Delphi XE3 form Open and Close - forms

Question

Can someone help me with this:
I have form 1 and form 2
in form1 1 :use form2.
in form1 put a button with code Form2.Showmodal;
form2 is made invisible
form2 has one button:
form2.close = works but does not close just hides the form.
-form2.free - either access violation or closes and the form1 is frozen (taskmngr to kill it)
Form2. release - acccess viololation or closes..if I click the open button on form1 to reopen the form it give access violation..
Form2.close + onClose action :=cafree; - access violation..
Form2.closemodal - has no effect..
how can I dispose and reuse form2 which is shown as modal from form1 ?
thanks a bunch..it has to be something simple Im overlooking.
s

Answer 1

form2.close = works but does not close just hides the form.
Yes, it does close the form. That is what the default behavior of a closed form is - to hide itself. In the case of a modal form, Close() merely set's the form's ModalResult to a non-zero value, which causes ShowModal() to exit and close/hide the form.
form2.free - either access violation or closes and the form1 is frozen (taskmngr to kill it)
It is not safe to Free() a form from inside of an event handler belonging to the same form. The VCL still needs to access the form object after the event handler exits. To safely free the form, you have to use Release() instead, which signals the form to automatically free itself at a later time when it is safe to do so.
Form2. release - acccess viololation or closes..if I click the open button on form1 to reopen the form it give access violation..
The only way Release() can cause an AV is if you are calling it using an invalid form pointer. If re-opening a form causes an AV, then you have some serious bugs in your code.
Form2.close + onClose action :=cafree; - access violation..
caFree causes the form to call Release() on itself. See above.
Form2.closemodal - has no effect..
You are not supposed to call CloseModal() directly. Use Close() or set the ModalResult instead.

Answer 2

First, remove Form 2 from auto-creating.
Project > Options > Forms
Remove Form 2 from "Auto-create forms"
This makes sure that this form is not automatically created.
When you create an instance of it, do not refer to it by its name (such as Form2). Instead, create a temporary variable. If you want to show it in the modal state, do it something like this:
procedure Button1Click(Sender: TObject);
var
F: TForm2;
begin
F:= TForm2.Create(nil);
try
F.ShowModal;
finally
F.Free;
end;
end;
Don't refer to your form by any name you may have given it, such as Form2. If you instantiate it as another variable as demonstrated above (with F), then make sure all calls you make to it are through this variable. In fact, as long as you remove this form from the auto-created forms, you may completely remove the declaration to this form:
var
Form2: TForm2;
If you want it to show in a non-modal state, while the main form is still accessible, it has to be done quite differently. Let me know if that's what you need, and I'll adjust my answer.

Answer 3

//this script for showing Form through Button with position
//change position by changing left or top by changing 120 and 300
//in Delphi 10.3 and above
// add form2 unit name in main unit in implementation as uses
//example
//implementation
//uses main;
procedure Button1Click(Sender: TObject);
var
F: TForm2; // Desired Form for Calling or showing
begin
F:= TForm2.Create(nil);
try
F.Left :=left+120; //Left position of Desired Form
F.Top :=top+300; //Top position of Desired Form
F.ShowModal;
finally
F.Free;
end;
end;