How to check if the tabSheet are already created in the TPageControl

Question

I create the tabsheets dynamically in RunTime and placed a Frame inside it using this code:

  procedure TForm1.Button2Click(Sender: TObject);
 var
  TabSheetG: TTabSheet;
begin
  TabSheetG := TTabSheet.Create(PageControl1);
  TabSheetG.Caption := 'Tab Sheet green  ';
  TabSheetG.PageControl := PageControl1;
  Frame3 := TFrame3.Create(nil);
  Frame3.Parent := TabSheetG;
  Frame3.Show;
end;

and now i want to knew if the tab are already created and just make it activate it when i click the same button

score 3 · Accepted Answer · answered Oct 29 '15 at 12:43

3

Add a private variable of type TTabSheet to your class.

type
  TForm1 = class(TForm)
  ....
  private
    FMyTabSheet: TTabSheet;
  end;

It will automatically be initialized to nil.

In the OnClick event handler, test whether the variable is nil. If not, create the tabsheet, otherwise, use the existing tabsheet.

procedure TForm1.Button1Click(Sender: TObject);
begin
  if not Assigned(FMyTabSheet) then
    FMyTabSheet := TTabSheet.Create(PageControl1);
    FMyTabSheet.PageControl := PageControl1;
    ... etc.
  end;
  PageControl1.ActivePage := FMyTabSheet;
end;

answered Oct 29 '15 at 12:43

David Heffernan

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Thanks it's nice solution but do you think it's functional if i got a 30 frame using 30 TabSheet? – Hamza Benzaoui Oct 29 '15 at 12:51
1

Yes, it will scale just fine. You might well opt to declare a enumerated type for the 30 different pages. Then have an array of tab sheets and frames, indexed by that enumerated type. – David Heffernan Oct 29 '15 at 12:53
I got i problem with his method , when i click the button the Tabsheet create just fine but when i close the Tabsheet it wont set to nil again so when i click the button again nothing happen because the TabSheet are not nill – Hamza Benzaoui Oct 31 '15 at 13:03
When you remove the tabsheet, set the reference to nil. – David Heffernan Oct 31 '15 at 13:59
It set dynamically, how i can do that in Designtime? i tired that on the Canclose event for the TpageControl but it set the reference to nil for all the Tabsheets on it. how to specify just the one i want to close? – Hamza Benzaoui Oct 31 '15 at 14:05
I've no idea what your code looks like now. If you have code that destroys the tabsheet, set the reference to nil there. – David Heffernan Oct 31 '15 at 14:09
What i meas is how to destroy a tabsheets dynamically created ? – Hamza Benzaoui Oct 31 '15 at 14:37
Call `Free` on the tabsheet object – David Heffernan Oct 31 '15 at 14:38
Yeah i knew but where? The Tabsheets has no events to do so? – Hamza Benzaoui Oct 31 '15 at 14:42
You have to provide some UI to allow the user to close a page. What is it? – David Heffernan Oct 31 '15 at 15:42
yes , i have to provide a littele close button on the tabsheet and when the user click on it , it should free and nil the tabsheet – Hamza Benzaoui Nov 01 '15 at 09:41
So, what's the problem with doing that? Where are you stuck? – David Heffernan Nov 01 '15 at 12:05

How to check if the tabSheet are already created in the TPageControl

1 Answers1