type t = Brr.G.timer_id ref * unit Note.E.send

let create
  : unit -> (t * unit Note.E.t)
  = fun () ->
    let event, send = Note.E.create () in
    (ref (-1), send), event

let stop
  : t -> unit
  = fun (id, _) ->
    Brr.G.stop_timer !id

let start
  : t -> float -> unit
  = fun (id, send) d ->

    Brr.G.stop_timer !id;
    let timer_id = Brr.G.set_interval
        ~ms:(int_of_float @@ d *. 1000.)
        (fun () -> send ()) in
    ignore @@ Brr.G.set_timeout ~ms:0 send;
    id:= timer_id;