pango:color-parse-with-alpha (spec)

spec -- a string specifying a color
color -- a newly created pango:color instance with the result, or nil
alpha -- an unsigned integer with the alpha value

Fill in the fields of a color from a string specification. The string can either one of a large set of standard names, taken from the CSS specification, or it can be a hexadecimal value in the form #rgb, #rrggbb, #rrrgggbbb or #rrrrggggbbbb where r, g and b are hex digits of the red, green, and blue components of the color, respectively. White in the four forms is #fff, #ffffff, #fffffffff and #ffffffffffff.

Additionally, parse strings of the form #rgba, #rrggbbaa, #rrrrggggbbbbaaaa, and set alpha to the value specified by the hex digits for a. If no alpha component is found in spec, alpha is set to 0xffff, for a solid color.