delphi中怎么实现点击关闭为缩小为系统托盘？

delphi系统托盘设置
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls,shellapi, Menus, AppEvnts,Registry;
const
mousemsg = wm_user + 1; //自定义消息，用于处理用户在图标上点击鼠标的事件
iid = 100; //用户自定义数值，在TnotifyIconDataA类型全局变量ntida中使用
type
TForm1 = class(TForm)
Button1: TButton;
PopupMenu1: TPopupMenu;
N1: TMenuItem;
ApplicationEvents1: TApplicationEvents;
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure Button1Click(Sender: TObject);
procedure ApplicationEvents1Minimize(Sender: TObject);
procedure FormShow(Sender: TObject);
private
procedure mousemessage(var message: tmessage); message mousemsg;
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
ntida:TNotifyIcondata