Confused about CWnd::OnLButtonDown() and CTreeCtrl::OnLButtonDown()

MFC Library Reference

CWnd::OnLButtonDown

void CMyCla::OnLButtonDown(UINT nFlags, CPoint point)
{
    CWnd::OnLButtonDown(nFlags, point);
}


void开发者_如何学C 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.

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
}

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

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);
}