static unsigned addChunk_zTXt(ucvector* out, const char* keyword, const char* textstring,
                              LodePNGCompressSettings* zlibsettings)
{
  unsigned error = 0;
  ucvector data, compressed;
  size_t i, textsize = strlen(textstring);

  ucvector_init(&data);
  ucvector_init(&compressed);
  for(i = 0; keyword[i] != 0; i++) ucvector_push_back(&data, (unsigned char)keyword[i]);
  if(i < 1 || i > 79) return 89; /*error: invalid keyword size*/
  ucvector_push_back(&data, 0); /*0 termination char*/
  ucvector_push_back(&data, 0); /*compression method: 0*/

  error = zlib_compress(&compressed.data, &compressed.size,
                        (unsigned char*)textstring, textsize, zlibsettings);
  if(!error)
  {
    for(i = 0; i < compressed.size; i++) ucvector_push_back(&data, compressed.data[i]);
    error = addChunk(out, "zTXt", data.data, data.size);
  }

  ucvector_cleanup(&compressed);
  ucvector_cleanup(&data);
  return error;
}
Unknown