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 #define VERTICAL_LOWER_BOUND 0x02f1
  40
  41 /**
  42  * Select a good charmap, prefer Microsoft Unicode charmaps.
  43  * Otherwise, let FreeType decide.
  44  */
  45 static void charmap_magic(ASS_Library *library, FT_Face face)
  46 {
  47     int i;
  48     int ms_cmap = -1;
  49
  50     // Search for a Microsoft Unicode cmap
  51     for (i = 0; i < face->num_charmaps; ++i) {
  52         FT_CharMap cmap = face->charmaps[i];
  53         unsigned pid = cmap->platform_id;
  54         unsigned eid = cmap->encoding_id;
  55         if (pid == 3 /*microsoft */
  56             && (eid == 1 /*unicode bmp */
  57                 || eid == 10 /*full unicode */ )) {
  58             FT_Set_Charmap(face, cmap);
  59             return;
  60         } else if (pid == 3 && ms_cmap < 0)
  61             ms_cmap = i;
  62     }
  63
  64     // Try the first Microsoft cmap if no Microsoft Unicode cmap was found
  65     if (ms_cmap >= 0) {
  66         FT_CharMap cmap = face->charmaps[ms_cmap];
  67         FT_Set_Charmap(face, cmap);
  68         return;
  69     }
  70
  71     if (!face->charmap) {
  72         if (face->num_charmaps == 0) {
  73             ass_msg(library, MSGL_WARN, "Font face with no charmaps");
  74             return;
  75         }
  76         ass_msg(library, MSGL_WARN,
  77                 "No charmap autodetected, trying the first one");
  78         FT_Set_Charmap(face, face->charmaps[0]);
  79         return;
  80     }
  81 }
  82
  83 /**
  84  * \brief find a memory font by name
  85  */
  86 static int find_font(ASS_Library *library, char *name)
  87 {
  88     int i;
  89     for (i = 0; i < library->num_fontdata; ++i)
  90         if (strcasecmp(name, library->fontdata[i].name) == 0)
  91             return i;
  92     return -1;
  93 }
  94
  95 static void face_set_size(FT_Face face, double size);
  96
  97 static void buggy_font_workaround(FT_Face face)
  98 {
  99     // Some fonts have zero Ascender/Descender fields in 'hhea' table.
 100     // In this case, get the information from 'os2' table or, as
 101     // a last resort, from face.bbox.
 102     if (face->ascender + face->descender == 0 || face->height == 0) {
 103         TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 104         if (os2) {
 105             face->ascender = os2->sTypoAscender;
 106             face->descender = os2->sTypoDescender;
 107             face->height = face->ascender - face->descender;
 108         } else {
 109             face->ascender = face->bbox.yMax;
 110             face->descender = face->bbox.yMin;
 111             face->height = face->ascender - face->descender;
 112         }
 113     }
 114 }
 115
 116 /**
 117  * \brief Select a face with the given charcode and add it to ASS_Font
 118  * \return index of the new face in font->faces, -1 if failed
 119  */
 120 static int add_face(void *fc_priv, ASS_Font *font, uint32_t ch)
 121 {
 122     char *path;
 123     int index;
 124     FT_Face face;
 125     int error;
 126     int mem_idx;
 127
 128     if (font->n_faces == ASS_FONT_MAX_FACES)
 129         return -1;
 130
 131     path =
 132         fontconfig_select(font->library, fc_priv, font->desc.family,
 133                           font->desc.treat_family_as_pattern,
 134                           font->desc.bold, font->desc.italic, &index, ch);
 135     if (!path)
 136         return -1;
 137
 138     mem_idx = find_font(font->library, path);
 139     if (mem_idx >= 0) {
 140         error =
 141             FT_New_Memory_Face(font->ftlibrary,
 142                                (unsigned char *) font->library->
 143                                fontdata[mem_idx].data,
 144                                font->library->fontdata[mem_idx].size, index,
 145                                &face);
 146         if (error) {
 147             ass_msg(font->library, MSGL_WARN,
 148                     "Error opening memory font: '%s'", path);
 149             free(path);
 150             return -1;
 151         }
 152     } else {
 153         error = FT_New_Face(font->ftlibrary, path, index, &face);
 154         if (error) {
 155             ass_msg(font->library, MSGL_WARN,
 156                     "Error opening font: '%s', %d", path, index);
 157             free(path);
 158             return -1;
 159         }
 160     }
 161     charmap_magic(font->library, face);
 162     buggy_font_workaround(face);
 163
 164     font->faces[font->n_faces++] = face;
 165     face_set_size(face, font->size);
 166     free(path);
 167     return font->n_faces - 1;
 168 }
 169
 170 /**
 171  * \brief Create a new ASS_Font according to "desc" argument
 172  */
 173 ASS_Font *ass_font_new(void *font_cache, ASS_Library *library,
 174                        FT_Library ftlibrary, void *fc_priv,
 175                        ASS_FontDesc *desc)
 176 {
 177     int error;
 178     ASS_Font *fontp;
 179     ASS_Font font;
 180
 181     fontp = ass_font_cache_find((Hashmap *) font_cache, desc);
 182     if (fontp)
 183         return fontp;
 184
 185     font.library = library;
 186     font.ftlibrary = ftlibrary;
 187     font.n_faces = 0;
 188     font.desc.family = strdup(desc->family);
 189     font.desc.treat_family_as_pattern = desc->treat_family_as_pattern;
 190     font.desc.bold = desc->bold;
 191     font.desc.italic = desc->italic;
 192     font.desc.vertical = desc->vertical;
 193
 194     font.scale_x = font.scale_y = 1.;
 195     font.v.x = font.v.y = 0;
 196     font.size = 0.;
 197
 198     error = add_face(fc_priv, &font, 0);
 199     if (error == -1) {
 200         free(font.desc.family);
 201         return 0;
 202     } else
 203         return ass_font_cache_add((Hashmap *) font_cache, &font);
 204 }
 205
 206 /**
 207  * \brief Set font transformation matrix and shift vector
 208  **/
 209 void ass_font_set_transform(ASS_Font *font, double scale_x,
 210                             double scale_y, FT_Vector *v)
 211 {
 212     font->scale_x = scale_x;
 213     font->scale_y = scale_y;
 214     if (v) {
 215         font->v.x = v->x;
 216         font->v.y = v->y;
 217     }
 218 }
 219
 220 static void face_set_size(FT_Face face, double size)
 221 {
 222     TT_HoriHeader *hori = FT_Get_Sfnt_Table(face, ft_sfnt_hhea);
 223     TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 224     double mscale = 1.;
 225     FT_Size_RequestRec rq;
 226     FT_Size_Metrics *m = &face->size->metrics;
 227     // VSFilter uses metrics from TrueType OS/2 table
 228     // The idea was borrowed from asa (http://asa.diac24.net)
 229     if (hori && os2) {
 230         int hori_height = hori->Ascender - hori->Descender;
 231         int os2_height = os2->usWinAscent + os2->usWinDescent;
 232         if (hori_height && os2_height)
 233             mscale = (double) hori_height / os2_height;
 234     }
 235     memset(&rq, 0, sizeof(rq));
 236     rq.type = FT_SIZE_REQUEST_TYPE_REAL_DIM;
 237     rq.width = 0;
 238     rq.height = double_to_d6(size * mscale);
 239     rq.horiResolution = rq.vertResolution = 0;
 240     FT_Request_Size(face, &rq);
 241     m->ascender /= mscale;
 242     m->descender /= mscale;
 243     m->height /= mscale;
 244 }
 245
 246 /**
 247  * \brief Set font size
 248  **/
 249 void ass_font_set_size(ASS_Font *font, double size)
 250 {
 251     int i;
 252     if (font->size != size) {
 253         font->size = size;
 254         for (i = 0; i < font->n_faces; ++i)
 255             face_set_size(font->faces[i], size);
 256     }
 257 }
 258
 259 /**
 260  * \brief Get maximal font ascender and descender.
 261  * \param ch character code
 262  * The values are extracted from the font face that provides glyphs for the given character
 263  **/
 264 void ass_font_get_asc_desc(ASS_Font *font, uint32_t ch, int *asc,
 265                            int *desc)
 266 {
 267     int i;
 268     for (i = 0; i < font->n_faces; ++i) {
 269         FT_Face face = font->faces[i];
 270         TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 271         if (FT_Get_Char_Index(face, ch)) {
 272             int y_scale = face->size->metrics.y_scale;
 273             if (os2) {
 274                 *asc = FT_MulFix(os2->usWinAscent, y_scale);
 275                 *desc = FT_MulFix(os2->usWinDescent, y_scale);
 276             } else {
 277                 *asc = FT_MulFix(face->ascender, y_scale);
 278                 *desc = FT_MulFix(-face->descender, y_scale);
 279             }
 280             if (font->desc.vertical && ch >= VERTICAL_LOWER_BOUND) {
 281                 *asc = FT_MulFix(face->max_advance_width, y_scale);
 282             }
 283             return;
 284         }
 285     }
 286
 287     *asc = *desc = 0;
 288 }
 289
 290 /*
 291  * Strike a glyph with a horizontal line; it's possible to underline it
 292  * and/or strike through it.  For the line's position and size, truetype
 293  * tables are consulted.  Obviously this relies on the data in the tables
 294  * being accurate.
 295  *
 296  */
 297 static int ass_strike_outline_glyph(FT_Face face, ASS_Font *font,
 298                                     FT_Glyph glyph, int under, int through)
 299 {
 300     TT_OS2 *os2 = FT_Get_Sfnt_Table(face, ft_sfnt_os2);
 301     TT_Postscript *ps = FT_Get_Sfnt_Table(face, ft_sfnt_post);
 302     FT_Outline *ol = &((FT_OutlineGlyph) glyph)->outline;
 303     int bear, advance, y_scale, i, dir;
 304
 305     if (!under && !through)
 306         return 0;
 307
 308     // Grow outline
 309     i = (under ? 4 : 0) + (through ? 4 : 0);
 310     ol->points = realloc(ol->points, sizeof(FT_Vector) *
 311                          (ol->n_points + i));
 312     ol->tags = realloc(ol->tags, ol->n_points + i);
 313     i = !!under + !!through;
 314     ol->contours = realloc(ol->contours, sizeof(short) *
 315                            (ol->n_contours + i));
 316
 317     // If the bearing is negative, the glyph starts left of the current
 318     // pen position
 319     bear = FFMIN(face->glyph->metrics.horiBearingX, 0);
 320     // We're adding half a pixel to avoid small gaps
 321     advance = d16_to_d6(glyph->advance.x) + 32;
 322     y_scale = face->size->metrics.y_scale;
 323
 324     // Reverse drawing direction for non-truetype fonts
 325     dir = FT_Outline_Get_Orientation(ol);
 326
 327     // Add points to the outline
 328     if (under && ps) {
 329         int pos, size;
 330         pos = FT_MulFix(ps->underlinePosition, y_scale * font->scale_y);
 331         size = FT_MulFix(ps->underlineThickness,
 332                          y_scale * font->scale_y / 2);
 333
 334         if (pos > 0 || size <= 0)
 335             return 1;
 336
 337         FT_Vector points[4] = {
 338             {.x = bear,      .y = pos + size},
 339             {.x = advance,   .y = pos + size},
 340             {.x = advance,   .y = pos - size},
 341             {.x = bear,      .y = pos - size},
 342         };
 343
 344         if (dir == FT_ORIENTATION_TRUETYPE) {
 345             for (i = 0; i < 4; i++) {
 346                 ol->points[ol->n_points] = points[i];
 347                 ol->tags[ol->n_points++] = 1;
 348             }
 349         } else {
 350             for (i = 3; i >= 0; i--) {
 351                 ol->points[ol->n_points] = points[i];
 352                 ol->tags[ol->n_points++] = 1;
 353             }
 354         }
 355
 356         ol->contours[ol->n_contours++] = ol->n_points - 1;
 357     }
 358
 359     if (through && os2) {
 360         int pos, size;
 361         pos = FT_MulFix(os2->yStrikeoutPosition, y_scale * font->scale_y);
 362         size = FT_MulFix(os2->yStrikeoutSize, y_scale * font->scale_y / 2);
 363
 364         if (pos < 0 || size <= 0)
 365             return 1;
 366
 367         FT_Vector points[4] = {
 368             {.x = bear,      .y = pos + size},
 369             {.x = advance,   .y = pos + size},
 370             {.x = advance,   .y = pos - size},
 371             {.x = bear,      .y = pos - size},
 372         };
 373
 374         if (dir == FT_ORIENTATION_TRUETYPE) {
 375             for (i = 0; i < 4; i++) {
 376                 ol->points[ol->n_points] = points[i];
 377                 ol->tags[ol->n_points++] = 1;
 378             }
 379         } else {
 380             for (i = 3; i >= 0; i--) {
 381                 ol->points[ol->n_points] = points[i];
 382                 ol->tags[ol->n_points++] = 1;
 383             }
 384         }
 385
 386         ol->contours[ol->n_contours++] = ol->n_points - 1;
 387     }
 388
 389     return 0;
 390 }
 391
 392 /**
 393  * Slightly embold a glyph without touching its metrics
 394  */
 395 static void ass_glyph_embolden(FT_GlyphSlot slot)
 396 {
 397     int str;
 398
 399     if (slot->format != FT_GLYPH_FORMAT_OUTLINE)
 400         return;
 401
 402     str = FT_MulFix(slot->face->units_per_EM,
 403                     slot->face->size->metrics.y_scale) / 64;
 404
 405     FT_Outline_Embolden(&slot->outline, str);
 406 }
 407
 408 /**
 409  * \brief Get a glyph
 410  * \param ch character code
 411  **/
 412 FT_Glyph ass_font_get_glyph(void *fontconfig_priv, ASS_Font *font,
 413                             uint32_t ch, ASS_Hinting hinting, int deco)
 414 {
 415     int error;
 416     int index = 0;
 417     int i;
 418     FT_Glyph glyph;
 419     FT_Face face = 0;
 420     int flags = 0;
 421     int vertical = font->desc.vertical;
 422
 423     if (ch < 0x20)
 424         return 0;
 425     // Handle NBSP like a regular space when rendering the glyph
 426     if (ch == 0xa0)
 427         ch = ' ';
 428     if (font->n_faces == 0)
 429         return 0;
 430
 431     for (i = 0; i < font->n_faces; ++i) {
 432         face = font->faces[i];
 433         index = FT_Get_Char_Index(face, ch);
 434         if (index)
 435             break;
 436     }
 437
 438 #ifdef CONFIG_FONTCONFIG
 439     if (index == 0) {
 440         int face_idx;
 441         ass_msg(font->library, MSGL_INFO,
 442                 "Glyph 0x%X not found, selecting one more "
 443                 "font for (%s, %d, %d)", ch, font->desc.family,
 444                 font->desc.bold, font->desc.italic);
 445         face_idx = add_face(fontconfig_priv, font, ch);
 446         if (face_idx >= 0) {
 447             face = font->faces[face_idx];
 448             index = FT_Get_Char_Index(face, ch);
 449             if (index == 0) {
 450                 ass_msg(font->library, MSGL_ERR,
 451                         "Glyph 0x%X not found in font for (%s, %d, %d)",
 452                         ch, font->desc.family, font->desc.bold,
 453                         font->desc.italic);
 454             }
 455         }
 456     }
 457 #endif
 458
 459     flags = FT_LOAD_NO_BITMAP | FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH
 460             | FT_LOAD_IGNORE_TRANSFORM;
 461     switch (hinting) {
 462     case ASS_HINTING_NONE:
 463         flags |= FT_LOAD_NO_HINTING;
 464         break;
 465     case ASS_HINTING_LIGHT:
 466         flags |= FT_LOAD_FORCE_AUTOHINT | FT_LOAD_TARGET_LIGHT;
 467         break;
 468     case ASS_HINTING_NORMAL:
 469         flags |= FT_LOAD_FORCE_AUTOHINT;
 470         break;
 471     case ASS_HINTING_NATIVE:
 472         break;
 473     }
 474
 475     error = FT_Load_Glyph(face, index, flags);
 476     if (error) {
 477         ass_msg(font->library, MSGL_WARN, "Error loading glyph, index %d",
 478                 index);
 479         return 0;
 480     }
 481     if (!(face->style_flags & FT_STYLE_FLAG_ITALIC) &&
 482         (font->desc.italic > 55)) {
 483         FT_GlyphSlot_Oblique(face->glyph);
 484     }
 485
 486     if (!(face->style_flags & FT_STYLE_FLAG_BOLD) &&
 487         (font->desc.bold > 80)) {
 488         ass_glyph_embolden(face->glyph);
 489     }
 490     error = FT_Get_Glyph(face->glyph, &glyph);
 491     if (error) {
 492         ass_msg(font->library, MSGL_WARN, "Error loading glyph, index %d",
 493                 index);
 494         return 0;
 495     }
 496
 497     // Rotate glyph, if needed
 498     if (vertical && ch >= VERTICAL_LOWER_BOUND) {
 499         FT_Matrix m = { 0, double_to_d16(-1.0), double_to_d16(1.0), 0 };
 500         FT_Outline_Transform(&((FT_OutlineGlyph) glyph)->outline, &m);
 501         FT_Outline_Translate(&((FT_OutlineGlyph) glyph)->outline,
 502                              face->glyph->metrics.vertAdvance,
 503                              0);
 504         glyph->advance.x = face->glyph->linearVertAdvance;
 505     }
 506
 507     // Apply scaling and shift
 508     FT_Matrix scale = { double_to_d16(font->scale_x), 0, 0,
 509                         double_to_d16(font->scale_y) };
 510     FT_Outline *outl = &((FT_OutlineGlyph) glyph)->outline;
 511     FT_Outline_Transform(outl, &scale);
 512     FT_Outline_Translate(outl, font->v.x, font->v.y);
 513     glyph->advance.x *= font->scale_x;
 514
 515     ass_strike_outline_glyph(face, font, glyph, deco & DECO_UNDERLINE,
 516                              deco & DECO_STRIKETHROUGH);
 517
 518     return glyph;
 519 }
 520
 521 /**
 522  * \brief Get kerning for the pair of glyphs.
 523  **/
 524 FT_Vector ass_font_get_kerning(ASS_Font *font, uint32_t c1, uint32_t c2)
 525 {
 526     FT_Vector v = { 0, 0 };
 527     int i;
 528
 529     if (font->desc.vertical)
 530         return v;
 531
 532     for (i = 0; i < font->n_faces; ++i) {
 533         FT_Face face = font->faces[i];
 534         int i1 = FT_Get_Char_Index(face, c1);
 535         int i2 = FT_Get_Char_Index(face, c2);
 536         if (i1 && i2) {
 537             if (FT_HAS_KERNING(face))
 538                 FT_Get_Kerning(face, i1, i2, FT_KERNING_DEFAULT, &v);
 539             return v;
 540         }
 541         if (i1 || i2)           // these glyphs are from different font faces, no kerning information
 542             return v;
 543     }
 544     return v;
 545 }
 546
 547 /**
 548  * \brief Deallocate ASS_Font
 549  **/
 550 void ass_font_free(ASS_Font *font)
 551 {
 552     int i;
 553     for (i = 0; i < font->n_faces; ++i)
 554         if (font->faces[i])
 555             FT_Done_Face(font->faces[i]);
 556     if (font->desc.family)
 557         free(font->desc.family);
 558     free(font);
 559 }
 560
 561 /**
 562  * \brief Calculate the cbox of a series of points
 563  */
 564 static void
 565 get_contour_cbox(FT_BBox *box, FT_Vector *points, int start, int end)
 566 {
 567     box->xMin = box->yMin = INT_MAX;
 568     box->xMax = box->yMax = INT_MIN;
 569     int i;
 570
 571     for (i = start; i <= end; i++) {
 572         box->xMin = (points[i].x < box->xMin) ? points[i].x : box->xMin;
 573         box->xMax = (points[i].x > box->xMax) ? points[i].x : box->xMax;
 574         box->yMin = (points[i].y < box->yMin) ? points[i].y : box->yMin;
 575         box->yMax = (points[i].y > box->yMax) ? points[i].y : box->yMax;
 576     }
 577 }
 578
 579 /**
 580  * \brief Determine winding direction of a contour
 581  * \return direction; 0 = clockwise
 582  */
 583 static int get_contour_direction(FT_Vector *points, int start, int end)
 584 {
 585     int i;
 586     long long sum = 0;
 587     int x = points[start].x;
 588     int y = points[start].y;
 589     for (i = start + 1; i <= end; i++) {
 590         sum += x * (points[i].y - y) - y * (points[i].x - x);
 591         x = points[i].x;
 592         y = points[i].y;
 593     }
 594     sum += x * (points[start].y - y) - y * (points[start].x - x);
 595     return sum > 0;
 596 }
 597
 598 /**
 599  * \brief Fix-up stroker result for huge borders by removing inside contours
 600  * that would reverse in size
 601  */
 602 void fix_freetype_stroker(FT_OutlineGlyph glyph, int border_x, int border_y)
 603 {
 604     int nc = glyph->outline.n_contours;
 605     int begin, stop;
 606     char modified = 0;
 607     char *valid_cont = malloc(nc);
 608     int start = 0;
 609     int end = -1;
 610     FT_BBox *boxes = malloc(nc * sizeof(FT_BBox));
 611     int i, j;
 612     int inside_direction;
 613
 614     inside_direction = FT_Outline_Get_Orientation(&glyph->outline) ==
 615         FT_ORIENTATION_TRUETYPE;
 616
 617     // create a list of cboxes of the contours
 618     for (i = 0; i < nc; i++) {
 619         start = end + 1;
 620         end = glyph->outline.contours[i];
 621         get_contour_cbox(&boxes[i], glyph->outline.points, start, end);
 622     }
 623
 624     // for each contour, check direction and whether it's "outside"
 625     // or contained in another contour
 626     end = -1;
 627     for (i = 0; i < nc; i++) {
 628         start = end + 1;
 629         end = glyph->outline.contours[i];
 630         int dir = get_contour_direction(glyph->outline.points, start, end);
 631         valid_cont[i] = 1;
 632         if (dir == inside_direction) {
 633             for (j = 0; j < nc; j++) {
 634                 if (i == j)
 635                     continue;
 636                 if (boxes[i].xMin >= boxes[j].xMin &&
 637                     boxes[i].xMax <= boxes[j].xMax &&
 638                     boxes[i].yMin >= boxes[j].yMin &&
 639                     boxes[i].yMax <= boxes[j].yMax)
 640                     goto check_inside;
 641             }
 642             /* "inside" contour but we can't find anything it could be
 643              * inside of - assume the font is buggy and it should be
 644              * an "outside" contour, and reverse it */
 645             for (j = 0; j < (end + 1 - start) / 2; j++) {
 646                 FT_Vector temp = glyph->outline.points[start + j];
 647                 char temp2 = glyph->outline.tags[start + j];
 648                 glyph->outline.points[start + j] = glyph->outline.points[end - j];
 649                 glyph->outline.points[end - j] = temp;
 650                 glyph->outline.tags[start + j] = glyph->outline.tags[end - j];
 651                 glyph->outline.tags[end - j] = temp2;
 652             }
 653             dir ^= 1;
 654         }
 655         check_inside:
 656         if (dir == inside_direction) {
 657             FT_BBox box;
 658             get_contour_cbox(&box, glyph->outline.points, start, end);
 659             int width = box.xMax - box.xMin;
 660             int height = box.yMax - box.yMin;
 661             if (width < border_x * 2 || height < border_y * 2) {
 662                 valid_cont[i] = 0;
 663                 modified = 1;
 664             }
 665         }
 666     }
 667
 668     // zero-out contours that can be removed; much simpler than copying
 669     if (modified) {
 670         for (i = 0; i < nc; i++) {
 671             if (valid_cont[i])
 672                 continue;
 673             begin = (i == 0) ? 0 : glyph->outline.contours[i - 1] + 1;
 674             stop = glyph->outline.contours[i];
 675             for (j = begin; j <= stop; j++) {
 676                 glyph->outline.points[j].x = 0;
 677                 glyph->outline.points[j].y = 0;
 678                 glyph->outline.tags[j] = 0;
 679             }
 680         }
 681     }
 682
 683     free(boxes);
 684     free(valid_cont);
 685 }
 686