-- -- 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   -- html '#' entity  c = c:gsub("&#35;", "#")   -- whitespace  c = c:match( '^%s*(.-)[%s;]*$' )   -- unstrip nowiki strip markers  c = mw.text.unstripNoWiki(c)   -- lowercase  c = c:lower()   -- first try to look it up  local L = HTMLcolor[c]  if (L ~= nil) then  return L  end   -- convert from hsl  if mw.ustring.match(c,'^hsl%([%s]*[0-9][0-9%.]*[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*%)$') 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  -- This exports the function for use in other modules. -- The colour is passed as a string. function p._lum(color)  return color2lum(color) end  function p._greatercontrast(args)  local bias = tonumber(args['bias'] or '0') or 0  local css = (args['css'] and args['css'] ~= '') and true or false  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 = -1;  local ratio2 = -1;  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   if css then  local c1 = args[1] or ''  if mw.ustring.match(c1, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') or  mw.ustring.match(c1, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') then  c1 = '#' .. c1  end  if mw.ustring.match(c2, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') or  mw.ustring.match(c2, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') then  c2 = '#' .. c2  end  if mw.ustring.match(v3, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') or  mw.ustring.match(v3, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') then  c3 = '#' .. c3  end  return 'background-color:' .. c1 .. '; color:' .. ((ratio1 > 0) and (ratio2 > 0) and ((ratio1 + bias > ratio2) and c2 or c3) or '') .. ';'  end   return (ratio1 > 0) and (ratio2 > 0) and ((ratio1 + bias > ratio2) and c2 or c3) or '' 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._styleratio(args)  local style = (args[1] or ''):lower()  local bg, fg = 'white', 'black'  local lum_bg, lum_fg = 1, 0   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(mw.ustring.gsub(mw.ustring.gsub(style or '', '&#[Xx]23;', '#'), '&#35;', '#'), ';')  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  --[[ Use {{#invoke:Color contrast|somecolor}} directly or {{#invoke:Color contrast}} from a wrapper template.  Parameters:  -- |1= — required; A color to check. --]] function p.lum(frame)  local color = frame.args[1] or frame:getParent().args[1]  return p._lum(color) 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