NAME

       XQueryColor, XQueryColors, XLookupColor, XParseColor - obtain color values

SYNTAX

       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, _Xconst char *color_name, XColor
              *exact_def_return, XColor *screen_def_return);

       Status  XParseColor(Display  *display,  Colormap  colormap,  _Xconst  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.

       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.

       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 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 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 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(3), XCreateColormap(3), XStoreColors(3)
       Xlib - C Language X Interface