كيف استخدام Maskedit لكتابة التاريخ

كود :
uses dateutils; 

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Mask,dateutils;

type
  TForm1 = class(TForm)
    MaskEdit1: TMaskEdit;
    procedure MaskEdit1Change(Sender: TObject);
    procedure MaskEdit1KeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

Function DateIsValide(s:string):boolean;
var
a,m,j: string;
aa,mm,jj:word;
aaa,mmm,jjj:integer;
valid:boolean;
begin
      a:=Copy(s,7,4);  if pos(' ',a)=0 then  aaa:=strtoint(a) else aaa:=0;
      m:=Copy(s,4,2);  if pos(' ',m)=0 then  mmm:=strtoint(m) else mmm:=0;
      j:=Copy(s,1,2);  if pos(' ',j)=0 then  jjj:=strtoint(j) else jjj:=0;

      aa:=Integer(aaa);
      mm:=Integer(mmm);
      jj:=Integer(jjj);

      if IsValidDate(aa,mm,jj) then valid:=true else valid:=false;
      result :=valid;
end;

procedure TForm1.MaskEdit1Change(Sender: TObject);
begin
if (MaskEdit1.Text<>'  /  /    ')  and (MaskEdit1.SelStart=10) then if DateIsValide(MaskEdit1.Text)   then
ShowMessage(MaskEdit1.Text+ '--->'+'Date Correcte') else  ShowMessage(MaskEdit1.Text+ '---> '+'Date Incorrecte') ;
end;

procedure TForm1.MaskEdit1KeyPress(Sender: TObject; var Key: Char);
begin
if not (Key in [#8,#13,'0'..'9']) then Key:=#0;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
MaskEdit1.EditMask:='!##/##/####;1;_';
end;

end.