+ unique_identifier = Column(Unicode(length=32), nullable=False)
+
+ def __init__(self, *args, **kwargs):
+ # Generate a unique hash if one isn't provided (which it shouldn't be)
+ if 'unique_identifier' not in kwargs:
+ ident = u''.join(random.choice(u'0123456789abcdef')
+ for _ in range(32))
+ kwargs['unique_identifier'] = ident
+
+ super(User, self).__init__(*args, **kwargs)
+
+ @property
+ def unique_colors(self):
+ """Returns a list of (width, '#rrggbb') tuples that semi-uniquely
+ identify this user.
+ """
+
+ width_blob, colors_blob = self.unique_identifier[0:8], \
+ self.unique_identifier[8:32]
+
+ widths = []
+ for i in range(4):
+ width_hex = width_blob[i*2:i*2+2]
+ widths.append(int(width_hex, 16))
+ total_width = sum(widths)
+
+ ret = []
+ for i in range(4):
+ h = int(colors_blob[i*6:i*6+2], 16) / 256.0
+ l = int(colors_blob[i*6+2:i*6+4], 16) / 256.0
+ s = int(colors_blob[i*6+4:i*6+6], 16) / 256.0
+
+ # Cap lightness to 0.25 to 0.75, so it's not too close to white or
+ # black
+ l = l * 0.5 + 0.25
+
+ # Cap saturation to 0.5 to 1.0, so the color isn't too gray
+ s = s * 0.5 + 0.5
+
+ r, g, b = colorsys.hls_to_rgb(h, l, s)
+ color = "#{0:02x}{1:02x}{2:02x}".format(
+ int(r * 256),
+ int(g * 256),
+ int(b * 256),
+ )
+
+ ret.append((1.0 * widths[i] / total_width, color))
+
+ return ret
+