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How to handle WM_KEYDOWN in a Dialog???

Posted on 2002-04-24
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Last Modified: 2013-11-25
Hello,
I have a problem.

I'm writing a standard application
on Visual C++, using Win32 and
the ATL classes included in
the headers ATLBase.h and ATLWin.h.
I use my own classes derived from:

CMyWindow : public CWindowImpl<CMyWindow>

CMyDialog : public CDialogImpl<CMyDialog>

I make my main window,
and then open a dialog at some time.

My question is:
How to handle for example the WM_KEYDOWN message in this
dialog.
I want when I press for example "Alt+A" and the focus
is in any of the controls in the dialog, this WM_KEYDOWN message to be handled from a single function
for example:
CMyDialog::OnKeyDown(.........),
not from this control's WM_KEYDOWN handler.

If this would help, I want to make the same as the Form KeyPreview property in Visual Basic does.
The WM_KEYDOWN should be handled somehow firstly by the dialog, and
then by the concreate control.

How could I do this???

Thank you in advance.

Pavel Tsekov, Varna, Bulgaria
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Question by:paul_tsekov
7 Comments
 
LVL 32

Accepted Solution

by:
jhance earned 1200 total points
ID: 6966852
A dialog window doesn't normally send your application WM_KEYDOWN messages.  So if you want to get them you must SUBCLASS the dialog and provide your own message handler.

See the SDK help for SubclassDlgItem() or SubclassWindow().
0
 
LVL 4

Expert Comment

by:mblat
ID: 6966910
There is an article Q117563 in Microsoft Knowleage Base.
HOWTO: How to Trap WM_KEYDOWN Messages in a CDialog.

It shows the way for MFC based app.  I see that you are using WTL, but it may point you to the right direction.

Hope it helps.
0
 
LVL 8

Expert Comment

by:Vinayak Kumbar
ID: 6967122
Hi,

I am not sure about the architecture of ur app. If u r using MFC, then using classwizard, map the PreTranslateMessage(...) function to ur dialong class and modify it as

BOOL CTestDlg::PreTranslateMessage(MSG* pMsg)
{
     if(pMsg->message == WM_KEYDOWN)
     {
          //Here U R when a key is hit, but, Alt is handled differently.
          //So u can get here by hitting any other key combinations. Like
          //if(pMsg->wParam == 'B')
          // Key B is hit
          //and
          //if(GetKeyState(VK_CONTROL) & 0x8000) && (pMsg->wParam == 'A'))
          // Key Ctrl+B is hit
     }

     //When Alt is hit check like this
     if((GetKeyState(VK_MENU) & 0x8000) && (pMsg->wParam == 'A'))
     {
          // U R Here as User hit Alt+A
          //Call Ur Function!!!!
          DoKeyProcess();
     }
     
     return CDialog::PreTranslateMessage(pMsg);
}

void CTestDlg::DoKeyProcess()
{
     AfxMessageBox("Alt+A Hit");
}

Here DoKeyProcess()is declared as void DoKeyProcess()in public section of dialog's .h file

Try it out.
VinExpert

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LVL 1

Expert Comment

by:Moondancer
ID: 6973515
Please finalize the following year 2001 question:
http://www.experts-exchange.com/jsp/qShow.jsp?ta=visualbasic&qid=20246850
Moondancer - EE Moderator
0
 

Expert Comment

by:SrinivasaRao
ID: 6974738
i think vinexpert is right:)
bsr
0
 
LVL 1

Author Comment

by:paul_tsekov
ID: 6979198
No, the EXPERT is not right.
I'm using the CDialogImpl<> class,
not CDialog.
I'm not talking about MFC here.
I talk about ATL!!!!!!!!!!!!!!!!
0
 
LVL 1

Author Comment

by:paul_tsekov
ID: 6979238
No, the EXPERT is not right.
I'm using the CDialogImpl<> class,
not CDialog.
I'm not talking about MFC here.
I talk about ATL!!!!!!!!!!!!!!!!
0

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