XQueryColor(3)
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
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