58 lines
1.9 KiB
Racket
58 lines
1.9 KiB
Racket
#lang scribble/doc
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@(require "common.rkt")
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@defclass/title[color% object% ()]{
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A color is an object representing a red-green-blue (RGB) combination
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of primary colors plus an ``alpha'' for opacity. Each red, green, or
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blue component of the color is an exact integer in the range 0 to
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255, inclusive, and the alpha value is a real number between 0 and 1,
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inclusive. For example, (0, 0, 0, 1.0) is solid black, (255, 255,
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255, 1.0) is solid white, (255, 0, 0, 1.0) is solid red, and (255, 0,
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0, 0.5) is translucent red.
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See @racket[color-database<%>] for information about obtaining a color
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object using a color name, and see also @racket[make-color].
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@defconstructor*/make[(()
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([red byte?] [green byte?] [blue byte?]
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[alpha (real-in 0 1) 1.0])
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([color-name string?]))]{
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Creates a new color with the given RGB values and alpha, or matching
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the given color name (using ``black'' if no color is given or if the
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name is not recognized). See @racket[color-database<%>] for more
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information on color names.
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}
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@defmethod[(copy-from [src (is-a?/c color%)]) (is-a?/c color%)]{
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Copies the RGB values of another color object to this one, returning
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this object as the result.}
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@defmethod[(is-immutable?) boolean?]{
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Returns @racket[#t] if the color object is immutable.}
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@defmethod[(ok?) boolean?]{
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Returns @racket[#t] if the color object is valid.}
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@defmethod[(red) byte?]{
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Returns the red component of the color.}
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@defmethod[(green) byte?]{
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Returns the green component of the color.}
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@defmethod[(blue) byte?]{
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Returns the blue component of the color.}
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@defmethod[(alpha) (real-in 0 1)]{
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Returns the alpha component (i.e., opacity) of the color.}
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@defmethod[(set [red byte?] [green byte?] [blue byte?]
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[alpha (real-in 0 1) 1.0])
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void?]{
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Sets the four (red, green, blue, and alpha) component values of the color.}
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}
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