XQueryColor(3)

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

   Status XParseColor(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.

   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

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