Know when a child popup dialog is opened

_Flaviu

Hi all of you. I have a dialogbar from where I open a popup dialog, let say CMyDialog, but it is opened in non modal way, dynamically created:

void CDialogBar::SomeButton()
{
CMyDialog* pDialog = new CMyDialog;
pDialog->Create(...);
}

From that dialogbar, it is possible to know if that CMyDialog is opened ?

void CDialogBar::OtherButton()
{
CWnd* pWnd = FindWindowEx(NULL, NULL, _T("Dialog"), NULL);
ASSERT(NULL != pWnd);
}

but the pWnd is always NULL, even when CMyDialog is open ... How can I know for sure if that CMyDialog is opened, without making pDialog as member variable of CDialogbar ?

Lost User

Check that you class name is correct for an MFC Dialog. you should also try to provide values for as many of the parameters as possible. [edit] See About Window Classes (Windows)[^] for correct system class names.

Jochen Arndt

See the hwndParent parameter at FindWindowEx function (Windows)[^]:

Quote:

If hwndParent is NULL, the function uses the desktop window as the parent window. The function searches among windows that are child windows of the desktop.

You did not show us the full Create call but if you have passed CDialogBar or any other window of your application as parent you must also pass it to FindWindowEx (using this for the CDialogBar here):

CWnd* pWnd = FindWindowEx(this->GetSafeHwnd(), NULL, _T("Dialog"), NULL);

But you should think about using a member variable. The only thing to do then is clearing the pointer when the dialog is closed. Otherwise you have to check for existance also in your SomeButton function to avoid creating multiple instances of your dialog.

_Flaviu

The creation of CMyDialog is:

pMyDialog->Create(CMyDialog::IDD, this);

I will try your advice, I hope to work. "But you should think about using a member variable. The only thing to do then is clearing the pointer when the dialog is closed. Otherwise you have to check for existance also in your SomeButton function to avoid creating multiple instances of your dialog." The CMyDialog could have only one instance, so, there is no problem with that.

Jochen Arndt

Flaviu2 wrote:

The CMyDialog could have only one instance, so, there is no problem with that.

How do you know that? If CDialogBar::SomeButton is called again (the name indicates that it requires only a mouse click), you would have multiple instances. When using a member variable you could then activate the existing dialog instead of creating a new one.

David Crow

Flaviu2 wrote:

CWnd* pWnd = FindWindowEx(NULL, NULL, _T("Dialog"), NULL);

Shouldn't the third parameter to FindWindowEx() be #32770?

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_Flaviu

I have try also this:

CWnd\* pWnd = FindWindowEx(GetSafeHwnd(), NULL, \_T("#32770"), NULL);
TRACE(">>>%p\\t%d\\n", pWnd, pWnd->GetSafeHwnd());

and the result is

>>>00000000 0

Strange ... I guess that only member variable are safe ...

Victor Nijegorodov

Flaviu2 wrote:

I have try also this:

CWnd* pWnd = FindWindowEx(GetSafeHwnd(), NULL, _T("#32770"), NULL);
TRACE(">>>%p\t%d\n", pWnd, pWnd->GetSafeHwnd());

GetSafeHwnd() returns the window handle (HWND), not the CWnd* pointer. So the result of FindWindowEx() as well as its handle being "0" is obvious!

_Flaviu

Good point ! I will try that.

_Flaviu

The CMyDialog are closed when he lost the focus, so, there is no way to be two (or more) instances.

Jochen Arndt

Quote:

The CMyDialog are closed when he lost the focus

OK. So it is some kind of popup or tooltip window. But the window will loose it's focus when clicking another button (as indicated by your CDialogBar::OtherButton()). I'm not sure what happens before. So it might be that the window is already destroyed when trying to find the handle. Even if not, you should not use the handle because the window would be destroyed shortly thereafter.

leon de boer

Can I say I have never seen such a ridiculously convoluted way to do this. Doing an atomic string search is first slow, and secondly mildly dangerous and unreliable. There are two MUCH SAFER standard windows ways to do such a thing and both require you to put code on the dialog handler 1.) In the dialog itself on the WM_INITDIALOG message either post back a message dialog is open, or even just set a global variable to the dialog window. In the WM_DESTROY of the dialog post back a closed message or just zero the global variable to the dialog window. Something like this is probably the simplest for you

HWND MyDialog = 0; // You can make this global or declare it extern on your .h or have a function to access it.

// Your dialog message handler
INT_PTR CALLBACK DialogProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
...

   case WM\_INITDIALOG:
         ...
         MyDialog = hDlg;        // Hold the handle to yourself for others
         break;
   case WM\_DESTROY:
         ...
         MyDialog = 0;           // Dialog about to destroy stop others accessing
         break;
 ...

2.) In the dialog handler itself respond back to a user WM_APP message with your handle. The message will be enumerated to all windows in your application and you will be the only responder.

// Your dialog message handler
INT_PTR CALLBACK DialogProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
...

   case WM\_APP + 100:             // Some user app number
         ...
         return (hDlg);          // Return your handle in response to the message
 ...

Method 1 you simply need to look at the global variable MyDialog to know if the dialog is open or not and what it's handle is. Method 2 you use SendMessage(0, WM_APP+100, 0, 0) and if your dialog is open you will get a response back which will the handle to your dialog. If you get 0 back the dialog is not open because no other window will respond to WM_APP + 100.

In vino veritas

_Flaviu

That is why I chosen to do m_pMyDialog as member variable, and everything it's all right now. Thank you all of you !