C / C++ / MFC Discussion Boards

Tomasz Sowinski3-Sep-02 3:16

3-Sep-02 3:16

Anonymous wrote:
I want to show on the status bar when the data was last time
saved successfully

Instead of standard 'Ready' message, right? If this is the case, override CFrameWnd::GetMessageString:

void CMainFrame::GetMessageString(UINT nID, CString & rMessage) const
{
if (AFX_IDS_IDLEMESSAGE == nID)
{
rMessage = "I'm on status bar";
return;
}

CMDIFrameWnd::GetMessageString(nID, rMessage);
}

Tomasz Sowinski -- http://www.shooltz.com

** Putt knot yore thrust inn spel chequers. **

Re: how to update StatusBar?

lucy3-Sep-02 3:49

lucy

3-Sep-02 3:49

have a look at this article http://www.codeproject.com/script/Submit/ViewHTML.asp?guid=%2Fuseritems%2Fstatusbar%2Easp%2D2%2F20%2F2002

HTH.

Broken link?

Anonymous3-Sep-02 22:38

Anonymous

3-Sep-02 22:38

The link is a dead end...? Or is it just my Netscape Navigator 4.75?

Re: how to update StatusBar?

MarkDoubson4-Sep-02 2:37

MarkDoubson

4-Sep-02 2:37

Use ((CFrameWnd*) AfxGetMainWnd())->SetMessageText("...");

Re: how to update StatusBar?

RalfPeter3-Sep-02 4:14

RalfPeter

3-Sep-02 4:14

I take that you're able to create a status bar in MainFrame (including setting pane # and size). Once outside of MainFrame, youneed to get a pointer to it to modify the status bar remotely.

#include "MainFrm.h"//or equivalent .h
.
.
.
CMainFrame* pFrame = (CMainFrame*)AfxGetApp()->m_pMainWnd;//pointer to mainframe object
.
.
.
pFrame->UpdateStatus(1, "1st panel message...");//and so on

ralf.riedel@usm.edu

SOLVED!!

Anonymous3-Sep-02 22:32

Anonymous

3-Sep-02 22:32

Aaaahh... I'm a moron (but not moron enough not to write under anonymous Wink | ;-)

1st: status bar has this default feature to show "ready" or tooltip on it. I forgot that.
I had made my own simple status bar, and I mixed on the way SetMessageText
and SetPaneText.

2nd: I couldn't get my hands on the CMainFrame object. Thanks to the
replies, now I could!

3rd: (back to the being stupid) When I was instructed to use pFrame->UpdateStatus(1, "1st panel message...")
I was just baffled ".. but there is no UpdateStatus in CFrameWnd class..." Smile | :)

Ok, here is how it works now, in case this helps someone else. I am NOT
updating the default message text on the status bar, I have created my own
pane with a text:

in MainFrm.h must be lines
public:
void UpdateStatusBar(CString sMessage = "");

- - - - - -

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CFrameWnd::OnCreate(lpCreateStruct) == -1)
return -1;

if (!m_wndStatusBar.Create(this) ||
!m_wndStatusBar.SetIndicators(indicators,
sizeof(indicators)/sizeof(UINT)))
{
TRACE0("Failed to create status bar\n");
return -1; // fail to create
}

UpdateStatusBar();

return 0;
}

- - - - - -

void CMainFrame::UpdateStatusBar(CString sMessage)
{
CWinApp* pApp = AfxGetApp();

// the values are read from the registry
CString strValue, strValue2;
strValue = pApp->GetProfileString("Latest update","Date");
strValue2 = pApp->GetProfileString("Latest update","State");

if (strValue.IsEmpty()) {
m_sPaneText = "Data saved: n/a"; }
else {
m_sPaneText.Format("Data saved: %s, %s", strValue, strValue2); }

CStatusBarCtrl &stCtrl = m_wndStatusBar.GetStatusBarCtrl();

// Let's keep it simple...
stCtrl.SetSimple();

// in case you want send a different message to the status bar
// m_sPaneText is a member of CMainFrame
if (sMessage.IsEmpty())
stCtrl.SetText(m_sPaneText,255,0);
else
stCtrl.SetText(sMessage,255,0);

}

- - - - - -
...and then at the same in another class...

In AppDoc.cpp must be line
#include "MainFrm.h"

- - - - - -

void CAppDoc::SaveDataToServer()
{
// blah blah blah... save data and other dull jobs...
// in my case write to registry. The values are read in
// UpdateStatusBar later on and displayed.

// update the status bar from CDocument class object
CMainFrame* pFrame = (CMainFrame*)AfxGetApp()->m_pMainWnd;//pointer to mainframe object
pFrame->UpdateStatusBar();

return;
}

- - - - - -

VTables

pankajdaga3-Sep-02 0:48

pankajdaga

3-Sep-02 0:48

Hi again everyone,

Does anyone know of a good web resource or a book where I can find information regarding vtables and how to manipulate them with C++.

Thanks,

Pankaj

Re: VTables

Tomasz Sowinski3-Sep-02 0:53

Tomasz Sowinski

3-Sep-02 0:53

pankajdaga wrote:
where I can find information regarding vtables and how to manipulate them with C++.

What do you mean by 'manipulating vtables'?

Tomasz Sowinski -- http://www.shooltz.com

** Putt knot yore thrust inn spel chequers. **

Re: VTables

pankajdaga3-Sep-02 1:35

pankajdaga

3-Sep-02 1:35

I was just wondering if it is possible to directly access the contents of a vtable.

Pankaj

Without struggle, there is no progress

Re: VTables

Tomasz Sowinski3-Sep-02 2:11

Tomasz Sowinski

3-Sep-02 2:11

pankajdaga wrote:
if it is possible to directly access the contents of a vtable

It isn't possible in portable manner. Why do you want to do this?

Tomasz Sowinski -- http://www.shooltz.com

** Putt knot yore thrust inn spel chequers. **

Re: VTables

pankajdaga3-Sep-02 3:20

pankajdaga

3-Sep-02 3:20

Just for educational reasons. I am a student at a university. Just wanted to know if it was possible to access the vtable pointer from the C++ code.

Pankaj

Without struggle, there is no progress

Re: VTables

Hostalet Wandosell3-Sep-02 0:59

Hostalet Wandosell

3-Sep-02 0:59

The main topic is not vtables, but there is very nice code, i like this link
http://www.codeproject.com/atl/atl_underthehood_.asp

regards

-----
Mit freundlichen Grüssen/Best Regards/Un cordial saludo.

Ing. José Manuel Hostalet Wandosell, Fraunhofer IPA, Abt.323/Robotersysteme
Nobelstrasse 12, D-70569 Stuttgart (Germany)
mailto:jose.hostalet@ipa.fhg.de, http://www.ipa.fhg.de

Re: VTables

Jeremy Pullicino3-Sep-02 2:06

Jeremy Pullicino

3-Sep-02 2:06

pankajdaga wrote:
vtables and how to manipulate them with C++.

You are one courageous programmer!

Jeremy Pullicino
Professional C++ Developer

Done any hacking lately?

Re: VTables

Joaquín M López Muñoz3-Sep-02 2:59

Joaquín M López Muñoz

3-Sep-02 2:59

Take a look at Jan Gray's article C++: Under the Hood[^] (warning, hardcore stuff).

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: VTables

Mike Nordell4-Sep-02 0:01

Mike Nordell

4-Sep-02 0:01

No I don't, but it's pretty easy for plain (non-MI and non-virtual-baseclass) classes with virtual functions.

Basically it looks like:

classA* pClass points to memory like:

pclass+0: vfptr
pclass+4: reast of classA data

The at what the vfptr points to you have
addr+0: vfunc1 (often scalar d'tor IIRC)
addr+4: vfunc2
addr+8: vfunc3
...

This is for MSVC6. I don't know if it's incompatible for MSVC7.

pointer to property page

Kash3-Sep-02 0:42

Kash

3-Sep-02 0:42

I have an MDI with a property sheet embedded into a CFormView. I have two pages CPage1 and CPage2 in my property sheet.

I want a pointer in CPage2 to access data in CPage1.

Any suggestions?

Re: pointer to property page

Jawache3-Sep-02 0:50

Jawache

3-Sep-02 0:50

When you add pages to the propertysheet can't you add a pointer to the CPage1 to CPage2?

Asim Hussain
e: asim@jawache.net
w: www.jawache.net

Re: pointer to property page

Pavel Klocek3-Sep-02 0:50

Pavel Klocek

3-Sep-02 0:50

In CPage1:

((CMyPropertySheet*)GetParent())->m_page2

Pavel
Sonork 100.15206

FILE and _FILEX problems..

Jawache3-Sep-02 0:41

Jawache

3-Sep-02 0:41

I am openeing a file using fopen and FILE*.

I am getting problems with this structure later It seems to think the FILE is a
_FILEX structure?!?!?!

When I open the file the call stack is.

fopen
_fsopen
_getstream

and the _getstream function definately returns a FILE object in the line

stream.c >>>>>>

retval = (FILE *)__piob[i];

but later it tries to read from the FILE stream using fgets. The call stack here
is

fgets
_lock_file

There is an exception in _lock_file I've figured out what it is and basicaly the
system thinks the FILE structure is a _FILEX structure and tries to access a non
existant member variable so it asserts.

void __cdecl _lock_file (
        void *pf
        )
{
        /*
         * The way the FILE (pointed to by pf) is locked depends on whether
         * it is part of _iob[] or not
         */
        if ( (pf >= (void *)_iob) && (pf <= (void *)(&_iob[_IOB_ENTRIES-1])) )
            /*
             * FILE lies in _iob[] so the lock lies in _locktable[].
             */
            _lock( _STREAM_LOCKS + ((FILE *)pf - _iob) );
        else
            /*
             * Not part of _iob[]. Therefore, *pf is a _FILEX and the
             * lock field of the struct is an initialized critical
             * section.
             */
            EnterCriticalSection( &(((_FILEX *)pf)->lock) );
}

An exception is raised at
EnterCriticalSection( &(((_FILEX *)pf)->lock) );

I have a STRONG suspision its a simple project settings or maybe library linkage
problem since I have the exact same code in another application and it works
fine....

Working on VC6 SP5
Windows 2000 SP2

Asim Hussain
e: asim@jawache.net
w: www.jawache.net

Re: FILE and _FILEX problems..

Tomasz Sowinski3-Sep-02 0:48

Tomasz Sowinski

3-Sep-02 0:48

Seems like you're mixing code using single-threaded and multi-threaded CRT. FILEX is just FILE in single-threaded CRT. In MT version, FILEX aggregates FILE with critical section.

Tomasz Sowinski -- http://www.shooltz.com

** Putt knot yore thrust inn spel chequers. **

Re: FILE and _FILEX problems..

Jawache3-Sep-02 0:59

Jawache

3-Sep-02 0:59

Thats a bit weird.

I had another look at my settings and changed from Static Linkage to Dynamic Linkage, In statis linkage it was using the Debug Multithreaded Archive and having the problems and in the dynamic linked build its using the Dynamic Multithreaded DLL and now it works?

Is this an issue with the Archive vs the DLL ? As I would really like to finaly make a static build and stop with all the installation problems i have.

Asim Hussain
e: asim@jawache.net
w: www.jawache.net

Re: FILE and _FILEX problems..

Tomasz Sowinski3-Sep-02 1:02

Tomasz Sowinski

3-Sep-02 1:02

Jawache wrote:
Is this an issue with the Archive vs the DLL

I'm not sure what are you talking about here. By 'archive' you mean 'static library' or something else?

Your app is single .exe, or you have .exe and your own .dlls? Are you using 3rd party libraries?

Tomasz Sowinski -- http://www.shooltz.com

** Putt knot yore thrust inn spel chequers. **

Re: FILE and _FILEX problems..

Jawache3-Sep-02 1:10

Jawache

3-Sep-02 1:10

Yeah i think i know whats going on now.

Yes i am using a third party library thats been dynamicaly linked and i had my application statically linked. So the object code to create the FILE object was staticaly linked in my app. Whereas the code to access the FILE object was in the shared DLL version of the library.

Asim Hussain
e: asim@jawache.net
w: www.jawache.net

Stopping the machine hibernating or going into standby

Dave Merrifield3-Sep-02 0:01

Dave Merrifield

3-Sep-02 0:01

Hi,

We have an application which connects to a database across a network and
want to prevent machines from hibernating.

We can catch the WM_POWERBROADCAST message and check for the PBT_APMQUERYSUSPEND message in the WParam and display a message. So something like this:-

ON_MESSAGE( WM_POWERBROADCAST, OnHibernate )

LRESULT CMainFrame::OnHibernate(WPARAM WParam, LPARAM LParam)
{
if( WParam == PBT_APMQUERYSUSPEND )
{
AfxMessageBox( _T("About to hibrenate or standby!"), MB_OK );
return BROADCAST_QUERY_DENY ;
}
return WParam;
}

The first time we run the app and select hibernate or suspend it is fine and the message pops up correctly however thereafter the screen goes greyed as usualy on a shutdown and the message is not displayed until I give my application focus. Obviously there is something else I need to do to handle the message.

Any suggestions?

Thanks

Dave

Re: Stopping the machine hibernating or going into standby

Tomasz Sowinski3-Sep-02 0:19

Tomasz Sowinski

3-Sep-02 0:19

From MSDN docs on PBT_APMQUERYSUSPEND:

lParam: A DWORD value that specifies action flags. If bit 0 is 1, the application can prompt the user for directions on how to prepare for the suspension; otherwise, the application must prepare without user interaction. All other bit values are reserved

...

The system allows approximately 20 seconds for an application to remove the WM_POWERBROADCAST message that is sending the PBT_APMQUERYSUSPEND event from the application's message queue. If an application does not remove the message from its queue in less then 20 seconds, the system will assume that the application is in a non-responsive state, and that the application agrees to the sleep request

Maybe you should check this lParam bit?

Tomasz Sowinski -- http://www.shooltz.com

** Putt knot yore thrust inn spel chequers. **

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.