Function SaveMultiChannelEXR

SampleFramework11/v1.02/TinyEXR.cpp:7540–7751

#endif

int SaveMultiChannelEXR(const EXRImage *exrImage, const char *filename,
                        const char **err) {
  if (exrImage == NULL || filename == NULL) {
    if (err) {
      (*err) = "Invalid argument.";
    }
    return -1;
  }

  FILE *fp = fopen(filename, "wb");
  if (!fp) {
    if (err) {
      (*err) = "Cannot write a file.";
    }
    return -1;
  }

  // Header
  {
    const char header[] = {0x76, 0x2f, 0x31, 0x01};
    size_t n = fwrite(header, 1, 4, fp);
    assert(n == 4);
  }

  // Version, scanline.
  {
    const char marker[] = {2, 0, 0, 0};
    size_t n = fwrite(marker, 1, 4, fp);
    assert(n == 4);
  }

  int numScanlineBlocks = 16; // 16 for ZIP compression.

  // Write attributes.
  {
    std::vector<unsigned char> data;

    std::vector<ChannelInfo> channels;
    for (int c = 0; c < exrImage->num_channels; c++) {
      ChannelInfo info;
      info.pLinear = 0;
      info.pixelType = 1; // Assume HALF
      info.xSampling = 1;
      info.ySampling = 1;
      info.name = std::string(exrImage->channel_names[c]);
      channels.push_back(info);
    }

    WriteChannelInfo(data, channels);

    WriteAttribute(fp, "channels", "chlist", &data.at(0),
                   data.size()); // +1 = null
  }

  {
    int compressionType = 3; // ZIP compression
    if (IsBigEndian()) {
      swap4(reinterpret_cast<unsigned int*>(&compressionType));