OnActivateView bug??

Jeff Wishnie -- jwishnie@swellsoft.com
Monday, May 20, 1996

Config: Win95 VisC++/MFC 4.1
App Details: Vanilla MDI app

In my CView subclass, I need to know whether OnActivateView is being called
because the entire application is being activated/deactivated (e.g. when the
user switches applications) or because the user has switched from another
view in the _same_ app (e.g. clicked in the other pane in a splitter or
activated a new MDI child window).

Here's what OnActivateView looks like:=20

virtual void OnActivateView( BOOL bActivate, CView* pActivateView, CView*
pDeactiveView );

And according to the MFC docs, if the view is being activated/deactivated
within the app pActivateView and pDeactivateView will be different.

If the method is being called because the app is being
activated/deactivated, the arguments should be equal.

>From the docs:

"The pActivateView and pDeactiveView parameters point to the same view if
the application's main frame window is activated with no change in the
active view=97for example, if the focus is being transferred from another
application to this one, rather than from one view to another within the
application or when switching amongst MDI child windows."

Here's the problem: the two arguments are _ALWAYS_ equal, no matter what
caused the activate event.

I created a completely generic AppWizard generated MDI app to test this.
Here is my views OnActivateView method:

void CActivateTestView::OnActivateView(BOOL bActivate, CView* pActivateView,
CView* pDeactiveView)=20
{
	TRACE("Activate View: %x DeactiveView: %x\n", pActivateView,=
 pDeactiveView);
	CView::OnActivateView(bActivate, pActivateView, pDeactiveView);
}

The output shows the two pointers are always equal.

Question:

Is this a known bug? (I couldn't find any mention in KB)
Is there a workaround?
Is it just a documentation bug, and the values _are_ supposed to be equal
when switching among MDI child windows???

Thanks for any help,

Jeff



=20
jwishnie@swellsoft.com
415 552-3125(w)

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Frederic Steppe -- FredericS@msn.com
Thursday, May 23, 1996

>Config: Win95 VisC++/MFC 4.1
>App Details: Vanilla MDI app

>In my CView subclass, I need to know whether OnActivateView is being called
>because the entire application is being activated/deactivated (e.g. when the
>user switches applications) or because the user has switched from another
>view in the _same_ app (e.g. clicked in the other pane in a splitter or
>activated a new MDI child window).

>And according to the MFC docs, if the view is being activated/deactivated
>within the app pActivateView and pDeactivateView will be different.

>If the method is being called because the app is being
>activated/deactivated, the arguments should be equal.

>Here's the problem: the two arguments are _ALWAYS_ equal, no matter what
>caused the activate event.

The same doc article also says :

These parameters differ when CFrameWnd::SetActiveView is called with a view 
that is different from what CFrameWnd::GetActiveView would return.

That means that is when two views are switched inside one frame (splitters).
I guess it can be a documentation mistake, as the two explainations seems to 
be contradictory.
You should try to trap OnActivateApp to deal with this.


Frederic Steppe (frederics@msn.com)

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