Não Deixar abrir 2 quot;instanciasquot; do programa na mes

(* Just include this unit in your project *)
(* ONE Instance APP
   Author  : Clément Doss
   Date    : 6 - DEZ - 2000
   VErsion : 0.0 - First relaease
*)
(* If you have any suggestions or bug reports please do
   email it to suporte@dhs.com.br *)

(* How it works *)
(* I am just trying to keep it simply stupid. I just wanted to add a unit
   to my project that will ensure that one and only one instance will be
   running.

   I never liked to change the Project Source to add stuff there... That´s why
   I wrote this unit.
   Just Add this unit to your project and only one application (with the same
   title) will be allowed to run.
*)

(* A few more details....
   I am using the Application.Title property as an application identifier.
   If you are using two application with the same Application.Title, then the
   second one will not open....

   I used the Title because it seems to be adequate to the following rules:
      1) No code will be added. Just add the unit!
      2) Two applications with the same title seems unlikely to happen.
      3) ... Just not figured this one yet...


   I am using MUTEXes to check the existance of a second instance of the same
   application.

   Both CreateMutex and WaitForSingleObjects are available for Win9x and Windows NT.

   I have tested it with Windows 2000 pro, and delphi 5 E. But it should work with
   earlier versions of delphi.

   Enjoy...
 *)

unit uDHSOneInstanceApp;

interface

implementation

uses Windows,   // THandle defined here
     SysUtils,  // strPCopy defined here
     Forms;     // Application defined here

type
  TdhsOneInstanceApp = Class(TObject)
  private
    FMutex     : THandle;
    FAppTitle  : Array[0..$100] of char;

    procedure CheckForAnotherInstance;
  public
    { Public declarations }
    constructor Create;
  end;
(* //////////  \\\\\\\\\\ *)
var
   OneInstanceApp : TdhsOneInstanceApp;
{ TdhsOnceInstance }
constructor TdhsOneInstanceApp.Create;
begin
     strPCopy(FappTitle,Application.Title);
     CheckForAnotherInstance;
end;

procedure TdhsOneInstanceApp.CheckForAnotherInstance;
var
   hRunningApp : THandle;
begin
  // .. This mutex will be freed when the applcation closes!
  FMutex := CreateMutex (nil, FALSE, FAppTitle );

  if WaitForSingleObject (FMutex, 0) = wait_TimeOut then begin
     // Found another instance
     SetWindowText(Application.Handle,´´); // We must not found this one again ;)

     // Retrieving handle of the first instance;
     hRunningApp := FindWindow(nil,FAppTitle);
     if hRunningApp<>0 then begin
        if IsIconic(hRunningApp) then
           // First instance is minimized.. Restore it
           ShowWindow(hRunningApp,SW_RESTORE);

        BringWindowToTop(hRunningApp);
        SetForegroundWindow(hRunningApp);

     end;

     // Finish this second instance ...
     Application.ShowMainForm := False; // Well... don´t show the main windows
     Application.Terminate;
     Halt(2);
  end;

end;


initialization
   OneInstanceApp := TdhsOneInstanceApp.Create;

finalization
   OneInstanceApp.Free;

end.