XQueryColor(3X11) XLIB FUNCTIONS 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 defini-
tion 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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XQueryColor(3X11) XLIB FUNCTIONS XQueryColor(3X11)
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 struc-
ture 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 spec-
ified 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 spec-
ified 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
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XQueryColor(3X11) XLIB FUNCTIONS XQueryColor(3X11)
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 pos-
sibly 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
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XQueryColor(3X11) XLIB FUNCTIONS XQueryColor(3X11)
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), XStoreCol-
ors(3X11)
Xlib - C Language X Interface
X Version 11 Release 6.4 4
