Difference between revisions of "Testing, if form exists"

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Sometimes a form may be launched from several places in a program. If it already exists, it only needs to be brought to the front. If not, it needs to be created.  
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Sometimes a [[TForm|form]] may be launched from several places in a program. If it already exists, it only needs to be brought to the front. If not, it needs to be created.  
  
 
This method is only needed if the form is not auto created. (It should be listed under Project|Project Options|Forms|Available forms.)
 
This method is only needed if the form is not auto created. (It should be listed under Project|Project Options|Forms|Available forms.)

Revision as of 22:06, 10 May 2014

Sometimes a form may be launched from several places in a program. If it already exists, it only needs to be brought to the front. If not, it needs to be created.

This method is only needed if the form is not auto created. (It should be listed under Project|Project Options|Forms|Available forms.)

The easiest way is:

if (MyForm = nil) then Application.CreateForm(TMyForm, MyForm);
MyForm.Show;

Use CloseAction := caFree in the form's OnClose event.

 procedure TMyForm.Formclose(Sender: Tobject; var Closeaction: Tcloseaction);
begin
  CloseAction := caFree;
  MyForm := nil;
End;

This method is taken from forum discussions.