No memory leak when setting form as frame's parent?

Question

Hello

To avoid the more complicated solution where the frame calls some routine in the parent form so that the form can kill the frame... I was wondering if it's OK to simply set the form as the frame's parent, and let Delphi call Frame.Free when the user closes the application?

procedure TForm1.FormShow(Sender: TObject);
var
  Frame2 : TFrame2;
begin
  //Frame2 := TFrame2.Create(nil);
  Frame2 := TFrame2.Create(Self);
  Frame2.Align := alClient;
  Frame2.Parent := Self;
  Frame2.Visible := True;
end;

Thank you.

Answer 1

Actually you are confusing parent and owner:

The owner is passed as parameter to the constructor and will take care of freeing the component, the parent is the control which contains the control visually.

Example:

You have got a form, a panel on that form and a label on that panel: The form usually is the owner of the panel and the label. The form is the parent of the panel and the panel is the parent of the label.

As for your question: It is perfectly OK to pass the form that contains the frame as the owner. When the form is freed, it will also free the frame. In addition you must set the parent to some other control for the frame to become visible. That can of course also be the form, but this will not have any effect on freeing the frame.

Answer 2

To be crystal clear:
- The Owner is responsible for the existence of its owned Components and frees them when it destroys itself (they are part of the owner and cannot exist without it).
- The Parent is in charge of showing its children (Controls - without a Parent their Visible property has no effect) and as such will also free its Controls when it destroys itself because nobody would be able to show them anymore.