WPF Treeview开启虚拟化后如何找到TreeViewItem

 用VirtualizingStackPanel的BringIndexIntoViewPublic方法就好，没必要像微软给的例子那样还要继承一个VirtualizingStackPanel

/// <summary>
/// Recursively search for an item in this subtree.
/// </summary>
/// <param name="container">
/// The parent ItemsControl. This can be a TreeView or a TreeViewItem.
/// </param>
/// <param name="item">
/// The item to search for.
/// </param>
/// <returns>
/// The TreeViewItem that contains the specified item.
/// </returns>
private TreeViewItem GetTreeViewItem(ItemsControl container, object item)
{if (container != null){if (container.DataContext == item){return container as TreeViewItem;}// Expand the current containerif (container is TreeViewItem && !((TreeViewItem)container).IsExpanded){container.SetValue(TreeViewItem.IsExpandedProperty, true);}// Try to generate the ItemsPresenter and the ItemsPanel.// by calling ApplyTemplate.  Note that in the// virtualizing case even if the item is marked// expanded we still need to do this step in order to// regenerate the visuals because they may have been virtualized away.container.ApplyTemplate();ItemsPresenter itemsPresenter =(ItemsPresenter)container.Template.FindName("ItemsHost", container);if (itemsPresenter != null){itemsPresenter.ApplyTemplate();}else{// The Tree template has not named the ItemsPresenter,// so walk the descendents and find the child.itemsPresenter = FindVisualChild<ItemsPresenter>(container);if (itemsPresenter == null){container.UpdateLayout();itemsPresenter = FindVisualChild<ItemsPresenter>(container);}}Panel itemsHostPanel = (Panel)VisualTreeHelper.GetChild(itemsPresenter, 0);// Ensure that the generator for this panel has been created.UIElementCollection children = itemsHostPanel.Children;VirtualizingStackPanel virtualizingPanel =itemsHostPanel as VirtualizingStackPanel;for (int i = 0, count = container.Items.Count; i < count; i++){TreeViewItem subContainer;if (virtualizingPanel != null){// Bring the item into view so// that the container will be generated.virtualizingPanel.BringIndexIntoViewPublic(i);subContainer =(TreeViewItem)container.ItemContainerGenerator.ContainerFromIndex(i);}else{subContainer =(TreeViewItem)container.ItemContainerGenerator.ContainerFromIndex(i);// Bring the item into view to maintain the// same behavior as with a virtualizing panel.subContainer.BringIntoView();}if (subContainer != null){// Search the next level for the object.TreeViewItem resultContainer = GetTreeViewItem(subContainer, item);if (resultContainer != null){return resultContainer;}else{// The object is not under this TreeViewItem// so collapse it.subContainer.IsExpanded = false;}}}}return null;
}/// <summary>
/// Search for an element of a certain type in the visual tree.
/// </summary>
/// <typeparam name="T">The type of element to find.</typeparam>
/// <param name="visual">The parent element.</param>
/// <returns></returns>
private T FindVisualChild<T>(Visual visual) where T : Visual
{for (int i = 0; i < VisualTreeHelper.GetChildrenCount(visual); i++){Visual child = (Visual)VisualTreeHelper.GetChild(visual, i);if (child != null){T correctlyTyped = child as T;if (correctlyTyped != null){return correctlyTyped;}T descendent = FindVisualChild<T>(child);if (descendent != null){return descendent;}}}return null;
}