Function addChunk_tRNS

deps/lodepng/lodepng.cpp:4995–5038

}

static unsigned addChunk_tRNS(ucvector* out, const LodePNGColorMode* info)
{
  unsigned error = 0;
  size_t i;
  ucvector tRNS;
  ucvector_init(&tRNS);
  if(info->colortype == LCT_PALETTE)
  {
    size_t amount = info->palettesize;
    /*the tail of palette values that all have 255 as alpha, does not have to be encoded*/
    for(i = info->palettesize; i != 0; --i)
    {
      if(info->palette[4 * (i - 1) + 3] == 255) --amount;
      else break;
    }
    /*add only alpha channel*/
    for(i = 0; i != amount; ++i) ucvector_push_back(&tRNS, info->palette[4 * i + 3]);
  }
  else if(info->colortype == LCT_GREY)
  {
    if(info->key_defined)
    {
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r & 255));
    }
  }
  else if(info->colortype == LCT_RGB)
  {
    if(info->key_defined)
    {
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r & 255));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_g >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_g & 255));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_b >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_b & 255));
    }
  }

  error = addChunk(out, "tRNS", tRNS.data, tRNS.size);
  ucvector_cleanup(&tRNS);

  return error;
}

static unsigned addChunk_IDAT(ucvector* out, const unsigned char* data, size_t datasize,
                              LodePNGCompressSettings* zlibsettings)