Keep a user in a TEdit

Question

I have to check a value of TEdit->Text when a user leaves it and return him to the TEdit, if the value is wrong. The code below works nice in a VCL but it doesn't work in a FMX. So it beeps but doesn't return.

void __fastcall TForm1::Edit1Exit(TObject *Sender)
{
if (Edit1->Text != "123")
    {
    Beep();
    Edit1->SetFocus();
    }
}

It is in a simple form with 2 TEdits only. What I do wrong and how to do it right?

Answer 1

I'll provide a solution in Delphi Firemonkey. Hopefully, the same principles apply in C++ Firemonkey. The following code replaces the invalid text in Edit1 with the word 'Invalid' and returns the focus to Edit1, with 'Invalid' selected ready for overtyping.

procedure TForm1.Edit1Validate(Sender: TObject; var Text: string);
begin
  if Text <> '123' then
  begin
    Text := 'Invalid';
    TThread.CreateAnonymousThread(
    procedure
      begin
        TThread.Synchronize(nil,
         procedure
          begin
            Edit1.SetFocus;
          end);
      end).Start;
  end;
end;