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How to identify if a TForm is created yet and open?

Posted on 1997-11-17
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Last Modified: 2010-04-04
I need a way for Form1 to know if Form2 is created and open.  Form1 is my Main (auto-created) form.  Form2 is created "on-the-fly" with a .Create method, and is then displayed with a .Show method.  Form2 does NOT have a caption, BTW.  How can I detect whether Form2 is created and open?
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Question by:Kapusta
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3 Comments
 
LVL 2

Accepted Solution

by:
Waldek earned 50 total points
ID: 1350787
Maybe
if assigned(TForm2) then (Form2 is created)
Check ComponentState property for testing open and destroy state
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Expert Comment

by:StevenB
ID: 1350788
 It's improtant to realise that this will only check whether Form2 <> Nil. If you ever destroy Form2 then it will still return  True to the above call, unless you explicitly set Form2 := Nil, after the Free method.

  Steven.
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Author Comment

by:Kapusta
ID: 1350789
Here is what I am trying to do...  do I need to add "Form2 := nil" as SteveB suggests?

procedure TForm1.Button1Click(Senter: TObject);
begin
      Timer1.Enabled := True;
      Form2:= TForm2.Create(Application);
      try
            Form2.ShowModal;
      finally
            Form2.Free;
      end;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
      Timer1.Enabled := False;
      if Assigned(Form2) then begin
            Form2.Button1.Click;
      end;
      MessageDlg('Time is up!',mtInformation, [mbOk], 0);
end;

I want to force the Form2 to close SHOULD it be open when the timer on Form1 triggers.

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