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CSliderCtrl notifications


ktm@ormec.com
Friday, September 27, 1996

Environment: Win 95, VC++ 4.2

I have a dialog with a slider control in it. Using ClassWizard, I added 
handlers for the notification messages I was interested in.

None of those methods are ever getting called! I used Spy++ to watch the 
window, and saw that no WM_NOTIFY messages are being sent at all! Instead, 
the CSliderCtrl window is getting window messages like WM_KILLFOCUS, 
WM_LBUTTONDOWN, WM_LBUTTONUP, etc. (instead of the NM_KILLFOCUS, NM_CLICK 
messages I expected). 

Do I need to add something to my code in order to ensure that the 
notification messages are actually sent? Or do I need to add something to 
the message map to handle the WM_ messages being sent to the control? 

Neither of the MFC samples (FIRE, CMNCTRLS) that use the slider control 
demonstrate notification messages for that control. I'd appreciate a good 
example.

- Katy
-- 
Katy Mulvey                            ktm@ormec.com
Software Development Engineer
ORMEC Systems
19 Linden Park; Rochester, NY 14625


ganeshs@nationwide.com
Monday, September 30, 1996

Environment: Win 95, VC++ 4.2

> I have a dialog with a slider control in it. Using ClassWizard, I added
> handlers for the notification messages I was interested in.

    To CSliderCtrl's message map?

> None of those methods are ever getting called! I used Spy++ to watch the
> window, and saw that no WM_NOTIFY messages are being sent at all! Instead,
> the CSliderCtrl window is getting window messages like WM_KILLFOCUS,
> WM_LBUTTONDOWN, WM_LBUTTONUP, etc. (instead of the NM_KILLFOCUS, NM_CLICK
> messages I expected).

    Which is what  should be happening, since a  slider control RECEIVES
Windows messages (like any Windows  window) and SENDS notifications like
NM_KILLFOCUS to  it's parent, (like any  child-window-control should...)
the dialog-box window.

> Do I need to add something to my code in order to ensure that the
> notification messages are actually sent? Or do I need to add something to
> the message map to handle the WM_ messages being sent to the control?

    Add your  notification handlers  to your  dialog's message  map, and
everything should be just fine...

/ ___|    / ___| __ _ _ __   ___  ___| |    I do not speak for
\___ \   | |  _ / _` | '_ \ / _ \/ __| '_ \ Tata   Unisys   or
 ___) |  | |_| | (_| | | | |  __/\__ \ | | |Nationwide    Ins.
|____(_)  \____|\__,_|_| |_|\___||___/_| |_|------------------


ktm@ormec.com
Thursday, October 03, 1996

[Mini-digest: 3 responses]

ganeshs@nationwide.com wrote:
> Katy Mulvey  wrote:
> > I have a dialog with a slider control in it. Using ClassWizard, I added
> > handlers for the notification messages I was interested in.
> 
> To CSliderCtrl's message map?

No, to the dialog message map - that is, it ends up looking like:

// From the .H file
        // Generated message map functions
        //{{AFX_MSG(CSliderDlg)
        //...
        afx_msg void OnKillfocusSlider1(NMHDR* pNMHDR, LRESULT* pResult);
        afx_msg void OnClickSlider1(NMHDR* pNMHDR, LRESULT* pResult);
        //}}AFX_MSG
        DECLARE_MESSAGE_MAP()

// From the .CPP file
BEGIN_MESSAGE_MAP(CSliderDlg, CDialog)
        //{{AFX_MSG_MAP(CSliderDlg)
        //...
        ON_NOTIFY(NM_KILLFOCUS, IDC_SLIDER1, OnKillfocusSlider1)
        ON_NOTIFY(NM_CLICK, IDC_SLIDER1, OnClickSlider1)
        //}}AFX_MSG_MAP
END_MESSAGE_MAP()

> > ...
> Which is what should be happening, since a slider control RECEIVES
> Windows messages (like any Windows window) and SENDS notifications like
> NM_KILLFOCUS to it's parent, (like any child-window-control should...)
> the dialog-box window.

Yes, I can see that I was confused here. But if I trace all messages in the 
application, no WM_NOTIFY or WM_NOTIFYPARENT messages are ever sent or
recieved by any window in the application. (For testing, it's just a simple 
dialog with a slider control and the OK and Cancel buttons.)

> > Do I need to add something to my code in order to ensure that the
> > notification messages are actually sent? Or do I need to add something to
> > the message map to handle the WM_ messages being sent to the control?
> 
> Add your notification handlers to your dialog's message map, and
> everything should be just fine...

Unfortunately, this is not the case.
  Katy
  ktm@ormec.com
-----From: ganeshs@nationwide.com

    What  I meant  here was,  add notification  handlers for  _WHATEVER_
messages  a  slider control  sends  to  it's parent.  The  documentation
clearly states that a slider receives WM_HSCROLL or WM_VSCROLL messages,
depending  on it's  orientation.  In  effect, it's  quite  similar to  a
scrollbar control (or  a scrollbar, for that matter). You  need to add a
WM_HSCROLL or WM_VSCROLL handler to your dialog.

/ ___|    / ___| __ _ _ __   ___  ___| |    I do not speak for
\___ \   | |  _ / _` | '_ \ / _ \/ __| '_ \ Tata   Unisys   or
 ___) |  | |_| | (_| | | | |  __/\__ \ | | |Nationwide    Ins.
|____(_)  \____|\__,_|_| |_|\___||___/_| |_|------------------
-----From: ktm@ormec.com

Katy Mulvey (ktm@ormec.com) wrote:
> Environment: Win 95, VC++ 4.2
>
> I have a dialog with a slider control in it. Using ClassWizard, I added 
> handlers for the notification messages I was interested in. 
> [... etc.]

I've been corresponding with S. Ganesh (ganeshs@nationwide.com), who responded 
to the original message, and have cleared up some of my confusion (but not all 
of it). Here's my current situation:

When you insert a slider control into a dialog template, ClassWizard allows you 
to add ON_NOTIFY handlers for the common notifications. (e.g., the ones that
start with NM_, like NM_KILLFOCUS, NM_CLICK). Additionally, the slider control 
sends either WM_HSCROLL or WM_VSCROLL messages to the dialog box when the slider
is moved.

In this case, I'm interested in knowing when the slider control loses focus, so 
using the class wizard, I added an ON_NOTIFY for NM_KILLFOCUS. However, using
Spy++, I can see that when the slider control loses focus, it gets a 
WM_KILLFOCUS message, but does not send a WM_NOTIFY message to the dialog, and 
so my handler never gets called. 

So I'm left with the questions:
  Does a slider control send WM_NOTIFY messages under the proper circumstances? 
    If so, what are those circumstances?
    If not, why does ClassWizard think that it does? 
  If I have a slider control in my dialog, how can I know when it loses focus?

  Katy
-- 
Katy Mulvey                            ktm@ormec.com
Software Development Engineer
ORMEC Systems
19 Linden Park; Rochester, NY 14625


ganeshs@nationwide.com
Monday, October 07, 1996

Environment: Win 95, VC++ 4.2

> So I'm left with the questions:
>   Does a slider control send WM_NOTIFY messages under the proper
> circumstances?
>     If so, what are those circumstances?
>     If not, why does ClassWizard think that it does?
>   If I have a slider control in my dialog, how can I know when it loses
> focus?

    Add  a  WM_KILLFOCUS handler  to  a  CSliderCtrl-derived class,  and
SubClass the dialog slider control... If you so prefer, Post a WM_NOTIFY
message to your parent-dialog in the KillFocus handler...

/ ___|    / ___| __ _ _ __   ___  ___| |    I do not speak for
\___ \   | |  _ / _` | '_ \ / _ \/ __| '_ \ Tata   Unisys   or
 ___) |  | |_| | (_| | | | |  __/\__ \ | | |Nationwide    Ins.
|____(_)  \____|\__,_|_| |_|\___||___/_| |_|------------------

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