Monday, May 19, 2008

Animating Child View Transitions - II

Now that I undestood how to animate child views in a Windows Mobile WTL 8.0 applicaction (see Animating Child View Transitions), it's time to remove all the animation code from the sample's main frame and move it into specialized classes. Child view animations are performed by the CChildViewAnimate mix-in class (see the sample project). To use it, you merely add it to your main frame's inheritance list:

class CMainFrame :
public CFrameWindowImpl<CMainFrame>,
public CUpdateUI<CMainFrame>,
public CChildViewAnimate<CMainFrame>,
public CMessageFilter,
public CIdleHandler

Next, change the main frame's PreTranslateMessage method to this:

return TRUE;

return ChildPreTranslateMessage(pMsg);

The call to ChildPreTranslateMessage ensures that the active child view class has a chance to do some custom message translation work. To enable this, you must derive all you child view classes from CChildView, like this:

class CSlideFormView :
public CDialogImpl<CSlideFormView>,
public CChildView<CSlideFormView>

If you need to do custom message translation, you must override the PreTranslateMessage:

virtual BOOL PreTranslateMessage(MSG* pMsg)
return FALSE;
return CWindow::IsDialogMessage(pMsg);

Note the IsWindow test: it is there to avoid having this method called when the child window is already destroyed.

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