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.
See color-database<%> for information about obtaining a color object using a color name, and see also make-color.
constructor
(make-object color%) → (is-a?/c color%)
(make-object color% red green blue [alpha]) → (is-a?/c color%) red : byte? green : byte? blue : byte? alpha : (real-in 0 1) = 1.0 (make-object color% color-name) → (is-a?/c color%) color-name : string?
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.
method
(send a-color is-immutable?) → boolean?
Returns #t if the color object is immutable.
See also make-color and find-color in color-database<%>.
Returns #t to indicate that the color object is valid.
(Historically, the result could be #f, but color objects
are now always valid.)