Message-ID: <431D8AA6.20102 at laposte.net>
Date: Tue, 06 Sep 2005 14:25:10 +0200
From: Matthieu Dubuget <matthieu.dubuget at laposte.net>
Reply-To: matthieu.dubuget at laposte.net
MIME-Version: 1.0
To: lablgtk at math.nagoya-u.ac.jp
Subject: Timeout (windows/linux comparison)
Content-Type: text/plain; charset=ISO-8859-1
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I'm trying to draw fast curves on screen using a drawing area from lablgtk2.
I experienced very low frequencies under windows.

I did a very small (and dirty) program, and ran it in bytecode version on
windows and linux in order to understand better my problem.

It appears that on windows :
- the timeout is different from the expected one
- there is a maximum (at about 60 Hz) of the frequency at which I can
have a timeout work.

The program just increments an int ref inside the timeout function, and
prints the frequency
obtained when the program stops.

Here are my results.

asked frequency                        windows                       linux
10                                             
9.1                                10
20                                             
16                                  19.9
30                                             
31.1                               39.7
80                                             
60.2                               82.6
120                                           
62.1                               123.9
160                                           
63.8                               165.0
200                                           
63.9                               198.0
250                                           
62.4                               247.3
320                                           
63.9                               329.8

I do not know if this is due to the windows implementation of the gimp
library managing this part or if
the results on windows can be improved by modifying some setting?

This surely is not one lablgtk problem, but maybe, someone here has an idea?

Thanks in advance

Matthieu Dubuget
_______________________________
(*
ocamlc -dtypes -I +lablgtk2 unix.cma lablgtk.cma gtkInit.cmo tmt.ml -o tmt
*)

open GMain

let main freq duration () =
  let compteur = ref 0 in
  let t0 = Unix.gettimeofday () in

  let window = GWindow.window ~border_width: 10 () in  
  let _ = window#connect#destroy ~callback:(fun () ->
                                              let t1 = Unix.gettimeofday
() in
                                                Printf.printf "%.1f
Hz\n" ( float !compteur /. (t1 -. t0 ))
                                           ) in
  let _ = window#connect#destroy ~callback:Main.quit in
  let vbx = GPack.vbox ~packing:window#add () in
  let quit = GButton.button ~label:"Quit" ~packing:vbx#add () in
  let _ = quit#connect#clicked ~callback:window#destroy in

  let timeout _ =
    compteur := succ !compteur;
    if Unix.gettimeofday () -. t0 > (float duration) then
      begin
        window # destroy ()
      end;
    true in
  let _ = Timeout.add ~ms:(truncate (1000. /. (float freq)))
~callback:timeout in

  let _ = window#show () in
    Main.main ()
                     
let _ = main (int_of_string Sys.argv.(1)) (int_of_string Sys.argv.(2)) ()
_______________________________