Difference between revisions of "Module:Color contrast"
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imported>Mr. Stradivarius m (whitespace fixes) |
imported>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) |
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| Line 7: | Line 7: | ||
-- | -- | ||
local p = {} | local p = {} | ||
| + | local HTMLcolor = mw.loadData( 'Module:Color contrast/colors' ) | ||
local function sRGB ( v ) | local function sRGB ( v ) | ||
| Line 22: | Line 23: | ||
return '' | return '' | ||
end | end | ||
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-- whitespace | -- whitespace | ||
c = c:match( '^%s*(.-)%s*$' ) | c = c:match( '^%s*(.-)%s*$' ) | ||
Revision as of 19:22, 25 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
