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

function p._greatercontrast(args) local bias = tonumber(args['bias'] or '0') or 0 local v1 = color2lum(args[1] or '') local c2 = args[2] or '#FFFFFF' local v2 = color2lum(c2) local c3 = args[3] or '#000000' local v3 = color2lum(c3) local ratio1 = 0; local ratio2 = 0; if (type(v1) == 'number' and type(v2) == 'number') then ratio1 = (v2 + 0.05)/(v1 + 0.05) ratio1 = (ratio1 < 1) and 1/ratio1 or ratio1 end if (type(v1) == 'number' and type(v3) == 'number') then ratio2 = (v3 + 0.05)/(v1 + 0.05) ratio2 = (ratio2 < 1) and 1/ratio2 or ratio2 end return (ratio1 + bias > ratio2) and c2 or c3 end

function p._ratio(args) local v1 = color2lum(args[1]) local v2 = color2lum(args[2]) if (type(v1) == 'number' and type(v2) == 'number') then -- v1 should be the brighter of the two. if v2 > v1 then v1, v2 = v2, v1		end return (v1 + 0.05)/(v2 + 0.05) else return args['error'] or '?' end end

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

function p.ratio(frame) local args = frame.args[1] and frame.args or frame:getParent.args return p._ratio(args) end

function p.greatercontrast(frame) local args = frame.args[1] and frame.args or frame:getParent.args return p._greatercontrast(args) end

return p