color Contrast

-- -- 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 rgbdec2lum( R, G, B ) if ( 0 <= R and R < 256 and 0 <= G and G < 256 and 0 <= B and B < 256 ) then return 0.2126 * sRGB(R/255) + 0.7152 * sRGB(G/255) + 0.0722 * sRGB(B/255) else return '' end end  local function hsl2lum( h, s, l ) 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 return rgbdec2lum(255*r, 255*g, 255*b) else return '' end 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, s, l = mw.ustring.match(c,'^hsl%([%s]*([0-9][0-9%.]*)[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*%)$') return hsl2lum(tonumber(h), tonumber(s)/100, tonumber(l)/100)    end     -- convert from rgb    if mw.ustring.match(c,'^rgb%([%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*[%s]*%)$') then local R, G, B = mw.ustring.match(c,'^rgb%([%s]*([0-9][0-9]*)[%s]*,[%s]*([0-9][0-9]*)[%s]*,[%s]*([0-9][0-9]*)[%s]*%)$') return rgbdec2lum(tonumber(R), tonumber(G), tonumber(B))    end     -- convert from rgb percent    if mw.ustring.match(c,'^rgb%([%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*%)$') then local R, G, B = mw.ustring.match(c,'^rgb%([%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*%)$') return rgbdec2lum(255*tonumber(R)/100, 255*tonumber(G)/100, 255*tonumber(B)/100)    end  -- remove leading # (if there is one) and whitespace c = mw.ustring.match(c, '^[%s#]*([a-f0-9]*)[%s]*$')  -- 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(mw.text.unstripNoWiki(args[1] or '')) local v2 = color2lum(mw.text.unstripNoWiki(args[2] or '')) 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._styleratio(args) local style = (args[1] or ''):lower() local bg, fg = 'white', '#202122' local lum_bg, lum_fg = 1, 0.016  if args[2] then local lum = color2lum(args[2]) if lum ~= '' then bg, lum_bg = args[2], lum end end if args[3] then local lum = color2lum(args[3]) if lum ~= '' then fg, lum_fg = args[3], lum end end  local slist = mw.text.split(style or '', ';') for k = 1, #slist do local s = slist[k] local k, v = s:match( '^[%s]*([^:]-):([^:]-)[%s;]*$' ) k = k or '' v = v or '' if (k:match('^[%s]*(background)[%s]*$') or k:match('^[%s]*(background%-color)[%s]*$')) then local lum = color2lum(v) if( lum ~= '' ) then bg, lum_bg = v, lum end elseif (k:match('^[%s]*(color)[%s]*$')) then local lum = color2lum(v) if( lum ~= '' ) then bg, lum_fg = v, lum end end end if lum_bg > lum_fg then return (lum_bg + 0.05)/(lum_fg + 0.05) else return (lum_fg + 0.05)/(lum_bg + 0.05) 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.styleratio(frame) local args = frame.args[1] and frame.args or frame:getParent().args return p._styleratio(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