Module:Color contrast

 --
 -- This module implements
 -- {{Color contrast ratio}}
 -- {{Greater color contrast ratio}}
 -- {{ColorToLum}}
 -- {{RGBColorToLum}}
 --
 localp={}
 localHTMLcolor=mw.loadData('Module:Color contrast/colors')

 localfunctionsRGB(v)
 if(v<=0.03928)then
 v=v/12.92
 else
 v=math.pow((v+0.055)/1.055,2.4)
 end
 returnv
 end

 localfunctionrgbdec2lum(R,G,B)
 if(0<=RandR<256and0<=GandG<256and0<=BandB<256)then
 return0.2126*sRGB(R/255)+0.7152*sRGB(G/255)+0.0722*sRGB(B/255)
 else
 return''
 end
 end

 localfunctionhsl2lum(h,s,l)
 if(0<=handh<360and0<=sands<=1and0<=landl<=1)then
 localc=(1-math.abs(2*l-1))*s
 localx=c*(1-math.abs(math.fmod(h/60,2)-1))
 localm=l-c/2

 localr,g,b=m,m,m
 if(0<=handh<60)then
 r=r+c
 g=g+x
 elseif(60<=handh<120)then
 r=r+x
 g=g+c
 elseif(120<=handh<180)then
 g=g+c
 b=b+x
 elseif(180<=handh<240)then
 g=g+x
 b=b+c
 elseif(240<=handh<300)then
 r=r+x
 b=b+c
 elseif(300<=handh<360)then
 r=r+c
 b=b+x
 end
 returnrgbdec2lum(255*r,255*g,255*b)
 else
 return''
 end
 end

 localfunctioncolor2lum(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
 localL=HTMLcolor[c]
 if(L~=nil)then
 returnL
 end

 -- convert from hsl
 ifmw.ustring.match(c,'^hsl%([%s]*[0-9][0-9%.]*[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*%)$')then
 localh,s,l=mw.ustring.match(c,'^hsl%([%s]*([0-9][0-9%.]*)[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*%)$')
 returnhsl2lum(tonumber(h),tonumber(s)/100,tonumber(l)/100)
 end

 -- convert from rgb
 ifmw.ustring.match(c,'^rgb%([%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*[%s]*%)$')then
 localR,G,B=mw.ustring.match(c,'^rgb%([%s]*([0-9][0-9]*)[%s]*,[%s]*([0-9][0-9]*)[%s]*,[%s]*([0-9][0-9]*)[%s]*%)$')
 returnrgbdec2lum(tonumber(R),tonumber(G),tonumber(B))
 end

 -- convert from rgb percent
 ifmw.ustring.match(c,'^rgb%([%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*%)$')then
 localR,G,B=mw.ustring.match(c,'^rgb%([%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*%)$')
 returnrgbdec2lum(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
 localcs=mw.text.split(cor'','')
 if(#cs==6)then
 localR=16*tonumber('0x'..cs[1])+tonumber('0x'..cs[2])
 localG=16*tonumber('0x'..cs[3])+tonumber('0x'..cs[4])
 localB=16*tonumber('0x'..cs[5])+tonumber('0x'..cs[6])

 returnrgbdec2lum(R,G,B)
 elseif(#cs==3)then
 localR=16*tonumber('0x'..cs[1])+tonumber('0x'..cs[1])
 localG=16*tonumber('0x'..cs[2])+tonumber('0x'..cs[2])
 localB=16*tonumber('0x'..cs[3])+tonumber('0x'..cs[3])

 returnrgbdec2lum(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.
 functionp._lum(color)
 returncolor2lum(color)
 end

 functionp._greatercontrast(args)
 localbias=tonumber(args['bias']or'0')or0
 localcss=(args['css']andargs['css']~='')andtrueorfalse
 localv1=color2lum(args[1]or'')
 localc2=args[2]or'white'
 localv2=color2lum(c2)
 localc3=args[3]or'black'
 localv3=color2lum(c3)
 localratio1=-1;
 localratio2=-1;
 if(type(v1)=='number'andtype(v2)=='number')then
 ratio1=(v2+0.05)/(v1+0.05)
 ratio1=(ratio1<1)and1/ratio1orratio1
 end
 if(type(v1)=='number'andtype(v3)=='number')then
 ratio2=(v3+0.05)/(v1+0.05)
 ratio2=(ratio2<1)and1/ratio2orratio2
 end

 ifcssthen
 localc1=args[1]or''
 ifmw.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
 ifmw.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
 ifmw.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)andc2orc3)or'')..';'
 end

 return(ratio1>0)and(ratio2>0)and((ratio1+bias>ratio2)andc2orc3)or''
 end

 functionp._ratio(args)
 localv1=color2lum(args[1])
 localv2=color2lum(args[2])
 if(type(v1)=='number'andtype(v2)=='number')then
 -- v1 should be the brighter of the two.
 ifv2>v1then
 v1,v2=v2,v1
 end
 return(v1+0.05)/(v2+0.05)
 else
 returnargs['error']or'?'
 end
 end

 functionp._styleratio(args)
 localstyle=(args[1]or''):lower()
 localbg,fg='white','black'
 locallum_bg,lum_fg=1,0

 ifargs[2]then
 locallum=color2lum(args[2])
 iflum~=''thenbg,lum_bg=args[2],lumend
 end
 ifargs[3]then
 locallum=color2lum(args[3])
 iflum~=''thenfg,lum_fg=args[3],lumend
 end

 localslist=mw.text.split(mw.ustring.gsub(mw.ustring.gsub(styleor'','&#[Xx]23;','#'),'&#35;','#'),';')
 fork=1,#slistdo
 locals=slist[k]
 localk,v=s:match('^[%s]*([^:]-):([^:]-)[%s;]*$')
 k=kor''
 v=vor''
 if(k:match('^[%s]*(background)[%s]*$')ork:match('^[%s]*(background%-color)[%s]*$'))then
 locallum=color2lum(v)
 if(lum~='')thenbg,lum_bg=v,lumend
 elseif(k:match('^[%s]*(color)[%s]*$'))then
 locallum=color2lum(v)
 if(lum~='')thenbg,lum_fg=v,lumend
 end
 end
 iflum_bg>lum_fgthen
 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.
 --]]
 functionp.lum(frame)
 localcolor=frame.args[1]orframe:getParent().args[1]
 returnp._lum(color)
 end

 functionp.ratio(frame)
 localargs=frame.args[1]andframe.argsorframe:getParent().args
 returnp._ratio(args)
 end

 functionp.styleratio(frame)
 localargs=frame.args[1]andframe.argsorframe:getParent().args
 returnp._styleratio(args)
 end

 functionp.greatercontrast(frame)
 localargs=frame.args[1]andframe.argsorframe:getParent().args
 returnp._greatercontrast(args)
 end

 returnp