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.
| (make-object color%) → (is-a?/c color%) |
| (make-object color% red green blue [alpha]) → (is-a?/c color%) |
| red : (integer-in 0 255) |
| green : (integer-in 0 255) |
| blue : (integer-in 0 255) |
| 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 alpha component (i.e., opacity) of the color.
| (send a-color blue) → (integer-in 0 255) |
Returns the blue component of the color.
Copies the RGB values of another color object to this one, returning
this object as the result.
| (send a-color green) → (integer-in 0 255) |
Returns the green component of the color.
Returns #t if the color object is valid.
| (send a-color red) → (integer-in 0 255) |
Returns the red component of the color.
| (send a-color set red green blue [alpha]) → void? |
| red : (integer-in 0 255) |
| green : (integer-in 0 255) |
| blue : (integer-in 0 255) |
| alpha : (real-in 0 1) = 1.0 |
Sets the four (red, green, blue, and alpha) component values of the color.