue_count--, zone-- )
+      {
+        FT_Pos  delta = zone->org_top - y;
+
+
+        if ( delta < -blues->blue_fuzz )
+          break;
+
+        if ( y >= zone->org_bottom - blues->blue_fuzz )
+          if ( blues->no_overshoots || delta < blues->blue_threshold )
+          {
+            point->cur_u = zone->cur_top;
+            psh_point_set_strong( point );
+            psh_point_set_fitted( point );
+          }
+      }
+    }
+  }
+
+
+  /* interpolate strong points with the help of hinted coordinates */
+  static void
+  psh_glyph_interpolate_strong_points( PSH_Glyph  glyph,
+                                       FT_Int     dimension )
+  {
+    PSH_Dimension  dim   = &glyph->globals->dimension[dimension];
+    FT_Fixed       scale = dim->scale_mult;
+
+    FT_UInt        count = glyph->num_points;
+    PSH_Point      point = glyph->points;
+
+
+    for ( ; count > 0; count--, point++ )
+    {
+      PSH_Hint  hint = point->hint;
+
+
+      if ( hint )
+      {
+        FT_Pos  delta;
+
+
+        if ( psh_point_is_edge_min( point ) )
+          point->cur_u = hint->cur_pos;
+
+        else if ( psh_point_is_edge_max( point ) )
+          point->cur_u = hint->cur_pos + hint->cur_len;
+
+        else
+        {
+          delta = point->org_u - hint->org_pos;
+
+          if ( delta <= 0 )
+            point->cur_u = hint->cur_pos + FT_MulFix( delta, scale );
+
+          else if ( delta >= hint->org_len )
+            point->cur_u = hint->cur_pos + hint->cur_len +
+                             FT_MulFix( delta - hint->org_len, scale );
+
+          else /* hint->org_len > 0 */
+            point->cur_u = hint->cur_pos +
+                             FT_MulDiv( delta, hint->cur_len,
+                                        hint->org_len );
+        }
+        psh_point_set_fitted( point );
+      }
+    }
+  }
+
+
+#define  PSH_MAX_STRONG_INTERNAL  16
+
+  static void
+  psh_glyph_interpolate_normal_points( PSH_Glyph  glyph,
+                                       FT_Int     dimension )
+  {
+
+#if 1
+    /* first technique: a point is strong if it is a local extremum */
+
+    PSH_Dimension  dim    = &glyph->globals->dimension[dimension];
+    FT_Fixed       scale  = dim->scale_mult;
+    FT_Memory      memory = glyph->memory;
+
+    PSH_Point*     strongs     = NULL;
+    PSH_Point      strongs_0[PSH_MAX_STRONG_INTERNAL];
+    FT_UInt        num_strongs = 0;
+
+    PSH_Point      points = glyph->points;
+    PSH_Point      points_end = points + glyph->num_points;
+    PSH_Point      point;
+
+
+    /* first count the number of strong points */
+    for ( point = points; point < points_end; point++ )
+    {
+      if ( psh_point_is_strong( point ) )
+        num_strongs++;
+    }
+
+    if ( num_strongs == 0 )  /* nothing to do here */
+      return;
+
+    /* allocate an array to store a list of points, */
+    /* stored in increasing org_u order             */
+    if ( num_strongs <= PSH_MAX_STRONG_INTERNAL )
+      strongs = strongs_0;
+    else
+    {
+      FT_Error  error;
+
+
+      if ( FT_NEW_ARRAY( strongs, num_strongs ) )
+        return;
+    }
+
+    num_strongs = 0;
+    for ( point = points; point < points_end; point++ )
+    {
+      PSH_Point*  insert;
+
+
+      if ( !psh_point_is_strong( point ) )
+        continue;
+
+      for ( insert = strongs + num_strongs; insert > strongs; insert-- )
+      {
+        if ( insert[-1]->org_u <= point->org_u )
+          break;
+
+        insert[0] = insert[-1];
+      }
+      insert[0] = point;
+      num_strongs++;
+    }
+
+    /* now try to interpolate all normal points */
+    for ( point = points; point < points_end; point++ )
+    {
+      if ( psh_point_is_strong( point ) )
+        continue;
+
+      /* sometimes, some local extrema are smooth points */
+      if ( psh_point_is_smooth( point ) )
+      {
+        if ( point->dir_in == PSH_DIR_NONE   ||
+             point->dir_in != point->dir_out )
+          continue;
+
+        if ( !psh_point_is_extremum( point ) &&
+             !psh_point_is_inflex( point )   )
+          continue;
+
+        point->flags &= ~PSH_POINT_SMOOTH;
+      }
+
+      /* find best enclosing point coordinates then interpolate */
+      {
+        PSH_Point   before, after;
+        FT_UInt     nn;
+
+
+        for ( nn = 0; nn < num_strongs; nn++ )
+          if ( strongs[nn]->org_u > point->org_u )
+            break;
+
+        if ( nn == 0 )  /* point before the first strong point */
+        {
+          after = strongs[0];
+
+          point->cur_u = after->cur_u +
+                           FT_MulFix( point->org_u - after->org_u,
+                                      scale );
+        }
+        else
+        {
+          before = strongs[nn - 1];
+
+          for ( nn = num_strongs; nn > 0; nn-- )
+            if ( strongs[nn - 1]->org_u < point->org_u )
+              break;
+
+          if ( nn == num_strongs )  /* point is after last strong point */
+          {
+            before = strongs[nn - 1];
+
+            point->cur_u = before->cur_u +
+                             FT_MulFix( point->org_u - before->org_u,
+                                        scale );
+          }
+          else
+          {
+            FT_Pos  u;
+
+
+            after = strongs[nn];
+
+            /* now interpolate point between before and after */
+            u = point->org_u;
+
+            if ( u == before->org_u )
+              point->cur_u = before->cur_u;
+
+            else if ( u == after->org_u )
+              point->cur_u = after->cur_u;
+
+            else
+              point->cur_u = before->cur_u +
+                               FT_MulDiv( u - before->org_u,
+                                          after->cur_u - before->cur_u,
+                                          after->org_u - before->org_u );
+          }
+        }
+        psh_point_set_fitted( point );
+      }
+    }
+
+    if ( strongs != strongs_0 )
+      FT_FREE( strongs );
+
+#endif /* 1 */
+
+  }
+
+
+  /* interpolate other points */
+  static void
+  psh_glyph_interpolate_other_points( PSH_Glyph  glyph,
+                                      FT_Int     dimension )
+  {
+    PSH_Dimension  dim          = &glyph->globals->dimension[dimension];
+    FT_Fixed       scale        = dim->scale_mult;
+    FT_Fixed       delta        = dim->scale_delta;
+    PSH_Contour    contour      = glyph->contours;
+    FT_UInt        num_contours = glyph->num_contours;
+
+
+    for ( ; num_contours > 0; num_contours--, contour++ )
+    {
+      PSH_Point  start = contour->start;
+      PSH_Point  first, next, point;
+      FT_UInt    fit_count;
+
+
+      /* count the number of strong points in this contour */
+      next      = start + contour->count;
+      fit_count = 0;
+      first     = 0;
+
+      for ( point = start; point < next; point++ )
+        if ( psh_point_is_fitted( point ) )
+        {
+          if ( !first )
+            first = point;
+
+          fit_count++;
+        }
+
+      /* if there are less than 2 fitted points in the contour, we */
+      /* simply scale and eventually translate the contour points  */
+      if ( fit_count < 2 )
+      {
+        if ( fit_count == 1 )
+          delta = first->cur_u - FT_MulFix( first->org_u, scale );
+
+        for ( point = start; point < next; point++ )
+          if ( point != first )
+            point->cur_u = FT_MulFix( point->org_u, scale ) + delta;
+
+        goto Next_Contour;
+      }
+
+      /* there are more than 2 strong points in this contour; we */
+      /* need to interpolate weak points between them            */
+      start = first;
+      do
+      {
+        point = first;
+
+        /* skip consecutive fitted points */
+        for (;;)
+        {
+          next = first->next;
+          if ( next == start )
+            goto Next_Contour;
+
+          if ( !psh_point_is_fitted( next ) )
+            break;
+
+          first = next;
+        }
+
+        /* find next fitted point after unfitted one */
+        for (;;)
+        {
+          next = next->next;
+          if ( psh_point_is_fitted( next ) )
+            break;
+        }
+
+        /* now interpolate between them */
+        {
+          FT_Pos    org_a, org_ab, cur_a, cur_ab;
+          FT_Pos    org_c, org_ac, cur_c;
+          FT_Fixed  scale_ab;
+
+
+          if ( first->org_u <= next->org_u )
+          {
+            org_a  = first->org_u;
+            cur_a  = first->cur_u;
+            org_ab = next->org_u - org_a;
+            cur_ab = next->cur_u - cur_a;
+          }
+          else
+          {
+            org_a  = next->org_u;
+            cur_a  = next->cur_u;
+            org_ab = first->org_u - org_a;
+            cur_ab = first->cur_u - cur_a;
+          }
+
+          scale_ab = 0x10000L;
+          if ( org_ab > 0 )
+            scale_ab = FT_DivFix( cur_ab, org_ab );
+
+          point = first->next;
+          do
+          {
+            org_c  = point->org_u;
+            org_ac = org_c - org_a;
+
+            if ( org_ac <= 0 )
+            {
+              /* on the left of the interpolation zone */
+              cur_c = cur_a + FT_MulFix( org_ac, scale );
+            }
+            else if ( org_ac >= org_ab )
+            {
+              /* on the right on the interpolation zone */
+              cur_c = cur_a + cur_ab + FT_MulFix( org_ac - org_ab, scale );
+            }
+            else
+            {
+              /* within the interpolation zone */
+              cur_c = cur_a + FT_MulFix( org_ac, scale_ab );
+            }
+
+            point->cur_u = cur_c;
+
+            point = point->next;
+
+          } while ( point != next );
+        }
+
+        /* keep going until all points in the contours have been processed */
+        first = next;
+
+      } while ( first != start );
+
+    Next_Contour:
+      ;
+    }
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     HIGH-LEVEL INTERFACE                      *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  FT_Error
+  ps_hints_apply( PS_Hints        ps_hints,
+                  FT_Outline*     outline,
+                  PSH_Globals     globals,
+                  FT_Render_Mode  hint_mode )
+  {
+    PSH_GlyphRec  glyphrec;
+    PSH_Glyph     glyph = &glyphrec;
+    FT_Error      error;
+#ifdef DEBUG_HINTER
+    FT_Memory     memory;
+#endif
+    FT_Int        dimension;
+
+
+    /* something to do? */
+    if ( outline->n_points == 0 || outline->n_contours == 0 )
+      return PSH_Err_Ok;
+
+#ifdef DEBUG_HINTER
+
+    memory = globals->memory;
+
+    if ( ps_debug_glyph )
+    {
+      psh_glyph_done( ps_debug_glyph );
+      FT_FREE( ps_debug_glyph );
+    }
+
+    if ( FT_NEW( glyph ) )
+      return error;
+
+    ps_debug_glyph = glyph;
+
+#endif /* DEBUG_HINTER */
+
+    error = psh_glyph_init( glyph, outline, ps_hints, globals );
+    if ( error )
+      goto Exit;
+
+    /* try to optimize the y_scale so that the top of non-capital letters
+     * is aligned on a pixel boundary whenever possible
+     */
+    {
+      PSH_Dimension  dim_x = &glyph->globals->dimension[0];
+      PSH_Dimension  dim_y = &glyph->globals->dimension[1];
+
+      FT_Fixed  x_scale = dim_x->scale_mult;
+      FT_Fixed  y_scale = dim_y->scale_mult;
+
+      FT_Fixed  old_x_scale = x_scale;
+      FT_Fixed  old_y_scale = y_scale;
+
+      FT_Fixed  scaled;
+      FT_Fixed  fitted;
+
+      FT_Bool  rescale = FALSE;
+
+
+      scaled = FT_MulFix( globals->blues.normal_top.zones->org_ref, y_scale );
+      fitted = FT_PIX_ROUND( scaled );
+
+      if ( fitted != 0 && scaled != fitted )
+      {
+        rescale = TRUE;
+
+        y_scale = FT_MulDiv( y_scale, fitted, scaled );
+
+        if ( fitted < scaled )
+          x_scale -= x_scale / 50;
+
+        psh_globals_set_scale( glyph->globals, x_scale, y_scale, 0, 0 );
+      }
+
+      glyph->do_horz_hints = 1;
+      glyph->do_vert_hints = 1;
+
+      glyph->do_horz_snapping = FT_BOOL( hint_mode == FT_RENDER_MODE_MONO ||
+                                         hint_mode == FT_RENDER_MODE_LCD  );
+
+      glyph->do_vert_snapping = FT_BOOL( hint_mode == FT_RENDER_MODE_MONO  ||
+                                         hint_mode == FT_RENDER_MODE_LCD_V );
+
+      glyph->do_stem_adjust   = FT_BOOL( hint_mode != FT_RENDER_MODE_LIGHT );
+
+      for ( dimension = 0; dimension < 2; dimension++ )
+      {
+        /* load outline coordinates into glyph */
+        psh_glyph_load_points( glyph, dimension );
+
+        /* compute local extrema */
+        psh_glyph_compute_extrema( glyph );
+
+        /* compute aligned stem/hints positions */
+        psh_hint_table_align_hints( &glyph->hint_tables[dimension],
+                                    glyph->globals,
+                                    dimension,
+                                    glyph );
+
+        /* find strong points, align them, then interpolate others */
+        psh_glyph_find_strong_points( glyph, dimension );
+        if ( dimension == 1 )
+          psh_glyph_find_blue_points( &globals->blues, glyph );
+        psh_glyph_interpolate_strong_points( glyph, dimension );
+        psh_glyph_interpolate_normal_points( glyph, dimension );
+        psh_glyph_interpolate_other_points( glyph, dimension );
+
+        /* save hinted coordinates back to outline */
+        psh_glyph_save_points( glyph, dimension );
+
+        if ( rescale )
+          psh_globals_set_scale( glyph->globals,
+                                 old_x_scale, old_y_scale, 0, 0 );
+      }
+    }
+
+  Exit:
+
+#ifndef DEBUG_HINTER
+    psh_glyph_done( glyph );
+#endif
+
+    return error;
+  }
+
+
+/* END */