XcmsQueryColor, XcmsQueryColors, XcmsLookupColor - obtain color values
Status XcmsQueryColor(Display *display, Colormap
    colormap, XcmsColor *color_in_out, XcmsColorFormat
    result_format);
Status XcmsQueryColors(Display *display, Colormap
    colormap, XcmsColor colors_in_out[], unsigned int
    ncolors, XcmsColorFormat result_format);
Status XcmsLookupColor(Display *display, Colormap
    colormap, _Xconst char *color_string, XcmsColor
    *color_exact_return, XcmsColor *color_screen_return,
    XcmsColorFormat result_format);
  - display
- Specifies the connection to the X server.
- colormap
- Specifies the colormap.
- color_exact_return
- Returns the color specification parsed from the color string or parsed
      from the corresponding string found in a color-name database.
- color_in_out
- Specifies the pixel member that indicates the color cell to query. The
      color specification stored for the color cell is returned in this
      XcmsColor structure.
- color_screen_return
- Returns the color that can be reproduced on the screen.
- color_string
- Specifies the color string.
- result_format
- Specifies the color format for the returned color specifications
      (color_screen_return and color_exact_return arguments). If the format is
      XcmsUndefinedFormat and the color string contains a numerical color
      specification, the specification is returned in the format used in that
      numerical color specification. If the format is XcmsUndefinedFormat
      and the color string contains a color name, the specification is returned
      in the format used to store the color in the database.
- ncolors
- Specifies the number of XcmsColor structures in the
      color-specification array.
The XcmsQueryColor function obtains the RGB value for the pixel value in
  the pixel member of the specified XcmsColor structure and then converts
  the value to the target format as specified by the result_format argument. If
  the pixel is not a valid index in the specified colormap, a BadValue
  error results. The XcmsQueryColors function obtains the RGB values for
  pixel values in the pixel members of XcmsColor structures and then
  converts the values to the target format as specified by the result_format
  argument. If a pixel is not a valid index into the specified colormap, a
  BadValue error results. If more than one pixel is in error, the one
  that gets reported is arbitrary.XcmsQueryColor and XcmsQueryColors can generate
    BadColor and BadValue errors.
The XcmsLookupColor 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. The values
    are returned in the format specified by result_format. 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.
    XcmsLookupColor returns XcmsSuccess or
    XcmsSuccessWithCompression if the name is resolved; otherwise, it
    returns XcmsFailure. If XcmsSuccessWithCompression is
    returned, the color specification returned in color_screen_return is the
    result of gamut compression.
  - 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.
XcmsAllocColor(3), XcmsStoreColor(3), XQueryColor(3)
Xlib - C Language X Interface