Next Prev Up
9.2 Color Functions
A color is represented by a CLX color object, in which each of the red,
green, and blue values is specified by an rgb-val -- a floating
point number between 0.0 and 1.0. (see paragraph 1.6, Data Types). The
value 0.0 represents the minimum intensity, while 1.0 represents the
maximum intensity. CLX automatically converts rgb-val values into
16-bit integers when sending colors to an X server. The X server, in
turn, scales 16-bit color values to match the actual intensity range
supported by the screen.
Colors used on :gray-scale screens must have the same value for
each of red, green, and blue. Only one of these values is used by
screen hardware to determine intensity; however, CLX does not define
which of red, green, or blue is actually used.
The following paragraphs describe the CLX functions used to create,
access, and modify colors.
| make-color
| &key (:blue
1.0) (:green 1.0) (:red 1.0) &allow-other-keys
| Function
|
|
|
-
:blue, :green, :red
-
rgb-val
values that specify the saturation for each primary.
Creates, initializes, and returns a new color object with
the specified values for red, green, and blue.
-
color
-
Type color.
|
| color-blue
| color
| Function
|
|
|
-
color
-
A color object.
Returns and (with setf) sets the value for blue in the color.
-
blue-intensity
-
Type rgb-val.
|
| color-green
| color
| Function
|
|
|
-
color
-
A color object.
Returns and (with setf) sets the value for green in the
color.
-
green-intensity
-
Type rgb-val.
|
|
|
Returns non-nil if the argument is a color object and nil otherwise.
-
color-p
-
Type boolean.
|
|
|
-
color
-
A color object.
Returns and (with setf) sets the value for red in the
color.
-
red-intensity
-
Type rgb-val.
|
|
|
-
color
-
A color object.
Returns the values for red, green, and blue in the color.
-
red, green, blue
-
Type rgb-val.
|
Next Prev Up
© 1988, 1989 Texas Instruments
Incorporated
Conversion to HTML made by
Gilbert Baumann.
Last build: Tue Dec 16 23:30:42 1997