Some trouble with C++ Builder 6

Question

I just tried write small program in C++ Builder 6(don't ask me why, its just a homework in institute). So, my program must hide button1 when i resizing form. But resize event raises after window created, its mean that after i start program button1 is already invisible.

void __fastcall TForm1::FormResize(TObject *Sender)
{
  Button1->Visible = false;
}

I tried use different resize events, but it don't works too. What I'm doing wrong?

PS. Sorry for my bad English.

Answer 1

There is nothing wrong. The Form really does resize while it is being created, that is why you get the event. There are many ways you can address this:

1. use a variable to ignore the first OnResize event until the form is ready:

   private:
       bool fReady;
   

   void __fastcall TForm1::FormResize(TObject *Sender)
   {
       if (!fReady)
           fReady = true;
       else
           Button1->Visible = false;
   }
   

2. use the Form's OnShow event to post a custom message to signal the form is ready:

   private:
       bool fReady;
   protected:
       virtual void __fastcall WndProc(TMessage &Message);
   

   const UINT WM_READY = WM_APP + 100;
   
   void __fastcall TForm1::WndProc(TMessage &Message)
   {
       if (Message.Msg == WM_READY)
           fReady = true;
       else
           TForm::WndProc(Message);
   }
   
   void __fastcall TForm1::FormShow(TObject *Sender)
   {
       PostMessage(Handle, WM_READY, 0, 0);
   }
   
   void __fastcall TForm1::FormResize(TObject *Sender)
   {
       if (fReady)
           Button1->Visible = false;
   }
   

3. use a short timer instead of a custom message:

   private:
       bool fReady;
   

   void __fastcall TForm1::Timer1Timer(TMessage &Message)
   {
       Timer1->Enabled = false;
       fReady = true;
   }
   
   void __fastcall TForm1::FormShow(TObject *Sender)
   {
       Timer1->Enabled = true;
   }
   
   void __fastcall TForm1::FormResize(TObject *Sender)
   {
       if (fReady)
           Button1->Visible = false;
   }
   

Just to name a few.