lib/tacvt.c

   1 /* tacvt.c */
   2
   3 /*
   4  * Copyright (C) 2011-2017 by Werner Lemberg.
   5  *
   6  * This file is part of the ttfautohint library, and may only be used,
   7  * modified, and distributed under the terms given in `COPYING'.  By
   8  * continuing to use, modify, or distribute this file you indicate that you
   9  * have read `COPYING' and understand and accept it fully.
  10  *
  11  * The file `COPYING' mentioned in the previous paragraph is distributed
  12  * with the ttfautohint library.
  13  */
  14
  15
  16 #include "ta.h"
  17
  18
  19 static FT_Error
  20 TA_sfnt_compute_global_hints(SFNT* sfnt,
  21                              FONT* font,
  22                              TA_Style style_idx)
  23 {
  24   FT_Error error;
  25   FT_Face face = sfnt->face;
  26   FT_ULong glyph_index;
  27   FT_Int32 load_flags;
  28
  29
  30   error = FT_Select_Charmap(face, FT_ENCODING_UNICODE);
  31   if (error)
  32   {
  33     if (font->symbol)
  34     {
  35       error = FT_Select_Charmap(face, FT_ENCODING_MS_SYMBOL);
  36       if (error)
  37         return TA_Err_Missing_Symbol_CMap;
  38     }
  39     else
  40       return TA_Err_Missing_Unicode_CMap;
  41   }
  42
  43   {
  44     TA_FaceGlobals globals = (TA_FaceGlobals)sfnt->face->autohint.data;
  45     FT_UShort* gstyles = globals->glyph_styles;
  46
  47     TA_StyleClass style_class = ta_style_classes[style_idx];
  48     TA_ScriptClass script_class = ta_script_classes[style_class->script];
  49
  50     TA_StyleMetricsRec dummy;
  51
  52     void* shaper_buf;
  53     const char* p;
  54
  55
  56     /* we don't have a `TA_Loader' object yet */
  57     dummy.globals = globals;
  58     dummy.style_class = style_class;
  59
  60     p = script_class->standard_charstring;
  61     shaper_buf = ta_shaper_buf_create(face);
  62
  63     /*
  64      * We check more than a single standard character to catch features
  65      * like `c2sc' (small caps from caps) that don't contain lowercase
  66      * letters by definition, or other features that mainly operate on
  67      * numerals.
  68      */
  69
  70     glyph_index = 0;
  71     while (*p)
  72     {
  73       unsigned int num_idx;
  74
  75
  76       while (*p == ' ')
  77         p++;
  78
  79       /* reject input that maps to more than a single glyph */
  80       p = ta_shaper_get_cluster(p, &dummy, shaper_buf, &num_idx);
  81       if (num_idx > 1)
  82         continue;
  83
  84       /* otherwise exit loop if we have a result */
  85       glyph_index = ta_shaper_get_elem(&dummy,
  86                                        shaper_buf,
  87                                        0,
  88                                        NULL,
  89                                        NULL);
  90       if (glyph_index)
  91         break;
  92     }
  93
  94     ta_shaper_buf_destroy(face, shaper_buf);
  95
  96     if (!glyph_index)
  97     {
  98       if (font->fallback_style == style_idx)
  99       {
 100         /* Having TA_STYLE_NONE_DFLT as the fallback script means */
 101         /* hinting without default characters */
 102         /* (and without script-specific blue zones), so we proceed */
 103         if (style_idx == TA_STYLE_NONE_DFLT)
 104           goto Symbol;
 105
 106         /* in case of a symbol font, we also proceed */
 107         if (font->symbol)
 108           goto Symbol;
 109       }
 110
 111       /* no standard characters to set up this style */
 112       return TA_Err_Missing_Glyph;
 113     }
 114
 115     /*
 116      * We now know that HarfBuzz can access the standard character in the
 117      * current OpenType feature.  However, this doesn't guarantee that there
 118      * actually *is* a standard character in the corresponding coverage,
 119      * since glyphs shifted with data from the GPOS table are ignored in the
 120      * coverage (but neverless used to derive stem widths).  For this
 121      * reason, search an arbitrary character from the current coverage to
 122      * trigger the coverage's metrics computation.
 123      */
 124     if ((gstyles[glyph_index] & TA_STYLE_MASK) != style_idx)
 125     {
 126       FT_ULong i;
 127
 128
 129       for (i = 0; i < (FT_ULong)globals->glyph_count; i++)
 130       {
 131         if ((gstyles[i] & TA_STYLE_MASK) == style_idx)
 132           break;
 133       }
 134
 135       if (i == (FT_ULong)globals->glyph_count)
 136         return TA_Err_Missing_Glyph;
 137
 138       glyph_index = i;
 139     }
 140   }
 141
 142 Symbol:
 143   load_flags = 1 << 29; /* vertical hinting only */
 144   error = ta_loader_load_glyph(font, face, (FT_UInt)glyph_index, load_flags);
 145
 146   return error;
 147 }
 148
 149
 150 static FT_Error
 151 TA_table_build_cvt(FT_Byte** cvt,
 152                    FT_ULong* cvt_len,
 153                    SFNT* sfnt,
 154                    FONT* font)
 155 {
 156   SFNT_Table* glyf_table = &font->tables[sfnt->glyf_idx];
 157   glyf_Data* data = (glyf_Data*)glyf_table->data;
 158
 159   TA_LatinAxis haxis;
 160   TA_LatinAxis vaxis;
 161
 162   FT_UInt hwidth_count;
 163   FT_UInt vwidth_count;
 164   FT_UInt blue_count;
 165
 166   FT_UInt i, j;
 167   FT_UInt buf_len;
 168   FT_UInt len;
 169   FT_Byte* buf;
 170   FT_Byte* bufp;
 171   FT_UInt cvt_offset;
 172
 173   FT_Error error;
 174
 175
 176   /* loop over all styles and collect the relevant CVT data */
 177   /* to compute the necessary array sizes and meta-information */
 178   hwidth_count = 0;
 179   vwidth_count = 0;
 180   blue_count = 0;
 181
 182   data->num_used_styles = 0;
 183
 184   for (i = 0; i < TA_STYLE_MAX; i++)
 185   {
 186     error = TA_sfnt_compute_global_hints(sfnt, font, (TA_Style)i);
 187     if (error == TA_Err_Missing_Glyph)
 188     {
 189       TA_FaceGlobals globals = (TA_FaceGlobals)sfnt->face->autohint.data;
 190       FT_UShort* gstyles = globals->glyph_styles;
 191       FT_Int nn;
 192
 193
 194       data->style_ids[i] = 0xFFFFU;
 195
 196       /* remove all references to this style; */
 197       /* otherwise blue zones are computed later on, which we don't want */
 198       for (nn = 0; nn < globals->glyph_count; nn++)
 199       {
 200         if ((gstyles[nn] & TA_STYLE_MASK) == i)
 201         {
 202           gstyles[nn] &= ~TA_STYLE_MASK;
 203           gstyles[nn] |= globals->font->fallback_style;
 204         }
 205       }
 206
 207       continue;
 208     }
 209     if (error)
 210       return error;
 211
 212     data->style_ids[i] = data->num_used_styles++;
 213
 214     /* XXX: generalize this to handle other metrics also */
 215     haxis = &((TA_LatinMetrics)font->loader->hints.metrics)->axis[0];
 216     vaxis = &((TA_LatinMetrics)font->loader->hints.metrics)->axis[1];
 217
 218     hwidth_count += haxis->width_count;
 219     vwidth_count += vaxis->width_count;
 220
 221     blue_count += vaxis->blue_count;
 222     /* if windows compatibility mode is active */
 223     /* we add two artificial blue zones at the end of the array */
 224     /* that are not part of `vaxis->blue_count' */
 225     if (font->windows_compatibility)
 226       blue_count += 2;
 227   }
 228
 229   /* exit if the font doesn't contain a single supported style, */
 230   /* and we don't have a symbol font */
 231   if (!data->num_used_styles && !font->symbol)
 232     return TA_Err_Missing_Glyph;
 233
 234   buf_len = cvtl_max_runtime /* runtime values 1 */
 235             + data->num_used_styles /* runtime values 2 (for scaling) */
 236             + 2 * data->num_used_styles /* runtime values 3 (blue data) */
 237             + 2 * data->num_used_styles /* vert. and horiz. std. widths */
 238             + hwidth_count
 239             + vwidth_count
 240             + 2 * blue_count; /* round and flat blue zones */
 241   buf_len <<= 1; /* we have 16bit values */
 242
 243   /* buffer length must be a multiple of four */
 244   len = (buf_len + 3) & ~3U;
 245   buf = (FT_Byte*)malloc(len);
 246   if (!buf)
 247     return FT_Err_Out_Of_Memory;
 248
 249   /* pad end of buffer with zeros */
 250   buf[len - 1] = 0x00;
 251   buf[len - 2] = 0x00;
 252   buf[len - 3] = 0x00;
 253
 254   bufp = buf;
 255
 256   /*
 257    * some CVT values are initialized (and modified) at runtime:
 258    *
 259    *   (1) the `cvtl_xxx' values (see `tabytecode.h')
 260    *   (2) a scaling value for each style
 261    *   (3) offset and size of the vertical widths array
 262    *       (needed by `bci_{smooth,strong}_stem_width') for each style
 263    */
 264   for (i = 0; i < (cvtl_max_runtime
 265                    + data->num_used_styles
 266                    + 2 * data->num_used_styles) * 2; i++)
 267     *(bufp++) = 0;
 268
 269   cvt_offset = (FT_UInt)(bufp - buf);
 270
 271   /* loop again over all styles and copy CVT data */
 272   for (i = 0; i < TA_STYLE_MAX; i++)
 273   {
 274     FT_UInt default_width = 50 * sfnt->face->units_per_EM / 2048;
 275
 276
 277     /* collect offsets */
 278     data->cvt_offsets[i] = ((FT_UInt)(bufp - buf) - cvt_offset) >> 1;
 279
 280     error = TA_sfnt_compute_global_hints(sfnt, font, (TA_Style)i);
 281     if (error == TA_Err_Missing_Glyph)
 282       continue;
 283     if (error)
 284       return error;
 285
 286     haxis = &((TA_LatinMetrics)font->loader->hints.metrics)->axis[0];
 287     vaxis = &((TA_LatinMetrics)font->loader->hints.metrics)->axis[1];
 288
 289     hwidth_count = haxis->width_count;
 290     vwidth_count = vaxis->width_count;
 291
 292     blue_count = vaxis->blue_count;
 293     if (font->windows_compatibility)
 294       blue_count += 2; /* with artificial blue zones */
 295
 296     /* horizontal standard width */
 297     if (hwidth_count > 0)
 298     {
 299       *(bufp++) = HIGH(haxis->widths[0].org);
 300       *(bufp++) = LOW(haxis->widths[0].org);
 301     }
 302     else
 303     {
 304       *(bufp++) = HIGH(default_width);
 305       *(bufp++) = LOW(default_width);
 306     }
 307
 308     for (j = 0; j < hwidth_count; j++)
 309     {
 310       if (haxis->widths[j].org > 0xFFFF)
 311         goto Err;
 312       *(bufp++) = HIGH(haxis->widths[j].org);
 313       *(bufp++) = LOW(haxis->widths[j].org);
 314     }
 315
 316     /* vertical standard width */
 317     if (vwidth_count > 0)
 318     {
 319       *(bufp++) = HIGH(vaxis->widths[0].org);
 320       *(bufp++) = LOW(vaxis->widths[0].org);
 321     }
 322     else
 323     {
 324       *(bufp++) = HIGH(default_width);
 325       *(bufp++) = LOW(default_width);
 326     }
 327
 328     for (j = 0; j < vwidth_count; j++)
 329     {
 330       if (vaxis->widths[j].org > 0xFFFF)
 331         goto Err;
 332       *(bufp++) = HIGH(vaxis->widths[j].org);
 333       *(bufp++) = LOW(vaxis->widths[j].org);
 334     }
 335
 336     data->cvt_blue_adjustment_offsets[i] = 0xFFFFU;
 337
 338     for (j = 0; j < blue_count; j++)
 339     {
 340       if (vaxis->blues[j].ref.org > 0xFFFF)
 341         goto Err;
 342       *(bufp++) = HIGH(vaxis->blues[j].ref.org);
 343       *(bufp++) = LOW(vaxis->blues[j].ref.org);
 344     }
 345
 346     for (j = 0; j < blue_count; j++)
 347     {
 348       if (vaxis->blues[j].shoot.org > 0xFFFF)
 349         goto Err;
 350       *(bufp++) = HIGH(vaxis->blues[j].shoot.org);
 351       *(bufp++) = LOW(vaxis->blues[j].shoot.org);
 352
 353       if (vaxis->blues[j].flags & TA_LATIN_BLUE_ADJUSTMENT)
 354         data->cvt_blue_adjustment_offsets[i] = j;
 355     }
 356
 357     data->cvt_horz_width_sizes[i] = hwidth_count;
 358     data->cvt_vert_width_sizes[i] = vwidth_count;
 359     data->cvt_blue_zone_sizes[i] = blue_count;
 360   }
 361
 362   *cvt = buf;
 363   *cvt_len = buf_len;
 364
 365   return FT_Err_Ok;
 366
 367 Err:
 368   free(buf);
 369   return TA_Err_Hinter_Overflow;
 370 }
 371
 372
 373 FT_Error
 374 TA_sfnt_build_cvt_table(SFNT* sfnt,
 375                         FONT* font)
 376 {
 377   FT_Error error;
 378
 379   SFNT_Table* glyf_table = &font->tables[sfnt->glyf_idx];
 380   glyf_Data* data = (glyf_Data*)glyf_table->data;
 381
 382   FT_Byte* cvt_buf;
 383   FT_ULong cvt_len;
 384
 385
 386   error = TA_sfnt_add_table_info(sfnt);
 387   if (error)
 388     goto Exit;
 389
 390   /* `glyf', `cvt', `fpgm', and `prep' are always used in parallel */
 391   if (glyf_table->processed)
 392   {
 393     sfnt->table_infos[sfnt->num_table_infos - 1] = data->cvt_idx;
 394     goto Exit;
 395   }
 396
 397   error = TA_table_build_cvt(&cvt_buf, &cvt_len, sfnt, font);
 398   if (error)
 399     goto Exit;
 400
 401   /* in case of success, `cvt_buf' gets linked */
 402   /* and is eventually freed in `TA_font_unload' */
 403   error = TA_font_add_table(font,
 404                             &sfnt->table_infos[sfnt->num_table_infos - 1],
 405                             TTAG_cvt, cvt_len, cvt_buf);
 406   if (error)
 407     free(cvt_buf);
 408   else
 409     data->cvt_idx = sfnt->table_infos[sfnt->num_table_infos - 1];
 410
 411 Exit:
 412   return error;
 413 }
 414
 415 /* end of tacvt.c */