@spec generate(
  [map()],
  struct()
) :: String.t()

Generates an SVG graph from measurement results.

Parameters

• results - List of measurement result maps containing:
  • :sample - Sample number
  • :wavelengths - List of wavelengths
  • :absorbance - List of absorbance values
• mode - A Nanodrop.Mode implementation (e.g., %Nanodrop.Mode.DNA{})

Returns

SVG string.

@spec generate_png([map()], struct(), keyword()) :: {:ok, binary()} | {:error, term()}

Generates a PNG binary with embedded metadata.

Returns {:ok, png_binary} or {:error, reason}.

The PNG includes spectrum data as JSON in the png-comment chunk. Additional metadata can be passed in the metadata option.

Options

• :metadata - Additional metadata map to merge into the embedded JSON

Example

result = %{
  sample: 1,
  wavelengths: [...],
  absorbance: [...],
  a260: 1.5,
  a280: 0.8,
  ratio: 1.87,
  concentration: 75.0
}
{:ok, png} = Nanodrop.Graph.generate_png([result], %Nanodrop.Mode.DNA{},
  metadata: %{timestamp: "2026-04-11T10:30:00Z", device_serial: "ABC123"}
)

@spec save([map()], String.t(), struct()) :: :ok

Generates an SVG graph and saves to file.

If filename ends in .png, converts SVG to PNG using Vix/libvips. Otherwise saves as SVG.

PNG files include spectrum data as metadata (JSON in png-comment chunk).