Loading 20000 children under a node kills the app for a long period of time.

[Andy]

I'm trying to figure this out (new rad control user, LOVE IT!!) but it takes FOREVER for the tree to load. My WCF service comes back almost instantly with 20000 records of data and loading that into the tree just seems to hang for minutes at end. Once loaded, they scroll great. So I know virtualization is working. How can I speed up the loading? It's blocking the main thread which makes the user think the webpage has crashed.

Here is my tree view + child item which is bound to the source. The source is an ObservableCollection.

 

<

 

 

telerik:RadTreeView Grid.Row="1" x:Name="allTopicsReportTreeview" IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling">

 

    <

 

 

telerik:RadTreeViewItem Header="Unreviewed" ItemsSource="{Binding CurrentReviewProject.TopicsReport.TopicsUnreviewed}" DisplayMemberPath="Title" IsExpanded="False">

 

[Andy]

Here is the class properties I'm binding to on the treeview. The class itself isn't bound to the tree, it is the datacontext of the layoutroot though. The treeview has childnodes each one bound to the ObservableCollection of the class.

public class TopicsViewModel : PropertyChangedNotifier
    {
        #region Commands
        public Commands.ActionDelegateCommand RefreshCommand { get; set; }
        #endregion

        #region Fields
        private bool _isLoading;
        private int _projectId;
        private int _userId;
        #endregion

        #region Constructors
        public TopicsViewModel(int projectId, int userId)
        {
            RefreshCommand = new Commands.ActionDelegateCommand(refresh);
            _projectId = projectId;
            _userId = userId;

            Topics = new ObservableCollection<SimpleTopicStatus>();
            TopicsActiveTasks = new ObservableCollection<SimpleTopicStatus>();
            TopicsSignedOffActiveTasks = new ObservableCollection<SimpleTopicStatus>();
            TopicsUnreviewed = new ObservableCollection<SimpleTopicStatus>();
            TopicsProposedTasks = new ObservableCollection<SimpleTopicStatus>();
            TopicsPendingSignOff = new ObservableCollection<SimpleTopicStatus>();
            TopicsCompleted = new ObservableCollection<SimpleTopicStatus>();
            TopicsTasksAlert = new ObservableCollection<SimpleTopicStatus>();
        }
        #endregion

        #region Dependency Properties
        #endregion

        #region Properties
        // All topics
        public ObservableCollection<SimpleTopicStatus> Topics { get; set; }

        // not signed off - !isClosed !isNew !isOwnerAlert = In progress
        public ObservableCollection<SimpleTopicStatus> TopicsActiveTasks { get; set; }

        // signed off - !isClosed !isNew !isOwnerAlert = In Progress
        public ObservableCollection<SimpleTopicStatus> TopicsSignedOffActiveTasks { get; set; }

        // not signed off - 0 tasks
        public ObservableCollection<SimpleTopicStatus> TopicsUnreviewed { get; set; }

        // not signed off OR signed off - isNew
        public ObservableCollection<SimpleTopicStatus> TopicsProposedTasks { get; set; }

        // not signed off - isClosed
        public ObservableCollection<SimpleTopicStatus> TopicsPendingSignOff { get; set; }

        // signed off - isClosed  OR  signed off 0 tasks
        public ObservableCollection<SimpleTopicStatus> TopicsCompleted { get; set; }

        // not signed off OR signed off - isOwnerAlert
        public ObservableCollection<SimpleTopicStatus> TopicsTasksAlert { get; set; }

        public bool IsLoading { get { return _isLoading; } set { _isLoading = value; OnPropertyChanged("IsLoading"); } }
        public int UserId { get { return _userId; } set { _userId = value; OnPropertyChanged("UserId"); } }
        #endregion

        #region Methods
        private void refresh()
        {
            if (!_isLoading)
            {
                Topics.Clear();                                 // All topics
                TopicsActiveTasks.Clear();                      // not signed off - !isClosed !isNew !isOwnerAlert = In progress
                TopicsSignedOffActiveTasks.Clear();             // signed off - !isClosed !isNew !isOwnerAlert = In Progress
                TopicsUnreviewed.Clear();                       // not signed off - 0 tasks
                TopicsProposedTasks.Clear();                    // not signed off OR signed off - isNew
                TopicsPendingSignOff.Clear();                   // not signed off - isClosed
                TopicsCompleted.Clear();                        // signed off - isClosed  OR  signed off 0 tasks
                TopicsTasksAlert.Clear();                       // not signed off OR signed off - isOwnerAlert

                IsLoading = true;

                ReportingClient.Execute(client =>
                {
                    client.Topics_GetStatusCompleted += (sender, e) =>
                    {
                        foreach (var item in e.Result)
                        {
                            Topics.Add(item);

                            // Check the data coming back to figure out which bucket it will go into
                            if (item.Tasks > 0)
                            {
                                if (item.SignedOff == false)
                                {
                                    if (item.TasksNew > 0)
                                        TopicsProposedTasks.Add(item);

                                    else if (item.TasksClosed > 0)
                                        TopicsPendingSignOff.Add(item);

                                    else if (item.TasksOwnerAlert > 0)
                                        TopicsTasksAlert.Add(item);

                                    else
                                        TopicsActiveTasks.Add(item);
                                }
                                else
                                {
                                    if (item.TasksNew > 0)
                                        TopicsProposedTasks.Add(item);

                                    else if (item.TasksClosed > 0)
                                        TopicsCompleted.Add(item);

                                    else if (item.TasksOwnerAlert > 0)
                                        TopicsTasksAlert.Add(item);

                                    else
                                        TopicsSignedOffActiveTasks.Add(item);
                                }

                            }
                            else
                            {
                                if (item.SignedOff)
                                    TopicsCompleted.Add(item);
                                else
                                    TopicsUnreviewed.Add(item);
                            }
                        }

                        IsLoading = false;
                    };

                    if (_userId == 0)
                        client.Topics_GetStatusAsync(_projectId, false, 0);
                    else
                        client.Topics_GetStatusAsync(_projectId, true, _userId);

                    client.CloseAsync();
                });
            }
        }
        #endregion
    }

[Andy]

Still unsure what to do. I bind a listbox to the same source, with a virtualizingStackPanel as the ItemsPanel, and it works flawlessly.

[Andy]

Well I decided to scrap my design and use a different way to present the data to the user.

[Tina Stancheva]

Hello Andy,

Please accept my apology for the delayed response.

Unfortunately the RadTreeView doesn't support scenarios where its Items are populated both in XAML and through data binding like in your case. This is perhaps the main reason for the issue. Therefore I wanted to ask you to try and databind the ItemsSource collection of the whole RadTreeView to the data from the WCF service. You can take a look at the performance demo of the RadTreeView.

Give it a try and let us know if you are still experiencing issues. However, if this doesn't help in solving the issue, if you can send us a sample project reproducing it, we will be more than happy to further investigate it.

Kind regards,
Tina Stancheva
the Telerik team