unit Unit2;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
 
type
  TForm2 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form2: TForm2;
 
implementation
 
{$R *.dfm}
 
uses
  MaskUtils;
 
// função entrontrada na internet
function Mascara(edt: String;str:String):string;
var
  i : integer;
begin
  for i := 1 to Length(edt) do
  begin
    if (str[i] = '9') and not (edt[i] in ['0'..'9']) and (Length(edt)=Length(str)+1) then
      delete(edt,i,1);
    if (str[i] <> '9') and (edt[i] in ['0'..'9']) then
      insert(str[i],edt, i);
  end;
 
  result := edt;
end;
 
// exemplo utilizando esta função
procedure TForm2.Button1Click(Sender: TObject);
begin
  ShowMessage(  Mascara('192168000010','999.999.999.999') );
end;
 
// alternativa usando as funções já disponíveis do Delphi
procedure TForm2.Button2Click(Sender: TObject);
begin
  ShowMessage( FormatMaskText('000\.000\.000\.000;0;', '192168000019'));
end;
 
 
end.

procedure TForm2.Button2Click(Sender: TObject);
begin
  ShowMessage( FormatMaskText('000\.000\.000\.000;0;', '192168000019'));
end;