procedure TUNIVERSAL_MAPS.Image321MouseWheelDown(Sender: TObject;
  Shift: TShiftState; MousePos: TPoint; var Handled: Boolean);
  var
xx,yy,ax,ay:extended;
begin

if Combobox1.ItemIndex >= 1 then
Combobox1.ItemIndex:=Combobox1.ItemIndex -1;

prepare_map(lng,lat);
preparedrawonmap;
end;

procedure TUNIVERSAL_MAPS.Image321MouseWheelUp(Sender: TObject;
  Shift: TShiftState; MousePos: TPoint; var Handled: Boolean);
    var
xx,yy,ax,ay:extended;
begin
if Combobox1.ItemIndex <= 17 then
Combobox1.ItemIndex:=Combobox1.ItemIndex +1;
prepare_map(lng,lat);
preparedrawonmap;
end;