Function readHeader

YUViewLib/src/decoder/decoderTarga.cpp:397–490

}

std::optional<Header> readHeader(std::ifstream &file)
{
  Header header;
  header.idLength     = read8(file);
  header.colormapType = read8(file);

  auto imageTypeIdx = read8(file);
  switch (imageTypeIdx)
  {
  case 0:
    header.imageType = ImageType::NoImage;
    break;
  case 1:
    header.imageType = ImageType::UncompressedIndexed;
    break;
  case 2:
    header.imageType = ImageType::UncompressedRgb;
    break;
  case 3:
    header.imageType = ImageType::UncompressedGray;
    break;
  case 9:
    header.imageType = ImageType::RleIndexed;
    break;
  case 10:
    header.imageType = ImageType::RleRgb;
    break;
  case 11:
    header.imageType = ImageType::RleGray;
    break;
  default:
    break;
  }

  header.colormapOrigin  = read16(file);
  header.colormapLength  = read16(file);
  header.colormapDepth   = read8(file);
  header.xOrigin         = read16(file);
  header.yOrigin         = read16(file);
  header.width           = read16(file);
  header.height          = read16(file);
  header.bitsPerPixel    = read8(file);
  header.imageDescriptor = read8(file);

  header.leftToRight = (!(header.imageDescriptor & 0x10));
  header.topToBottom = (header.imageDescriptor & 0x20);

  // Invalid image size
  if (header.width == 0 || header.height == 0)
    return {};

  // Skip ID string (idLength bytes)
  if (header.idLength > 0)
  {
    auto i = header.idLength;
    while (i--)
    {
      auto chr = read8(file);