/// <summary>
/// Execute method is called when any item is requested for load-on-demand items.
/// </summary>
/// <param name="obj">TreeViewNode is passed as default parameter </param>
private void ExecuteOnDemandLoading(object obj)
{
var node = obj as TreeViewNode;
// Skip the repeated population of child items when every time the node expands.
if (node.ChildNodes.Count > 0)
{
node.IsExpanded = true;
return;
}
//Animation starts for expander to show progressing of load on demand
node.ShowExpanderAnimation = true;
treeViewNodes.Add(node);
Application.Current.MainWindow.Dispatcher.BeginInvoke(DispatcherPriority.Background,
new Action(async() =>
{
await Task.Delay(1000);
foreach (var item in treeViewNodes)
{
if (!item.ShowExpanderAnimation)
{
continue;
}
currentNode = item;
break;
}
MusicInfo musicInfo = currentNode.Content as MusicInfo;
//Fetching child items to add
var items = GetSubMenu(musicInfo.ID);
// Populating child items for the node in on-demand
currentNode.PopulateChildNodes(items);
if (items.Count() > 0)
{
//Expand the node after child items are added.
currentNode.IsExpanded = true;
}
//Stop the animation after load on demand is executed, if animation not stopped, it remains still after execution of load on demand.
currentNode.ShowExpanderAnimation = false;
treeViewNodes.Remove(currentNode);
}));
}
private void Timer_Tick(object sender, EventArgs e)
{
MusicInfo musicInfo = currentNode.Content as MusicInfo;
//Fetching child items to add
var items = GetSubMenu(musicInfo.ID);
// Populating child items for the node in on-demand
currentNode.PopulateChildNodes(items);
if (items.Count() > 0)
{
//Expand the node after child items are added.
currentNode.IsExpanded = true;
}
//Stop the animation after load on demand is executed, if animation not stopped, it remains still after execution of load on demand.
currentNode.ShowExpanderAnimation = false;
timer.Stop();
}