OCX Hit testing...

Muthu Kumar -- muthu@mbtpost.agw.bt.co.uk
Friday, March 01, 1996

VC++ 4.0/Win95/VB4/NT 3.51

	How do I find out when the mouse pointer leaves & enters the OCX
	control?

	I was using global timer with 100 milliseconds interval.
	Is this efficient solution? Will it affect the performance
	of the Container? What would be the correct time interval
	for tracing the mouse pointer?

	I also tried OnNcHitTest. The problem is it is not working
	with the Containers like VC++, VB4 etc

	Any thoughts would be highly appreciated.

	Thanks in advance.

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K. Muthu Kumar
14 Shreeji Apartments,
Kondi Vitta Village,
Bombay - 59.
INDIA.
Ph: (O) +91-22-836 78 42
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Crucial Software -- crucial@ix.netcom.com
Monday, March 04, 1996

[Mini-digest: 2 responses]

>>	How do I find out when the mouse pointer leaves & enters the OCX
>>	control?

WM_MOUSEMOVE messages.

But, the problem seems to be a little more complex than that.  You've
titled the message "hit testing", so I'm guessing that the question you
wanted to ask was:

	How do I find out when the mouse pointer leaves & enters the OCX
	control while the mouse button is down?

If that's what you want to know, you should capture the mouse input when
you get WM_LBUTTONDOWN (or whatever button).

>>	I was using global timer with 100 milliseconds interval.
>>	Is this efficient solution?

Yikes!  Messages mean we don't have to poll anymore.  :-)  When you capture
the mouse movement, you'll get WM_MOUSEMOVE messages, even when the mouse
moves "outside" of the window that's capturing it.

For instance, what buttons do (not having looked at the Windows source
code, I'm using my own experience here :-) is capture the mouse movement
on WM_LBUTTONDOWN.  WM_MOUSEMOVE messages while captured are used to
determine if the current mouse position is over the button, and a repaint
when moving from one state to the other occurs.  If you click down and hold
the left MB over a button, then move the mouse over and off the button,
you will notice the button moves up and down.

I am presuming this is what you're after.

--
Brad Wilson, Crucial Software     crucial@ix.netcom.com    +1 (810) 620-9803
Custom software engineering services for Microsoft Windows NT and Windows 95

"A suited man smiled, said: 'It's just a matter of time; you can have the
 world at your feet by tomorrow, just sign on this line.'"   - Dream Theater
-----From: Deepak Saxena 

I've never tried this, but here's an idea that popped into my head that 
should work:

In response to WM_MOUSEMOVE:

CMyCtrl::OnMouseMove(CPoint point, ...)
{
        if( GetCapture() != this )
        {
                // Since we don't have the mouse yet, we only
                // receive WM_MOUSEMOVE when the mouse is over
                // the window.  Since we set capture as soon as 
                // we receive a WM_MOUSEMOVE message, it means
                // that the mouse must be entering the window.
                SetCapture();              
                OnMouseEnter();                 // Your handler
        }
        else
        {
                // If we have captured the mouse, we can check if it is  
                // in the window or not by getting the client rect and
                // doing a hit test. If your control is not rectangular
                // you can use your own customized hit testing

                CRect rect = GetClientRect();   // Or whatever function  
                                                // is called
                if( !rect.PtInRect(point))
                {
                        ReleaseCapture();
                        OnMouseLeave();         // Your handler
                }
        }
}

Hope this helps(and works)

Deepak Saxena

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