Eigene Komponente mit OnClose-Event

[Sir Rufo]

Also ich weiß nicht, was da nicht funtionieren sollte, denn das funktioniert hier einwandfrei:

Die Komponente

Delphi-Quellcode:

unit MyComponent;

interface

uses
  System.Classes;

type
  TMyComponent = class( TComponent )
  private
    FOnDestroy: TNotifyEvent;
  protected
    procedure NotifyOnDestroy;
  public
    procedure BeforeDestruction; override;
  published
    property OnDestroy: TNotifyEvent read FOnDestroy write FOnDestroy;
  end;

implementation

{ TMyComponent }

procedure TMyComponent.BeforeDestruction;
begin
  NotifyOnDestroy( );
  inherited;

end;

procedure TMyComponent.NotifyOnDestroy;
begin
  if Assigned( FOnDestroy ) then
    FOnDestroy( Self );
end;

end.

und die Form

Delphi-Quellcode:

unit Unit2;

interface

uses
  MyComponent,

  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;
    Button2: TButton;
    procedure FormCreate( Sender: TObject );
    procedure Button1Click( Sender: TObject );
    procedure Button2Click( Sender: TObject );
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    FMyComponent: TMyComponent;
    procedure CreateMyComponent;
    procedure MyComponentDestroy( Sender: TObject );
  public
    { Public-Deklarationen }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click( Sender: TObject );
begin
  FreeAndNil( FMyComponent );
end;

procedure TForm2.Button2Click( Sender: TObject );
begin
  CreateMyComponent( );
end;

procedure TForm2.CreateMyComponent;
begin
  FreeAndNil( FMyComponent );
  FMyComponent := TMyComponent.Create( Self );
  FMyComponent.OnDestroy := MyComponentDestroy;
end;

procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  Action := caFree;
end;

procedure TForm2.FormCreate( Sender: TObject );
begin
  CreateMyComponent( );
end;

procedure TForm2.MyComponentDestroy( Sender: TObject );
begin
  if not( csDestroying in Application.ComponentState ) then
    ShowMessage( 'Ich bin dann mal weg!' );
end;

end.

Solange die Anwendung selber nicht beendet wird, erscheint immer die Message.