Barry Warsaw | 2406b1d | 1998-01-31 00:29:41 +0000 | [diff] [blame^] | 1 | """Color Database. |
| 2 | |
| 3 | To create a class that contains color lookup methods, use the module global |
| 4 | function `get_colordb(file)'. This function will try to examine the file to |
| 5 | figure out what the format of the file is. If it can't figure out the file |
| 6 | format, or it has trouble reading the file, None is returned. You can pass |
| 7 | get_colordb() an optional filetype argument. |
| 8 | |
| 9 | Supporte file types are: |
| 10 | |
| 11 | X_RGB_TXT -- X Consortium rgb.txt format files. Three columns of numbers |
| 12 | from 0 .. 255 separated by whitespace. Arbitrary trailing |
| 13 | columns used as the color name. |
| 14 | """ |
| 15 | |
| 16 | import sys |
| 17 | import re |
| 18 | |
| 19 | |
| 20 | # generic class |
| 21 | class ColorDB: |
| 22 | def __init__(self, fp, lineno): |
| 23 | # Maintain several dictionaries for indexing into the color database. |
| 24 | # Note that while Tk supports RGB intensities of 4, 8, 12, or 16 bits, |
| 25 | # for now we only support 8 bit intensities. At least on OpenWindows, |
| 26 | # all intensities in the /usr/openwin/lib/rgb.txt file are 8-bit |
| 27 | # |
| 28 | # key is rrggbb, value is (name, [aliases]) |
| 29 | self.__byrrggbb = {} |
| 30 | # |
| 31 | # key is name, value is (red, green, blue, rrggbb) |
| 32 | self.__byname = {} |
| 33 | # |
| 34 | while 1: |
| 35 | line = fp.readline() |
| 36 | if not line: |
| 37 | break |
| 38 | # get this compiled regular expression from derived class |
| 39 | mo = self._re.match(line) |
| 40 | if not mo: |
| 41 | sys.stderr.write('Error in %s, line %d\n' % (fp.name, lineno)) |
| 42 | lineno = lineno + 1 |
| 43 | continue |
| 44 | # |
| 45 | # extract the red, green, blue, and name |
| 46 | red, green, blue = map(int, mo.group('red', 'green', 'blue')) |
| 47 | name = mo.group('name') |
| 48 | # |
| 49 | # calculate the 24 bit representation of the color |
| 50 | rrggbb = (red << 16) + (blue << 8) + green |
| 51 | # |
| 52 | # TBD: for now the `name' is just the first named color with the |
| 53 | # rgb values we find. Later, we might want to make the two word |
| 54 | # version the `name', or the CapitalizedVersion, etc. |
| 55 | foundname, aliases = self.__byrrggbb.get(rrggbb, (name, [])) |
| 56 | if foundname <> name and foundname not in aliases: |
| 57 | aliases.append(name) |
| 58 | # |
| 59 | # add to by 24bit value |
| 60 | self.__byrrggbb[rrggbb] = (foundname, aliases) |
| 61 | # |
| 62 | # add to byname lookup |
| 63 | point = (red, green, blue, rrggbb) |
| 64 | self.__byname[name] = point |
| 65 | lineno = lineno + 1 |
| 66 | |
| 67 | def find(self, red, green, blue): |
| 68 | rrggbb = (red << 16) + (blue << 8) + green |
| 69 | return self.__byrrggbb.get(rrggbb, (None, [])) |
| 70 | |
| 71 | def find_byname(self, name): |
| 72 | # TBD: is the unfound value right? |
| 73 | return self.__byname.get(name, (0, 0, 0, 0)) |
| 74 | |
| 75 | def nearest(self, red, green, blue): |
| 76 | # TBD: use Voronoi diagrams, Delaunay triangulation, or octree for |
| 77 | # speeding up the locating of nearest point. This is really |
| 78 | # inefficient! |
| 79 | nearest = -1 |
| 80 | nearest_name = '' |
| 81 | for name, (r, g, b, rrggbb) in self.__byname.items(): |
| 82 | rdelta = red - r |
| 83 | gdelta = green - g |
| 84 | bdelta = blue - b |
| 85 | distance = rdelta * rdelta + gdelta * gdelta + bdelta * bdelta |
| 86 | if nearest == -1 or distance < nearest: |
| 87 | nearest = distance |
| 88 | nearest_name = name |
| 89 | return nearest_name |
| 90 | |
| 91 | |
| 92 | class RGBColorDB(ColorDB): |
| 93 | _re = re.compile( |
| 94 | '\s*(?P<red>\d+)\s+(?P<green>\d+)\s+(?P<blue>\d+)\s+(?P<name>.*)') |
| 95 | |
| 96 | |
| 97 | |
| 98 | # format is a tuple (RE, SCANLINES, CLASS) where RE is a compiled regular |
| 99 | # expression, SCANLINES is the number of header lines to scan, and CLASS is |
| 100 | # the class to instantiate if a match is found |
| 101 | |
| 102 | X_RGB_TXT = re.compile('XConsortium'), 1, RGBColorDB |
| 103 | |
| 104 | def get_colordb(file, filetype=X_RGB_TXT): |
| 105 | colordb = None |
| 106 | fp = None |
| 107 | typere, scanlines, class_ = filetype |
| 108 | try: |
| 109 | try: |
| 110 | lineno = 0 |
| 111 | fp = open(file) |
| 112 | while lineno < scanlines: |
| 113 | line = fp.readline() |
| 114 | if not line: |
| 115 | break |
| 116 | mo = typere.search(line) |
| 117 | if mo: |
| 118 | colordb = class_(fp, lineno) |
| 119 | break |
| 120 | lineno = lineno + 1 |
| 121 | except IOError: |
| 122 | pass |
| 123 | finally: |
| 124 | if fp: |
| 125 | fp.close() |
| 126 | return colordb |
| 127 | |
| 128 | |
| 129 | if __name__ == '__main__': |
| 130 | import string |
| 131 | |
| 132 | colordb = get_colordb('/usr/openwin/lib/rgb.txt') |
| 133 | if not colordb: |
| 134 | print 'No parseable color database found' |
| 135 | sys.exit(1) |
| 136 | # on my system, this color matches exactly |
| 137 | target = 'navy' |
| 138 | target = 'snow' |
| 139 | red, green, blue, rrggbb = colordb.find_byname(target) |
| 140 | print target, ':', red, green, blue, hex(rrggbb) |
| 141 | name, aliases = colordb.find(red, green, blue) |
| 142 | print 'name:', name, 'aliases:', string.join(aliases, ", ") |
| 143 | target = (1, 1, 128) # nearest to navy |
| 144 | target = (145, 238, 144) # nearest to lightgreen |
| 145 | target = (255, 251, 250) # snow |
| 146 | print 'finding nearest to', target, '...' |
| 147 | import time |
| 148 | t0 = time.time() |
| 149 | nearest = apply(colordb.nearest, target) |
| 150 | t1 = time.time() |
| 151 | print 'found nearest color', nearest, 'in', t1-t0, 'seconds' |