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152 lines
4.6 KiB
Python
152 lines
4.6 KiB
Python
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"""Color Database.
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To create a class that contains color lookup methods, use the module global
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function `get_colordb(file)'. This function will try to examine the file to
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figure out what the format of the file is. If it can't figure out the file
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format, or it has trouble reading the file, None is returned. You can pass
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get_colordb() an 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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"""
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import sys
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import re
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# generic class
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class ColorDB:
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def __init__(self, fp, lineno):
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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 rrggbb, value is (name, [aliases])
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self.__byrrggbb = {}
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#
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# key is name, value is (red, green, blue, rrggbb)
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self.__byname = {}
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#
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while 1:
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line = fp.readline()
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if not line:
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break
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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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sys.stderr.write('Error in %s, line %d\n' % (fp.name, lineno))
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lineno = lineno + 1
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continue
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#
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# extract the red, green, blue, and name
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red, green, blue = map(int, mo.group('red', 'green', 'blue'))
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name = mo.group('name')
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#
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# calculate the 24 bit representation of the color
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rrggbb = (red << 16) + (blue << 8) + green
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#
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# TBD: 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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foundname, aliases = self.__byrrggbb.get(rrggbb, (name, []))
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if foundname <> name and foundname not in aliases:
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aliases.append(name)
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#
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# add to by 24bit value
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self.__byrrggbb[rrggbb] = (foundname, aliases)
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#
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# add to byname lookup
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point = (red, green, blue, rrggbb)
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self.__byname[name] = point
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lineno = lineno + 1
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def find(self, red, green, blue):
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rrggbb = (red << 16) + (blue << 8) + green
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return self.__byrrggbb.get(rrggbb, (None, []))
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def find_byname(self, name):
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# TBD: is the unfound value right?
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return self.__byname.get(name, (0, 0, 0, 0))
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def nearest(self, red, green, blue):
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# TBD: use Voronoi diagrams, Delaunay triangulation, or octree for
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# speeding up the locating of nearest point. This is really
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# inefficient!
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nearest = -1
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nearest_name = ''
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for name, (r, g, b, rrggbb) in self.__byname.items():
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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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class RGBColorDB(ColorDB):
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_re = re.compile(
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'\s*(?P<red>\d+)\s+(?P<green>\d+)\s+(?P<blue>\d+)\s+(?P<name>.*)')
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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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X_RGB_TXT = re.compile('XConsortium'), 1, RGBColorDB
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def get_colordb(file, filetype=X_RGB_TXT):
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colordb = None
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fp = None
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typere, scanlines, class_ = filetype
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try:
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try:
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lineno = 0
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fp = open(file)
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while lineno < scanlines:
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line = fp.readline()
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if not line:
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break
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mo = typere.search(line)
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if mo:
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colordb = class_(fp, lineno)
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break
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lineno = lineno + 1
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except IOError:
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pass
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finally:
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if fp:
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fp.close()
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return colordb
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if __name__ == '__main__':
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import string
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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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target = 'snow'
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red, green, blue, rrggbb = colordb.find_byname(target)
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print target, ':', red, green, blue, hex(rrggbb)
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name, aliases = colordb.find(red, green, blue)
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print 'name:', name, 'aliases:', string.join(aliases, ", ")
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target = (1, 1, 128) # nearest to navy
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target = (145, 238, 144) # nearest to lightgreen
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target = (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 = apply(colordb.nearest, target)
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t1 = time.time()
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print 'found nearest color', nearest, 'in', t1-t0, 'seconds'
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