NAME
XQueryColor, XQueryColors, XLookupColor, XParseColor - obtain color values
SYNTAX
int
XQueryColor(Display * display, Colormap colormap, XColor *
def_in_out);
int
XQueryColors(Display * display, Colormap colormap, XColor
defs_in_out[], int ncolors);
Status
XLookupColor(Display * display, Colormap colormap, char *
color_name, XColor * exact_def_return, XColor *
screen_def_return);
Status
XParseColor(Display * display, Colormap colormap, char *
spec, XColor * exact_def_return);
ARGUMENTS
- colormap
- Specifies the colormap.
- color_name
- Specifies the color name string (for example, red) whose
color definition structure you want returned.
- def_in_out
- Specifies and returns the RGB values for the pixel
specified in the structure.
- defs_in_out
- Specifies and returns an array of color definition
structures for the pixel specified in the structure.
- display
- Specifies the connection to the X server.
- exact_def_return
- Returns the exact RGB values.
- ncolors
- Specifies the number of XColor structures in the
color definition array.
- screen_def_return
- Returns the closest RGB values provided by the
hardware.
- spec
- Specifies the color name string; case is ignored.
- exact_def_return
- Returns the exact color value for later use and sets the
DoRed, DoGreen, and DoBlue flags.
DESCRIPTION
The
XQueryColor function returns the current RGB value for the pixel in
the
XColor structure and sets the
DoRed,
DoGreen, and
DoBlue flags. The
XQueryColors function returns the RGB value
for each pixel in each
XColor structure and sets the
DoRed,
DoGreen, and
DoBlue flags in each structure.
XQueryColor and
XQueryColors can generate
BadColor and
BadValue errors.
The
XLookupColor function looks up the string name of a color with
respect to the screen associated with the specified colormap. It returns both
the exact color values and the closest values provided by the screen with
respect to the visual type of the specified colormap. If the color name is not
in the Host Portable Character Encoding, the result is
implementation-dependent. Use of uppercase or lowercase does not matter.
XLookupColor returns nonzero if the name is resolved; otherwise, it
returns zero.
The
XParseColor function looks up the string name of a color with respect
to the screen associated with the specified colormap. It returns the exact
color value. If the color name is not in the Host Portable Character Encoding,
the result is implementation-dependent. Use of uppercase or lowercase does not
matter.
XParseColor returns nonzero if the name is resolved; otherwise,
it returns zero.
XLookupColor and
XParseColor can generate
BadColor error.
COLOR NAMES
An RGB Device specification is identified by the prefix ``rgb:'' and conforms to
the following syntax:
rgb: <red>/<green>/<blue>
<red>, <green>, <blue> := h | hh | hhh | hhhh
h := single hexadecimal digits (case insignificant)
Note that
h indicates the value scaled in 4 bits,
hh the value
scaled in 8 bits,
hhh the value scaled in 12 bits, and
hhhh the
value scaled in 16 bits, respectively.
For backward compatibility, an older syntax for RGB Device is supported, but its
continued use is not encouraged. The syntax is an initial sharp sign character
followed by a numeric specification, in one of the following formats:
#RGB |
(4 bits each) |
#RRGGBB |
(8 bits each) |
#RRRGGGBBB |
(12 bits each) |
#RRRRGGGGBBBB |
(16 bits each) |
The R, G, and B represent single hexadecimal digits. When fewer than 16 bits
each are specified, they represent the most significant bits of the value
(unlike the ``rgb:'' syntax, in which values are scaled). For example, the
string ``#3a7'' is the same as ``#3000a0007000''.
An RGB intensity specification is identified by the prefix ``rgbi:'' and
conforms to the following syntax:
rgbi: <red>/<green>/<blue>
Note that red, green, and blue are floating-point values between 0.0 and 1.0,
inclusive. The input format for these values is an optional sign, a string of
numbers possibly containing a decimal point, and an optional exponent field
containing an E or e followed by a possibly signed integer string.
The standard device-independent string specifications have the following syntax:
CIEXYZ: <X>/<Y>/<Z>
CIEuvY: <u>/<v>/<Y>
CIExyY: <x>/<y>/<Y>
CIELab: <L>/<a>/<b>
CIELuv: <L>/<u>/<v>
TekHVC: <H>/<V>/<C>
All of the values (C, H, V, X, Y, Z, a, b, u, v, y, x) are floating-point
values. The syntax for these values is an optional plus or minus sign, a
string of digits possibly containing a decimal point, and an optional exponent
field consisting of an ``E'' or ``e'' followed by an optional plus or minus
followed by a string of digits.
DIAGNOSTICS
- BadColor
- A value for a Colormap argument does not name a defined
Colormap.
- BadValue
- Some numeric value falls outside the range of values
accepted by the request. Unless a specific range is specified for an
argument, the full range defined by the argument's type is accepted. Any
argument defined as a set of alternatives can generate this error.
SEE ALSO
XAllocColor(3), XCreateColormap(3), XStoreColors(3)
Xlib - C Language X Interface