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Mouse notification when leaving the client area

Posted on 1997-07-21
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Last Modified: 2013-11-20
How can I be notified when the mouse leaves a child view in an MDI App when no mouse buttons are down?  Is there a way that doesn't involvethe CWnd::SetCapture() method?  I am implementing a customized cursor and need to do some GDI cleanup when the mouse leaves the client window.
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Question by:derrickh
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10 Comments
 
LVL 8

Expert Comment

by:gelbert
ID: 1302712
Use OnMouseMove, it gives you coordinates of cursor. Based on them you can figure out where you are.
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Author Comment

by:derrickh
ID: 1302713
I AM using the OnMouseMove() notification for processing inside  of the client area.  My view does not receive notification of mouse messages when it is outside of the client area. I am trying to determine when the mouse leaves the client area.  There is a nice function (I forget the name) that does notify the view when the mouse leaves IF the left mouse button is down, but I need it when the mouse button is up. Is there a straightforward way to do this?
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LVL 10

Accepted Solution

by:
RONSLOW earned 50 total points
ID: 1302714
There is an article in Windows Developers Journal Sept 1996 which describes how to implement a WM_MOUSEMOVEIN and WM_MOUSEMOVEOUT message.  It discusses a couple of different ways to implement this, and implements a "best" method.  You can download the code from the WDJ site or I can send you the source code if you like.

e-Mail me at Roger_Onslow@compsys.com.au

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Author Comment

by:derrickh
ID: 1302715
This code is an SDK solution. I was looking for a MFC way to do this.
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LVL 10

Expert Comment

by:RONSLOW
ID: 1302716
You simply override PumpMessage for your CMyApp to do normal pump message then call the special dispatch code using m_msgCur

(Please refer to my e-Mail reply for details).

I'll see if I can get it working in my own app and will post some code here for reference.  If you get it working first, let me know.

Roger

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Expert Comment

by:asker
ID: 1302717
If you are working under NT, check TrackMouseEvent routine in Win32 API.
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Author Comment

by:derrickh
ID: 1302718
Nope.  I found that already, and to my dismay it only works for NT (as you said).  We're writing the software for Windows 95 AND NT.  It must be compatible with both. :-(
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LVL 10

Expert Comment

by:RONSLOW
ID: 1302719
I've got it working - will post solution here shortly (when I get a break from my real work :-)

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LVL 10

Expert Comment

by:RONSLOW
ID: 1302720
Here is my code (seems to work OK).

in my WinApp.h
====================
extern const UINT WM_MOUSEMOVEIN;
extern const UINT WM_MOUSEMOVEOUT;

class QWinApp : public CWinApp {
      ...
      bool m_bMouseIn;
      bool m_bMouseInOutUnknown;
      bool m_bGenerateMouseInOutMessages;
      ...
      //{{AFX_VIRTUAL(QWinApp)
      ...
      virtual BOOL PumpMessage();
      ...
      //}}AFX_VIRTUAL
      ...
};

in my WinApp.cpp
====================

const UINT WM_MOUSEMOVEIN = ::RegisterWindowMessage("WM_MOUSEMOVEIN");
const UINT WM_MOUSEMOVEOUT = ::RegisterWindowMessage("WM_MOUSEMOVEOUT");

QWinApp::QWinApp() :
      ...
      , m_bMouseIn(FALSE)      // doesn't matter because don't know yet
      , m_bMouseInOutUnknown(TRUE)      // don't know whether in or out yet
      , m_bGenerateMouseInOutMessages(FALSE)      // TRUE if you want mouse move in/out message generated
{
      ...
}

BOOL QWinApp::PumpMessage() {
      BOOL ok = CWinApp::PumpMessage();
      if (ok && m_bGenerateMouseInOutMessages) {
            //If mouse is in then check if it has gone out. If
            //mouse is not in then check if it has come in.
            if (m_bMouseIn || m_bMouseInOutUnknown) {
                  //As long as there is no message for this application
                  //track the mouse cursor position.
                  while(!PeekMessage(&m_msgCur, 0, 0, 0, PM_NOREMOVE)) {
                        CWnd* pMainWnd = ::AfxGetMainWnd();
                        if (pMainWnd) {
                              CPoint pt; GetCursorPos(&pt);
                              CWnd* pMsgWnd = CWnd::WindowFromPoint(pt);
                              //If window at mouse cursor position is not this
                              //app's window and not any of its child windows
                              //then it means mouse has left the app area.
                              if (pMsgWnd != pMainWnd && !pMainWnd->IsChild(pMsgWnd)) {
                                    m_bMouseIn = FALSE;
                                    m_bMouseInOutUnknown = FALSE;
                                    pMainWnd->PostMessage(WM_MOUSEMOVEOUT, 0, 0L);
                                    break;
                              }
                        }
                  }
            }
            if (! m_bMouseIn || m_bMouseInOutUnknown) {
                  //If the mouse is not in and the app has received
                  //mouse move message the it means mouse has entered.
                  if (
                        m_msgCur.message == WM_MOUSEMOVE ||
                        m_msgCur.message == WM_NCMOUSEMOVE
                  ) {
                        CWnd* pMainWnd = ::AfxGetMainWnd();
                        if (pMainWnd) {
                              m_bMouseIn = TRUE;
                              m_bMouseInOutUnknown = FALSE;
                              pMainWnd->PostMessage(WM_MOUSEMOVEIN, 0, 0L);
                        }
                  }
            }
      }
      return ok;
}

example of how to handle a message in MainFrame.h/cpp
============================================================

BEGIN_MESSAGE_MAP(QMainFrame, CFrameWnd)
...
ON_REGISTERED_MESSAGE(WM_MOUSEMOVEIN, OnMouseMoveIn)
ON_REGISTERED_MESSAGE(WM_MOUSEMOVEOUT, OnMouseMoveOut)
...
END_MESSAGE_MAP()

LRESULT QMainFrame::OnMouseMoveIn(WPARAM /*wparam*/, LPARAM /*lparam*/) {
      TRACE("OnMouseMoveIn\n");
      return 0;
}

LRESULT QMainFrame::OnMouseMoveOut(WPARAM /*wparam*/, LPARAM /*lparam*/) {
      TRACE("OnMouseMoveOut\n");
      return 0;
}

Hope this helps.

Roger

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Author Comment

by:derrickh
ID: 1302721
This I can work with. Thank for the time you put in!
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