Confused about CWnd::OnLButtonDown() and CTreeCtrl::OnLButtonDown() - c++

Question

MFC Library Reference
CWnd::OnLButtonDown
void CMyCla::OnLButtonDown(UINT nFlags, CPoint point)
{
CWnd::OnLButtonDown(nFlags, point);
}
void CMyTreeCla::OnLButtonDown(UINT nFlags, CPoint point)
{
CTreeCtrl::OnLButtonDown(nFlags, point);
}
I know the inheritance.
class CTreeCtrl : public CWnd
{
......
}
Is there any clear rule to follow when i want to call OnLButtonDown()?
Thank you.

Answer 1

I think this is what you want.
In your class header, you will need to declare the message map, and also write the function header.
Class myCWnd : public CWnd
{
DECLARE_MESSAGE_MAP() //note, no semi colon
afx_msg void OnLButtonDown( UINT nFlags, CPoint pt );
};
in the cpp file:
BEGIN_MESSAGE_MAP(myCWnd, CWnd)
ON_WM_LBUTTONDOWN()
END_MESSAGE_MAP()
void myCWnd::OnLButtonDown( UINT nFlags, CPoint pt )
{
//do what you want here
CWnd::OnLButtonDown(nFlags, pt); //call base class method
}

Answer 2

If you want the parent class implementation to be called first then you call the parent class's OnLButtonDown() and then add your implementation.

Answer 3

Usually, you do what you want to do with the event in your implementation and then you call the implementation of the parent class. This codeguru post shows a nice example in step 2 of the tutorial. But this depends on what exactly you want to do with the OnLButtonDown event, so it might be the other way around in your case.
I assume the inheritance in your example is as follows:
class CMyCla : public CWnd
{
}
class CMyTreeCla : public CTreeCtrl
{
......
}
So indeed, as you do, you do your thing in either OnLButtonDown and then call the parent implementation:
void CMyCla::OnLButtonDown(UINT nFlags, CPoint point)
{
// Your stuff here
// blah
// end your stuff
CWnd::OnLButtonDown(nFlags, point);
}
void CMyTreeCla::OnLButtonDown(UINT nFlags, CPoint point)
{
// Your stuff here
// blah
// end your stuff
CTreeCtrl::OnLButtonDown(nFlags, point);
}