initial release

cosmic rage/lua/colors.lua

@@ -0,0 +1,269 @@
+-----------------------------------------------------------------------------
+-- Provides support for color manipulation in HSL color space.
+--
+-- http://sputnik.freewisdom.org/lib/colors/
+--
+-- License: MIT/X
+-- 
+-- (c) 2008 Yuri Takhteyev (yuri@freewisdom.org) *
+--
+-- * rgb_to_hsl() implementation was contributed by Markus Fleck-Graffe.
+-----------------------------------------------------------------------------
+
+module(..., package.seeall)
+
+local Color = {}
+local Color_mt = {__metatable = {}, __index = Color}
+
+-----------------------------------------------------------------------------
+-- Instantiates a new "color".
+--
+-- @param H              hue (0-360) _or_ an RGB string ("#930219")
+-- @param S              saturation (0.0-1.0)
+-- @param L              lightness (0.0-1.0)
+-- @return               an instance of Color
+-----------------------------------------------------------------------------
+function new(H, S, L)
+   if type(H) == "string" and H:sub(1,1)=="#" and H:len() == 7 then
+      H, S, L = rgb_string_to_hsl(H)
+   end
+   assert(Color_mt)
+   return setmetatable({H = H, S = S, L = L}, Color_mt)
+end
+
+-----------------------------------------------------------------------------
+-- Converts an HSL triplet to RGB
+-- (see http://homepages.cwi.nl/~steven/css/hsl.html).
+-- 
+-- @param h              hue (0-360)
+-- @param s              saturation (0.0-1.0)
+-- @param L              lightness (0.0-1.0)
+-- @return               an R, G, and B component of RGB
+-----------------------------------------------------------------------------
+
+function hsl_to_rgb(h, s, L)
+   h = h/360
+   local m1, m2
+   if L<=0.5 then 
+      m2 = L*(s+1)
+   else 
+      m2 = L+s-L*s
+   end
+   m1 = L*2-m2
+
+   local function _h2rgb(m1, m2, h)
+      if h<0 then h = h+1 end
+      if h>1 then h = h-1 end
+      if h*6<1 then 
+         return m1+(m2-m1)*h*6
+      elseif h*2<1 then 
+         return m2 
+      elseif h*3<2 then 
+         return m1+(m2-m1)*(2/3-h)*6
+      else
+         return m1
+      end
+   end
+
+   return _h2rgb(m1, m2, h+1/3), _h2rgb(m1, m2, h), _h2rgb(m1, m2, h-1/3)
+end
+
+-----------------------------------------------------------------------------
+-- Converts an RGB triplet to HSL.
+-- (see http://easyrgb.com)
+-- 
+-- @param r              red (0.0-1.0)
+-- @param g              green (0.0-1.0)
+-- @param b              blue (0.0-1.0)
+-- @return               corresponding H, S and L components
+-----------------------------------------------------------------------------
+
+function rgb_to_hsl(r, g, b)
+   --r, g, b = r/255, g/255, b/255
+   local min = math.min(r, g, b)
+   local max = math.max(r, g, b)
+   local delta = max - min
+
+   local h, s, l = 0, 0, ((min+max)/2)
+
+   if l > 0 and l < 0.5 then s = delta/(max+min) end
+   if l >= 0.5 and l < 1 then s = delta/(2-max-min) end
+
+   if delta > 0 then
+      if max == r and max ~= g then h = h + (g-b)/delta end
+      if max == g and max ~= b then h = h + 2 + (b-r)/delta end
+      if max == b and max ~= r then h = h + 4 + (r-g)/delta end
+      h = h / 6;
+   end
+
+   if h < 0 then h = h + 1 end
+   if h > 1 then h = h - 1 end
+
+   return h * 360, s, l
+end
+
+function rgb_string_to_hsl(rgb)
+   return rgb_to_hsl(tonumber(rgb:sub(2,3), 16)/255, 
+                     tonumber(rgb:sub(4,5), 16)/255,
+                     tonumber(rgb:sub(6,7), 16)/255)
+end
+
+-----------------------------------------------------------------------------
+-- Converts the color to an RGB string.
+--
+-- @return               a 6-digit RGB representation of the color prefixed
+--                       with "#" (suitable for inclusion in HTML)
+-----------------------------------------------------------------------------
+
+function Color:to_rgb()
+   local rgb = {hsl_to_rgb(self.H, self.S, self.L)}
+   local buffer = "#"
+   for i,v in ipairs(rgb) do
+	  buffer = buffer..string.format("%02x",math.floor(v*255+0.5))
+   end
+   return buffer
+end
+
+-----------------------------------------------------------------------------
+-- Creates a new color with hue different by delta.
+--
+-- @param delta          a delta for hue.
+-- @return               a new instance of Color.
+-----------------------------------------------------------------------------
+function Color:hue_offset(delta)
+   return new((self.H + delta) % 360, self.S, self.L)
+end
+
+-----------------------------------------------------------------------------
+-- Creates a complementary color.
+--
+-- @return               a new instance of Color
+-----------------------------------------------------------------------------
+function Color:complementary() 
+   return self:hue_offset(180)
+end
+
+-----------------------------------------------------------------------------
+-- Creates two neighboring colors (by hue), offset by "angle".
+--
+-- @param angle          the difference in hue between this color and the 
+--                       neighbors
+-- @return               two new instances of Color
+-----------------------------------------------------------------------------
+function Color:neighbors(angle)
+   local angle = angle or 30
+   return self:hue_offset(angle), self:hue_offset(360-angle)
+end
+
+-----------------------------------------------------------------------------
+-- Creates two new colors to make a triadic color scheme.
+--
+-- @return               two new instances of Color
+-----------------------------------------------------------------------------
+function Color:triadic() 
+   return self:neighbors(120)
+end
+
+-----------------------------------------------------------------------------
+-- Creates two new colors, offset by angle from this colors complementary.
+--
+-- @param angle          the difference in hue between the complementary and
+--                       the returned colors
+-- @return               two new instances of Color
+-----------------------------------------------------------------------------
+function Color:split_complementary(angle)
+   return self:neighbors(180-(angle or 30))
+end
+
+-----------------------------------------------------------------------------
+-- Creates a new color with saturation set to a new value.
+--
+-- @param saturation     the new saturation value (0.0 - 1.0)
+-- @return               a new instance of Color
+-----------------------------------------------------------------------------
+function Color:desaturate_to(saturation)
+   return new(self.H, saturation, self.L)
+end
+
+-----------------------------------------------------------------------------
+-- Creates a new color with saturation set to a old saturation times r.
+--
+-- @param r              the multiplier for the new saturation
+-- @return               a new instance of Color
+-----------------------------------------------------------------------------
+function Color:desaturate_by(r)
+   return new(self.H, self.S*r, self.L)
+end	      
+
+-----------------------------------------------------------------------------
+-- Creates a new color with lightness set to a new value.
+--
+-- @param lightness      the new lightness value (0.0 - 1.0)
+-- @return               a new instance of Color
+-----------------------------------------------------------------------------
+function Color:lighten_to(lightness)
+   return new(self.H, self.S, lightness)
+end
+
+-----------------------------------------------------------------------------
+-- Creates a new color with lightness set to a old lightness times r.
+--
+-- @param r              the multiplier for the new lightness
+-- @return               a new instance of Color
+-----------------------------------------------------------------------------
+function Color:lighten_by(r)
+   return new(self.H, self.S, self.L*r)
+end
+
+-----------------------------------------------------------------------------
+-- Creates n variations of this color using supplied function and returns
+-- them as a table.
+--
+-- @param f              the function to create variations
+-- @param n              the number of variations
+-- @return               a table with n values containing the new colors
+-----------------------------------------------------------------------------
+function Color:variations(f, n)
+   n = n or 5
+   local results = {}
+   for i=1,n do
+	  table.insert(results, f(self, i, n))
+   end
+   return results
+end
+
+-----------------------------------------------------------------------------
+-- Creates n tints of this color and returns them as a table
+--
+-- @param n              the number of tints
+-- @return               a table with n values containing the new colors
+-----------------------------------------------------------------------------
+function Color:tints(n)
+   local f = function (color, i, n) 
+                return color:lighten_to(color.L + (1-color.L)/n*i)
+             end
+   return self:variations(f, n)
+end
+
+-----------------------------------------------------------------------------
+-- Creates n shades of this color and returns them as a table
+--
+-- @param n              the number of shades
+-- @return               a table with n values containing the new colors
+-----------------------------------------------------------------------------
+function Color:shades(n)
+   local f = function (color, i, n) 
+                return color:lighten_to(color.L - (color.L)/n*i)
+             end
+   return self:variations(f, n)
+end
+
+function Color:tint(r)
+      return self:lighten_to(self.L + (1-self.L)*r)
+end
+
+function Color:shade(r)
+      return self:lighten_to(self.L - self.L*r)
+end
+
+Color_mt.__tostring = Color.to_rgb