src/freetype/autohint/ahglobal.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ahglobal.c                                                             */
   4 /*                                                                         */
   5 /*    Routines used to compute global metrics automatically (body).        */
   6 /*                                                                         */
   7 /*  Copyright 2000 Catharon Productions Inc.                               */
   8 /*  Author: David Turner                                                   */
   9 /*                                                                         */
  10 /*  This file is part of the Catharon Typography Project and shall only    */
  11 /*  be used, modified, and distributed under the terms of the Catharon     */
  12 /*  Open Source License that should come with this file under the name     */
  13 /*  `CatharonLicense.txt'.  By continuing to use, modify, or distribute    */
  14 /*  this file you indicate that you have read the license and              */
  15 /*  understand and accept it fully.                                        */
  16 /*                                                                         */
  17 /*  Note that this license is compatible with the FreeType license.        */
  18 /*                                                                         */
  19 /***************************************************************************/
  20
  21
  22 #ifdef FT_FLAT_COMPILE
  23
  24 #include "ahglobal.h"
  25 #include "ahglyph.h"
  26
  27 #else
  28
  29 #include <autohint/ahglobal.h>
  30 #include <autohint/ahglyph.h>
  31
  32 #endif
  33
  34
  35 #define MAX_TEST_CHARACTERS  12
  36
  37   static
  38   const char*  blue_chars[ah_blue_max] =
  39   {
  40     "THEZOCQS",
  41     "HEZLOCUS",
  42     "xzroesc",
  43     "xzroesc",
  44     "pqgjy"
  45   };
  46
  47
  48   /* simple insertion sort */
  49   static
  50   void  sort_values( FT_Int   count,
  51                      FT_Pos*  table )
  52   {
  53     FT_Int  i, j, swap;
  54
  55
  56     for ( i = 1; i < count; i++ )
  57     {
  58       for ( j = i; j > 1; j-- )
  59       {
  60         if ( table[j] > table[j - 1] )
  61           break;
  62
  63         swap         = table[j];
  64         table[j]     = table[j - 1];
  65         table[j - 1] = swap;
  66       }
  67     }
  68   }
  69
  70
  71   static
  72   FT_Error  ah_hinter_compute_blues( AH_Hinter*  hinter )
  73   {
  74     AH_Blue       blue;
  75     AH_Globals*   globals = &hinter->globals->design;
  76     FT_Pos        flats [MAX_TEST_CHARACTERS];
  77     FT_Pos        rounds[MAX_TEST_CHARACTERS];
  78     FT_Int        num_flats;
  79     FT_Int        num_rounds;
  80
  81     FT_Face       face;
  82     FT_GlyphSlot  glyph;
  83     FT_Error      error;
  84     FT_CharMap    charmap;
  85
  86
  87     face  = hinter->face;
  88     glyph = face->glyph;
  89
  90     /* save current charmap */
  91     charmap = face->charmap;
  92
  93     /* do we have a Unicode charmap in there? */
  94     error = FT_Select_Charmap( face, ft_encoding_unicode );
  95     if ( error )
  96       goto Exit;
  97
  98     /* we compute the blues simply by loading each character from the */
  99     /* 'blue_chars[blues]' string, then compute its top-most and      */
 100     /* bottom-most points                                             */
 101
 102     AH_LOG(( "blue zones computation\n" ));
 103     AH_LOG(( "------------------------------------------------\n" ));
 104
 105     for ( blue = ah_blue_capital_top; blue < ah_blue_max; blue++ )
 106     {
 107       const char*  p     = blue_chars[blue];
 108       const char*  limit = p + MAX_TEST_CHARACTERS;
 109       FT_Pos       *blue_ref, *blue_shoot;
 110
 111
 112       AH_LOG(( "blue %3d: ", blue ));
 113
 114       num_flats  = 0;
 115       num_rounds = 0;
 116
 117       for ( ; p < limit; p++ )
 118       {
 119         FT_UInt     glyph_index;
 120         FT_Vector*  extremum;
 121         FT_Vector*  points;
 122         FT_Vector*  point_limit;
 123         FT_Vector*  point;
 124         FT_Bool     round;
 125
 126
 127         /* exit if we reach the end of the string */
 128         if ( !*p )
 129           break;
 130
 131         AH_LOG(( "`%c'", *p ));
 132
 133         /* load the character in the face -- skip unknown or empty ones */
 134         glyph_index = FT_Get_Char_Index( face, (FT_UInt)*p );
 135         if ( glyph_index == 0 )
 136           continue;
 137
 138         error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE );
 139         if ( error || glyph->outline.n_points <= 0 )
 140           continue;
 141
 142         /* now compute min or max point indices and coordinates */
 143         points      = glyph->outline.points;
 144         point_limit = points + glyph->outline.n_points;
 145         point       = points;
 146         extremum    = point;
 147         point++;
 148
 149         if ( AH_IS_TOP_BLUE( blue ) )
 150         {
 151           for ( ; point < point_limit; point++ )
 152             if ( point->y > extremum->y )
 153               extremum = point;
 154         }
 155         else
 156         {
 157           for ( ; point < point_limit; point++ )
 158             if ( point->y < extremum->y )
 159               extremum = point;
 160         }
 161
 162         AH_LOG(( "%5d", (int)extremum->y ));
 163
 164         /* now, check whether the point belongs to a straight or round  */
 165         /* segment; we first need to find in which contour the extremum */
 166         /* lies, then see its previous and next points                  */
 167         {
 168           FT_Int  index = extremum - points;
 169           FT_Int  n;
 170           FT_Int  first, last, prev, next, end;
 171           FT_Pos  dist;
 172
 173
 174           last  = -1;
 175           first = 0;
 176
 177           for ( n = 0; n < glyph->outline.n_contours; n++ )
 178           {
 179             end = glyph->outline.contours[n];
 180             if ( end >= index )
 181             {
 182               last = end;
 183               break;
 184             }
 185             first = end + 1;
 186           }
 187
 188           /* XXX: should never happen! */
 189           if ( last < 0 )
 190             continue;
 191
 192           /* now look for the previous and next points that are not on the */
 193           /* same Y coordinate.  Threshold the `closeness'...              */
 194
 195           prev = index;
 196           next = prev;
 197
 198           do
 199           {
 200             if ( prev > first )
 201               prev--;
 202             else
 203               prev = last;
 204
 205             dist = points[prev].y - extremum->y;
 206             if ( dist < -5 || dist > 5 )
 207               break;
 208
 209           } while ( prev != index );
 210
 211           do
 212           {
 213             if ( next < last )
 214               next++;
 215             else
 216               next = first;
 217
 218             dist = points[next].y - extremum->y;
 219             if ( dist < -5 || dist > 5 )
 220               break;
 221
 222           } while ( next != index );
 223
 224           /* now, set the `round' flag depending on the segment's kind */
 225           round =
 226             FT_CURVE_TAG( glyph->outline.tags[prev] ) != FT_Curve_Tag_On ||
 227             FT_CURVE_TAG( glyph->outline.tags[next] ) != FT_Curve_Tag_On ;
 228
 229           AH_LOG(( "%c ", round ? 'r' : 'f' ));
 230         }
 231
 232         if ( round )
 233           rounds[num_rounds++] = extremum->y;
 234         else
 235           flats[num_flats++] = extremum->y;
 236       }
 237
 238       AH_LOG(( "\n" ));
 239
 240       /* we have computed the contents of the `rounds' and `flats' tables, */
 241       /* now determine the reference and overshoot position of the blue;   */
 242       /* we simply take the median value after a simple short              */
 243       sort_values( num_rounds, rounds );
 244       sort_values( num_flats,  flats  );
 245
 246       blue_ref   = globals->blue_refs + blue;
 247       blue_shoot = globals->blue_shoots + blue;
 248       if ( num_flats == 0 && num_rounds == 0 )
 249       {
 250         *blue_ref   = -10000;
 251         *blue_shoot = -10000;
 252       }
 253       else if ( num_flats == 0 )
 254       {
 255         *blue_ref   =
 256         *blue_shoot = rounds[num_rounds / 2];
 257       }
 258       else if ( num_rounds == 0 )
 259       {
 260         *blue_ref   =
 261         *blue_shoot = flats[num_flats / 2];
 262       }
 263       else
 264       {
 265         *blue_ref   = flats[num_flats / 2];
 266         *blue_shoot = rounds[num_rounds / 2];
 267       }
 268
 269       /* there are sometimes problems: if the overshoot position of top     */
 270       /* zones is under its reference position, or the opposite for bottom  */
 271       /* zones.  We must thus check everything there and correct the errors */
 272       if ( *blue_shoot != *blue_ref )
 273       {
 274         FT_Pos   ref      = *blue_ref;
 275         FT_Pos   shoot    = *blue_shoot;
 276         FT_Bool  over_ref = ( shoot > ref );
 277
 278
 279         if ( AH_IS_TOP_BLUE( blue ) ^ over_ref )
 280           *blue_shoot = *blue_ref = ( shoot + ref ) / 2;
 281       }
 282
 283       AH_LOG(( "-- ref = %ld, shoot = %ld\n", *blue_ref, *blue_shoot ));
 284     }
 285
 286     /* reset original face charmap */
 287     FT_Set_Charmap( face, charmap );
 288     error = 0;
 289
 290   Exit:
 291     return error;
 292   }
 293
 294
 295   static
 296   FT_Error  ah_hinter_compute_widths( AH_Hinter*  hinter )
 297   {
 298     /* scan the array of segments in each direction */
 299     AH_Outline*  outline = hinter->glyph;
 300     AH_Segment*  segments;
 301     AH_Segment*  limit;
 302     AH_Globals*  globals = &hinter->globals->design;
 303     FT_Pos*      widths;
 304     FT_Int       dimension;
 305     FT_Int*      p_num_widths;
 306     FT_Error     error = 0;
 307     FT_Pos       edge_distance_threshold = 32000;
 308
 309
 310     globals->num_widths  = 0;
 311     globals->num_heights = 0;
 312
 313     /* For now, compute the standard width and height from the `o'       */
 314     /* character.  I started computing the stem width of the `i' and the */
 315     /* stem height of the "-", but it wasn't too good.  Moreover, we now */
 316     /* have a single character that gives us standard width and height.  */
 317     {
 318       FT_UInt   glyph_index;
 319
 320
 321       glyph_index = FT_Get_Char_Index( hinter->face, 'o' );
 322       if ( glyph_index == 0 )
 323         return 0;
 324
 325       error = FT_Load_Glyph( hinter->face, glyph_index, FT_LOAD_NO_SCALE );
 326       if ( error )
 327         goto Exit;
 328
 329       error = ah_outline_load( hinter->glyph, hinter->face );
 330       if ( error )
 331         goto Exit;
 332
 333       ah_outline_compute_segments( hinter->glyph );
 334       ah_outline_link_segments( hinter->glyph );
 335     }
 336
 337     segments     = outline->horz_segments;
 338     limit        = segments + outline->num_hsegments;
 339     widths       = globals->heights;
 340     p_num_widths = &globals->num_heights;
 341
 342     for ( dimension = 1; dimension >= 0; dimension-- )
 343     {
 344       AH_Segment*  seg = segments;
 345       AH_Segment*  link;
 346       FT_Int       num_widths = 0;
 347
 348
 349       for ( ; seg < limit; seg++ )
 350       {
 351         link = seg->link;
 352         /* we only consider stem segments there! */
 353         if ( link && link->link == seg && link > seg )
 354         {
 355           FT_Int  dist;
 356
 357
 358           dist = seg->pos - link->pos;
 359           if ( dist < 0 )
 360             dist = -dist;
 361
 362           if ( num_widths < 12 )
 363             widths[num_widths++] = dist;
 364         }
 365       }
 366
 367       sort_values( num_widths, widths );
 368       *p_num_widths = num_widths;
 369
 370       /* we will now try to find the smallest width */
 371       if ( num_widths > 0 && widths[0] < edge_distance_threshold )
 372         edge_distance_threshold = widths[0];
 373
 374       segments     = outline->vert_segments;
 375       limit        = segments + outline->num_vsegments;
 376       widths       = globals->widths;
 377       p_num_widths = &globals->num_widths;
 378
 379     }
 380
 381     /* Now, compute the edge distance threshold as a fraction of the */
 382     /* smallest width in the font. Set it in `hinter.glyph' too!     */
 383     if ( edge_distance_threshold == 32000 )
 384       edge_distance_threshold = 50;
 385
 386     /* let's try 20% */
 387     hinter->glyph->edge_distance_threshold = edge_distance_threshold / 5;
 388
 389   Exit:
 390     return error;
 391   }
 392
 393
 394   LOCAL_FUNC
 395   FT_Error  ah_hinter_compute_globals( AH_Hinter*  hinter )
 396   {
 397     return ah_hinter_compute_widths( hinter ) ||
 398            ah_hinter_compute_blues ( hinter );
 399   }
 400
 401
 402 /* END */