Re: Custom Control - Notifcation Messages

From:

Dan Bloomquist <public21@lakeweb.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sun, 05 Aug 2007 17:04:24 GMT

Message-ID:

<sqnti.13474$B25.8931@news01.roc.ny>

Nobody wrote:

Hi Scott,

Thanks for the quick response.
Your absolutely right about the Send/Post.
I just started messing around making my own notification messages.
I'm just curious as to how Notification messages actually work.
I am a bit confused about WM_PARENTNOTIFY and WM_NOTIFY.
I think I am on the right track. I just need verification.

I take it you have read technical notes 61 and 62. I do believe you
should never use WM_PARENTNOTIFY as has well defined system behavior.

Here, I have created my own notification message.
struct MOUSE
{
HWND hwndFrom;
UINT idFrom;
UINT code;
UINT nFlags;
CPoint point;
};

If you are going to write notifications, stick with the paradigm and use
NMHDR as the first structure member:

//notify clicks ............................
typedef struct tagCLVCLICKA
{
    NMHDR hdr;
    int iItem;
    int iSubItem;
    CPoint ptClick;
    LPARAM lParam;

} CLVCLICKA, *LPCLVCLICKA;

This is so all notifications have the same signature. What if you:

BOOL CSomeCtrl::OnWndMsg( UINT message, WPARAM wParam, LPARAM lParam,
LRESULT* pResult )
{
   if( message == WM_NOTIFY )
   {
     NMHDR& hdr= *reinterpret_cast<NMHDR*>( lParam );
     ...
   }
   return CListCtrl::OnWndMsg( message, wParam, lParam, pResult );
}

Yes, your structure would work but NMHDR sets the discipline.

Then, in OnLButtonDown, OnLButtonUp, OnMouseMove, I send a Notifcation message.
if(GetMouseEvents()) //If MouseEvents Notifcation Messages Enabled
{
Mouse.hwndFrom = GetSafeHwnd();
Mouse.idFrom = ID_MYCONTROL;
Mouse.code = UWM_MYCONTROL_LBUTTONDOWN;
Mouse.nFlags = nFlags;
Mouse.point = point;
GetParent()->PostMessage(WM_NOTIFY, UWM_MYCONTROL_LBUTTONDOWN, (LPARAM)&Mouse);
}

Is that basically how it is done?

Yes, but that you should not hardwire the IDs. (I'm not sure how you got
that to work.)

if( ... )
{
   //Check with parent if new row is ok
   MYSTRUCT nr;
   nr.hdr.code= CLVN_NEWITEM;
   nr.hdr.hwndFrom= GetSafeHwnd( );
   nr.hdr.idFrom= GetDlgCtrlID( );
   nr.iItem= iItem;

   if( GetParent( )->
     SendMessage(WM_NOTIFY, GetParent( )->GetDlgCtrlID( ), (LPARAM)&nr))
       return;

   InsertRowSet( ... );
   ...
}

Best, Dan.