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271 lines
8.6 KiB
Python
271 lines
8.6 KiB
Python
"""Color Database.
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This file contains one class, called ColorDB, and several utility functions.
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The class must be instantiated by the get_colordb() function in this file,
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passing it a filename to read a database out of.
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The get_colordb() function will try to examine the file to figure out what the
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format of the file is. If it can't figure out the file format, or it has
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trouble reading the file, None is returned. You can pass get_colordb() an
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optional filetype argument.
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Supporte file types are:
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X_RGB_TXT -- X Consortium rgb.txt format files. Three columns of numbers
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from 0 .. 255 separated by whitespace. Arbitrary trailing
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columns used as the color name.
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The utility functions are useful for converting between the various expected
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color formats, and for calculating other color values.
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"""
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import sys
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import re
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from types import *
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class BadColor(Exception):
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pass
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DEFAULT_DB = None
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SPACE = ' '
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COMMASPACE = ', '
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# generic class
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class ColorDB:
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def __init__(self, fp):
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lineno = 2
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self.__name = fp.name
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# Maintain several dictionaries for indexing into the color database.
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# Note that while Tk supports RGB intensities of 4, 8, 12, or 16 bits,
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# for now we only support 8 bit intensities. At least on OpenWindows,
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# all intensities in the /usr/openwin/lib/rgb.txt file are 8-bit
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#
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# key is (red, green, blue) tuple, value is (name, [aliases])
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self.__byrgb = {}
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# key is name, value is (red, green, blue)
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self.__byname = {}
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# all unique names (non-aliases). built-on demand
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self.__allnames = None
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for line in fp:
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# get this compiled regular expression from derived class
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mo = self._re.match(line)
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if not mo:
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print('Error in', fp.name, ' line', lineno, file=sys.stderr)
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lineno += 1
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continue
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# extract the red, green, blue, and name
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red, green, blue = self._extractrgb(mo)
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name = self._extractname(mo)
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keyname = name.lower()
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# BAW: for now the `name' is just the first named color with the
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# rgb values we find. Later, we might want to make the two word
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# version the `name', or the CapitalizedVersion, etc.
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key = (red, green, blue)
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foundname, aliases = self.__byrgb.get(key, (name, []))
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if foundname != name and foundname not in aliases:
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aliases.append(name)
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self.__byrgb[key] = (foundname, aliases)
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# add to byname lookup
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self.__byname[keyname] = key
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lineno = lineno + 1
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# override in derived classes
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def _extractrgb(self, mo):
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return [int(x) for x in mo.group('red', 'green', 'blue')]
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def _extractname(self, mo):
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return mo.group('name')
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def filename(self):
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return self.__name
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def find_byrgb(self, rgbtuple):
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"""Return name for rgbtuple"""
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try:
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return self.__byrgb[rgbtuple]
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except KeyError:
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raise BadColor(rgbtuple) from None
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def find_byname(self, name):
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"""Return (red, green, blue) for name"""
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name = name.lower()
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try:
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return self.__byname[name]
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except KeyError:
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raise BadColor(name) from None
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def nearest(self, red, green, blue):
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"""Return the name of color nearest (red, green, blue)"""
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# BAW: should we use Voronoi diagrams, Delaunay triangulation, or
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# octree for speeding up the locating of nearest point? Exhaustive
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# search is inefficient, but seems fast enough.
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nearest = -1
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nearest_name = ''
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for name, aliases in self.__byrgb.values():
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r, g, b = self.__byname[name.lower()]
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rdelta = red - r
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gdelta = green - g
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bdelta = blue - b
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distance = rdelta * rdelta + gdelta * gdelta + bdelta * bdelta
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if nearest == -1 or distance < nearest:
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nearest = distance
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nearest_name = name
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return nearest_name
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def unique_names(self):
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# sorted
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if not self.__allnames:
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self.__allnames = []
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for name, aliases in self.__byrgb.values():
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self.__allnames.append(name)
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self.__allnames.sort(key=str.lower)
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return self.__allnames
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def aliases_of(self, red, green, blue):
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try:
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name, aliases = self.__byrgb[(red, green, blue)]
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except KeyError:
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raise BadColor((red, green, blue)) from None
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return [name] + aliases
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class RGBColorDB(ColorDB):
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_re = re.compile(
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r'\s*(?P<red>\d+)\s+(?P<green>\d+)\s+(?P<blue>\d+)\s+(?P<name>.*)')
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class HTML40DB(ColorDB):
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_re = re.compile(r'(?P<name>\S+)\s+(?P<hexrgb>#[0-9a-fA-F]{6})')
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def _extractrgb(self, mo):
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return rrggbb_to_triplet(mo.group('hexrgb'))
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class LightlinkDB(HTML40DB):
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_re = re.compile(r'(?P<name>(.+))\s+(?P<hexrgb>#[0-9a-fA-F]{6})')
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def _extractname(self, mo):
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return mo.group('name').strip()
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class WebsafeDB(ColorDB):
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_re = re.compile('(?P<hexrgb>#[0-9a-fA-F]{6})')
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def _extractrgb(self, mo):
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return rrggbb_to_triplet(mo.group('hexrgb'))
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def _extractname(self, mo):
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return mo.group('hexrgb').upper()
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# format is a tuple (RE, SCANLINES, CLASS) where RE is a compiled regular
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# expression, SCANLINES is the number of header lines to scan, and CLASS is
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# the class to instantiate if a match is found
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FILETYPES = [
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(re.compile('Xorg'), RGBColorDB),
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(re.compile('XConsortium'), RGBColorDB),
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(re.compile('HTML'), HTML40DB),
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(re.compile('lightlink'), LightlinkDB),
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(re.compile('Websafe'), WebsafeDB),
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]
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def get_colordb(file, filetype=None):
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colordb = None
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fp = open(file)
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try:
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line = fp.readline()
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if not line:
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return None
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# try to determine the type of RGB file it is
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if filetype is None:
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filetypes = FILETYPES
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else:
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filetypes = [filetype]
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for typere, class_ in filetypes:
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mo = typere.search(line)
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if mo:
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break
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else:
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# no matching type
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return None
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# we know the type and the class to grok the type, so suck it in
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colordb = class_(fp)
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finally:
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fp.close()
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# save a global copy
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global DEFAULT_DB
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DEFAULT_DB = colordb
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return colordb
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_namedict = {}
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def rrggbb_to_triplet(color):
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"""Converts a #rrggbb color to the tuple (red, green, blue)."""
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rgbtuple = _namedict.get(color)
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if rgbtuple is None:
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if color[0] != '#':
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raise BadColor(color)
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red = color[1:3]
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green = color[3:5]
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blue = color[5:7]
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rgbtuple = int(red, 16), int(green, 16), int(blue, 16)
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_namedict[color] = rgbtuple
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return rgbtuple
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_tripdict = {}
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def triplet_to_rrggbb(rgbtuple):
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"""Converts a (red, green, blue) tuple to #rrggbb."""
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global _tripdict
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hexname = _tripdict.get(rgbtuple)
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if hexname is None:
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hexname = '#%02x%02x%02x' % rgbtuple
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_tripdict[rgbtuple] = hexname
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return hexname
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def triplet_to_fractional_rgb(rgbtuple):
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return [x / 256 for x in rgbtuple]
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def triplet_to_brightness(rgbtuple):
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# return the brightness (grey level) along the scale 0.0==black to
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# 1.0==white
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r = 0.299
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g = 0.587
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b = 0.114
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return r*rgbtuple[0] + g*rgbtuple[1] + b*rgbtuple[2]
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if __name__ == '__main__':
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colordb = get_colordb('/usr/openwin/lib/rgb.txt')
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if not colordb:
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print('No parseable color database found')
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sys.exit(1)
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# on my system, this color matches exactly
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target = 'navy'
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red, green, blue = rgbtuple = colordb.find_byname(target)
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print(target, ':', red, green, blue, triplet_to_rrggbb(rgbtuple))
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name, aliases = colordb.find_byrgb(rgbtuple)
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print('name:', name, 'aliases:', COMMASPACE.join(aliases))
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r, g, b = (1, 1, 128) # nearest to navy
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r, g, b = (145, 238, 144) # nearest to lightgreen
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r, g, b = (255, 251, 250) # snow
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print('finding nearest to', target, '...')
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import time
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t0 = time.time()
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nearest = colordb.nearest(r, g, b)
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t1 = time.time()
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print('found nearest color', nearest, 'in', t1-t0, 'seconds')
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# dump the database
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for n in colordb.unique_names():
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r, g, b = colordb.find_byname(n)
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aliases = colordb.aliases_of(r, g, b)
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print('%20s: (%3d/%3d/%3d) == %s' % (n, r, g, b,
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SPACE.join(aliases[1:])))
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