let zoom (factor:float) pixbuf =
let formule = (fun x -> (float_of_int x) *. factor +. 0.5 ) || int_of_float in
let width = pixbuf => (GdkPixbuf.get_width || formule) in
let height = pixbuf => (GdkPixbuf.get_height || formule) in
prerr_endline ("Old width="^(string_of_int (GdkPixbuf.get_width pixbuf)));
prerr_endline ("Old height="^(string_of_int (GdkPixbuf.get_height pixbuf))^"\n");
scaleTo (width,height) pixbuf