color_palette.py

#!/usr/bin/env python

#http://hse-at-work.blogspot.com/2006/11/color-scheme-generator-for-charts.html
from random import randint
class Color:
   __c = [0, 0, 0]
   __cB = None
   def __init__(self, r=-1, g=-1, b=-1):
       if r == -1:
           r = randint(1,255)
       if g == -1:
           g = randint(1,255)
       if b == -1:
           b = randint(1,255)
       self.__c = [r, g, b]
   def __getitem__(self, key):
       return self.__c[key]
   def __setitem__(self, key, value):
       self.__c[key] = value
       self.__cB = None
   def getBritness(self):
       if self.__cB:
           return self.__cB
       else:
           self.__cB = ((self.__c[0] * 299) +
                       (self.__c[1] * 587) +
                       (self.__c[2] * 114)) / 1000
           return self.__cB
   def __sub__(self, other):
       return ((max(self.__c[0], other[0]) - min(self.__c[0], other[0])) +
               (max(self[1], other[1]) - min(self[1], other[1])) +
               (max(self[2], other[2]) - min(self[2], other[2])))
   def __str__(self):
       return "%02x%02x%02x" % (self.__c[0], self.__c[1], self.__c[2])


def generate(num=25):
  colors = []
  comparedNum = 5

  c = Color()
  colors.append(c)
  stopper = 100000

  minBrit = 35
  minColDiff = 100

  for n in range(num)[1:]:
     while stopper:
         newC = Color()
         passed = 0
         for back in range(comparedNum):
             testedNum = n-(back+1)
             if testedNum < 0:
                 passed += 1
                 continue
             c = colors[testedNum]
             bDiff = abs(c.getBritness() - newC.getBritness())
             cDiff = c - newC
             if  cDiff >= minColDiff and  bDiff > minBrit:
                 passed += 1
             else:
                 break
         if passed == comparedNum:
             colors.append(newC)
             break

         stopper -= 1

  if not stopper > 0:
     raise InvalidState

  return colors

if __name__ == '__main__':
  for c in generate(5): print c