How do I close a modal form right after opening it?

Question

From my application I wish to open a dialog, which should close immediately (after a short message) under some circumstances.

I've tried this:

procedure TForm2.FormActivate(Sender: TObject);
begin
  if SomeCondition then
  begin
    ShowMessage('You can''t use this dialog right now.');
    close;
    modalresult := mrCancel;
  end;
end;

but the dialog remains open. I've also tried to put the code in the OnShow event, but the result is the same.

Why doesn't this work?

score 20 · Answer 1 · answered Aug 06 '10 at 09:03

20

Post a WM_CLOSE message instead of calling close directly;

ShowMessage('You can''t use this dialog right now.');
PostMessage(Handle, WM_CLOSE, 0, 0);
modalresult := mrCancel;

answered Aug 06 '10 at 09:03

Sertac Akyuz

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I accepted Bharat's answer, even though your answer was almost identical. Sorry. He beat you by two seconds :-) – Svein Bringsli Aug 06 '10 at 09:09
2

@Svein - Here, SO shows my answer beat his with 37 seconds. But anyway it is close enough not to make a fuss about it. :-) – Sertac Akyuz Aug 06 '10 at 09:23
2

As Einstein said: the perception of time depends on your speed. – Uwe Raabe Aug 06 '10 at 09:29
1

Voted for this answer because of mrCancel – Michael Riley - AKA Gunny Apr 17 '16 at 11:48

score 16 · Accepted Answer · answered Aug 06 '10 at 09:04

16

try this one

procedure TForm2.FormActivate(Sender: TObject);
begin
  ShowMessage('You can''t use this dialog right now.');
  PostMessage(Self.Handle,wm_close,0,0);
end;

answered Aug 06 '10 at 09:04

Bharat

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James · Answer 3 · 2010-08-06T09:11:46.610

5

Wouldn't it be easier to check the certain circumstance before the form opens, and not open it?

I can't see a reason for the form to stay open, it should disappear immediatly after clicking OK on the show message dialog.

The showmessage is blocking so you won't be able to close until that's OK'd (if you need to close before then you could return a different modal result (or make your own up which doesn't clash with the existing ones like mrUnavailable = 12). Then you could show the message if the ModalResult was mrunavailable.

If it is running the code and just not closing then try using Release instead of close.

Edit: if you re-using the same form in several places don't use Release unless you want to recreate the form every time! Post the close message as the others have suggested

edited Aug 06 '10 at 09:11

answered Aug 06 '10 at 08:57

James

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I open the dialog from several places, and I don't want to check every place. – Svein Bringsli Aug 06 '10 at 08:59
5

Then use a method that you can call from several places. Do the checks in that method and if ok, only then open the form – Marjan Venema Aug 06 '10 at 09:45

score 0 · Answer 4 · edited May 26 '16 at 19:05

0

You can try a timer:

set the timer a low interval (20)
on the OnTimer event, close the form;
enable the timer on the FormActivate event

edited May 26 '16 at 19:05

Mad Physicist

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answered May 26 '16 at 18:52

Mauro

1

How do I close a modal form right after opening it?

4 Answers4