Module:Color contrast: Difference between revisions

    From Nonbinary Wiki
    m>Mr. Stradivarius
    (split the color data out to Module:Color contrast/colors and load it with mw.loadData - this way we only create the table once per page rather than every time color2lum is called)
    m>Mr. Stradivarius
    m (Protected Module:Color contrast: High-risk Lua module ([Edit=Allow only autoconfirmed users] (indefinite) [Move=Allow only autoconfirmed users] (indefinite)))
    (No difference)

    Revision as of 03:05, 27 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 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
    	-- 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