lib/taloca.c

   1 /* taloca.c */
   2
   3 /*
   4  * Copyright (C) 2011-2022 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 FT_Error
  20 TA_sfnt_build_loca_table(SFNT* sfnt,
  21                          FONT* font)
  22 {
  23   SFNT_Table* loca_table = &font->tables[sfnt->loca_idx];
  24   SFNT_Table* glyf_table = &font->tables[sfnt->glyf_idx];
  25   SFNT_Table* head_table = &font->tables[sfnt->head_idx];
  26
  27   glyf_Data* data = (glyf_Data*)glyf_table->data;
  28   GLYPH* glyph;
  29
  30   FT_ULong offset;
  31   FT_Byte loca_format;
  32   FT_Byte* buf_new;
  33   FT_Byte* p;
  34   FT_UShort i;
  35
  36
  37   if (loca_table->processed)
  38     return TA_Err_Ok;
  39
  40   /* get largest offset */
  41   offset = 0;
  42   glyph = data->glyphs;
  43
  44   for (i = 0; i < data->num_glyphs; i++, glyph++)
  45   {
  46     /* glyph records should have offsets which are multiples of 4 */
  47     offset = (offset + 3) & ~3U;
  48     offset += glyph->len1 + glyph->len2
  49               + glyph->ins_extra_len + glyph->ins_len;
  50     /* add two bytes for the instructionLength field */
  51     if (glyph->len2 || glyph->ins_len)
  52       offset += 2;
  53   }
  54
  55   /* to make the short format of the `loca' table always work, */
  56   /* the `glyf' table's length is adjusted to an even value */
  57   offset = (offset + 1) & ~1U;
  58
  59   if (offset > 0xFFFF * 2)
  60     loca_format = 1;
  61   else
  62     loca_format = 0;
  63
  64   /* fill table */
  65   if (loca_format)
  66   {
  67     loca_table->len = (data->num_glyphs + 1) * 4;
  68     buf_new = (FT_Byte*)realloc(loca_table->buf, loca_table->len);
  69     if (!buf_new)
  70       return FT_Err_Out_Of_Memory;
  71     else
  72       loca_table->buf = buf_new;
  73
  74     p = loca_table->buf;
  75     offset = 0;
  76     glyph = data->glyphs;
  77
  78     for (i = 0; i < data->num_glyphs; i++, glyph++)
  79     {
  80       offset = (offset + 3) & ~3U;
  81
  82       *(p++) = BYTE1(offset);
  83       *(p++) = BYTE2(offset);
  84       *(p++) = BYTE3(offset);
  85       *(p++) = BYTE4(offset);
  86
  87       offset += glyph->len1 + glyph->len2
  88                 + glyph->ins_extra_len + glyph->ins_len;
  89       if (glyph->len2 || glyph->ins_len)
  90         offset += 2;
  91     }
  92
  93     /* last element holds the size of the `glyf' table */
  94     offset = (offset + 1) & ~1U;
  95     *(p++) = BYTE1(offset);
  96     *(p++) = BYTE2(offset);
  97     *(p++) = BYTE3(offset);
  98     *(p++) = BYTE4(offset);
  99   }
 100   else
 101   {
 102     loca_table->len = (data->num_glyphs + 1) * 2;
 103     buf_new = (FT_Byte*)realloc(loca_table->buf,
 104                                 (loca_table->len + 3) & ~3U);
 105     if (!buf_new)
 106       return FT_Err_Out_Of_Memory;
 107     else
 108       loca_table->buf = buf_new;
 109
 110     p = loca_table->buf;
 111     offset = 0;
 112     glyph = data->glyphs;
 113
 114     for (i = 0; i < data->num_glyphs; i++, glyph++)
 115     {
 116       offset = (offset + 1) & ~1U;
 117
 118       *(p++) = HIGH(offset);
 119       *(p++) = LOW(offset);
 120
 121       offset += (glyph->len1 + glyph->len2
 122                  + glyph->ins_extra_len + glyph->ins_len + 1) >> 1;
 123       if (glyph->len2 || glyph->ins_len)
 124         offset += 1;
 125     }
 126
 127     /* last element holds the size of the `glyf' table -- */
 128     /* this value must *not* be aligned to a multiple of 4 */
 129     *(p++) = HIGH(offset);
 130     *(p++) = LOW(offset);
 131
 132     /* pad `loca' table to make its length a multiple of 4 */
 133     if (loca_table->len % 4 == 2)
 134     {
 135       *(p++) = 0;
 136       *(p++) = 0;
 137     }
 138   }
 139
 140   loca_table->checksum = TA_table_compute_checksum(loca_table->buf,
 141                                                    loca_table->len);
 142   loca_table->processed = 1;
 143
 144   head_table->buf[LOCA_FORMAT_OFFSET] = loca_format;
 145
 146   return TA_Err_Ok;
 147 }
 148
 149 /* end of taloca.c */