Nochmal: Ermiteln ob Objekt freigegeben wurde

[dataspider]

Du musst die Methode Notification überschreiben. Da wirst du über das Freigeben des Formulares informiert:

Delphi-Quellcode:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    FForm2: TForm;
    { Private-Deklarationen }
  protected
    procedure Notification(AComponent : TComponent; Operation : TOperation);
        override;
  public
    constructor Create(AOwner: TComponent); override;
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

uses Unit2;

{$R *.dfm}

constructor TForm1.Create(AOwner: TComponent);
begin
  inherited;
  FForm2 := nil;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  // Form erzeugen, wenn nicht vorhanden
  if not Assigned(FForm2) then
  begin
    FForm2 := TForm2.Create(Self);
    // FForm2.FreeNotification(Self);
    FForm2.Show;
  end;
end;

procedure TForm1.Notification(AComponent : TComponent; Operation : TOperation);
begin
  inherited Notification( AComponent, Operation);
  if Assigned(FForm2) then
    if (Operation = opRemove) and (AComponent = FForm2) then
      FForm2 := nil;
end;

end.

Gruß, Frank