C / C++ / MFC

27-May-02 1:21

Open the files for binary input and output.

Does it work then?

Re: CArchive - query

Ravi Sudhakar27-May-02 2:27

Ravi Sudhakar

27-May-02 2:27

i tried using CFiles as well.
but when i use this file at a later stage, it retrieves using CArchive
and it gives a problem while reading.
It expects certain string but it archive << str; returns series of strings.

So, i thought of using CArchive initially only.

Any other go?

ATL/COM + MFC: Dialogs?

Dominik Reichl27-May-02 0:53

27-May-02 0:53

Hi
Currently i am programming a shell extension. Everything works nice, except a new dialog. I created a new dialog with the visual editor and used the class wizard to generate a new MFC class for the dialog. But when i try to show the dialog in the InvokeCommand() function with .DoModal() it isn't displayed! But the InvokeCommand() function works well! I replaced the dialog showing code with a message box and it is displayed correctly! But why doesn't the dialog work?
I used the standard call form to show the dialog:
CDisplayInfoDlg dlg;
dlg.DoModal();

but it doesn't work. Anyone knows a solution? Confused | :confused:

Martin Ziacek27-May-02 1:00

27-May-02 1:00

Does your shell extension contain CWinApp derived class?

Dominik Reichl27-May-02 1:04

27-May-02 1:04

The main class is
class CCryptoCtxApp : public CWinApp

but the class which should display the dialog is

<br />
class ATL_NO_VTABLE CCryptoShlExt : <br />
	public CComObjectRootEx<CComSingleThreadModel>,<br />
	public CComCoClass<CCryptoShlExt, &CLSID_CryptoShlExt>,<br />
	public IDispatchImpl<ICryptoShlExt, &IID_ICryptoShlExt, &LIBID_CRYPTOCTXLib>,<br />
    public IShellExtInit,<br />
    public IContextMenu<br />

Martin Ziacek27-May-02 1:19

27-May-02 1:19

And what is the return value from DoModal()? DoModal() usually fails, when it cannot locate resources for dialog.

Dominik Reichl27-May-02 1:22

27-May-02 1:22

DoModal() returns IDCANCEL.
Confused | :confused:

Martin Ziacek27-May-02 1:48

27-May-02 1:48

Problem is, that MFC works well within MFC application. Your shell extension is running under explorer.exe and that's not MFC application. DoModal() function can fail for two reasons - cannot locate resources or it is not happy with your main window - explorer window. I had similar problem and I finished with writing my own DoModal() function. I can send it to you this evening, if you want. Try to debug DoModal(), to find out, where it fails.

Dominik Reichl27-May-02 1:51

Re: ATL/COM + MFC: Dialogs? - this is very long message

27-May-02 1:51

No, i will not try to debug it anymore. I tried it about 2 hours. Enough now Smile | :)

Perhaps i create a new MFC DLL containing the dialog.... i need the MFC functions in my program. But you may send me your DoModal() version.

thanks for your help
-Dominik

Martin Ziacek27-May-02 8:38

Returning a refrence from a function

27-May-02 8:38

This is my class, which should help you. It uses my CSeException class from this site. Note, you must pass handle of your main window to DoModal() function.

class CDominikDlg : public CDialog
{
// Construction
public:
CDominikDlg(DWORD dwID, CWnd* pParent = NULL); // standard constructor

// Dialog Data
//{{AFX_DATA(CDominikDlg)
//}}AFX_DATA

MSG m_msgCur;

// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CDominikDlg)
public:
virtual int DoModal(HWND hWndParent);
virtual int RunModalLoop(DWORD dwFlags = 0);
virtual BOOL PumpMessage(void);
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
//}}AFX_VIRTUAL

// Implementation
protected:
CFont m_font;
// Generated message map functions
//{{AFX_MSG(CDominikDlg)
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};

#define WM_KICKIDLE 0x036A // (params unused) causes idles to kick in

CDominikDlg::CDominikDlg(DWORD dwID,CWnd* pParent /*=NULL*/)
: CDialog(dwID, pParent)
{
//{{AFX_DATA_INIT(CDominikDlg)
//}}AFX_DATA_INIT
m_font.CreateFont(8, 6, 0, 0, FW_THIN, 0, 0, 0, DEFAULT_CHARSET,
OUT_CHARACTER_PRECIS, CLIP_CHARACTER_PRECIS, DEFAULT_QUALITY,
DEFAULT_PITCH | FF_DONTCARE, _T("Courier New"));
}

void CDominikDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CDominikDlg)
//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CDominikDlg, CDialog)
//{{AFX_MSG_MAP(CDominikDlg)
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CDominikDlg message handlers

int CDominikDlg::DoModal(HWND hWndParent)
{
// can be constructed with a resource template or InitModalIndirect
ASSERT(m_lpszTemplateName != NULL || m_hDialogTemplate != NULL ||
m_lpDialogTemplate != NULL);

// load resource as necessary
LPCDLGTEMPLATE lpDialogTemplate = m_lpDialogTemplate;
HGLOBAL hDialogTemplate = m_hDialogTemplate;
HINSTANCE hInst = g_hDll;

HINSTANCE hinTmp = afxCurrentInstanceHandle;
HINSTANCE hresTmp = afxCurrentResourceHandle;
afxCurrentResourceHandle = g_hDll;
afxCurrentInstanceHandle = g_hDll;

if (m_lpszTemplateName != NULL) {
HRSRC hResource = ::FindResourceEx(g_hDll,RT_DIALOG,m_lpszTemplateName,MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL));
hDialogTemplate = LoadResource(hInst, hResource);
}
if (hDialogTemplate != NULL)
lpDialogTemplate = (LPCDLGTEMPLATE)LockResource(hDialogTemplate);

// return -1 in case of failure to load the dialog template resource
if (lpDialogTemplate == NULL)
return -1;

// disable parent (before creating dialog)
//HWND hWndParent = PreModal();
//AfxUnhookWindowCreate();
BOOL bEnableParent = FALSE;
if (hWndParent != NULL && ::IsWindowEnabled(hWndParent)) {
::EnableWindow(hWndParent, FALSE);
bEnableParent = TRUE;
}

try {
// create modeless dialog
//AfxHookWindowCreate(this);
if (CreateDlgIndirect(lpDialogTemplate,
CWnd::FromHandle(hWndParent), hInst)) {
if (m_nFlags & WF_CONTINUEMODAL) {
// enter modal loop
DWORD dwFlags = MLF_SHOWONIDLE;
if (GetStyle() & DS_NOIDLEMSG)
dwFlags |= MLF_NOIDLEMSG;
VERIFY(RunModalLoop(dwFlags) == m_nModalResult);
}

// hide the window before enabling the parent, etc.
if (m_hWnd != NULL)
SetWindowPos(NULL, 0, 0, 0, 0, SWP_HIDEWINDOW|
SWP_NOSIZE|SWP_NOMOVE|SWP_NOACTIVATE|SWP_NOZORDER);
}
} catch(CSeException *e) {
DUMPEXCEPTION(e);
::SetLastError((unsigned long)NTE_FAIL);
e->Delete();
} catch (...) {
TRACE(_T("%s(%d): Unknown exception.\n"),__FILE__,__LINE__);
m_nModalResult = -1;
}

if (bEnableParent)
::EnableWindow(hWndParent, TRUE);

if (hWndParent != NULL && ::GetActiveWindow() == m_hWnd)
::SetActiveWindow(hWndParent);

// destroy modal window
DestroyWindow();
PostModal();

// unlock/free resources as necessary
if (m_lpszTemplateName != NULL || m_hDialogTemplate != NULL)
UnlockResource(hDialogTemplate);

if (m_lpszTemplateName != NULL)
FreeResource(hDialogTemplate);

afxCurrentInstanceHandle = hinTmp;
afxCurrentResourceHandle = hresTmp;

return m_nModalResult;
}

int CDominikDlg::RunModalLoop(DWORD dwFlags)
{
ASSERT(::IsWindow(m_hWnd)); // window must be created
ASSERT(!(m_nFlags & WF_MODALLOOP)); // window must not already be in modal state

// for tracking the idle time state
BOOL bIdle = TRUE;
LONG lIdleCount = 0;
BOOL bShowIdle = (dwFlags & MLF_SHOWONIDLE) && !(GetStyle() & WS_VISIBLE);
HWND hWndParent = ::GetParent(m_hWnd);
m_nFlags |= (WF_MODALLOOP|WF_CONTINUEMODAL);
MSG* pMsg = &m_msgCur;

// acquire and dispatch messages until the modal state is done
for (;;) {
ASSERT(ContinueModal());

// phase1: check to see if we can do idle work
while (bIdle &&
!::PeekMessage(pMsg, NULL, NULL, NULL, PM_NOREMOVE)) {

ASSERT(ContinueModal());

// show the dialog when the message queue goes idle
if (bShowIdle) {
ShowWindow(SW_SHOWNORMAL);
UpdateWindow();
bShowIdle = FALSE;
}

// call OnIdle while in bIdle state
if (!(dwFlags & MLF_NOIDLEMSG) && hWndParent != NULL && lIdleCount == 0) {
// send WM_ENTERIDLE to the parent
::SendMessage(hWndParent, WM_ENTERIDLE, MSGF_DIALOGBOX, (LPARAM)m_hWnd);
}
if ((dwFlags & MLF_NOKICKIDLE) ||
!SendMessage(WM_KICKIDLE, MSGF_DIALOGBOX, lIdleCount++)) {
// stop idle processing next time
bIdle = FALSE;
}
}

// phase2: pump messages while available
do {
ASSERT(ContinueModal());

// pump message, but quit on WM_QUIT
if (!PumpMessage()) {
AfxPostQuitMessage(0);
return -1;
}

// show the window when certain special messages rec'd
if (bShowIdle &&
(pMsg->message == 0x118 || pMsg->message == WM_SYSKEYDOWN)) {
ShowWindow(SW_SHOWNORMAL);
UpdateWindow();
bShowIdle = FALSE;
}

if (!ContinueModal())
goto ExitModal;

} while (::PeekMessage(pMsg, NULL, NULL, NULL, PM_NOREMOVE));
}

ExitModal:
m_nFlags &= ~(WF_MODALLOOP|WF_CONTINUEMODAL);
return m_nModalResult;
}

BOOL CDominikDlg::PumpMessage()
{
ASSERT_VALID(this);

if (!::GetMessage(&m_msgCur, NULL, NULL, NULL)) {
return FALSE;
}

// process this message
if (m_msgCur.message != WM_KICKIDLE && !PreTranslateMessage(&m_msgCur)) {
::TranslateMessage(&m_msgCur);
::DispatchMessage(&m_msgCur);
}
return TRUE;
}

Abhishek Narula27-May-02 0:08

Abhishek Narula

27-May-02 0:08

Hi there ,
I have a class lets say CMyClass, it contains a member variable of type CArray of lets say int.

Now I have a public function of this Class GetValue(int nIndex) now this function returns the Reference of int which is actually a reference to a particular index of my CArray type member variable.

Now here is the problem .. My GetValue function performs some checks before returning the Refrence . now in case the checks fails I dont want to return the reference .. in that case WHAT DO I RETUNR FROM MY CODE.

does any body understand what I am trying to ask ?

Abhishek Narula

"Learn to appreciate others ... World would appreciate you"

markkuk27-May-02 0:18

markkuk

27-May-02 0:18

Throw an exception. There's no reference equivalent of a NULL pointer, so you must either return a valid reference or throw.

Abhishek Narula27-May-02 0:25

Abhishek Narula

27-May-02 0:25

Wonderfull Idea !! thanks .. please tell me more about throwing exceptions also ..

Abhishek Narula

"Learn to appreciate others ... World would appreciate you"

Joaquín M López Muñoz27-May-02 0:14

Joaquín M López Muñoz

27-May-02 0:14

Throw an exception.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Abhishek Narula27-May-02 0:24

Abhishek Narula

27-May-02 0:24

Hmm that seems a better idea .. please throw some light on thoring exceptions also ..

Abhishek Narula

"Learn to appreciate others ... World would appreciate you"

Joaquín M López Muñoz27-May-02 0:28

Joaquín M López Muñoz

27-May-02 0:28

Essentially, you just throw with throw, which interrupts the normal flow of execution and throws an object that can be catched by some point up the call stack with catch.
Just read your docs for throw and catch, and/or search some tutorial on the net, sure there're many out there.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo