Re: Passing from a CDialog logic to a CView one

From:

David Wilkinson <no-reply@effisols.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 16 May 2007 13:24:51 -0400

Message-ID:

<ueDiZ89lHHA.3888@TK2MSFTNGP05.phx.gbl>

mosfet wrote:

Hi,

I am developping with MFC under Pocket PC and for some technical reasons
I would like to convert an SDI application using a view and some dialogs
into one using only views.

Let's consider the following scenario :

I have my SDI application that display a welcome view(CFormView).
Inside this welcome view I have a button to accept or not Terms and
conditions.
If user accept conditions I would like to switch to the main view, if
not, I would like to display a goodbye view.

The problem is here :

void CWelcomeView::OnYesCommand()
{

if ( ... == TRUE){
CViewMgr::GetInstance()->SwitchView( IDD_MAINVIEW_DLG );
}
else{
CViewMgr::GetInstance()->SwitchView( IDD_GOODBYE_DLG );
}
}

SwitchView(at the end of this post)- is a method that :
1) Replace current view with the one given as parameter
2) Destroy the old view.

If we go back to the fonction above there will be a problem since
SwitchView is not asynchronous, it means that SwitchView will try to
replace and destroy the current view but we haven't still exist from
this function.
So it will crash everything.

mosfet:

There are two ways to switch views:

Destroy and Create
Hide and Show (and switch ID's)

If you use Hide and Show you will not have this problem.

Another idea is to PostMessage() to the main window and have the main
handler switch the views.

[Are you sure that destroying your view really does crash the program?]

BTW, never test an expression against TRUE. TRUE is defined to be 1; all
non-zero values are "true".

David Wilkinson
Visual C++ MVP