Module:Color contrast

-- -- This module implements -- --  --  -- local p = {}

local function sRGB ( v ) if (v <= 0.03928) then v = v / 12.92 else v = math.pow((v+0.055)/1.055, 2.4) end return v end

local function color2lum( c ) if (c == nil) then return '' end

local HTMLcolor = { white = 1, silver = 0.52711512570581, gray = 0.2158605001139, black = 0, red = 0.2126, maroon = 0.045891942324215, yellow = 0.9278, olive = 0.20027537200568, lime = 0.7152, green = 0.15438342968146, aqua = 0.7874, teal = 0.16996855778968, blue = 0.0722, navy = 0.015585128108224, fuchsia = 0.2848, purple = 0.061477070432439, orange = 0.4817026703631,

gold = 0.69860877428159, pink = 0.63271070702466, lightpink = 0.58566152734898, hotpink = 0.34658438169715, deeppink = 0.23866895828276, palevioletred = 0.28754994117889, mediumvioletred = 0.14371899849357, lightsalmon = 0.4780675225206, salmon = 0.36977241527596, darksalmon = 0.40541471563381, lightcoral = 0.35522120733135, indianred = 0.21406134963884, crimson = 0.16042199953026, firebrick = 0.10724525535015, darkred = 0.054889674531132, orangered = 0.25516243753416, tomato = 0.30638612719415, coral = 0.37017930872924, darkorange = 0.40016167026524, lightyellow = 0.98161818392882, lemonchiffon = 0.94038992245622, lightgoldenrodyellow = 0.93348351018297, papayawhip = 0.87797100199835, moccasin = 0.80083000991567, peachpuff = 0.74905589878251, palegoldenrod = 0.78792647887614, khaki = 0.77012343394121, darkkhaki = 0.45747326349994, cornsilk = 0.93562110372965, blanchedalmond = 0.85084439608156, bisque = 0.80732327372979, navajowhite = 0.76519682342785, wheat = 0.74909702820482, burlywood = 0.51559844533893, tan = 0.48237604163921, rosybrown = 0.32319457649407, sandybrown = 0.46628543696283, goldenrod = 0.41919977809569, darkgoldenrod = 0.27264703559993, peru = 0.30113074877936, chocolate = 0.23898526114557, saddlebrown = 0.097922285020521, sienna = 0.13697631337098, brown = 0.098224287876511, }   -- whitespace c = c:match( '^%s*(.-)%s*$' ) -- lowercase c = c:lower -- first try to look it up	local L = HTMLcolor[c] if (L ~= nil) then return L	end -- remove leading # (if there is one) and whitespace c = mw.ustring.match(c, '^[%s#]*([a-f0-9]*)[%s]*$')

-- split into rgb local cs = mw.text.split(c or , ) if( #cs == 6 ) then local R = sRGB( (16*tonumber('0x' .. cs[1]) + tonumber('0x' .. cs[2]))/255 ) local G = sRGB( (16*tonumber('0x' .. cs[3]) + tonumber('0x' .. cs[4]))/255 ) local B = sRGB( (16*tonumber('0x' .. cs[5]) + tonumber('0x' .. cs[6]))/255 ) L = 0.2126 * R + 0.7152 * G + 0.0722 * B		return L	elseif ( #cs == 3 ) then local R = sRGB( (16*tonumber('0x' .. cs[1]) + tonumber('0x' .. cs[1]))/255 ) local G = sRGB( (16*tonumber('0x' .. cs[2]) + tonumber('0x' .. cs[2]))/255 ) local B = sRGB( (16*tonumber('0x' .. cs[3]) + tonumber('0x' .. cs[3]))/255 ) L = 0.2126 * R + 0.7152 * G + 0.0722 * B		return L	end -- failure, return blank return '' end

local function colors2ratio(c1,c2) local v1 = color2lum(c1) local v2 = color2lum(c2) if (type(v1) == 'number' and type(v2) == 'number') then return (v2 + 0.05)/(v1 + 0.05) else return '' end end

function p.lum(frame) return color2lum(frame.args[1] or frame:getParent.args[1]) end

function p.ratio(frame) local r = colors2ratio(		frame.args[1] or frame:getParent.args[1],		frame.args[2] or frame:getParent.args[2]		) if (r ~= '') then return r	else return frame.args['error'] or frame:getParent.args['error'] or '?' end end return p