WPF + UserControl + OnClosing event

I write an application in WPF where I have one main page and one user control in it. I need to ca开发者_StackOverflow中文版ll function when I close the page where user control is embedded. I can't call this function from the main page, I need to do it directly in user control (as I don't have access to main page). There is an event unloaded for user control, but it is called to late. How can I get something like onclosing event?