Why doesn't this data binding work?

Question

I have a ViewModel class that contains a list of points, and I am trying to bind it to a Polyline. The Polyline picks up the initial list of points, but does not notice when

Answer 1

Change your PointCollections Property to a dependency property:

public PointCollection Pts
        {
            get { return (PointCollection)GetValue(PtsProperty); }
            set { SetValue(PtsProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Pts.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty PtsProperty =
            DependencyProperty.Register("Pts", typeof(PointCollection), typeof(ViewModel), new UIPropertyMetadata(new PointCollection()));

BTW Doing this, you won't need to fire the PropertyChanged event.

Oh sorry, and your object needs to inherit from DependencyObject

    public class ViewModel : DependencyObject 
{ 
//... 
}