XQueryColor(3X11) X Version 11 (Release 5) XQueryColor(3X11)
NAME
XQueryColor, XQueryColors, XLookupColor, XParseColor -
obtain color values
SYNTAX
XQueryColor(display, colormap, def_in_out)
Display *display;
Colormap colormap;
XColor *def_in_out;
XQueryColors(display, colormap, defs_in_out, ncolors)
Display *display;
Colormap colormap;
XColor defs_in_out[];
int ncolors;
Status XLookupColor(display, colormap, color_name,
exact_def_return, screen_def_return)
Display *display;
Colormap colormap;
char *color_name;
XColor *exact_def_return, *screen_def_return;
Status XParseColor(display, colormap, spec,
exact_def_return)
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.
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XQueryColor(3X11) X Version 11 (Release 5) XQueryColor(3X11)
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
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XQueryColor(3X11) X Version 11 (Release 5) XQueryColor(3X11)
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, #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 '+' or '-' 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 '+' or
'-' followed by a string of digits.
DIAGNOSTICS
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XQueryColor(3X11) X Version 11 (Release 5) XQueryColor(3X11)
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(3X11), XCreateColormap(3X11), XStoreColors(3X11)
Xlib - C Language X Interface
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