Module:Color/sandbox

-- Introduction: https://colorspace.r-forge.r-project.org/articles/color_spaces.html

local p = {}

local function isEmpty(value) return value == nil or value == '' end

local function isNotEmpty(value) return value ~= nil and value ~= '' end

local function argDefault(value, default) if (value == nil or value == '') then return default else return value end end

local function numArgDefault(value, default) if (value == nil or value == '') then return default else return tonumber(value) end end

local function isArgTrue(value) return (value ~= nil and value ~= '' and value ~= '0') end

local function isEmpty(value) return value == nil or value == '' end

local function isNotEmpty(value) return value ~= nil and value ~= '' end

local function hexToRgb(hexColor) local cleanColor = hexColor:gsub('&#35;', '#'):match('^[%s#]*(.-)[%s;]*$') if (#cleanColor == 6) then return tonumber(string.sub(cleanColor, 1, 2), 16), tonumber(string.sub(cleanColor, 3, 4), 16), tonumber(string.sub(cleanColor, 5, 6), 16) elseif (#cleanColor == 3) then return 17 * tonumber(string.sub(cleanColor, 1, 1), 16), 17 * tonumber(string.sub(cleanColor, 2, 2), 16), 17 * tonumber(string.sub(cleanColor, 3, 3), 16) end error('Invalid hexadecimal color ' .. cleanColor, 1) end

local function round(value) if (value < 0) then return math.ceil(value - 0.5) else return math.floor(value + 0.5) end end

local function rgbToHex(r, g, b)	return string.format('%02X%02X%02X', round(r), round(g), round(b)) end

local function checkRgb(r, g, b)	if (r > 255 or g > 255 or b > 255 or r < 0 or g < 0 or b < 0) then error('Color level out of bounds') end end

local function rgbToCmyk(r, g, b)	local c = 1 - r / 255 local m = 1 - g / 255 local y = 1 - b / 255 local k = math.min(c, m, y)	if (k == 1) then c = 0 m = 0 y = 0 else local kc = 1 - k		c = (c - k) / kc		m = (m - k) / kc		y = (y - k) / kc	end return c * 100, m * 100, y * 100, k * 100 end

local function rgbToHsl(r, g, b)	local channelMax = math.max(r, g, b)	local channelMin = math.min(r, g, b)	local range = channelMax - channelMin local h, s	if (range == 0) then h = 0 elseif (channelMax == r) then h = 60 * ((g - b) / range) if (h < 0) then h = 360 + h		end elseif (channelMax == g) then h = 60 * (2 + (b - r) / range) else h = 60 * (4 + (r - g) / range) end local L = channelMax + channelMin if (L == 0 or L == 510) then s = 0 else s = 100 * range / math.min(L, 510 - L)	end return h, s, L * 50 / 255 end

local function rgbToHsv(r, g, b)	local channelMax = math.max(r, g, b)	local channelMin = math.min(r, g, b)	local range = channelMax - channelMin local h, s	if (range == 0) then h = 0 elseif (channelMax == r) then h = 60 * ((g - b) / range) if (h < 0) then h = 360 + h		end elseif (channelMax == g) then h = 60 * (2 + (b - r) / range) else h = 60 * (4 + (r - g) / range) end if (channelMax == 0) then s = 0 else s = 100 * range / channelMax end return h, s, channelMax * 100 / 255 end

local function checkHsv(h, s, v)	if (s > 100 or v > 100 or s < 0 or v < 0) then error('Color level out of bounds') end end

local function hsvToRgb(h, s, v)	local hn = (h / 60 - 6 * math.floor(h / 360)) local hi = math.floor(hn) local hr = hn - hi	local sn = s / 100 local vs = v * 255 / 100 local p = vs * (1 - sn); local q = vs * (1 - sn * hr); local t = vs * (1 - sn * (1 - hr)); if (hi < 3) then if (hi == 0) then return vs, t, p		elseif (hi == 1) then return q, vs, p		else return p, vs, t		end else if (hi == 3) then return p, q, vs		elseif (hi == 4) then return t, p, vs		else return vs, p, q		end end end

-- c in [0, 255], condition tweaked for no discontinuity -- http://entropymine.com/imageworsener/srgbformula/ local function toLinear(c) if (c > 10.314300250662591) then return math.pow((c + 14.025) / 269.025, 2.4) else return c / 3294.6 end end

local function toNonLinear(c) if (c > 0.00313066844250063) then return 269.025 * math.pow(c, 1.0/2.4) - 14.025 else return 3294.6 * c	end end

local function srgbToCielchuvD65o2deg(r, g, b)	local R = toLinear(r) local G = toLinear(g) local B = toLinear(b) -- https://github.com/w3c/csswg-drafts/issues/5922 local X = 0.1804807884018343 * B + 0.357584339383878 * G + 0.41239079926595934 * R	local Y = 0.07219231536073371 * B + 0.21263900587151027 * R + 0.715168678767756 * G	local Z = 0.01933081871559182 * R + 0.11919477979462598 * G + 0.9505321522496607 * B	local L, C, h	if (Y > 0.00885645167903563082) then L = 116 * math.pow(Y, 1/3) - 16 else L = Y * 903.2962962962962962963 end if ((r == g and g == b) or L == 0) then C = 0 h = 0 else d = X + 3 * Z + 15 * Y		if (d == 0) then C = 0 h = 0 else -- 0.19783... and 0.4631... computed with extra precision from (X,Y,Z) when (R,G,B) = (1,1,1), -- in which case (u,v) ≈ (0,0) local us = 4 * X / d - 0.19783000664283678994 local vs = 9 * Y / d - 0.46831999493879099801 h = math.atan2(vs, us) * 57.2957795130823208768 if (h < 0) then h = h + 360 elseif (h == 0) then h = 0 -- ensure zero is positive end C = math.sqrt(us * us + vs * vs) * 13 * L			if (C == 0) then C = 0 h = 0 end end end return L, C, h end

local function checkInterpolationParameter(t) if (t > 1 or t < 0) then error('Interpolation parameter out of bounds') end end

local function srgbMix(t, r0, g0, b0, r1, g1, b1) local tc = 1 - t	return toNonLinear(tc * toLinear(r0) + t * toLinear(r1)), toNonLinear(tc * toLinear(g0) + t * toLinear(g1)), toNonLinear(tc * toLinear(b0) + t * toLinear(b1)) end

-- functions for generating gradients, inspired by OKLCH but not needing gamut mapping local function adjustHueToCielch(h) local n = 180 * math.floor(h / 180) local d = h - n	if (d < 60) then d = 73.7 * d / 60 elseif (d < 120) then d = 0.6975 * d + 31.85 else d = 1.07416666666666666667 * d - 13.35 end return n + d end

local function unadjustHueFromCielch(h) local n = 180 * math.floor(h / 180) local d = h - n	if (d < 73.7) then d = 0.81411126187245590231 * d	elseif (d < 115.55) then d = 1.43369175627240143369 * d - 45.66308243727598566308 else d = 0.93095422808378588053 * d + 12.42823894491854150504 end return n + d end

local function getLightness(r, g, b)	local Y = 0.07219231536073371 * toLinear(b) + 0.21263900587151027 * toLinear(r) + 0.715168678767756 * toLinear(g) if (Y > 0.00885645167903563082) then return 116 * math.pow(Y, 1/3) - 16 else return Y * 903.2962962962962962963 end end

local function adjustLightness(L, r, g, b)	if (L >= 100) then return 255, 255, 255 end local Yc	if (L > 8) then Yc = (L + 16) / 116 Yc = Yc * Yc * Yc	else Yc = L * 0.00110705645987945385 end local R = toLinear(r) local G = toLinear(g) local B = toLinear(b) local Y = 0.07219231536073371 * B + 0.21263900587151027 * R + 0.715168678767756 * G	if (Y > 0) then local scale = Yc / Y		R = R * scale G = G * scale B = B * scale local cmax = math.max(R, G, B)		if (cmax > 1) then R = R / cmax G = G / cmax B = B / cmax local d = 0.07219231536073371 * (1 - B) + 0.21263900587151027 * (1 - R) + 0.715168678767756 * (1 - G)			if (d <= 0) then R = 1 G = 1 B = 1 else local strength = 0.5 -- 1 yields equal lightness local t = (Yc - 0.07219231536073371 * B - 0.21263900587151027 * R - 0.715168678767756 * G) / d				R = R + strength * (1 - R) * t				G = G + strength * (1 - G) * t				B = B + strength * (1 - B) * t			end end else R = Yc		G = Yc		B = Yc	end return toNonLinear(R), toNonLinear(G), toNonLinear(B) end

local function interpolateHue(t, r0, g0, b0, r1, g1, b1, direction) local h0, s0, v0 = rgbToHsv(r0, g0, b0) local h1, s1, v1 = rgbToHsv(r1, g1, b1) if (s0 == 0) then h0 = h1		if (v0 == 0) then s0 = s1		end end if (s1 == 0) then h1 = h0		if (v1 == 0) then s1 = s1		end end local hn0 = h0 / 360 local hn1 = h1 / 360 if (direction == 0) then local dhn = hn1 - hn0 if (dhn > 0.5) then dhn = dhn - math.ceil(dhn - 0.5) elseif (dhn < -0.5) then dhn = dhn - math.floor(dhn + 0.5) end if (dhn >= 0) then hn0 = hn0 - math.floor(hn0) hn1 = hn0 + dhn else hn1 = hn1 - math.floor(hn1) hn0 = hn1 - dhn end elseif (direction > 0) then hn1 = 1 - math.ceil(hn1 - hn0) - math.floor(hn0) + hn1 hn0 = hn0 - math.floor(hn0) else hn0 = 1 - math.ceil(hn0 - hn1) - math.floor(hn1) + hn0 hn1 = hn1 - math.floor(hn1) end if (t < 0) then t = 0 elseif (t > 1) then t = 1 end local tc = 1 - t	local ha = tc * adjustHueToCielch(360 * hn0) + t * adjustHueToCielch(360 * hn1) local r, g, b = hsvToRgb(unadjustHueFromCielch(ha), tc * s0 + t * s1, tc * v0 + t * v1) local L0 = getLightness(r0, g0, b0) local L1 = getLightness(r1, g1, b1) return adjustLightness(tc * L0 + t * L1, r, g, b) end

local function formatToPrecision(value, p) return string.format('%.' .. p .. 'f', value) end

local function getFractionalZeros(p) if (p > 0) then return '.' .. string.rep('0', p)	else return '' end end

local function polyMix(t, palette) if (t <= 0) then return palette[1] elseif (t >= 1) then return palette[#palette] end local n, f = math.modf(t * (#palette - 1)) if (f == 0) then return palette[n + 1] else local r0, g0, b0 = hexToRgb(palette[n + 1]) local r1, g1, b1 = hexToRgb(palette[n + 2]) return rgbToHex(srgbMix(f, r0, g0, b0, r1, g1, b1)) end end

-- same principle: https://colorspace.r-forge.r-project.org/articles/hcl_palettes.html -- the darkest colors do not yield an WCAG AA contrast with text, maybe this can be solved by using HCL Wizard from R's Colorspace package -- https://colorspace.r-forge.r-project.org/articles/approximations.html -- R's Colorspace does gamut mapping through simple clipping (as do most other color libraries, such as chroma.js and colorio), which is fast but not good local function brewerGradient(t, palette) local colors = { spectral = { '9E0142', 'D53E4F', 'F46D43', 'FDAE61', 'FEE08B', 'FFFFBF', 'E6F598', 'ABDDA4', '66C2A5', '3288BD', '5E4FA2' }, rdylgn = { 'A50026', 'D73027', 'F46D43', 'FDAE61', 'FEE08B', 'FFFFBF', 'D9EF8B', 'A6D96A', '66BD63', '1A9850', '006837' }, rdylbu = { 'A50026', 'D73027', 'F46D43', 'FDAE61', 'FEE090', 'FFFFBF', 'E0F3F8', 'ABD9E9', '74ADD1', '4575B4', '313695' }, piyg = { '8E0152', 'C51B7D', 'DE77AE', 'F1B6DA', 'FDE0EF', 'F7F7F7', 'E6F5D0', 'B8E186', '7FBC41', '4D9221', '276419' }, brbg = { '543005', '8C510A', 'BF812D', 'DFC27D', 'F6E8C3', 'F5F5F5', 'C7EAE5', '80CDC1', '35978F', '01665E', '003C30' }, rdbu = { '67001F', 'B2182B', 'D6604D', 'F4A582', 'FDDBC7', 'F7F7F7', 'D1E5F0', '92C5DE', '4393C3', '2166AC', '053061' }, prgn = { '40004B', '762A83', '9970AB', 'C2A5CF', 'E7D4E8', 'F7F7F7', 'D9F0D3', 'A6DBA0', '5AAE61', '1B7837', '00441B' }, puor = { '7F3B08', 'B35806', 'E08214', 'FDB863', 'FEE0B6', 'F7F7F7', 'D8DAEB', 'B2ABD2', '8073AC', '542788', '2D004B' }, rdgy = { '67001F', 'B2182B', 'D6604D', 'F4A582', 'FDDBC7', 'FFFFFF', 'E0E0E0', 'BABABA', '878787', '4D4D4D', '1A1A1A' }, pubugn = { 'FFF7FB', 'ECE2F0', 'D0D1E6', 'A6BDDB', '67A9CF', '3690C0', '02818A', '016C59', '014636' }, ylorrd = { 'FFFFCC', 'FFEDA0', 'FED976', 'FEB24C', 'FD8D3C', 'FC4E2A', 'E31A1C', 'BD0026', '800026' }, ylorbr = { 'FFFFE5', 'FFF7BC', 'FEE391', 'FEC44F', 'FE9929', 'EC7014', 'CC4C02', '993404', '662506' }, ylgnbu = { 'FFFFD9', 'EDF8B1', 'C7E9B4', '7FCDBB', '41B6C4', '1D91C0', '225EA8', '253494', '081D58' }, gnbu = { 'F7FCF0', 'E0F3DB', 'CCEBC5', 'A8DDB5', '7BCCC4', '4EB3D3', '2B8CBE', '0868AC', '084081' }, orrd = { 'FFF7EC', 'FEE8C8', 'FDD49E', 'FDBB84', 'FC8D59', 'EF6548', 'D7301F', 'B30000', '7F0000' }, ylgn = { 'FFFFE5', 'F7FCB9', 'D9F0A3', 'ADDD8E', '78C679', '41AB5D', '238443', '006837', '004529' }, bugn = { 'F7FCFD', 'E5F5F9', 'CCECE6', '99D8C9', '66C2A4', '41AE76', '238B45', '006D2C', '00441B' }, pubu = { 'FFF7FB', 'ECE7F2', 'D0D1E6', 'A6BDDB', '74A9CF', '3690C0', '0570B0', '045A8D', '023858' }, purd = { 'F7F4F9', 'E7E1EF', 'D4B9DA', 'C994C7', 'DF65B0', 'E7298A', 'CE1256', '980043', '67001F' }, rdpu = { 'FFF7F3', 'FDE0DD', 'FCC5C0', 'FA9FB5', 'F768A1', 'DD3497', 'AE017E', '7A0177', '49006A' }, bupu = { 'F7FCFD', 'E0ECF4', 'BFD3E6', '9EBCDA', '8C96C6', '8C6BB1', '88419D', '810F7C', '4D004B' }, oranges = { 'FFF5EB', 'FEE6CE', 'FDD0A2', 'FDAE6B', 'FD8D3C', 'F16913', 'D94801', 'A63603', '7F2704' }, greens = { 'F7FCF5', 'E5F5E0', 'C7E9C0', 'A1D99B', '74C476', '41AB5D', '238B45', '006D2C', '00441B' }, blues = { 'F7FBFF', 'DEEBF7', 'C6DBEF', '9ECAE1', '6BAED6', '4292C6', '2171B5', '08519C', '08306B' }, reds = { 'FFF5F0', 'FEE0D2', 'FCBBA1', 'FC9272', 'FB6A4A', 'EF3B2C', 'CB181D', 'A50F15', '67000D' }, purples = { 'FCFBFD', 'EFEDF5', 'DADAEB', 'BCBDDC', '9E9AC8', '807DBA', '6A51A3', '54278F', '3F007D' }, greys = { 'FFFFFF', 'F0F0F0', 'D9D9D9', 'BDBDBD', '969696', '737373', '525252', '252525', '000000' } }	return polyMix(t, colors[palette]) end

local function softSigmoid(x) local ax = math.abs(x) if (ax > 0.000000000000000111) then return x / (1 + ax) else return x	end end

function p.hexToRgbTriplet(frame) local args = frame.args or frame:getParent.args local hex = args[1] if (isEmpty(hex)) then return '' end local r, g, b = hexToRgb(hex) return r .. ', ' .. g .. ', ' .. b end

function p.hexToCmyk(frame) local args = frame.args or frame:getParent.args local hex = args[1] if (isEmpty(hex)) then return '' end local p = numArgDefault(args.precision, 0) local s = args.pctsign or '1' local c, m, y, k = rgbToCmyk(hexToRgb(hex)) local fk = formatToPrecision(k, p)	local fc, fm, fy	local fracZeros = getFractionalZeros(p) if (fk == 100 .. fracZeros) then local fZero = 0 .. fracZeros fc = fZero fm = fZero fy = fZero else fc = formatToPrecision(c, p)		fm = formatToPrecision(m, p)		fy = formatToPrecision(y, p)	end if (s ~= '0') then return fc .. '%, ' .. fm .. '%, ' .. fy .. '%, ' .. fk .. '%'	else return fc .. ', ' .. fm .. ', ' .. fy .. ', ' .. fk	end end

function p.hexToHsl(frame) local args = frame.args or frame:getParent.args local hex = args[1] if (isEmpty(hex)) then return '' end local p = numArgDefault(args.precision, 0) local h, s, l = rgbToHsl(hexToRgb(hex)) local fl = formatToPrecision(l, p)	local fs, fh	local fracZeros = getFractionalZeros(p) local fZero = 0 .. fracZeros if (fl == fZero or fl == 100 .. fracZeros) then fs = fZero fh = fZero else fs = formatToPrecision(s, p)		if (fs == fZero) then fh = fZero else fh = formatToPrecision(h, p) if (fh == 360 .. fracZeros) then fh = fZero -- handle rounding to 360 end end end return fh .. '°, ' .. fs .. '%, ' .. fl .. '%' end

function p.hexToHsv(frame) local args = frame.args or frame:getParent.args local hex = args[1] if (isEmpty(hex)) then return '' end local p = numArgDefault(args.precision, 0) local h, s, v = rgbToHsv(hexToRgb(hex)) local fv = formatToPrecision(v, p)	local fs, fh	local fracZeros = getFractionalZeros(p) local fZero = 0 .. fracZeros if (fv == fZero) then fh = fZero fs = fZero else fs = formatToPrecision(s, p)		if (fs == fZero) then fh = fZero else fh = formatToPrecision(h, p) if (fh == 360 .. fracZeros) then fh = fZero -- handle rounding to 360 end end end return fh .. '°, ' .. fs .. '%, ' .. fv .. '%' end

function p.hexToCielch(frame) local args = frame.args or frame:getParent.args local hex = args[1] if (isEmpty(hex)) then return '' end local p = numArgDefault(args.precision, 0) local L, C, h = srgbToCielchuvD65o2deg(hexToRgb(hex)) local fL = formatToPrecision(L, p)	local fC, fh	local fracZeros = getFractionalZeros(p) local fZero = 0 .. fracZeros if (fL == fZero or fL == 100 .. fracZeros) then fC = fZero fh = fZero else fC = formatToPrecision(C, p)		if (fC == fZero) then fh = fZero else fh = formatToPrecision(h, p) if (fh == 360 .. fracZeros) then fh = fZero -- handle rounding to 360 end end end return fL .. ', ' .. fC .. ', ' .. fh .. '°' end

function p.hexMix(frame) local args = frame.args or frame:getParent.args local hex0 = args[1] local hex1 = args[2] if (isEmpty(hex0) or isEmpty(hex1)) then return '' end local t = args[3] if (isEmpty(t)) then t = 0.5 else t = tonumber(t) local amin = numArgDefault(args.min, 0) local amax = numArgDefault(args.max, 100) if (amax == amin) then t = 0.5 else t = (t - amin) / (amax - amin) if (t > 1) then t = 1 elseif (t < 0) then t = 0 end end end local r0, g0, b0 = hexToRgb(hex0) local r1, g1, b1 = hexToRgb(hex1) return rgbToHex(srgbMix(t, r0, g0, b0, r1, g1, b1)) end

function p.hexInterpolate(frame) local args = frame.args or frame:getParent.args local hex0 = args[1] local hex1 = args[2] if (isEmpty(hex0)) then return hex1 elseif (isEmpty(hex1)) then return hex0 end local t = args[3] if (isEmpty(t)) then t = 0.5 else t = tonumber(t) local amin = numArgDefault(args.min, 0) local amax = numArgDefault(args.max, 100) if (amax == amin) then t = 0.5 else t = (t - amin) / (amax - amin) if (t > 1) then t = 1 elseif (t < 0) then t = 0 end end end local direction = numArgDefault(args.direction, 0) local r0, g0, b0 = hexToRgb(hex0) local r1, g1, b1 = hexToRgb(hex1) return rgbToHex(interpolateHue(t, r0, g0, b0, r1, g1, b1, direction)) end

function p.hexBrewerGradient(frame) local args = frame.args or frame:getParent.args local pal = argDefault(args.pal, 'spectral'):lower local value = args[1] local t	if (isEmpty(value)) then t = 0.5 else value = tonumber(value) local high = numArgDefault(args.high, 100) local low = numArgDefault(args.low, -100) if (isEmpty(args.low)) then if (pal ~= 'spectral' and pal ~= 'rdylgn' and pal ~= 'rdylbu' and (pal:len ~= 4 or				(pal ~= 'rdgy' and pal ~= 'rdbu' and pal ~= 'puor' and pal ~= 'prgn' and pal ~= 'piyg' and pal ~= 'brbg'))) then low = 0 end end if (high == low) then t = 0.5 elseif (isArgTrue(args.inv)) then t = (high - value) / (high - low) else t = (value - low) / (high - low) end end if (isArgTrue(args.comp)) then t = 0.5 * softSigmoid(2 * t - 1) + 0.5 end return brewerGradient(t, pal) end

return p