XQueryColor(3X11)XQueryColor(3X11)NAME
XQueryColor, XQueryColors, XLookupColor, XParseColor - obtain color
values
SYNOPSIS
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
Specifies the colormap. Specifies the color name string (for example,
red) whose color definition structure you want returned. Specifies and
returns the RGB values for the pixel specified in the structure. Spec‐
ifies and returns an array of color definition structures for the pixel
specified in the structure. Specifies the connection to the X server.
Returns the exact RGB values. Specifies the number of XColor struc‐
tures in the color definition array. Returns the closest RGB values
provided by the hardware. Specifies the color name string; case is
ignored. 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; oth‐
erwise, 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 con‐
forms 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 sup‐
ported, but its continued use is not encouraged. The syntax is an ini‐
tial 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 follow‐
ing 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
A value for a Colormap argument does not name a defined Colormap. 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 ALSOXAllocColor(3X11), XCreateColormap(3X11), XStoreColors(3X11)
Xlib -- C Language X Interface
XQueryColor(3X11)
