Returns an object of type color-space. The
string specifies a public identifier identifying the color-space
family. The remaining arguments specify parameters to the color-space
family. The type and number of the remaining arguments depend on the
color-space family as described below.
(color-space? obj)
Returns #t if obj is a color-space, and otherwise returns
#f.
(color color-space arg )
Returns an object of type color. color-space is
the color-space relative to which color is to be specified. The
type and number of the remaining arguments depend on the color-space
family to which color-space belongs. If no arguments other than
color-space are specified, then the default color in
color-space is returned.
(color? obj)
Returns #t if obj is a color, and otherwise returns
#f.
This International Standard defines the following color-space families:
| • ISO/IEC 10179:1996//Color-Space Family::Device Gray |
| • ISO/IEC 10179:1996//Color-Space Family::Device RGB |
| • ISO/IEC 10179:1996//Color-Space Family::Device CMYK |
| • ISO/IEC 10179:1996//Color-Space Family::Device KX |
| • ISO/IEC 10179:1996//Color-Space Family::CIE LAB |
| • ISO/IEC 10179:1996//Color-Space Family::CIE LUV |
| • ISO/IEC 10179:1996//Color-Space Family::CIE Based ABC |
| • ISO/IEC 10179:1996//Color-Space Family::CIE Based A |
The semantics of each of these color-space families is that of
the corresponding color-space family in ISO/IEC 10180.
The additional arguments required by color-space when one of these
color-space families is specified as the first argument are determined
by the parameters of the corresponding Color-Space Object in ISO/IEC
10180.
When the ISO/IEC 10180 Color-Space Object has no parameters,
color-space
takes no additional arguments. When the ISO/IEC 10180 Color-Space
Object
has a single parameter of type Dictionary, color-space accepts
a keyword argument for each key allowed in the Dictionary. The name
of each keyword is derived from the name of the Dictionary key
by inserting a hyphen before each upper-case letter in the name
that is not the first letter and that is followed by a lower-case letter,
and by then mapping all characters to lower-case. The type of each
keyword argument shall be determined by the type of the corresponding
Dictionary value:
| • If the ISO/IEC 10180 type is a number, then the argument type shall be
a number. |
| • If the ISO/IEC 10180 type is a procedure, then the argument type shall
be a procedure. |
| • If the ISO/IEC 10180 type is a reference to a vector of numbers, then the
argument type shall be a list of numbers of the same length. |
| • If the ISO/IEC 10180 type is a reference to a vector of procedures,
then the argument type shall be a list of procedures of the same length. |
The number and type of the additional arguments required by the
color procedure when the first argument is a color-space that
belongs to one of these families shall be determined by the number and
type
of the argument required by the ISO/IEC 10180
SetColor operator to specify
a color in the corresponding ISO/IEC 10180 color-space. These
additional
arguments are all required arguments (not keyword arguments). Their
types are determined from the ISO/IEC 10180 types in the same manner as
the arguments for color-space.
The default color for each color-space is determined by the value
that ISO/IEC 10180 defines the CurrentColor Graphics State Variable
to have immediately after execution of the SetColorSpace operator
for the corresponding ISO/IEC 10180 color-space.
| A color specified in a color-space with a procedure argument may be
transformed in a device-independent manner to a color specified in a
color-space without any procedure arguments. There is, therefore, no
need when implementing the style language with output to an ISO/IEC 10180
device to be able to compile an arbitrary expression into the language
defined in ISO/IEC 10180. |
|