Module:Color contrast

    From Nonbinary Wiki
    Revision as of 18:14, 25 July 2015 by m>Mr. Stradivarius (whitespace fixes)

    Documentation for this module may be created at Module:Color contrast/doc

    --
    -- This module implements 
    --  {{Color contrast ratio}}
    --  {{Greater color contrast ratio}}
    --  {{ColorToLum}}
    --  {{RGBColorToLum}}
    --
    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