Allow rbg and rgba , hsl and hsla as valid colors.

https://github.com/jupyter-widgets/ipywidgets/blob/381180372b912e7780cc2d2ebd4f89e281bea3b9/ipywidgets/widgets/trait_types.py#L13-L26

Think we can use

^(#[0-9a-f]{3}|#(?:[0-9a-f]{2}){2,4}|(rgb|hsl)a?\((\d+%?(deg|rad|grad|turn)?[,\s]+){2,3}[\s\/]*[\d\.]+%?\))

As regex to also validate

hence change to

 _color_re = re.compile(r'#[a-fA-F0-9]{3}(?:[a-fA-F0-9]{3})?$') 
_rbg_rgba_hsl_hsla = re.compile('^(#[0-9a-f]{3}|#(?:[0-9a-f]{2}){2,4}|(rgb|hsl)a?\((\d+%?(deg|rad|grad|turn)?[,\s]+){2,3}[\s\/]*[\d\.]+%?\))')
  
  
 class Color(traitlets.Unicode): 
     """A string holding a valid HTML color such as 'blue', '#060482', '#A80'""" 
  
     info_text = 'a valid HTML color' 
     default_value = traitlets.Undefined 
  
     def validate(self, obj, value): 
         if value.lower() in _color_names or _color_re.match(value) or _rbg_rgba_hsl_hsla.match(color) : 
             return value 
         self.error(obj, value) 

checked with code:

import re

_rbg_rgba_hsl_hsla = re.compile('^(#[0-9a-f]{3}|#(?:[0-9a-f]{2}){2,4}|(rgb|hsl)a?\((\d+%?(deg|rad|grad|turn)?[,\s]+){2,3}[\s\/]*[\d\.]+%?\))')

test_list = [
    
	'rgb(255, 0, 0, 0.3)',  # red 
	'rgb(0, 255, 700)',     # green 
	'rgb(0, 0, 255)',      # blue 

	# RGBA Colors 
	'rgba(255, 0, 0, 3)',  # red with opacity 
	'rgba(0, 255, 0)',     # green with opacity 
	'rgba(0, 0, 255, 1)',  # blue with opacity 

	#  HSL Colors 
	'hsl(120, 100%, 500%)', # green 
	'hsl(120, 100%, 75)',   # light green 
	'hsl(120, 100%, 25%)', # dark green 
	'hsl(120,  60%, 70)',   # pastel green 

	# HSLA Colors 
	'hsl(120, 100%, 50%, 0.2)',   # green with opacity 
	'hsla(120, 100%, 75%, 40)',   # light green with opacity 
	'hsl(120, 100%, 70%, 0.6)',   # dark green with opacity 
	'hsla(120,  60%, 70%, 2)',    # pastel green with opacity 
]

result = []
for color in test_list: 
     result.append(_rbg_rgba_hsl_hsla.match(color))
    
dict(zip(test_list,result))

[vidartf]

Actually, I see that the tests does not include any HSL values. They might have gotten lost somewhere. Putting that as a TODO on the PR.

[DanielAristidou]

vidartf-fullcolor has been merged and closes this issue.