您有3個選擇： - 您禁用項目虛擬化：，但這可能會影響性能 - 您管理每個項目的itemContainerGenerator狀態（某些代碼作爲示例提供）。相當複雜。 - 爲層次結構添加層次結構視圖模型，併爲每個節點層次實施「IsExpanded」屬性。最好的解決方案。
禁用虛擬化：
<TreeView VirtualizingStackPanel.IsVirtualizing="False">
好運...
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Threading;
using HQ.Util.General;
namespace HQ.Util.Wpf.WpfUtil
{
public static class TreeViewExtensions
{
// ******************************************************************
public delegate void OnTreeViewVisible(TreeViewItem tvi);
public delegate void OnItemExpanded(TreeViewItem tvi, object item);
public delegate void OnAllItemExpanded();
// ******************************************************************
private static void SetItemHierarchyVisible(ItemContainerGenerator icg, IList listOfRootToNodeItemPath, OnTreeViewVisible onTreeViewVisible = null)
{
Debug.Assert(icg != null);
if (icg != null)
{
if (listOfRootToNodeItemPath.Count == 0) // nothing to do
return;
TreeViewItem tvi = icg.ContainerFromItem(listOfRootToNodeItemPath[0]) as TreeViewItem;
if (tvi != null) // Due to threading, always better to verify
{
listOfRootToNodeItemPath.RemoveAt(0);
if (listOfRootToNodeItemPath.Count == 0)
{
if (onTreeViewVisible != null)
onTreeViewVisible(tvi);
}
else
{
if (!tvi.IsExpanded)
tvi.IsExpanded = true;
SetItemHierarchyVisible(tvi.ItemContainerGenerator, listOfRootToNodeItemPath, onTreeViewVisible);
}
}
else
{
ActionHolder actionHolder = new ActionHolder();
EventHandler itemCreated = delegate(object sender, EventArgs eventArgs)
{
var icgSender = sender as ItemContainerGenerator;
tvi = icgSender.ContainerFromItem(listOfRootToNodeItemPath[0]) as TreeViewItem;
if (tvi != null) // Due to threading, it is always better to verify
{
SetItemHierarchyVisible(icg, listOfRootToNodeItemPath, onTreeViewVisible);
actionHolder.Execute();
}
};
actionHolder.Action = new Action(() => icg.StatusChanged -= itemCreated);
icg.StatusChanged += itemCreated;
return;
}
}
}
// ******************************************************************
/// <summary>
/// You cannot rely on this method to be synchronous. If you have any action that depend on the TreeViewItem
/// (last item of collectionOfRootToNodePath) to be visible, you should set it in the 'onTreeViewItemVisible' method.
/// This method should work for Virtualized and non virtualized tree.
/// The difference with ExpandItem is that this one open up the tree up to the target but will not expand the target itself,
/// while ExpandItem expand the target itself.
/// </summary>
/// <param name="treeView">TreeView where an item has to be set visible</param>
/// <param name="listOfRootToNodePath">Any collectionic List. The collection should have every objet of the path to the targeted item from the root
/// to the target. For example for an apple tree: AppleTree (index 0), Branch4, SubBranch3, Leaf2 (index 3)</param>
/// <param name="onTreeViewVisible">Optionnal</param>
public static void SetItemHierarchyVisible(this TreeView treeView, IEnumerable<object> listOfRootToNodePath, OnTreeViewVisible onTreeViewVisible = null)
{
ItemContainerGenerator icg = treeView.ItemContainerGenerator;
if (icg == null)
return; // Is tree loaded and initialized ???
SetItemHierarchyVisible(icg, new List<object>(listOfRootToNodePath), onTreeViewVisible);
}
// ******************************************************************
private static void ExpandItem(ItemContainerGenerator icg, IList listOfRootToNodePath, OnTreeViewVisible onTreeViewVisible = null)
{
Debug.Assert(icg != null);
if (icg != null)
{
if (listOfRootToNodePath.Count == 0) // nothing to do
return;
TreeViewItem tvi = icg.ContainerFromItem(listOfRootToNodePath[0]) as TreeViewItem;
if (tvi != null) // Due to threading, always better to verify
{
listOfRootToNodePath.RemoveAt(0);
if (!tvi.IsExpanded)
tvi.IsExpanded = true;
if (listOfRootToNodePath.Count == 0)
{
if (onTreeViewVisible != null)
onTreeViewVisible(tvi);
}
else
{
SetItemHierarchyVisible(tvi.ItemContainerGenerator, listOfRootToNodePath, onTreeViewVisible);
}
}
else
{
ActionHolder actionHolder = new ActionHolder();
EventHandler itemCreated = delegate(object sender, EventArgs eventArgs)
{
var icgSender = sender as ItemContainerGenerator;
tvi = icgSender.ContainerFromItem(listOfRootToNodePath[0]) as TreeViewItem;
if (tvi != null) // Due to threading, it is always better to verify
{
SetItemHierarchyVisible(icg, listOfRootToNodePath, onTreeViewVisible);
actionHolder.Execute();
}
};
actionHolder.Action = new Action(() => icg.StatusChanged -= itemCreated);
icg.StatusChanged += itemCreated;
return;
}
}
}
// ******************************************************************
/// <summary>
/// You cannot rely on this method to be synchronous. If you have any action that depend on the TreeViewItem
/// (last item of collectionOfRootToNodePath) to be visible, you should set it in the 'onTreeViewItemVisible' method.
/// This method should work for Virtualized and non virtualized tree.
/// The difference with SetItemHierarchyVisible is that this one open the target while SetItemHierarchyVisible does not try to expand the target.
/// (SetItemHierarchyVisible just ensure the target will be visible)
/// </summary>
/// <param name="treeView">TreeView where an item has to be set visible</param>
/// <param name="listOfRootToNodePath">The collection should have every objet of the path, from the root to the targeted item.
/// For example for an apple tree: AppleTree (index 0), Branch4, SubBranch3, Leaf2</param>
/// <param name="onTreeViewVisible">Optionnal</param>
public static void ExpandItem(this TreeView treeView, IEnumerable<object> listOfRootToNodePath, OnTreeViewVisible onTreeViewVisible = null)
{
ItemContainerGenerator icg = treeView.ItemContainerGenerator;
if (icg == null)
return; // Is tree loaded and initialized ???
ExpandItem(icg, new List<object>(listOfRootToNodePath), onTreeViewVisible);
}
// ******************************************************************
private static void ExpandSubWithContainersGenerated(ItemsControl ic, Action<TreeViewItem, object> actionItemExpanded, ReferenceCounterTracker referenceCounterTracker)
{
ItemContainerGenerator icg = ic.ItemContainerGenerator;
foreach (object item in ic.Items)
{
var tvi = icg.ContainerFromItem(item) as TreeViewItem;
actionItemExpanded(tvi, item);
tvi.IsExpanded = true;
ExpandSubContainers(tvi, actionItemExpanded, referenceCounterTracker);
}
}
// ******************************************************************
/// <summary>
/// Expand any ItemsControl (TreeView, TreeViewItem, ListBox, ComboBox, ...) and their childs if any (TreeView)
/// </summary>
/// <param name="ic"></param>
/// <param name="actionItemExpanded"></param>
/// <param name="referenceCounterTracker"></param>
public static void ExpandSubContainers(ItemsControl ic, Action<TreeViewItem, object> actionItemExpanded, ReferenceCounterTracker referenceCounterTracker)
{
ItemContainerGenerator icg = ic.ItemContainerGenerator;
{
if (icg.Status == GeneratorStatus.ContainersGenerated)
{
ExpandSubWithContainersGenerated(ic, actionItemExpanded, referenceCounterTracker);
}
else if (icg.Status == GeneratorStatus.NotStarted)
{
ActionHolder actionHolder = new ActionHolder();
EventHandler itemCreated = delegate(object sender, EventArgs eventArgs)
{
var icgSender = sender as ItemContainerGenerator;
if (icgSender.Status == GeneratorStatus.ContainersGenerated)
{
ExpandSubWithContainersGenerated(ic, actionItemExpanded, referenceCounterTracker);
// Never use the following method in BeginInvoke due to ICG recycling. The same icg could be
// used and will keep more than one subscribers which is far from being intended
// ic.Dispatcher.BeginInvoke(actionHolder.Action, DispatcherPriority.Background);
// Very important to unsubscribe as soon we've done due to ICG recycling.
actionHolder.Execute();
referenceCounterTracker.ReleaseRef();
}
};
referenceCounterTracker.AddRef();
actionHolder.Action = new Action(() => icg.StatusChanged -= itemCreated);
icg.StatusChanged += itemCreated;
// Next block is only intended to protect against any race condition (I don't know if it is possible ? How Microsoft implemented it)
// I mean the status changed before I subscribe to StatusChanged but after I made the check about its state.
if (icg.Status == GeneratorStatus.ContainersGenerated)
{
ExpandSubWithContainersGenerated(ic, actionItemExpanded, referenceCounterTracker);
}
}
}
}
// ******************************************************************
/// <summary>
/// This method is asynchronous.
/// Expand all items and subs recursively if any. Does support virtualization (item recycling).
/// But honestly, make you a favor, make your life easier en create a model view around your hierarchy with
/// a IsExpanded property for each node level and bind it to each TreeView node level.
/// </summary>
/// <param name="treeView"></param>
/// <param name="actionItemExpanded"></param>
/// <param name="actionAllItemExpanded"></param>
public static void ExpandAll(this TreeView treeView, Action<TreeViewItem, object> actionItemExpanded = null, Action actionAllItemExpanded = null)
{
var referenceCounterTracker = new ReferenceCounterTracker(actionAllItemExpanded);
referenceCounterTracker.AddRef();
treeView.Dispatcher.BeginInvoke(new Action(() => ExpandSubContainers(treeView, actionItemExpanded, referenceCounterTracker)), DispatcherPriority.Background);
referenceCounterTracker.ReleaseRef();
}
// ******************************************************************
}
}
而且
using System;
using System.Threading;
namespace HQ.Util.General
{
public delegate void CountToZeroAction();
public class ReferenceCounterTracker
{
private Action _actionOnCountReachZero = null;
private int _count = 0;
public ReferenceCounterTracker(Action actionOnCountReachZero)
{
_actionOnCountReachZero = actionOnCountReachZero;
}
public void AddRef()
{
Interlocked.Increment(ref _count);
}
public void ReleaseRef()
{
int count = Interlocked.Decrement(ref _count);
if (count == 0)
{
if (_actionOnCountReachZero != null)
{
_actionOnCountReachZero();
}
}
}
}
}
不是，只有其中一些是treeview的孩子。樹視圖層次很深。每件事都有一個對它的父項的引用，但不包括它的TreeViewItem容器。這就是我想要弄明白的。我可以輕鬆地從綁定的對象內上下樹，我只是不知道如何獲取特定對象的TreeViewItem容器。 – ConditionRacer
將堆棧中的每個對象推送到根項目，您知道根對應的ItemContainerGenerator，因此您可以使用它來獲取堆棧中下一個對象的容器，然後可以使用此TreeViewItem的ItemContainerGenerator來獲取堆棧中的下一個對象的容器等等，直到你的堆棧爲空，並且你擁有容器爲你的初始事物。 –
我想這就好。感謝您的想法！ – ConditionRacer