# 模組:Color contrast

{{Color contrast ratio}}
{{ColorToLum}} / {{RGBColorToLum}}
{{Color contrast conformance}}
{{Ensure AAA contrast ratio}}
{{Ensure AA contrast ratio}}
{{Greater color contrast ratio}}

Module:Navbox
Module:Userbox
Module:Episode list

Module:College color

## 函數說明

• sRGB(v)：從sRGB色彩空间的非線性轉換：此函數所用到的常數則是使用${\displaystyle \left({\frac {K_{0}+a}{1+a}}\right)^{\gamma }={\frac {K_{0}}{\phi }}}$${\displaystyle \gamma \left({\frac {K_{0}+a}{1+a}}\right)^{\gamma -1}\left({\frac {1}{1+a}}\right)={\frac {1}{\phi }}}$這2個方程式代入${\displaystyle a=0.055}$${\displaystyle \gamma =2.4}$得到${\displaystyle \phi =12.92}$${\displaystyle K_{0}=0.03928}$
• rgbdec2lum(R,G,B)：從三原色光模式轉成CIE XYZ的Y值
• hsl2lum(h,s,l)：從HSL色彩空间轉成CIE XYZ的Y值，其中h所用的單位為
• color2lum(c)：從HTML顏色轉成CIE XYZ的Y值

## 用法

{{ColorToLum|color}} or {{#invoke:Color contrast|lum|color}}

{{Color contrast ratio|color1|color2|error=?}} or {{#invoke:Color contrast|ratio|color1|color2|error=?}}

{{Greater color contrast ratio|color1|color2a|color2b}} or {{#invoke:Color contrast|greatercontrast|color1|color2a|color2b}}

{{#invoke:Color contrast|styleratio|css style statement string|default background color|default text color}}

--
-- 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