Initial revision

Tools/pynche/ColorDB.py

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+"""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 re
+
+
+# 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 rrggbb, value is (name, [aliases])
+	self.__byrrggbb = {}
+	#
+	# key is name, value is (red, green, blue, rrggbb)
+	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')
+	    #
+	    # calculate the 24 bit representation of the color
+	    rrggbb = (red << 16) + (blue << 8) + green
+	    #
+	    # 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.
+	    foundname, aliases = self.__byrrggbb.get(rrggbb, (name, []))
+	    if foundname <> name and foundname not in aliases:
+		aliases.append(name)
+	    #
+	    # add to by 24bit value
+	    self.__byrrggbb[rrggbb] = (foundname, aliases)
+	    #
+	    # add to byname lookup
+	    point = (red, green, blue, rrggbb)
+	    self.__byname[name] = point
+	    lineno = lineno + 1
+
+    def find(self, red, green, blue):
+	rrggbb = (red << 16) + (blue << 8) + green
+	return self.__byrrggbb.get(rrggbb, (None, []))
+
+    def find_byname(self, name):
+	# TBD: is the unfound value right?
+	return self.__byname.get(name, (0, 0, 0, 0))
+
+    def nearest(self, red, green, blue):
+	# TBD: use Voronoi diagrams, Delaunay triangulation, or octree for
+	# speeding up the locating of nearest point.  This is really
+	# inefficient!
+	nearest = -1
+	nearest_name = ''
+	for name, (r, g, b, rrggbb) in self.__byname.items():
+	    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()
+    return colordb
+
+
+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, rrggbb = colordb.find_byname(target)
+    print target, ':', red, green, blue, hex(rrggbb)
+    name, aliases = colordb.find(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'