(***********************************************************************)
(*                                                                     *)
(*                 MLTk, Tcl/Tk interface of Objective Caml            *)
(*                                                                     *)
(*    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 Objective Caml source tree. *)
(*                                                                     *)
(***********************************************************************)
open Camltk

let version = "$Id: frx_listbox.ml,v 1.3 2002/07/23 14:11:56 doligez Exp $"

(* 
 * Link a scrollbar and a listbox
 *)
let scroll_link sb lb =
  Listbox.configure lb 
        [YScrollCommand (Scrollbar.set sb)];
  Scrollbar.configure sb 
        [ScrollCommand (Listbox.yview lb)]

(* 
 * Completion for listboxes, Macintosh style. 
 * As long as you type fast enough, the listbox is repositioned to the
 * first entry "greater" than the typed prefix.
 * assumes: 
 *   sorted list (otherwise it's stupid)
 *   fixed size, because we don't recompute size at each callback invocation
 *)

let add_completion lb action =
  let prefx = ref ""              (* current match prefix *)
  and maxi = Listbox.size lb - 1 (* maximum index (doesn't matter actually) *)
  and current = ref 0             (* current position *)
  and lastevent = ref 0 in

  let rec move_forward () =
    if Listbox.get lb (Number !current) < !prefx then
      if !current < maxi then begin incr current; move_forward() end

  and recenter () =
    let element = Number !current in
     (* Clean the selection *)
     Listbox.selection_clear lb (Number 0) End;
     (* Set it to our unique element *)
     Listbox.selection_set lb element element;
     (* Activate it, to keep consistent with Up/Down.
        You have to be in Extended or Browse mode *)
     Listbox.activate lb element;
     Listbox.selection_anchor lb element;
     Listbox.see lb element in

  let complete time s =
    if time - !lastevent < 500 then   (* sorry, hard coded limit *)
      prefx := !prefx ^ s
    else begin (* reset *)
      current := 0;
      prefx := s
    end;
    lastevent := time;
    move_forward();
    recenter() in


  bind lb [[], KeyPress] 
      (BindSet([Ev_Char; Ev_Time], 
          (function ev -> 
             (* consider only keys producing characters. The callback is called
              * even if you press Shift.
              *)
             if ev.ev_Char <> "" then complete ev.ev_Time ev.ev_Char)));
  (* Key specific bindings override KeyPress *)
  bind lb [[], KeyPressDetail "Return"] (BindSet([], action));
  (* Finally, we have to set focus, otherwise events dont get through *)
  Focus.set lb;
  recenter()   (* so that first item is selected *)

let new_scrollable_listbox top options =
  let f = Frame.create top [] in
  let lb = Listbox.create f options 
  and sb = Scrollbar.create f [] in
    scroll_link sb lb;
    pack [lb] [Side Side_Left; Fill Fill_Both; Expand true];
    pack [sb] [Side Side_Left; Fill Fill_Y];
    f, lb
