Returns a textual specification of this in the form `rgb(r,g,b)` or `rgba(r,g,b,a)`, where “r”, “g”, “b” and “a” represent the red, green, blue and alpha values respectively.
“r”, “g”, and “b” are represented as integers in the range 0 to 255, and “a” is represented as a floating point value in the range 0 to 1.
These string forms are string forms that are supported by the CSS3 colors module, and can be parsed by [method@Gdk.RGBA.parse].
Note that this string representation may lose some precision, since “r”, “g” and “b” are represented as 8-bit integers. If this is a concern, you should use a different representation.
A newly allocated text string