unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TAnalyseThread = class(TThread)
  private
  protected
    procedure Execute; override;
  public
    Status : AnsiString;
    OnReady : TNotifyEvent;

    constructor Create(CreateSuspended : Boolean);
    destructor Destroy; override;
  end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private-Deklarationen }
    AnalyseThread : TAnalyseThread;

    procedure OnAnalyseReady(Sender: TObject);
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  if Assigned(AnalyseThread) then
  begin
    AnalyseThread.Terminate;
    FreeAndNil(AnalyseThread);
  end;

  AnalyseThread := TAnalyseThread.Create(True);

  if Assigned(AnalyseThread) then
  begin
    AnalyseThread.OnReady := OnAnalyseReady;

    AnalyseThread.Start;
  end;
end;

procedure TForm1.OnAnalyseReady(Sender: TObject);
begin
  //Auswertung des Daten...

  if Assigned(AnalyseThread) then
  begin
    AnalyseThread.Terminate;
    FreeAndNil(AnalyseThread);
  end;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  if Assigned(AnalyseThread) then
  begin
    AnalyseThread.Terminate;
    FreeAndNil(AnalyseThread);
  end;
end;

{ TAnalyseThread }

constructor TAnalyseThread.Create(CreateSuspended: Boolean);
begin
  inherited Create(CreateSuspended);

  FreeOnTerminate := False;
end;

destructor TAnalyseThread.Destroy;
begin
  inherited Destroy;
end;

procedure TAnalyseThread.Execute;
begin
  inherited;

  //Tue irgendwas bis fertig...

  if Assigned(OnReady) then
    OnReady(Self);
end;

end.