Subscribing to changes in a WPF object

While there are events for WPF objects such as SizeChanged for a Window, there are other DependencyObjects that do not notify you if their content changes.

I recently found out that SizeToContent will change if the user manually resizes the window.  Since I was depending on this property to resize the window when the size of the contents changed, this caused a problem.  Fortunately WPF provides a method to find out these changes.  All dependency objects can be monitored by using the following method.

First get a DependencyPropertyDescriptor using the following:

Dim descriptor As DependencyPropertyDescriptor = DependencyPropertyDescriptor.FromProperty(Window.SizeToContentProperty, GetType(Window))

Then you can add a handler to monitor changes within the DependencyObject using the following:

descriptor.AddValueChanged(Me, New EventHandler(AddressOf SizeToContentsChanged))

Then every time the contents of the DependencyObject changes the code in your handler will be called and you can take the appropriate action.

Just thought I would pass this on as it seems like something that might be helpful.

Have a good one.

Lloyd Sheen