A color is an object representing a red-green-blue (RGB) combination of primary colors plus an “alpha” for opacity. Each red, green, or blue component of the color is an exact integer in the range 0 to 255, inclusive, and the alpha value is a real number between 0 and 1, inclusive. For example, (0, 0, 0, 1.0) is solid black, (255, 255, 255, 1.0) is solid white, (255, 0, 0, 1.0) is solid red, and (255, 0, 0, 0.5) is translucent red.
Creates a new color with the given RGB values and alpha, or matching the given color name (using "black" if no color is given or if the name is not recognized). See color-database<%> for more information on color names.
Returns the red component of the color.
Returns the green component of the color.
Returns the blue component of the color.
Returns the alpha component (i.e., opacity) of the color.
Sets the four (red, green, blue, and alpha) component values of the color.
Copies the RGB values of another color object to this one, returning this object as the result.
Returns #t if the color object is immutable.
Returns #t to indicate that the color object is valid.
(Historically, the result could be #f, but color objects are now always valid.)