libass/ass_font.c

   1 /*
   2  * Copyright (C) 2006 Evgeniy Stepanov <eugeni.stepanov@gmail.com>
   3  *
   4  * This file is part of libass.
   5  *
   6  * libass is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * libass is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with libass; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include "config.h"
  22
  23 #include <inttypes.h>
  24 #include <ft2build.h>
  25 #include FT_FREETYPE_H
  26 #include FT_SYNTHESIS_H
  27 #include FT_GLYPH_H
  28 #include FT_TRUETYPE_TABLES_H
  29 #include FT_OUTLINE_H
  30
  31 #include "ass.h"
  32 #include "ass_library.h"
  33 #include "ass_font.h"
  34 #include "ass_bitmap.h"
  35 #include "ass_cache.h"
  36 #include "ass_fontconfig.h"
  37 #include "ass_utils.h"
  38
  39 /**
  40  * Select Microfost Unicode CharMap, if the font has one.
  41  * Otherwise, let FreeType decide.
  42  */
  43 static void charmap_magic(ASS_Library *library, FT_Face face)
  44 {
  45     int i;
  46     for (i = 0; i < face->num_charmaps; ++i) {
  47         FT_CharMap cmap = face->charmaps[i];
  48         unsigned pid = cmap->platform_id;
  49         unsigned eid = cmap->encoding_id;
  50         if (pid == 3 /*microsoft */
  51             && (eid == 1 /*unicode bmp */
  52                 || eid == 10 /*full unicode */ )) {
  53             FT_Set_Charmap(face, cmap);
  54             return;
  55         }
  56     }
  57
  58     if (!face->charmap) {
  59         if (face->num_charmaps == 0) {
  60             ass_msg(library, MSGL_WARN, "Font face with no charmaps");
  61             return;
  62         }
  63         ass_msg(library, MSGL_WARN,
  64                 "No charmap autodetected, trying the first one");
  65         FT_Set_Charmap(face, face->charmaps[0]);
  66         return;
  67     }
  68 }
  69
  70 static void update_transform(ASS_Font *font)
  71 {
  72     int i;
  73     FT_Matrix m;
  74     m.xx = double_to_d16(font->scale_x);
  75     m.yy = double_to_d16(font->scale_y);
  76     m.xy = m.yx = 0;
  77     for (i = 0; i < font->n_faces; ++i)
  78         FT_Set_Transform(font->faces[i], &m, &font->v);
  79 }
  80
  81 /**
  82  * \brief find a memory font by name
  83  */
  84 static int find_font(ASS_Library *library, char *name)
  85 {
  86     int i;
  87     for (i = 0; i < library->num_fontdata; ++i)
  88         if (strcasecmp(name, library->fontdata[i].name) == 0)
  89             return i;
  90     return -1;
  91 }
  92
  93 static void face_set_size(FT_Face face, double size);
  94
  95 static void buggy_font_workaround(FT_Face face)
  96 {
  97     // Some fonts have zero Ascender/Descender fields in 'hhea' table.
  98     // In this case, get the information from 'os2' table or, as
  99     // a last resort, from face.bbox.
 100     if (face->ascender + face->descender == 0 || face->height == 0) {
 101         TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 102         if (os2) {
 103             face->ascender = os2->sTypoAscender;
 104             face->descender = os2->sTypoDescender;
 105             face->height = face->ascender - face->descender;
 106         } else {
 107             face->ascender = face->bbox.yMax;
 108             face->descender = face->bbox.yMin;
 109             face->height = face->ascender - face->descender;
 110         }
 111     }
 112 }
 113
 114 /**
 115  * \brief Select a face with the given charcode and add it to ASS_Font
 116  * \return index of the new face in font->faces, -1 if failed
 117  */
 118 static int add_face(void *fc_priv, ASS_Font *font, uint32_t ch)
 119 {
 120     char *path;
 121     int index;
 122     FT_Face face;
 123     int error;
 124     int mem_idx;
 125
 126     if (font->n_faces == ASS_FONT_MAX_FACES)
 127         return -1;
 128
 129     path =
 130         fontconfig_select(font->library, fc_priv, font->desc.family,
 131                           font->desc.treat_family_as_pattern,
 132                           font->desc.bold, font->desc.italic, &index, ch);
 133     if (!path)
 134         return -1;
 135
 136     mem_idx = find_font(font->library, path);
 137     if (mem_idx >= 0) {
 138         error =
 139             FT_New_Memory_Face(font->ftlibrary,
 140                                (unsigned char *) font->library->
 141                                fontdata[mem_idx].data,
 142                                font->library->fontdata[mem_idx].size, 0,
 143                                &face);
 144         if (error) {
 145             ass_msg(font->library, MSGL_WARN,
 146                     "Error opening memory font: '%s'", path);
 147             free(path);
 148             return -1;
 149         }
 150     } else {
 151         error = FT_New_Face(font->ftlibrary, path, index, &face);
 152         if (error) {
 153             ass_msg(font->library, MSGL_WARN,
 154                     "Error opening font: '%s', %d", path, index);
 155             free(path);
 156             return -1;
 157         }
 158     }
 159     charmap_magic(font->library, face);
 160     buggy_font_workaround(face);
 161
 162     font->faces[font->n_faces++] = face;
 163     update_transform(font);
 164     face_set_size(face, font->size);
 165     free(path);
 166     return font->n_faces - 1;
 167 }
 168
 169 /**
 170  * \brief Create a new ASS_Font according to "desc" argument
 171  */
 172 ASS_Font *ass_font_new(void *font_cache, ASS_Library *library,
 173                        FT_Library ftlibrary, void *fc_priv,
 174                        ASS_FontDesc *desc)
 175 {
 176     int error;
 177     ASS_Font *fontp;
 178     ASS_Font font;
 179
 180     fontp = ass_font_cache_find((Hashmap *) font_cache, desc);
 181     if (fontp)
 182         return fontp;
 183
 184     font.library = library;
 185     font.ftlibrary = ftlibrary;
 186     font.n_faces = 0;
 187     font.desc.family = strdup(desc->family);
 188     font.desc.treat_family_as_pattern = desc->treat_family_as_pattern;
 189     font.desc.bold = desc->bold;
 190     font.desc.italic = desc->italic;
 191
 192     font.scale_x = font.scale_y = 1.;
 193     font.v.x = font.v.y = 0;
 194     font.size = 0.;
 195
 196     error = add_face(fc_priv, &font, 0);
 197     if (error == -1) {
 198         free(font.desc.family);
 199         return 0;
 200     } else
 201         return ass_font_cache_add((Hashmap *) font_cache, &font);
 202 }
 203
 204 /**
 205  * \brief Set font transformation matrix and shift vector
 206  **/
 207 void ass_font_set_transform(ASS_Font *font, double scale_x,
 208                             double scale_y, FT_Vector *v)
 209 {
 210     font->scale_x = scale_x;
 211     font->scale_y = scale_y;
 212     if (v) {
 213         font->v.x = v->x;
 214         font->v.y = v->y;
 215     }
 216     update_transform(font);
 217 }
 218
 219 static void face_set_size(FT_Face face, double size)
 220 {
 221     TT_HoriHeader *hori = FT_Get_Sfnt_Table(face, ft_sfnt_hhea);
 222     TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 223     double mscale = 1.;
 224     FT_Size_RequestRec rq;
 225     FT_Size_Metrics *m = &face->size->metrics;
 226     // VSFilter uses metrics from TrueType OS/2 table
 227     // The idea was borrowed from asa (http://asa.diac24.net)
 228     if (hori && os2) {
 229         int hori_height = hori->Ascender - hori->Descender;
 230         int os2_height = os2->usWinAscent + os2->usWinDescent;
 231         if (hori_height && os2_height)
 232             mscale = (double) hori_height / os2_height;
 233     }
 234     memset(&rq, 0, sizeof(rq));
 235     rq.type = FT_SIZE_REQUEST_TYPE_REAL_DIM;
 236     rq.width = 0;
 237     rq.height = double_to_d6(size * mscale);
 238     rq.horiResolution = rq.vertResolution = 0;
 239     FT_Request_Size(face, &rq);
 240     m->ascender /= mscale;
 241     m->descender /= mscale;
 242     m->height /= mscale;
 243 }
 244
 245 /**
 246  * \brief Set font size
 247  **/
 248 void ass_font_set_size(ASS_Font *font, double size)
 249 {
 250     int i;
 251     if (font->size != size) {
 252         font->size = size;
 253         for (i = 0; i < font->n_faces; ++i)
 254             face_set_size(font->faces[i], size);
 255     }
 256 }
 257
 258 /**
 259  * \brief Get maximal font ascender and descender.
 260  * \param ch character code
 261  * The values are extracted from the font face that provides glyphs for the given character
 262  **/
 263 void ass_font_get_asc_desc(ASS_Font *font, uint32_t ch, int *asc,
 264                            int *desc)
 265 {
 266     int i;
 267     for (i = 0; i < font->n_faces; ++i) {
 268         FT_Face face = font->faces[i];
 269         TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 270         if (FT_Get_Char_Index(face, ch)) {
 271             int y_scale = face->size->metrics.y_scale;
 272             if (os2) {
 273                 *asc = FT_MulFix(os2->usWinAscent, y_scale);
 274                 *desc = FT_MulFix(os2->usWinDescent, y_scale);
 275             } else {
 276                 *asc = FT_MulFix(face->ascender, y_scale);
 277                 *desc = FT_MulFix(-face->descender, y_scale);
 278             }
 279             return;
 280         }
 281     }
 282
 283     *asc = *desc = 0;
 284 }
 285
 286 /*
 287  * Strike a glyph with a horizontal line; it's possible to underline it
 288  * and/or strike through it.  For the line's position and size, truetype
 289  * tables are consulted.  Obviously this relies on the data in the tables
 290  * being accurate.
 291  *
 292  */
 293 static int ass_strike_outline_glyph(FT_Face face, ASS_Font *font,
 294                                     FT_Glyph glyph, int under, int through)
 295 {
 296     TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 297     TT_Postscript *ps = FT_Get_Sfnt_Table(face, ft_sfnt_post);
 298     FT_Outline *ol = &((FT_OutlineGlyph) glyph)->outline;
 299     int bear, advance, y_scale, i, dir;
 300
 301     if (!under && !through)
 302         return 0;
 303
 304     // Grow outline
 305     i = (under ? 4 : 0) + (through ? 4 : 0);
 306     ol->points = realloc(ol->points, sizeof(FT_Vector) *
 307                          (ol->n_points + i));
 308     ol->tags = realloc(ol->tags, ol->n_points + i);
 309     i = !!under + !!through;
 310     ol->contours = realloc(ol->contours, sizeof(short) *
 311                            (ol->n_contours + i));
 312
 313     // If the bearing is negative, the glyph starts left of the current
 314     // pen position
 315     bear = FFMIN(face->glyph->metrics.horiBearingX, 0);
 316     // We're adding half a pixel to avoid small gaps
 317     advance = d16_to_d6(glyph->advance.x) + 32;
 318     y_scale = face->size->metrics.y_scale;
 319
 320     // Reverse drawing direction for non-truetype fonts
 321     dir = FT_Outline_Get_Orientation(ol);
 322
 323     // Add points to the outline
 324     if (under && ps) {
 325         int pos, size;
 326         pos = FT_MulFix(ps->underlinePosition, y_scale * font->scale_y);
 327         size = FT_MulFix(ps->underlineThickness,
 328                          y_scale * font->scale_y / 2);
 329
 330         if (pos > 0 || size <= 0)
 331             return 1;
 332
 333         FT_Vector points[4] = {
 334             {.x = bear,      .y = pos + size},
 335             {.x = advance,   .y = pos + size},
 336             {.x = advance,   .y = pos - size},
 337             {.x = bear,      .y = pos - size},
 338         };
 339
 340         if (dir == FT_ORIENTATION_TRUETYPE) {
 341             for (i = 0; i < 4; i++) {
 342                 ol->points[ol->n_points] = points[i];
 343                 ol->tags[ol->n_points++] = 1;
 344             }
 345         } else {
 346             for (i = 3; i >= 0; i--) {
 347                 ol->points[ol->n_points] = points[i];
 348                 ol->tags[ol->n_points++] = 1;
 349             }
 350         }
 351
 352         ol->contours[ol->n_contours++] = ol->n_points - 1;
 353     }
 354
 355     if (through && os2) {
 356         int pos, size;
 357         pos = FT_MulFix(os2->yStrikeoutPosition, y_scale * font->scale_y);
 358         size = FT_MulFix(os2->yStrikeoutSize, y_scale * font->scale_y / 2);
 359
 360         if (pos < 0 || size <= 0)
 361             return 1;
 362
 363         FT_Vector points[4] = {
 364             {.x = bear,      .y = pos + size},
 365             {.x = advance,   .y = pos + size},
 366             {.x = advance,   .y = pos - size},
 367             {.x = bear,      .y = pos - size},
 368         };
 369
 370         if (dir == FT_ORIENTATION_TRUETYPE) {
 371             for (i = 0; i < 4; i++) {
 372                 ol->points[ol->n_points] = points[i];
 373                 ol->tags[ol->n_points++] = 1;
 374             }
 375         } else {
 376             for (i = 3; i >= 0; i--) {
 377                 ol->points[ol->n_points] = points[i];
 378                 ol->tags[ol->n_points++] = 1;
 379             }
 380         }
 381
 382         ol->contours[ol->n_contours++] = ol->n_points - 1;
 383     }
 384
 385     return 0;
 386 }
 387
 388 /**
 389  * Slightly embold a glyph without touching its metrics
 390  */
 391 static void ass_glyph_embolden(FT_GlyphSlot slot)
 392 {
 393     int str;
 394
 395     if (slot->format != FT_GLYPH_FORMAT_OUTLINE)
 396         return;
 397
 398     str = FT_MulFix(slot->face->units_per_EM,
 399                     slot->face->size->metrics.y_scale) / 64;
 400
 401     FT_Outline_Embolden(&slot->outline, str);
 402 }
 403
 404 /**
 405  * \brief Get a glyph
 406  * \param ch character code
 407  **/
 408 FT_Glyph ass_font_get_glyph(void *fontconfig_priv, ASS_Font *font,
 409                             uint32_t ch, ASS_Hinting hinting, int deco)
 410 {
 411     int error;
 412     int index = 0;
 413     int i;
 414     FT_Glyph glyph;
 415     FT_Face face = 0;
 416     int flags = 0;
 417
 418     if (ch < 0x20)
 419         return 0;
 420     // Handle NBSP like a regular space when rendering the glyph
 421     if (ch == 0xa0)
 422         ch = ' ';
 423     if (font->n_faces == 0)
 424         return 0;
 425
 426     for (i = 0; i < font->n_faces; ++i) {
 427         face = font->faces[i];
 428         index = FT_Get_Char_Index(face, ch);
 429         if (index)
 430             break;
 431     }
 432
 433 #ifdef CONFIG_FONTCONFIG
 434     if (index == 0) {
 435         int face_idx;
 436         ass_msg(font->library, MSGL_INFO,
 437                 "Glyph 0x%X not found, selecting one more "
 438                 "font for (%s, %d, %d)", ch, font->desc.family,
 439                 font->desc.bold, font->desc.italic);
 440         face_idx = add_face(fontconfig_priv, font, ch);
 441         if (face_idx >= 0) {
 442             face = font->faces[face_idx];
 443             index = FT_Get_Char_Index(face, ch);
 444             if (index == 0) {
 445                 ass_msg(font->library, MSGL_ERR,
 446                         "Glyph 0x%X not found in font for (%s, %d, %d)",
 447                         ch, font->desc.family, font->desc.bold,
 448                         font->desc.italic);
 449             }
 450         }
 451     }
 452 #endif
 453
 454     flags = FT_LOAD_NO_BITMAP | FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH;
 455     switch (hinting) {
 456     case ASS_HINTING_NONE:
 457         flags |= FT_LOAD_NO_HINTING;
 458         break;
 459     case ASS_HINTING_LIGHT:
 460         flags |= FT_LOAD_FORCE_AUTOHINT | FT_LOAD_TARGET_LIGHT;
 461         break;
 462     case ASS_HINTING_NORMAL:
 463         flags |= FT_LOAD_FORCE_AUTOHINT;
 464         break;
 465     case ASS_HINTING_NATIVE:
 466         break;
 467     }
 468
 469     error = FT_Load_Glyph(face, index, flags);
 470     if (error) {
 471         ass_msg(font->library, MSGL_WARN, "Error loading glyph, index %d",
 472                 index);
 473         return 0;
 474     }
 475     if (!(face->style_flags & FT_STYLE_FLAG_ITALIC) &&
 476         (font->desc.italic > 55)) {
 477         FT_GlyphSlot_Oblique(face->glyph);
 478     }
 479
 480     if (!(face->style_flags & FT_STYLE_FLAG_BOLD) &&
 481         (font->desc.bold > 80)) {
 482         ass_glyph_embolden(face->glyph);
 483     }
 484     error = FT_Get_Glyph(face->glyph, &glyph);
 485     if (error) {
 486         ass_msg(font->library, MSGL_WARN, "Error loading glyph, index %d",
 487                 index);
 488         return 0;
 489     }
 490
 491     ass_strike_outline_glyph(face, font, glyph, deco & DECO_UNDERLINE,
 492                              deco & DECO_STRIKETHROUGH);
 493
 494     return glyph;
 495 }
 496
 497 /**
 498  * \brief Get kerning for the pair of glyphs.
 499  **/
 500 FT_Vector ass_font_get_kerning(ASS_Font *font, uint32_t c1, uint32_t c2)
 501 {
 502     FT_Vector v = { 0, 0 };
 503     int i;
 504
 505     for (i = 0; i < font->n_faces; ++i) {
 506         FT_Face face = font->faces[i];
 507         int i1 = FT_Get_Char_Index(face, c1);
 508         int i2 = FT_Get_Char_Index(face, c2);
 509         if (i1 && i2) {
 510             if (FT_HAS_KERNING(face))
 511                 FT_Get_Kerning(face, i1, i2, FT_KERNING_DEFAULT, &v);
 512             return v;
 513         }
 514         if (i1 || i2)           // these glyphs are from different font faces, no kerning information
 515             return v;
 516     }
 517     return v;
 518 }
 519
 520 /**
 521  * \brief Deallocate ASS_Font
 522  **/
 523 void ass_font_free(ASS_Font *font)
 524 {
 525     int i;
 526     for (i = 0; i < font->n_faces; ++i)
 527         if (font->faces[i])
 528             FT_Done_Face(font->faces[i]);
 529     if (font->desc.family)
 530         free(font->desc.family);
 531     free(font);
 532 }