Re: Numeric spin control,

From:
"Jeff Partch" <jeffp@mvps.org>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 13 Jul 2006 02:07:11 -0500
Message-ID:
<eX#D5rkpGHA.2328@TK2MSFTNGP05.phx.gbl>
"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:0auab218hbltneuuf1ssd8ub9prt55m81i@4ax.com...

LRESULT CMyControl::OnSetText(WPARAM, LPARAM lParam)
  {
   CString s;
   // format s for the desired state
   return CMyParent::OnSetText(0, (LPARAM)(LPCTSTR)s);
  }

This is what I should be able to write. But of course, due to terminal
brain death of
some MFC designer, this cannot possibly work. So one idea is


******
With three exceptions: COleControl, CMiniFrameWnd and CStatusBar, I believe
that the MFC designer has otherwise all but ignored the existance of
WM_SETTEXT. Is your complaint here that there is no OnSetText? Or that if
there were it would probably end up calling Default?
******

LRESULT CMyControl::OnSetText(WPARAM, LPARAM lParam)
  {
   CString s;
   // format s for the desired state
   return SendMessage(WM_SETTEXT, 0, (LPARAM)(LPCTSTR)s);
  }
of course, this generates an infinitely recrusive loop so I get a stack
overflow.


******
Yes it would, but isn't the solution only a bool member flag?
******

LRESULT CMyControl::OnSetText(WPARAM, LPARAM lParam)
 {
  CString s;
  // format s
  DefWindowProc(m_hWnd, WM_SETTEXT, 0, (LPARAM)(LPCSTR)s);
  }

works, but if CMyControl is a subclass of CMyBetterEdit, which is a
subclass of
CMyCoolEdit, then DefWindowProc bypasses everything.


******
Couldn't your CMyCoolEdit make the DefWindowProc call?

LRESULT CMyCoolEdit::OnSetText(WPARAM, LPARAM lParam)
{
 CString s;
 // format s
 DefWindowProc(WM_SETTEXT, 0, (LPARAM)(LPCSTR)s);
}

LRESULT CMyBetterEdit::OnSetText(WPARAM, LPARAM lParam)
{
 CString s;
 // format s
return CMyCoolEdit::OnSetText(0, (LPARAM)(LPCTSTR)s);
}

LRESULT CMyControl::OnSetText(WPARAM, LPARAM lParam)
{
 CString s;
 // format s
return CMyBetterEdit::OnSetText(0, (LPARAM)(LPCTSTR)s);
}

Or somesuch. We could both of us come up with a better implementation I
reckon.

******

OTOH, if I had a "buddy notification" message, I could do

void CMyControl::OnBuddySet(CSpinButtonCtrl * buddy)
  {
   int n = buddy->GetPos();
   double f = (double)n / 100.0;
   // format f as appropriate
   SetWindowText(s); // update the text
  }

where the default handler in the edit control would be to format the
position as an
integer and setting the text. By overriding that, I get the behavior I
want. But this
isn't how it was done.


******
I thought your original contention was that it sent its buddy no messages at
all. I see now that your complaint was that it didn't send it the message
you want it to. Sorry.
******

(have you noticed that spin buttons can also work with list boxes and
combo boxes? And it
doesn't do a WM_SETTEXT)

******
I knew it did a test for a WC_LISTBOX buddy and sent it an LB_SETCURSEL and
LB_GETCURSEL (as well as sending the parent an LBN_SELCHANGE) instead. I
chose to ignore it as an extraneous corner case, but see that was probably a
mistake. I did not know it did anything special for a WC_COMBOBOX.
******

/////////////////////////////////////////////////////////////////////////////
// CScaledSpinCtrl message handlers

void CScaledSpinCtrl::OnDeltapos(NMHDR* pNMHDR, LRESULT* pResult)
  {
   NM_UPDOWN* pNMUpDown = (NM_UPDOWN*)pNMHDR;
   PostMessage(UWM_UPDATE_BUDDY);

   *pResult = 0;
  }

/****************************************************************************
* CScaledSpinCtrl::OnUpdateBuddy
* Inputs:
* WPARAM: ignored
* LPARAM: ignored
* Result: LRESULT
* Logically void, 0, always
* Effect:
* Updates the buddy control
****************************************************************************/

LRESULT CScaledSpinCtrl::OnUpdateBuddy(WPARAM, LPARAM)
   {
    CFloatingEdit * buddy = (CFloatingEdit *)GetBuddy();
    if(buddy == NULL)
return 0;

    double d = GetPos(); // REQ
#209
    CString s;
    s.Format(fmt, d);
    CString old;
    buddy->GetWindowText(old);
    if(s != old)
buddy->SetWindowText(s);
    return 0;
   } // CScaledSpinCtrl::OnUpdateBuddy


******
While this is probably neither here nor there in the great scheme of things,
I suspect that by the time this handler returns your buddy has received two
WM_SETTEXT and two WM_GETTEXT messages. Anyway, what would you do here when
your CBetterScaledSpinCtrl wanted to process this message and pass it on to
its base?
******

--
Jeff Partch [VC++ MVP]

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