A subcommand of [Tk]'s [winfo] command.

'''winfo rgb''' ''window color''

Returns a list containing three decimal values, which are the red, green, and blue intensities that correspond to ''color'' in the window given by ''window''. ''Color'' may be specified in any of the forms acceptable for a color option.

According to Jeff Hobbs, the decimal values are always 16 bits
[http://www.google.com/groups?selm=3E55CDEB.9070206%40ActiveState.com].

----

Here's a quick way to parse the return string into three separate variables:

    foreach {r g b} [winfo rgb . $some_color] break

...or if you don't like the "break":

    foreach {red green blue} [winfo rgb . "AntiqueWhite"] {}

The technique may seem obscure at first, but apparently it's an accepted idiom in TCL [http://wiki.tcl.tk/1024].


----
Note that "winfo rgb" is ''not'' idempotent (or surjective) over the space of decimal triples.  [CL]
believes that the point is that the range space of "winfo rgb" is the display's color palette
(is that the right GUI vernacular?), and
is thus smaller than the full cartesian product ([[0-65535]],[[0-65535]],[[0-65535]]) one might
otherwise expect.

This presented with [VNC] service for which 
    winfo rgb . #ffff1fffffff
is 
    65535 0 65535
rather than the
    65535 7967 65535
delivered by a better-endowed display.

A start to a work-around for this is ...

[DKF]: The result from '''winfo rgb''' is a triple that describes the colour that is actually fed into the display hardware.  Different display subsystems interpret this in different ways; that [VNC] server is obviously using a round-down rule on a 15-bit display...

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