Forums Ultimate UI for WPF
Your Privacy Matters: We use our own and third-party cookies to improve your experience on our website. By continuing to use the website we understand that you accept their use. Cookie Policy
Close
Mark Horowitz
245
MVVM TwoWay bindable SelectedItem/ActiveNode extremely slow with even medium data-sets
posted

Hello!
I used the CustomXamDataTree obtained from
http://www.infragistics.com/community/forums/p/58081/296039.aspx#296039
(BindingSelectedNode.zip)

This allows me to programmatically select the to-be-selected (active) node in my view-model, and, through data-binding, get the appropriate node in the XamDataTree activated. That works.

However, with data-sets of even a few thousand lines, scrolling becomes ridiculously slow.
It seems to be spending much of its time in the FindCorrespondingNode() method, which matches the value object, really my view-model object,
with the appropriate node in the XamDataTree, so that it can be selected.
This is a recursive method, which check the current node for a match and if one is not found, its children are checked.

Something is going on here in this method!  It recurses based on your data-structure "XamDataTreeNodesCollection".
Why is it so very slow? What is the data-structure used there? A Map? A List? Just the tree structure itself?

Many thanks,
Mark

P.S. The call in "OnPropertyChangedCallback()" to "FindCorrespondingNode()" in my opinion only needs to be called when the user DID NOT click on a graphical tree-node item, but rather only when the View-Model SelectedItem (bound property) is programatically selected.  Can you please confirm?

Here is a copy of the code posted in the above-mentioned link:

namespace GraphicalTree
{
    public class CustomXamDataTree : XamDataTree
    {
        private static XamDataTreeNodesCollection nodes;
        private static bool mMouseLeftButtonDownOrKeyDownCame;

        public static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.Register(
            "SelectedItem",
            typeof(object),
            typeof(CustomXamDataTree),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender,
                new PropertyChangedCallback(OnPropertyChangedCallback)));

        public CustomXamDataTree()
        {
            base.ActiveNodeChanged += new EventHandler<ActiveNodeChangedEventArgs>(CustXamDataTree_ActiveNodeChanged);
            nodes = Nodes;
        }

        public static void OnPropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            FindCorrespondingNode(nodes, e.NewValue);
        }

        void CustXamDataTree_ActiveNodeChanged(object sender, ActiveNodeChangedEventArgs e)
        {
            if (e.NewActiveTreeNode != null)
                SelectedItem = e.NewActiveTreeNode.Data;
        }

        public object SelectedItem
        {
            get { return (object)GetValue(SelectedItemsProperty); }
            set
            {
                SetValue(SelectedItemsProperty, value);
            }
        }

        private static void FindCorrespondingNode(XamDataTreeNodesCollection nodes, object value)
        {
            foreach (XamDataTreeNode node in nodes)
            {
                if (node.Data.Equals(value))
                {
                    node.IsActive = true;
                    node.IsSelected = true;
                    return;
                }

                if (node.HasChildren)
                {
                    FindCorrespondingNode(node.Nodes, value);
                }

            }
        }
    }
}



Parents Reply Children
No Data