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.
ncolors Specifies the number of XColor structures in the color
definition array.
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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.
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XQueryColor(3X11) X Version 11(Release 5) XQueryColor(3X11)
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
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.
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XQueryColor(3X11) X Version 11(Release 5) XQueryColor(3X11)
SEE ALSO
XAllocColor(3X11), XCreateColormap(3X11), XStoreColors(3X11)
Xlib - C Language X Interface
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