(***********************************************************************)

(*                                                                     *)

(*                 MLTk, Tcl/Tk interface of OCaml                     *)

(*                                                                     *)

(*    Francois Rouaix, Francois Pessaux, Jun Furuse and Pierre Weis    *)

(*               projet Cristal, INRIA Rocquencourt                    *)

(*            Jacques Garrigue, Kyoto University RIMS                  *)

(*                                                                     *)

(*  Copyright 2002 Institut National de Recherche en Informatique et   *)

(*  en Automatique and Kyoto University.  All rights reserved.         *)

(*  This file is distributed under the terms of the GNU Library        *)

(*  General Public License, with the special exception on linking      *)

(*  described in file LICENSE found in the OCaml source tree.          *)

(*                                                                     *)

(***********************************************************************)

open Camltk

open Protocol

module StringSet = Set.Make(struct type t = string let compare = compare end)

(* should we keep a negative cache ? *)

let available_colors = ref (StringSet.empty)

let check s =

  if StringSet.mem s !available_colors then true

  else begin

    try

      let f = Frame.create_named Widget.default_toplevel "frxcolorcheck"

          [Background (NamedColor s)] in

      available_colors := StringSet.add s !available_colors;

      destroy f;

      true

    with

      TkError _ -> false

  end