lib/tattf.c

   1 /* tattf.c */
   2
   3 /*
   4  * Copyright (C) 2011-2014 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 /* If `do_complete' is 0, only return `header_len'. */
  20
  21 FT_Error
  22 TA_sfnt_build_TTF_header(SFNT* sfnt,
  23                          FONT* font,
  24                          FT_Byte** header_buf,
  25                          FT_ULong* header_len,
  26                          FT_Int do_complete)
  27 {
  28   SFNT_Table* tables = font->tables;
  29
  30   SFNT_Table_Info* table_infos = sfnt->table_infos;
  31   FT_ULong num_table_infos = sfnt->num_table_infos;
  32
  33   FT_Byte* buf;
  34   FT_ULong len;
  35
  36   FT_Byte* table_record;
  37
  38   FT_Byte* head_buf = NULL; /* pointer to `head' table */
  39   FT_ULong head_checksum; /* checksum in `head' table */
  40
  41   FT_ULong num_tables_in_header;
  42   FT_ULong i;
  43
  44
  45   num_tables_in_header = 0;
  46   for (i = 0; i < num_table_infos; i++)
  47   {
  48     /* ignore empty tables */
  49     if (table_infos[i] != MISSING)
  50       num_tables_in_header++;
  51   }
  52
  53   len = 12 + 16 * num_tables_in_header;
  54   if (!do_complete)
  55   {
  56     *header_len = len;
  57     return TA_Err_Ok;
  58   }
  59   buf = (FT_Byte*)malloc(len);
  60   if (!buf)
  61     return FT_Err_Out_Of_Memory;
  62
  63   /* SFNT version */
  64   buf[0] = 0x00;
  65   buf[1] = 0x01;
  66   buf[2] = 0x00;
  67   buf[3] = 0x00;
  68
  69   /* number of tables */
  70   buf[4] = HIGH(num_tables_in_header);
  71   buf[5] = LOW(num_tables_in_header);
  72
  73   /* auxiliary data */
  74   {
  75     FT_ULong search_range, entry_selector, range_shift;
  76     FT_ULong i, j;
  77
  78
  79     for (i = 1, j = 2; j <= num_tables_in_header; i++, j <<= 1)
  80       ;
  81
  82     entry_selector = i - 1;
  83     search_range = 0x10 << entry_selector;
  84     range_shift = (num_tables_in_header << 4) - search_range;
  85
  86     buf[6] = HIGH(search_range);
  87     buf[7] = LOW(search_range);
  88     buf[8] = HIGH(entry_selector);
  89     buf[9] = LOW(entry_selector);
  90     buf[10] = HIGH(range_shift);
  91     buf[11] = LOW(range_shift);
  92   }
  93
  94   /* location of the first table info record */
  95   table_record = &buf[12];
  96
  97   head_checksum = 0;
  98
  99   /* loop over all tables */
 100   for (i = 0; i < num_table_infos; i++)
 101   {
 102     SFNT_Table_Info table_info = table_infos[i];
 103     SFNT_Table* table;
 104
 105
 106     /* ignore empty slots */
 107     if (table_info == MISSING)
 108       continue;
 109
 110     table = &tables[table_info];
 111
 112     if (table->tag == TTAG_head)
 113     {
 114       FT_ULong date_high;
 115       FT_ULong date_low;
 116
 117
 118       /* we always reach this IF clause since FreeType would */
 119       /* have aborted already if the `head' table were missing */
 120
 121       head_buf = table->buf;
 122
 123       /* reset checksum in `head' table for recalculation */
 124       head_buf[8] = 0x00;
 125       head_buf[9] = 0x00;
 126       head_buf[10] = 0x00;
 127       head_buf[11] = 0x00;
 128
 129       /* update modification time */
 130       TA_get_current_time(&date_high, &date_low);
 131
 132       head_buf[28] = BYTE1(date_high);
 133       head_buf[29] = BYTE2(date_high);
 134       head_buf[30] = BYTE3(date_high);
 135       head_buf[31] = BYTE4(date_high);
 136
 137       head_buf[32] = BYTE1(date_low);
 138       head_buf[33] = BYTE2(date_low);
 139       head_buf[34] = BYTE3(date_low);
 140       head_buf[35] = BYTE4(date_low);
 141
 142       table->checksum = TA_table_compute_checksum(table->buf, table->len);
 143     }
 144
 145     head_checksum += table->checksum;
 146
 147     table_record[0] = BYTE1(table->tag);
 148     table_record[1] = BYTE2(table->tag);
 149     table_record[2] = BYTE3(table->tag);
 150     table_record[3] = BYTE4(table->tag);
 151
 152     table_record[4] = BYTE1(table->checksum);
 153     table_record[5] = BYTE2(table->checksum);
 154     table_record[6] = BYTE3(table->checksum);
 155     table_record[7] = BYTE4(table->checksum);
 156
 157     table_record[8] = BYTE1(table->offset);
 158     table_record[9] = BYTE2(table->offset);
 159     table_record[10] = BYTE3(table->offset);
 160     table_record[11] = BYTE4(table->offset);
 161
 162     table_record[12] = BYTE1(table->len);
 163     table_record[13] = BYTE2(table->len);
 164     table_record[14] = BYTE3(table->len);
 165     table_record[15] = BYTE4(table->len);
 166
 167     table_record += 16;
 168   }
 169
 170   /* the font header is complete; compute `head' checksum */
 171   head_checksum += TA_table_compute_checksum(buf, len);
 172   head_checksum = 0xB1B0AFBAUL - head_checksum;
 173
 174   /* store checksum in `head' table; */
 175   head_buf[8] = BYTE1(head_checksum);
 176   head_buf[9] = BYTE2(head_checksum);
 177   head_buf[10] = BYTE3(head_checksum);
 178   head_buf[11] = BYTE4(head_checksum);
 179
 180   *header_buf = buf;
 181   *header_len = len;
 182
 183   return TA_Err_Ok;
 184 }
 185
 186
 187 FT_Error
 188 TA_font_build_TTF(FONT* font)
 189 {
 190   SFNT* sfnt = &font->sfnts[0];
 191
 192   SFNT_Table* tables;
 193   FT_ULong num_tables;
 194
 195   FT_ULong SFNT_offset;
 196
 197   FT_Byte* DSIG_buf;
 198
 199   FT_Byte* header_buf;
 200   FT_ULong header_len;
 201
 202   FT_ULong i;
 203   FT_Error error;
 204
 205
 206   /* replace an existing `DSIG' table with a dummy */
 207
 208   if (font->have_DSIG)
 209   {
 210     error = TA_sfnt_add_table_info(sfnt);
 211     if (error)
 212       return error;
 213
 214     error = TA_table_build_DSIG(&DSIG_buf);
 215     if (error)
 216       return error;
 217
 218     /* in case of success, `DSIG_buf' gets linked */
 219     /* and is eventually freed in `TA_font_unload' */
 220     error = TA_font_add_table(font,
 221                               &sfnt->table_infos[sfnt->num_table_infos - 1],
 222                               TTAG_DSIG, DSIG_LEN, DSIG_buf);
 223     if (error)
 224     {
 225       free(DSIG_buf);
 226       return error;
 227     }
 228   }
 229
 230   TA_sfnt_sort_table_info(sfnt, font);
 231
 232   /* the first SFNT table immediately follows the header */
 233   (void)TA_sfnt_build_TTF_header(sfnt, font, NULL, &SFNT_offset, 0);
 234   TA_font_compute_table_offsets(font, SFNT_offset);
 235
 236   error = TA_sfnt_build_TTF_header(sfnt, font,
 237                                    &header_buf, &header_len, 1);
 238   if (error)
 239     return error;
 240
 241   /* build font */
 242
 243   tables = font->tables;
 244   num_tables = font->num_tables;
 245
 246   /* get font length from last SFNT table array element */
 247   font->out_len = tables[num_tables - 1].offset
 248                   + ((tables[num_tables - 1].len + 3) & ~3);
 249   font->out_buf = (FT_Byte*)malloc(font->out_len);
 250   if (!font->out_buf)
 251   {
 252     error = FT_Err_Out_Of_Memory;
 253     goto Err;
 254   }
 255
 256   memcpy(font->out_buf, header_buf, header_len);
 257
 258   for (i = 0; i < num_tables; i++)
 259   {
 260     SFNT_Table* table = &tables[i];
 261
 262
 263     /* buffer length is a multiple of 4 */
 264     memcpy(font->out_buf + table->offset,
 265            table->buf, (table->len + 3) & ~3);
 266   }
 267
 268   error = TA_Err_Ok;
 269
 270 Err:
 271   free(header_buf);
 272
 273   return error;
 274 }
 275
 276 /* end of tattf.c */