Page 115	Table of Contents	Index	Page 117
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E

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CHAPTER 13. DRAWING IN COLOR

=> make-rgb-color red green blue [Function]
Returns a member of class color. The red, green, and blue arguments are real numbers between
0 and 1 (inclusive) that specify the values of the corresponding color components.

=> make-ihs-color intensity hue saturation [Function]
Returns a member of class color. The intensity argument is a real number between 0 and sqrt(3)
(inclusive). The hue and saturation arguments are real numbers between 0 and 1 (inclusive).

=> make-gray-color luminance [Function]
Returns a member of class color. luminance is a real number between 0 and 1 (inclusive). On
a black-on-white display device, 0 means black, 1 means white, and the values in between are
shades of gray. On a white-on-black display device, 0 means white, 1 means black, and the values
in between are shades of gray.

The following two functions comprise the color protocol. Both of them return the components
of a color. All subclasses of color must implement methods for these generic functions.

=> color-rgb color [Generic Function]
Returns three values, the red, green, and blue components of the color color. The values are real
numbers between 0 and 1 (inclusive).

=> color-ihs color [Generic Function]
Returns three values, the intensity, hue, and saturation components of the color color. The first
value is a real number between 0 and sqrt(3) (inclusive). The second and third values are real
numbers between 0 and 1 (inclusive).


13.3.1 Standard Color Names

Table 13.1 lists all the provided color constants. Application programs can define other colors;
these are provided because they are commonly used in the X Windows community, not because
there is anything special about these particular colors. This table is a subset of the color listed
in the file /X11/R4/mit/rgb/rgb.txt, from the X11 R4 distribution.


13.3.2 Contrasting Colors

=> make-contrasting-inks n &optional k [Function]
If k is not supplied, this returns a vector of n designs with recognizably different appearance.
Elements of the vector are guaranteed to be acceptable values for the :ink argument to the
drawing functions, and will not include +foreground-ink+, +background-ink+, or nil. Their
class is otherwise unspecified. The vector is a fresh object that may be modified.

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Page 115	Table of Contents	Index	Page 117
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E