FindWindow and Data Copy Problem

From:
Asanka Abeykoon
Newsgroups:
microsoft.public.vc.mfc
Date:
Fri, 05 Mar 2010 00:09:00 -0800
Message-ID:
<2010353857asanka.itfac@gmail.com>
Hi,

I want to exchange data between two MFC applications.So
I created two MFc application and I have a problem with
FindWindow() function to proceed with data copy.

In one appication I have following code to register the class in InitInstance()

LPCTSTR lpszUniqueClass = _T("ASANKATEST");
WNDCLASS wndcls;

memset(&wndcls, 0, sizeof(WNDCLASS));
wndcls.style = CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
wndcls.lpfnWndProc = ::DefWindowProc;
wndcls.hInstance = AfxGetInstanceHandle();
wndcls.hIcon = LoadIcon(IDR_MAINFRAME); //
wndcls.hCursor = LoadCursor( IDC_ARROW );
wndcls.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1);
wndcls.lpszMenuName = NULL;
wndcls.lpszClassName = lpszUniqueClass;

// Register new class and exit if it fails
if(!AfxRegisterClass(&wndcls)) {
TRACE("Class Registration Failed\n");
MessageBox(NULL, L"Class Registration Failed", NULL, NULL);
}else{

MessageBox(NULL, L"Class Registration Successfull", NULL, NULL);
}

Then after in another MFC application which is dialog based i have called

HWND hWindow = ::FindWindow(lpszUniqueClass,NULL);

if(hWindow == NULL){

 AfxMessageBox(L" NOT found Application");
}

It says that class registration is successful but FindWindow is not working.Can any one help please..

Asanka

Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
23-Jun-08

dwData is DWORD i.e. 32 bits, so it is not possible to use a GUID (because a
GUID is 128 bits) here.

But it could be possible to put a GUID as header bytes for
COPYDATASTRUCT.lpData .

Giovanni

Previous Posts In This Thread:

On Monday, June 16, 2008 10:39 AM
Anders Eriksson wrote:

WM_COPYDATA between two applications
Hello,

I'm running VC++ 2005.

I have two program and want to exchange some data, a string, between them.

In the sender program I have this function:

BOOL CFSGClientDlg::SendCommand(CString command)
{
    COPYDATASTRUCT cds;
    LRESULT rc;
    TCHAR *buf;

    buf = new TCHAR[MAX_COPY_LENGTH];
    memset(buf,'\0',MAX_COPY_LENGTH);
    _tcscpy_s(buf,MAX_COPY_LENGTH,sOrderno.GetBuffer());
    sOrderno.ReleaseBuffer();

    cds.dwData = 0;
    cds.cbData = sOrderno.GetLength()+1;
    cds.lpData = (void*)buf;

    rc = m_pSCMLaserCWnd->SendMessage(WM_COPYDATA,
        (WPARAM)AfxGetApp()->m_pMainWnd->GetSafeHwnd(),
        (LPARAM)&cds);

    if (rc ==NULL)
    {
        DWORD errcode = GetLastError();
        return false;
    } // if (rc==NULL)
    return true;
}

And in the receiver program I have this:

BOOL CMainFrame::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct)
{
    CString sData=(TCHAR*)(pCopyDataStruct->lpData);
..... doing stuff with sData...
    return CFrameWnd::OnCopyData(pWnd, pCopyDataStruct);
}

I can see that the string I send is OK, but when I get to the receiving
part I get a couple of characters correkt and then just rubbish...

What have I done wrong?

// Anders
--
English is not my first, or second, language
so anything strange, or insulting, is due to
the translation.
Please correct me so I may improve my English!

On Monday, June 16, 2008 10:51 AM
AliR \(VC++ MVP\) wrote:

Do both of your applications have the same unicode settings?
Do both of your applications have the same unicode settings?

should this line:

be:

AliR.

On Monday, June 16, 2008 11:02 AM
Anders Eriksson wrote:

Re: WM_COPYDATA between two applications
On Mon, 16 Jun 2008 09:51:36 -0500, AliR (VC++ MVP) wrote:

Hello AliR,

Yes both applications has the same unicode settings and I have changed to
the above but I still get rubbish.

The string that I send is "test4" and the string I receive is "tes??????????????????"

I think is has something to do with me using unicode but I can't figure out
what I have done wrong?

// Anders
--
English is not my first, or second, language
so anything strange, or insulting, is due to
the translation.
Please correct me so I may improve my English!

On Monday, June 16, 2008 11:16 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
it is:

cds.cbData = sOrderno.GetLength() * sizeof(TCHAR);

(scale * by sizeof(TCHAR))

Giovanni

On Monday, June 16, 2008 11:21 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
"Anders Eriksson" <andis59@gmail.com> ha scritto nel messaggio
news:1s37n3yj1am4g.dlg@ostling.com...

Pass input string by reference:

 BOOL CFSGClientDlg::SendCommand(const CString & command)

Do:

  memset( buf, 0, MAX_COPY_LENGTH * sizeof( TCHAR ) );

or

  ZeroMemory( buf, MAX_COPY_LENGTH * sizeof( TCHAR ) );

No need of GetBuffer here; try this:

 _tcscpy_s(buf, MAX_COPY_LENGTH, sOrderno );

That should be OK (there's implicit LPCTSTR conversion operator defined for
CString).

The above should be:

 cds.cbData = (sOrderno.GetLength()+1) * sizeof(TCHAR);

Giovanni

On Monday, June 16, 2008 11:30 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
"Giovanni Dicanio" <giovanni.dicanio@invalid.com> ha scritto nel messaggio
news:Owbh6T8zIHA.3920@TK2MSFTNGP02.phx.gbl...

BTW: why do you allocate a fixed size "big" buffer (using MAX_COPY_LENGTH) ?

You may consider not wasting memory, and just allocate required bytes:

 // Number of TCHAR's, including NUL end-of-string (+1)
 int tcharCount = command.GetLength() + 1;

 // Allocate buffer to store them
 TCHAR * buf = new TCHAR[ tcharCount ];

 // Copy from original string
 StringCchCopy( buf, tcharCount, command );

 ...

 cds.cbData = tcharCount * sizeof(TCHAR);

Moreover, note that someone must delete[] the buffer allocated new[]. Else,
you will have memory leaks.

HTH,
Giovanni

On Monday, June 16, 2008 11:37 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
"AliR (VC++ MVP)" <AliR@online.nospam> ha scritto nel messaggio
news:z5v5k.5263$N87.121@nlpi068.nbdc.sbc.com...

I believe AliR meant * sizeof(TCHAR) (not + ).

However, there is also the need to transmit NUL (0 end-of-string).

So (...GetLength() + 1) * sizeof(TCHAR) should be used.

Giovanni

On Monday, June 16, 2008 11:47 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
Not related to your problem, but I think worth correcting:

.....

The function returns BOOL, so you should use TRUE and FALSE instead of
'true' and 'false' (which are fine for 'bool').

Giovanni

On Monday, June 16, 2008 12:16 PM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
"Anders Eriksson" <andis59@gmail.com> ha scritto nel messaggio
news:1s37n3yj1am4g.dlg@ostling.com...

I did a small MFC test using a dialog-based app, and developed this routine
for sending (it works for me in Unicode builds with VS2008):

<code>

BOOL CDataSenderDlg::SendCommand( const CString & command )
{
    // Number of TCHAR's, including terminating NUL
    int charCount = command.GetLength() + 1;

    // Dynamically allocate buffer for string
    TCHAR * buf = new TCHAR[ charCount ];

    // Copy source string to destination buffer
    _tcscpy_s( buf, charCount, command );

    // Prepare structure for WM_COPYDATA
    COPYDATASTRUCT copyData;
    copyData.dwData = /* some ID code here... */;
    copyData.cbData = charCount * sizeof(TCHAR);
    copyData.lpData = (void * )buf;

    // Send message
    BOOL processed = (BOOL) m_pWndReceiver->SendMessage(
        WM_COPYDATA,
        reinterpret_cast<WPARAM>( this->GetSafeHwnd() ),
        reinterpret_cast<LPARAM>( &copyData )
    );

    // Cleanup allocated buffer
    delete[] buf;
    buf = NULL;

    if ( !processed )
    {
        // ... do something for error here
        return FALSE;
    }

    // All right
    return TRUE;
}

</code>

HTH,
Giovanni

On Monday, June 16, 2008 2:51 PM
AliR \(VC++ MVP\) wrote:

Re: WM_COPYDATA between two applications
Hi Giovanni,

Thanks for correcting my mistake. :)

AliR.

On Monday, June 16, 2008 3:19 PM
Karsten Schulz wrote:

Hi Anders,u cant copy data from one process to another.
Hi Anders,

u cant copy data from one process to another. Inprocess
u can handel WM_COPYDATA so:

void CBitmapView::SendCopyData(CLICKEVENT Event,CPoint pt /*=CPoint(0,0)*/)
{
 if(!m_pParentWnd || !m_pParentWnd->m_hWnd)
  return;

 CCrossFocus *pHair = m_gdiobj.GetFocus();
 int id=-1;

 if(pHair)
 {
   pt = pHair->GetFocus();
   id = pHair->GetId();
 }

 m_vclick.PosX = pt.x;
 m_vclick.PosY = pt.y;
 m_vclick.FocusId = id;
 m_vclick.PixelUnit = m_gdiobj.GetPixelUnits();
 m_vclick.Event = Event;

 m_pParentWnd->SendMessage(WM_COPYDATA,(WPARAM)(HWND) m_hWnd,(LPARAM)
(LPVOID) &m_MyCDS);
}

"Anders Eriksson" <andis59@gmail.com> schrieb im Newsbeitrag
news:1s37n3yj1am4g.dlg@ostling.com...

On Monday, June 16, 2008 3:22 PM
Karsten Schulz wrote:

Hi Anders,u cant copy data from one process to another.
Hi Anders,

u cant copy data from one process to another. Inprocess
u can handel WM_COPYDATA so:

typedef struct ViewClick
{
  int PosX;
  int PosY;
  int FocusId;
  double PixelUnit;
  CLICKEVENT Event;
}VIEWCLICK;

void CBitmapView::SendCopyData(CLICKEVENT Event,CPoint pt /*=CPoint(0,0)*/)
{
 if(!m_pParentWnd || !m_pParentWnd->m_hWnd)
  return;

 CCrossFocus *pHair = m_gdiobj.GetFocus();
 int id=-1;

 if(pHair)
 {
   pt = pHair->GetFocus();
   id = pHair->GetId();
 }

 m_vclick.PosX = pt.x;
 m_vclick.PosY = pt.y;
 m_vclick.FocusId = id;
 m_vclick.PixelUnit = m_gdiobj.GetPixelUnits();
 m_vclick.Event = Event;

 m_pParentWnd->SendMessage(WM_COPYDATA,(WPARAM)(HWND) m_hWnd,(LPARAM)
(LPVOID) &m_MyCDS);
}

After send data u can handle it in your Dialog :

BOOL CCamInspectTestDlg::OnCopyData(CWnd* pWnd, COPYDATASTRUCT*
pCopyDataStruct)
{
 VIEWCLICK *pVclk=0;
 if(pCopyDataStruct->dwData == VIEWCLICKMSG)
  if(pCopyDataStruct->cbData == sizeof(VIEWCLICK))
   if((pVclk = (VIEWCLICK *)pCopyDataStruct->lpData))
   {
    double cal(pVclk->PixelUnit);
    CString str; str.Format("X(%0.4f):Y(%0.4f) Cal(%0.4f) Id(%d) Evt(%d)",
    pVclk->PosX*cal,pVclk->PosY*cal,cal,pVclk->FocusId,pVclk->Event);
    SetWindowText(str);
   }

 return CDialog::OnCopyData(pWnd, pCopyDataStruct);
}

"Anders Eriksson" <andis59@gmail.com> schrieb im Newsbeitrag
news:1s37n3yj1am4g.dlg@ostling.com...

On Monday, June 16, 2008 5:46 PM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
"AliR (VC++ MVP)" <AliR@online.nospam> ha scritto nel messaggio

This kind of typos can happen to everyone when we do not use the compiler to
build the code.

Giovanni

On Monday, June 16, 2008 8:31 PM
David Ching wrote:

Re: WM_COPYDATA between two applications
I am sorry, but this is not true. WM_COPYDATA marshalls the data across
process boundaries. That is in fact why it exists!

-- David

On Tuesday, June 17, 2008 1:04 AM
Anders Eriksson wrote:

Re: WM_COPYDATA between two applications
On Mon, 16 Jun 2008 16:39:40 +0200, Anders Eriksson wrote:

Thank you all for your answers! A special Thank You to mr Giovanni Dicanio
that took the time to explain in detail!

// Anders
--
English is not my first, or second, language
so anything strange, or insulting, is due to
the translation.
Please correct me so I may improve my English!

On Tuesday, June 17, 2008 3:39 AM
Karsten Schulz wrote:

Re: WM_COPYDATA between two applications
ok nice, but code works.

On Tuesday, June 17, 2008 10:30 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
You're welcome Anders.

BTW: "Giovanni" works better than "Mr. Giovanni Dicanio" ;-)

Giovanni

On Wednesday, June 18, 2008 5:12 PM
Tom Serface wrote:

Re: WM_COPYDATA between two applications
Or there is always "G" :o)

Tom

On Wednesday, June 18, 2008 6:23 PM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
Yes :-)

G

On Sunday, June 22, 2008 8:56 PM
Joseph M. Newcomer wrote:

Actually, I would not use 'new'. I would doCByteArray buf;buf.
Actually, I would not use 'new'. I would do

CByteArray buf;
buf.SetSize( (command.GetLength() + 1) * sizeof(TCHAR));

and do

cds.cbData = buf.GetSize();
and
cds.lpData = buf.GetData();

so there would be no need to remember to do the delete at all.

In addition, I have been seriously done in by irresponsible programmers who did a
    SendMessage(HWND_BROADCAST, WM_COPYDATA, ...)
so I now put a GUID as the first 128 bits of the message and double-check it; see my essay
on WM_COPYDATA.
                    joe

On Mon, 16 Jun 2008 17:30:06 +0200, "Giovanni Dicanio" <giovanni.dicanio@invalid.com>
wrote:

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

On Monday, June 23, 2008 4:17 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
"Joseph M. Newcomer" <newcomer@flounder.com> ha scritto nel messaggio
news:5vst54dfklnsarqdgjil3g910ufrmrkg4e@4ax.com...

I agree with you about using a container class.
I would use std::vector< BYTE >.

I used 'new' just to keep the code as near as possible to original OP's
version.

I do agree with you.
In fact in code I posted I wrote "some ID code here ..." (and GUID you
suggested is an excellent option, of course).

<code>
.....
    // Prepare structure for WM_COPYDATA
    COPYDATASTRUCT copyData;
    copyData.dwData = /* some ID code here... */;
.....
</code>

Giovanni

On Monday, June 23, 2008 4:34 AM
Giovanni Dicanio wrote:

Re: WM_COPYDATA between two applications
dwData is DWORD i.e. 32 bits, so it is not possible to use a GUID (because a
GUID is 128 bits) here.

But it could be possible to put a GUID as header bytes for
COPYDATASTRUCT.lpData .

Giovanni

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