Palette color type (typically a variant of color names).

Convert a color name string to the palette type.

Color names are case-insensitive and use kebab-case format.

  (* Look up a basic color *)
  let red = Spectrum_palettes.Terminal.Xterm256.of_string "red" in
  Printf.printf "Found color: red\n"

  (* Look up compound name *)
  let color = Spectrum_palettes.Terminal.Xterm256.of_string "dark-orange" in
  Printf.printf "Found: dark-orange\n"

  (* Handle invalid names *)
  try
    let _ = Spectrum_palettes.Terminal.Xterm256.of_string "not-a-color" in
    ()
  with Spectrum_palette_ppx.Palette.InvalidColorName name ->
    Printf.printf "Invalid color: %s\n" name

• raises InvalidColorName

  if the name is not in the palette

Get the ANSI color code for a palette color.

Returns the terminal escape sequence code for this color.

  (* Get code for red *)
  let red = Spectrum_palettes.Terminal.Xterm256.of_string "red" in
  let code = Spectrum_palettes.Terminal.Xterm256.to_code red in
  Printf.printf "\027[38;5;%dm■\027[0m Red is code %d\n" code code

  (* Print all basic colors with their codes *)
  List.iter (fun name ->
      let color = Spectrum_palettes.Terminal.Basic.of_string name in
      let code = Spectrum_palettes.Terminal.Basic.to_code color in
      Printf.printf "%s: %d\n" name code
    ) ["basic-red"; "basic-green"; "basic-blue"]

Convert a palette color to its RGB representation.

Returns the color as a Gg.v4 RGBA value.

  (* Get RGB value for a color *)
  let green = Spectrum_palettes.Terminal.Xterm256.of_string "green" in
  let color = Spectrum_palettes.Terminal.Xterm256.to_color green in
  let rgba = Spectrum_tools.Convert.Color.to_rgba color in
  Printf.printf "Green: RGB(%d, %d, %d)\n" rgba.r rgba.g rgba.b

  (* Compare colors numerically *)
  let red = Spectrum_palettes.Terminal.Basic.of_string "basic-red" in
  let blue = Spectrum_palettes.Terminal.Basic.of_string "basic-blue" in
  let red_color = Spectrum_palettes.Terminal.Basic.to_color red in
  let blue_color = Spectrum_palettes.Terminal.Basic.to_color blue in
  if Gg.Color.equal red_color blue_color then
    Printf.printf "Colors are equal\n"
  else
    Printf.printf "Colors are different\n"

List of all colors in the palette (in order).

Returns a list of all palette colors as Gg.v4 values.

  (* Count colors in palette *)
  let colors = Spectrum_palettes.Terminal.Xterm256.color_list in
  Printf.printf "Xterm256 has %d colors\n" (List.length colors)
  (* Output: Xterm256 has 256 colors *)

  (* Find average color *)
  let colors = Spectrum_palettes.Terminal.Basic.color_list in
  let sum_r, sum_g, sum_b, count =
    List.fold_left (fun (r, g, b, n) color ->
        let rgba = Spectrum_tools.Convert.Color.to_rgba' color in
        (r +. rgba.r, g +. rgba.g, b +. rgba.b, n + 1)
      ) (0., 0., 0., 0) colors
  in
  let n = float_of_int count in
  Printf.printf "Average: (%.2f, %.2f, %.2f)\n"
    (sum_r /. n) (sum_g /. n) (sum_b /. n)

  (* Print all colors *)
  let colors = Spectrum_palettes.Terminal.Basic.color_list in
  List.iter (fun color ->
      let rgba = Spectrum_tools.Convert.Color.to_rgba color in
      Printf.printf "RGB(%d, %d, %d)\n" rgba.r rgba.g rgba.b
    ) colors

Find the nearest palette color to the given color using perceptual distance (LAB color space).

Uses octree-based spatial indexing in LAB space for efficient nearest-neighbor search. The returned color is guaranteed to be in the palette.

  (* Find nearest xterm-256 color to orange *)
  let orange = Gg.Color.v_srgb 1.0 0.5 0.0 in
  let nearest = Spectrum_palettes.Terminal.Xterm256.nearest orange in
  let rgba = Spectrum_tools.Convert.Color.to_rgba nearest in
  Printf.printf "Nearest to orange: RGB(%d, %d, %d)\n"
    rgba.r rgba.g rgba.b

  (* Quantize a gradient *)
  for i = 0 to 10 do
    let t = float_of_int i /. 10. in
    let color = Gg.Color.v_srgb t 0.0 (1.0 -. t) in
    let nearest = Spectrum_palettes.Terminal.Basic.nearest color in
    let rgba = Spectrum_tools.Convert.Color.to_rgba nearest in
    Printf.printf "%.1f -> RGB(%d, %d, %d)\n" t rgba.r rgba.g rgba.b
  done

  (* Find nearest basic color *)
  let custom = Gg.Color.v_srgb 0.7 0.3 0.8 in
  let nearest = Spectrum_palettes.Terminal.Basic.nearest custom in
  (* Result is one of the 16 basic ANSI colors *)