Module:Color contrast

-- -- This module implements -- --  --  --  -- local p = {} local HTMLcolor = mw.loadData( 'Module:Color contrast/colors' )

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 rgbdec2lum( R, G, B ) return 0.2126 * sRGB(R/255) + 0.7152 * sRGB(G/255) + 0.0722 * sRGB(B/255) end

local function hsl2lum( h, s, l ) local lum = '' if ( 0 <= h and h < 360 and 0 <= s and s <= 1 and 0 <= l and l <= 1 ) then local c = (1 - math.abs(2*l - 1))*s local x = c*(1 - math.abs( math.fmod(h/60, 2) - 1) ) local m = l - c/2

local r, g, b = m, m, m		if( 0 <= h and h < 60 ) then r = r + c			g = g + x		elseif( 60 <= h and h < 120 ) then r = r + x			g = g + c		elseif( 120 <= h and h < 180 ) then g = g + c			b = b + x		elseif( 180 <= h and h < 240 ) then g = g + x			b = b + c		elseif( 240 <= h and h < 300 ) then r = r + x			b = b + c		elseif( 300 <= h and h < 360 ) then r = r + c			b = b + x		end lum = rgbdec2lum(255*r, 255*g, 255*b) end return lum end

local function color2lum( c )

if (c == nil) then return '' end -- 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

-- convert from hsl if mw.ustring.match(c,'^hsl%([%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*%%[%s]*,[%s]*[0-9][0-9]*%%[%s]*%)$') then local h = mw.ustring.match(c,'^hsl%([%s]*([0-9][0-9]*)[%s]*,[%s]*[0-9][0-9]*%%[%s]*,[%s]*[0-9][0-9]*%%[%s]*%)$') local s = mw.ustring.match(c,'^hsl%([%s]*[0-9][0-9]*[%s]*,[%s]*([0-9][0-9]*)%%[%s]*,[%s]*[0-9][0-9]*%%[%s]*%)$') local l = mw.ustring.match(c,'^hsl%([%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*%%[%s]*,[%s]*([0-9][0-9]*)%%[%s]*%)$') return hsl2lum(tonumber(h), tonumber(s)/100, tonumber(l)/100) 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 = 16*tonumber('0x' .. cs[1]) + tonumber('0x' .. cs[2]) local G = 16*tonumber('0x' .. cs[3]) + tonumber('0x' .. cs[4]) local B = 16*tonumber('0x' .. cs[5]) + tonumber('0x' .. cs[6])

return rgbdec2lum(R, G, B)	elseif ( #cs == 3 ) then local R = 16*tonumber('0x' .. cs[1]) + tonumber('0x' .. cs[1]) local G = 16*tonumber('0x' .. cs[2]) + tonumber('0x' .. cs[2]) local B = 16*tonumber('0x' .. cs[3]) + tonumber('0x' .. cs[3])

return rgbdec2lum(R, G, B)	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