910124 - how to realize when user switches between views?

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hi in an MDI application, when user switches between views something have to be updated. what's the best message to handle for realizing when this happens?
in my application a document has only one view, but logically i want to get notified when switch is between documents.
thx

Posted 12-Apr-12 3:02am

ilostmyid2

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Jochen Arndt · Answer 1 · 2012-04-12T04:56:00

Solution 1

When a window becomes active or inactive, a WM_NCACTIVATE message is send to update the title bar. With view windows, the message is send to the parent frame window of the view (a CMDIChildWnd derived class).

So you may add such handlers to your child frame classes. From the handler, you may use the CFrameWnd member functions GetActiveDocument() and GetActiveView() to pass information to your document and related view.

Posted 12-Apr-12 4:56am

Jochen Arndt

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ilostmyid2 12-Apr-12 11:02am

thank u :)
i added ON_WM_MDIACTIVATE to the child frame's message map and added the handler CChildFrame::OnMDIActivate. is it ok?

ilostmyid2 12-Apr-12 11:27am

this is also a problem! see the following:
t22 activated, t21 deactivated, in CChildFrame::OnMDIActivate
t21 activated, t22 deactivated, in CChildFrame::OnMDIActivate
t22 activated, t21 deactivated, in CChildFrame::OnMDIActivate
t22::OnDraw
t21::OnDraw
this is the result of two traces, one in CChildFrame::OnMDIActivate and one in Ct2View::OnDraw. this is the result of a File/New command. it indicates that when i add a new document, it gets first activated, then deactivated, then activated again, then drawn and then the deactivated view is also drawn! when the MDI application is of kind tabbed views, how this behavior is justifiable?
so my questions are:
1. after activating the new document, why it gets deactivated and activated again?!
2. a view which is completely hidden must not be drawn.

Jochen Arndt 12-Apr-12 12:01pm

It's not always traceable why and when messages are send by the Windows framework. I assume that the frames must be activated upon creation of new views. I suggest to ignore all messages for new views (while CView::OnInitalUpdate hasn't been called and finished) and the deactivation messages.

Jochen Arndt 12-Apr-12 12:07pm

It is not always traceable why and when messages are send by the framework. I assume that the frame must be activated upon creation and initial drawing. I suggest to ignore all messages while the frame/view is created (until CView::OnInitialUpdate has been called) and all deactivation messages.

Jochen Arndt 12-Apr-12 12:07pm

It is not always traceable why and when messages are send by the framework. I assume that the frame must be activated upon creation and initial drawing. I suggest to ignore all messages while the frame/view is created (until CView::OnInitialUpdate has called) and all deactivation messages.

ilostmyid2 12-Apr-12 12:06pm

i need to pay attention to the messages for that i need to know when and in what function i have to update the property list.

Jochen Arndt 12-Apr-12 12:15pm

It would be good to know what you want to do when a view becomes the active view. If the content should be updated in some way, you may override the OnUpdate() function and use the lHint and/or pHint parameters to specify what should be updated. Then call UpdateAllViews() from the document. In your view class, you may ignore the update call when nothing must be updated. When doing it this way, it doesn't matter when called multiple times from the WM_NCACTIVATE handler.

ilostmyid2 12-Apr-12 12:20pm

i've to think more about what u said and examine it in the code.
thx