Module:Color contrast: Difference between revisions

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    Line 21: Line 21:
    local lum = ''
    local lum = ''
    if ( 0 <= h and h < 360 and 0 <= s and s <= 1 and 0 <= l and l <= 1 ) then
    if ( 0 <= h and h < 360 and 0 <= s and s <= 1 and 0 <= l and l <= 1 ) then
    local c = (1 - abs(2*l - 1))*s
    local c = (1 - math.abs(2*l - 1))*s
    local x = c*(1 - abs( mod(h/60, 2) - 1) )
    local x = c*(1 - math.abs( math.fmod(h/60, 2) - 1) )
    local m = l - c/2
    local m = l - c/2



    Revision as of 18:55, 30 July 2015

    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 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 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 = R + c
    			B = G + x
    		elseif( 180 <= h and h < 240 ) then
    			G = R + x
    			B = G + c
    		elseif( 240 <= h and h < 300 ) then
    			R = R + x
    			B = G + c
    		elseif( 300 <= h and h < 360 ) then
    			R = R + c
    			B = G + x
    		end
    		lum = 0.2126 * sRGB(R) + 0.7152 * sRGB(G) + 0.0722 * sRGB(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 = 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