Automatic Scrolling in a Silverlight List Box

Question

How can I programmatically force a silverlight list box to scroll to the bottom so that the last item added is always visible.

I\'ve tried simply selecting the item

Answer 1

Use the ListBox's ScrollIntoView method passing in the last item. You may need to call UpdateLayout immediately before it for it to work.

Answer 2

The ScrollIntoView() method will scroll the last item into view, however listBox.UpdateLayout() must be called just before ScrollIntoView(). Here is a complete method with code:

    // note that I am programming Silverlight on Windows Phone 7

    public void AddItemAndScrollToBottom(string message)
    {
        string timestamp = DateTime.Now.ToString("mm:ss");
        var item = new ListBoxItem();
        item.Content = string.Format("{0} {1}", timestamp, message);
        // note that when I added a string directly to the listbox, and tried to call ScrollIntoView() it did not work, but when I add the string to a ListBoxItem first, that worked great
        listBoxEvents.Items.Add(item);

        if (listBoxEvents.Items.Count > 0)
        {
            listBoxEvents.UpdateLayout();
            var itemLast = (ListBoxItem)listBoxEvents.Items[listBoxEvents.Items.Count - 1];
            listBoxEvents.UpdateLayout();
            listBoxEvents.ScrollIntoView(itemLast);
        }
    }

Answer 3

Slightly refactored to reduce the lines of code:

 listBoxEvents.Add(item)
 listBoxEvents.UpdateLayout()
 listBoxEvents.ScrollIntoView(listBoxEvents.Items(listBoxEvents.Items.Count - 1))

Answer 4

Just went through this and none of the solutions above worked in a Silverlight 5 app. The solution turned out to be this:

 public void ScrollSelectedItemIntoView(object item)
 {
      if (item != null)
      {                
          FrameworkElement frameworkElement = listbox.ItemContainerGenerator.ContainerFromItem(item) as FrameworkElement;
          if (frameworkElement != null)
          {
              var scrollHost = listbox.GetScrollHost();                    
              scrollHost.ScrollIntoView(frameworkElement);
          }
      }                
 }