Delphi - Image move inside form coordinates.

[SHKODRAN]

Hello everybody.

I have created a small application, which should move images so smoothly into the desktop coordinates.
I was wondering how can I limit that the image remains inside the desktop?

I have try like that to move the image: 

procedure TForm1.Timer1Timer(Sender: TObject);
Var
  X, Y :Integer;
begin
  X:= random(2+1);
   Y:= random(2+1);
    Image1.Left:= Image1.Left + X;
     Image1.Top:= Image1.Top + Y;
      Image1.Refresh;
end; 

Any help is appreciated.

Thanks.

[Departure]

screen.width

screen.height 

This what you will need, and compare with current position