add event to component in the run time

Question

Hi any idea how to add event to the constructed button in the run time? I understand how to build component in the run time, but adding event is another thing. Got any example to explain how it works?

Thanks

Answer 1

A VCL event is just a pointer to a class method for a particular object. You can assign that pointer directly, eg:

__fastcall TForm1::TForm1(TComponent *Owner)
    : TForm(Owner)
{
    TButton *btn = new TButton(this);
    btn->Parent = this;
    // set other properties as needed...

    btn->OnClick = &ButtonClicked;
    /*
    behind the scenes, this is actually doing the equivalent of this:

    TMethod m;
    m.Data = this; // the value of the method's hidden 'this' parameter
    m.Code = &TForm1::ButtonClicked; // the address of the method itself
    btn->OnClick = reinterpret_cast<TNotifyEvent&>(m);
    */
}

void __fastcall TForm1::ButtonClicked(TObject *Sender)
{
    // do something ...
}