RGB to HSL

color.gd

extends Node

const S_FOREGROUND = 100 / 255.0
const L_FOREGROUND = 217 / 255.0

const PRELOADED_COLORS = {
  red = Color('f44336'),
  pink = Color('e91e63'),
  purple = Color('9c27b0'),
  deep_purple = Color('673ab7'),
  indigo = Color('3f51b5'),
  blue = Color('2196f3'),
  light_blue = Color('03a9f4'),
  cyan = Color('00bcd4'),
  teal =Color('009688'),
  green = Color('4caf50'),
  light_green = Color('8bc34a'),
  lime = Color('cddc39'),
  yellow = Color('ffeb3b'),
  amber = Color('ffc107'),
  orange = Color('ff9800'),
  deep_orange = Color('ff5722'),
  brown = Color('795548'),
  grey = Color('9e9e9e'),
  blue_grey = Color('607d8b')
}


static func to_hsl(r, g, b):
  var max_value = max(max(r, g), b)
  var min_value = min(min(r, g), b)

  var h = (max_value + min_value) / 2.0
  var s = (max_value + min_value) / 2.0
  var l = (max_value + min_value) / 2.0

  if max_value == min_value:
    h = 0
    s = 0
  else:
    var d = max_value - min_value * 1.0

    if l > 0.5:
      s = d / (2.0 - max_value - min_value)
    else:
      s = d / (max_value + min_value)

    if max_value == r:
      h = (g - b) / d

      if g < b:
        h += 6.0

    elif max_value == g:
      h = (b - r) / d + 2
    else:
      h = (r - g) / d + 4

    h /= 6.0

  return [h, s, l]

static func hue2rgb(p, q, t):
  if t < 0:
    t += 1

  if t > 1:
    t -= 1

  if t < 1 / 6.0:
    return p + (q - p) * 6.0 * t

  if t < 1 / 2.0:
    return q

  if t < 2 / 3.0:
    return p + (q - p) * (2 / 3.0 - t) * 6.0

  return p

static func to_rgb(h, s, l):
  var r
  var g
  var b

  if s == 0:
    r = 1
    g = 1
    b = 1
  else:
    var q = l + s - l * s

    if l < 0.5:
      q = l * (1 + s)

    var p = 2 * l - q

    r = hue2rgb(p, q, h + 1 / 3.0)
    g = hue2rgb(p, q, h)
    b = hue2rgb(p, q, h - 1 / 3.0)

  return Color(r, g, b)

static func get_color_from_name(name):
  return PRELOADED_COLORS[name]

static func compute_foreground_color(colors):
  var melted_color = Color(0.0, 0.0, 0.0)

  for raw_color in colors:
    var color_item = get_color_from_name(raw_color)

    melted_color.r += color_item.r
    melted_color.g += color_item.g
    melted_color.b += color_item.b

  melted_color.r = melted_color.r / colors.size()
  melted_color.g = melted_color.g / colors.size()
  melted_color.b = melted_color.b / colors.size()

  var hsl = to_hsl(melted_color.r, melted_color.g, melted_color.b)

  return to_rgb(hsl[0], S_FOREGROUND, L_FOREGROUND)

I used a stackoverflow question to create this script:
https://stackoverflow.com/questions/2353211/hsl-to-rgb-color-conversion