Graphics color library

[ebautis]

Is there a way to check if a user has input a valid color from the graphics color library? I'm planning to write a getValidColor() function for my program that accepts input from a user in the form of a string (i.e. "white" "blue" etc.) Help?

[bvdet]

What graphics color library are you referring to? In Tkinter, colors are represented "#000"-"#fff", "#000000"-"#ffffff", "#000000000 ", "#fffffffff ", and the basic colors like "green", "blue", etc. In the software I use in my work, SDS/2, colors are represented as tuples of the RGB values 0-255. You can create a function to test the validity of user input of these types. Following are two functions I wrote to test for SDS/2 colors:

def validColTup(s):
    '''
    Given a string representing a color tuple, return the tuple.
    Return tuple (255,0,0) if string has an invalid number
    or is formatted improperly.
    '''
    try:
        tt = eval(s)
    except:
        tt = s
    try:
        if False in [[False, True][0 <= i <= 255 or 0] for i in tt] or len(tt) != 3:
            Warning('Invalid color - using (255,0,0)')
            return 255,0,0
    except:
        Warning('Incorrect color tuple - using (255,0,0)')
        return 255,0,0 
    return tt

import re
color_patt = re.compile(r"^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$")

def validColorStr(s):
    '''
    A color tuple is represented by three integers between 0-255
    separated by commas.
    Examples:
        (255,0,0) - red
        (120,120,120) - gray
    Possible string input representing a color tuple.
    '255,0,0' and '120,120,120'
    Test a string for proper form to represent a color tuple.
    Raise an exception if string is not valid.    '''
    # there must be no spaces
    if len(s.split()) == 1:
        colList = s.split(',')
        # R,G,B
        if len(colList) == 3:
            # check each primary color for validity
            if None not in [color_patt.match(octet) for octet in colList]:
                return s
    raise ValueError