How to control the scroll position of a ListBox in a MVVM WPF app

Question

I have got a big ListBox with vertical scrolling enabled, my MVVM has New and Edit ICommands. I am adding new item to the end of the collection but I want the scrollbar also

Answer 1

Using this in MVVM can be easily accomplished via an attached behavior like so:

using System.Windows.Controls;
using System.Windows.Interactivity;

namespace Jarloo.Sojurn.Behaviors
{
    public sealed class ScrollIntoViewBehavior : Behavior
    {
        protected override void OnAttached()
        {
            base.OnAttached();
            AssociatedObject.SelectionChanged += ScrollIntoView;
        }

        protected override void OnDetaching()
        {
            AssociatedObject.SelectionChanged -= ScrollIntoView;
            base.OnDetaching();
        }

        private void ScrollIntoView(object o, SelectionChangedEventArgs e)
        {
            ListBox b = (ListBox) o;
            if (b == null)
                return;
            if (b.SelectedItem == null)
                return;

            ListBoxItem item = (ListBoxItem) ((ListBox) o).ItemContainerGenerator.ContainerFromItem(((ListBox) o).SelectedItem);
            if (item != null) item.BringIntoView();
        }
    }
}

Then in the View ad this reference at the top:

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

And do this:

Now when the SelectedItem changes the behavior will do the BringIntoView() call for you.