"""Color Database.
This file contains one class, called ColorDB, and several utility functions.
The class must be instantiated by the get_colordb() function in this file,
passing it a filename to read a database out of.
The get_colordb() function will try to examine the file to figure out what the
format of the file is. If it can't figure out the file format, or it has
trouble reading the file, None is returned. You can pass get_colordb() an
optional filetype argument.
Supporte file types are:
X_RGB_TXT -- X Consortium rgb.txt format files. Three columns of numbers
from 0 .. 255 separated by whitespace. Arbitrary trailing
columns used as the color name.
The utility functions are useful for converting between the various expected
color formats, and for calculating other color values.
"""
import sys
import re
from types import *
import operator
class BadColor(Exception):
pass
DEFAULT_DB = None
SPACE = ' '
COMMASPACE = ', '
# generic class
class ColorDB:
def __init__(self, fp):
lineno = 2
self.__name = fp.name
# Maintain several dictionaries for indexing into the color database.
# Note that while Tk supports RGB intensities of 4, 8, 12, or 16 bits,
# for now we only support 8 bit intensities. At least on OpenWindows,
# all intensities in the /usr/openwin/lib/rgb.txt file are 8-bit
#
# key is (red, green, blue) tuple, value is (name, [aliases])
self.__byrgb = {}
# key is name, value is (red, green, blue)
self.__byname = {}
# all unique names (non-aliases). built-on demand
self.__allnames = None
for line in fp:
# get this compiled regular expression from derived class
mo = self._re.match(line)
if not mo:
print >> sys.stderr, 'Error in', fp.name, ' line', lineno
lineno += 1
continue
# extract the red, green, blue, and name
red, green, blue = self._extractrgb(mo)
name = self._extractname(mo)
keyname = name.lower()
# BAW: for now the `name' is just the first named color with the
# rgb values we find. Later, we might want to make the two word
# version the `name', or the CapitalizedVersion, etc.
key = (red, green, blue)
foundname, aliases = self.__byrgb.get(key, (name, []))
if foundname <> name and foundname not in aliases:
aliases.append(name)
self.__byrgb[key] = (foundname, aliases)
# add to byname lookup
self.__byname[keyname] = key
lineno = lineno + 1
# override in derived classes
def _extractrgb(self, mo):
return [int(x) for x in mo.group('red', 'green', 'blue')]
def _extractname(self, mo):
return mo.group('name')
def filename(self):
return self.__name
def find_byrgb(self, rgbtuple):
"""Return name for rgbtuple"""
try:
return self.__byrgb[rgbtuple]
except KeyError:
raise BadColor(rgbtuple)
def find_byname(self, name):
"""Return (red, green, blue) for name"""
name = name.lower()
try:
return self.__byname[name]
except KeyError:
raise BadColor(name)
def nearest(self, red, green, blue):
"""Return the name of color nearest (red, green, blue)"""
# BAW: should we use Voronoi diagrams, Delaunay triangulation, or
# octree for speeding up the locating of nearest point? Exhaustive
# search is inefficient, but seems fast enough.
nearest = -1
nearest_name = ''
for name, aliases in self.__byrgb.values():
r, g, b = self.__byname[name.lower()]
rdelta = red - r
gdelta = green - g
bdelta = blue - b
distance = rdelta * rdelta + gdelta * gdelta + bdelta * bdelta
if nearest == -1 or distance < nearest:
nearest = distance
nearest_name = name
return nearest_name
def unique_names(self):
# sorted
if not self.__allnames:
self.__allnames = []
for name, aliases in self.__byrgb.values():
self.__allnames.append(name)
# sort irregardless of case
def nocase_cmp(n1, n2):
return cmp(n1.lower(), n2.lower())
self.__allnames.sort(nocase_cmp)
return self.__allnames
def aliases_of(self, red, green, blue):
try:
name, aliases = self.__byrgb[(red, green, blue)]
except KeyError:
raise BadColor((red, green, blue))
return [name] + aliases
class RGBColorDB(ColorDB):
_re = re.compile(
'\s*(?P<red>\d+)\s+(?P<green>\d+)\s+(?P<blue>\d+)\s+(?P<name>.*)')
class HTML40DB(ColorDB):
_re = re.compile('(?P<name>\S+)\s+(?P<hexrgb>#[0-9a-fA-F]{6})')
def _extractrgb(self, mo):
return rrggbb_to_triplet(mo.group('hexrgb'))
class LightlinkDB(HTML40DB):
_re = re.compile('(?P<name>(.+))\s+(?P<hexrgb>#[0-9a-fA-F]{6})')
def _extractname(self, mo):
return mo.group('name').strip()
class WebsafeDB(ColorDB):
_re = re.compile('(?P<hexrgb>#[0-9a-fA-F]{6})')
def _extractrgb(self, mo):
return rrggbb_to_triplet(mo.group('hexrgb'))
def _extractname(self, mo):
return mo.group('hexrgb').upper()
# format is a tuple (RE, SCANLINES, CLASS) where RE is a compiled regular
# expression, SCANLINES is the number of header lines to scan, and CLASS is
# the class to instantiate if a match is found
FILETYPES = [
(re.compile('Xorg'), RGBColorDB),
(re.compile('XConsortium'), RGBColorDB),
(re.compile('HTML'), HTML40DB),
(re.compile('lightlink'), LightlinkDB),
(re.compile('Websafe'), WebsafeDB),
]
def get_colordb(file, filetype=None):
colordb = None
fp = open(file)
try:
line = fp.readline()
if not line:
return None
# try to determine the type of RGB file it is
if filetype is None:
filetypes = FILETYPES
else:
filetypes = [filetype]
for typere, class_ in filetypes:
mo = typere.search(line)
if mo:
break
else:
# no matching type
return None
# we know the type and the class to grok the type, so suck it in
colordb = class_(fp)
finally:
fp.close()
# save a global copy
global DEFAULT_DB
DEFAULT_DB = colordb
return colordb
_namedict = {}
def rrggbb_to_triplet(color):
"""Converts a #rrggbb color to the tuple (red, green, blue)."""
rgbtuple = _namedict.get(color)
if rgbtuple is None:
if color[0] <> '#':
raise BadColor(color)
red = color[1:3]
green = color[3:5]
blue = color[5:7]
rgbtuple = int(red, 16), int(green, 16), int(blue, 16)
_namedict[color] = rgbtuple
return rgbtuple
_tripdict = {}
def triplet_to_rrggbb(rgbtuple):
"""Converts a (red, green, blue) tuple to #rrggbb."""
global _tripdict
hexname = _tripdict.get(rgbtuple)
if hexname is None:
hexname = '#%02x%02x%02x' % rgbtuple
_tripdict[rgbtuple] = hexname
return hexname
_maxtuple = (256.0,) * 3
def triplet_to_fractional_rgb(rgbtuple):
return map(operator.__div__, rgbtuple, _maxtuple)
def triplet_to_brightness(rgbtuple):
# return the brightness (grey level) along the scale 0.0==black to
# 1.0==white
r = 0.299
g = 0.587
b = 0.114
return r*rgbtuple[0] + g*rgbtuple[1] + b*rgbtuple[2]
if __name__ == '__main__':
colordb = get_colordb('/usr/openwin/lib/rgb.txt')
if not colordb:
print 'No parseable color database found'
sys.exit(1)
# on my system, this color matches exactly
target = 'navy'
red, green, blue = rgbtuple = colordb.find_byname(target)
print target, ':', red, green, blue, triplet_to_rrggbb(rgbtuple)
name, aliases = colordb.find_byrgb(rgbtuple)
print 'name:', name, 'aliases:', COMMASPACE.join(aliases)
r, g, b = (1, 1, 128) # nearest to navy
r, g, b = (145, 238, 144) # nearest to lightgreen
r, g, b = (255, 251, 250) # snow
print 'finding nearest to', target, '...'
import time
t0 = time.time()
nearest = colordb.nearest(r, g, b)
t1 = time.time()
print 'found nearest color', nearest, 'in', t1-t0, 'seconds'
# dump the database
for n in colordb.unique_names():
r, g, b = colordb.find_byname(n)
aliases = colordb.aliases_of(r, g, b)
print '%20s: (%3d/%3d/%3d) == %s' % (n, r, g, b,
SPACE.join(aliases[1:]))
