/// <summary>
/// 在结点被收缩起来时，应该它的子结点的所有数据在_objectItems中对应的项都移除。
/// </summary>
/// <param name="treeNode"></param>
private void OnNodeCollapsed(TreeGridRow treeNode)
{
//处理 LazyLoading
//结点被折叠后事件。
//如果懒加载开启后，则在折叠时清空所有子结点。
//不处理根结点。
if (treeNode != this.RootNode)
{
//更新布局
var itemKey = GetId(treeNode.DataContext);
_renderExpansion.Remove(itemKey);
if (this.IsLazyLoading && this.ClearCollapsedNodes && treeNode.Items.Count > 0)
{
//deregisters listeners for all ancestors
if (this.ObserveChildItems)
{
_monitor.RemoveNodes(treeNode.Items);
}
treeNode.ItemsSource = null;
TreeGridHelper.CreateDummyItem(treeNode);
//TODO do we have collapsed event if all childs are being filtered?
//if yes, we need to set the dummy nodes visibility depending
//on the filtered childs (visible if at least 1 visible child)
}
}
}
/// <summary>
/// Updates the tree with newly added items.
/// </summary>
/// <param name="observed">The observed collection.</param>
/// <param name="e">Collection event args.</param>
public void HandleNewChildItems(ICollection observed, NotifyCollectionChangedEventArgs e)
{
IList childs = e.NewItems;
if (childs.Count == 0)
{
return;
}
//get the node of the parent item that contains the evented childs
var parentNode = GetParentNode(childs[0], observed);
if (parentNode == null)
{
return;
}
//if the node is expanded or does not load lazily, or
//already contains valid items, create nodes
if (parentNode.IsExpanded || !tree.IsLazyLoading || !TreeGridHelper.ContainsDummyNode(parentNode))
{
var rawLayout = tree._renderExpansion;
try
{
tree._renderExpansion = null;
parentNode.ItemsSource = childs;
}
finally
{
tree._renderExpansion = rawLayout;
}
//refresh the node in order to apply sorting (or any other
//features that will be incorporated)
parentNode.Items.Refresh();
}
else if (parentNode.Items.Count == 0)
{
//if the tree is in lazy loading mode and the item did
//not contain any childs before, we have to add a dummy
//node to render a expander
parentNode.Items.Add(TreeGridHelper.CreateDummyItem());
}
}
