| """Color Database. |
| |
| To create a class that contains color lookup methods, use the module global |
| function `get_colordb(file)'. This 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. |
| """ |
| |
| import sys |
| import string |
| import re |
| from types import * |
| import operator |
| |
| class BadColor(Exception): |
| pass |
| |
| DEFAULT_DB = None |
| |
| |
| # generic class |
| class ColorDB: |
| def __init__(self, fp, lineno): |
| # 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 = {} |
| # |
| while 1: |
| line = fp.readline() |
| if not line: |
| break |
| # get this compiled regular expression from derived class |
| mo = self._re.match(line) |
| if not mo: |
| sys.stderr.write('Error in %s, line %d\n' % (fp.name, lineno)) |
| lineno = lineno + 1 |
| continue |
| # |
| # extract the red, green, blue, and name |
| # |
| red, green, blue = map(int, mo.group('red', 'green', 'blue')) |
| name = mo.group('name') |
| keyname = string.lower(name) |
| # |
| # TBD: 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 |
| |
| def find_byrgb(self, rgbtuple): |
| try: |
| return self.__byrgb[rgbtuple] |
| except KeyError: |
| raise BadColor(rgbtuple) |
| |
| def find_byname(self, name): |
| name = string.lower(name) |
| try: |
| return self.__byname[name] |
| except KeyError: |
| raise BadColor(name) |
| |
| def nearest(self, rgbtuple): |
| # TBD: use Voronoi diagrams, Delaunay triangulation, or octree for |
| # speeding up the locating of nearest point. Exhaustive search is |
| # inefficient, but may be fast enough. |
| red, green, blue = rgbtuple |
| nearest = -1 |
| nearest_name = '' |
| for name, aliases in self.__byrgb.values(): |
| r, g, b = self.__byname[string.lower(name)] |
| 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 |
| |
| |
| class RGBColorDB(ColorDB): |
| _re = re.compile( |
| '\s*(?P<red>\d+)\s+(?P<green>\d+)\s+(?P<blue>\d+)\s+(?P<name>.*)') |
| |
| |
| |
| # 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 |
| |
| X_RGB_TXT = re.compile('XConsortium'), 1, RGBColorDB |
| |
| def get_colordb(file, filetype=X_RGB_TXT): |
| colordb = None |
| fp = None |
| typere, scanlines, class_ = filetype |
| try: |
| try: |
| lineno = 0 |
| fp = open(file) |
| while lineno < scanlines: |
| line = fp.readline() |
| if not line: |
| break |
| mo = typere.search(line) |
| if mo: |
| colordb = class_(fp, lineno) |
| break |
| lineno = lineno + 1 |
| except IOError: |
| pass |
| finally: |
| if fp: |
| fp.close() |
| # save a global copy |
| global DEFAULT_DB |
| DEFAULT_DB = colordb |
| return colordb |
| |
| |
| |
| _namedict = {} |
| def rrggbb_to_triplet(color, atoi=string.atoi): |
| """Converts a #rrggbb color to the tuple (red, green, blue).""" |
| rgbtuple = _namedict.get(color) |
| if rgbtuple is None: |
| assert color[0] == '#' |
| red = color[1:3] |
| green = color[3:5] |
| blue = color[5:7] |
| rgbtuple = (atoi(red, 16), atoi(green, 16), atoi(blue, 16)) |
| _namedict[color] = rgbtuple |
| return rgbtuple |
| |
| |
| _tripdict = {} |
| def triplet_to_rrggbb(rgbtuple): |
| """Converts a (red, green, blue) tuple to #rrggbb.""" |
| 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_pmwrgb(rgbtuple): |
| return map(operator.__div__, rgbtuple, _maxtuple) |
| |
| |
| |
| if __name__ == '__main__': |
| import string |
| |
| 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' |
| target = 'snow' |
| red, green, blue = colordb.find_byname(target) |
| print target, ':', red, green, blue, hex(rrggbb) |
| name, aliases = colordb.find_byrgb((red, green, blue)) |
| print 'name:', name, 'aliases:', string.join(aliases, ", ") |
| target = (1, 1, 128) # nearest to navy |
| target = (145, 238, 144) # nearest to lightgreen |
| target = (255, 251, 250) # snow |
| print 'finding nearest to', target, '...' |
| import time |
| t0 = time.time() |
| nearest = apply(colordb.nearest, target) |
| t1 = time.time() |
| print 'found nearest color', nearest, 'in', t1-t0, 'seconds' |
| |