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Table of Contents
XQueryColor, XQueryColors,
XLookupColor, XParseColor - obtain color values
- 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);
- 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
-
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.
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.
An RGB Device specification
is identified by the prefix ``rgb:'' and conforms to the following syntax:
0
0>=40 .vs 0u
0<=39 .vs 0p
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:
0
0>=40 .vs 0u
0<=39 .vs 0p
#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:
0
0>=40 .vs 0u
0<=39 .vs 0p
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:
0
0>=40 .vs 0u
0<=39 .vs 0p
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.
- 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.
XAllocColor(3X11)
, XCreateColormap(3X11)
, XStoreColors(3X11)
Xlib - C Language X Interface
Table of Contents
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