WPF:选择树视图项已断开根级别

问题是嵌套的 ItemContainerGenerators 不是一开始就生成的,而是按需生成的。更重要的是,它们是在一个单独的线程中生成的,所以你必须听 StatusChanged

有些人建议玩这个游戏 Dispatcher ( like in this Bea's post ). 我试图实现Dispatcher解决方案,但由于某些原因,它没有起作用。。。发电机还是空的=(

因此,我最后使用了另一种方法,您特别要求树更新其布局,从而生成扩展节点。这里是最后的方法。。。您可能需要对它进行一些测试,以验证它是否符合您的需要。它可能会折叠一些在运行前已展开的节点。

    private static bool SetSelected(TreeView treeView, ItemsControl parentControl, INestable itemToSelect)
    {
        if (parentControl == null || itemToSelect == null)
        {
            return false;
        }
        foreach (INestable item in parentControl.Items)
        {
            TreeViewItem container = parentControl.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;

            if (item.ID == itemToSelect.ID)
            { // just comparing instances failed
                    container.IsSelected = true;
                    container.Focus();
                    return true;
            }
            container.IsExpanded = true;
            treeView.UpdateLayout();
            WaitForPriority(DispatcherPriority.Background);
            if (SetSelected(treeView, container, itemToSelect))
                return true;
            else
                container.IsExpanded = false;
        }
        return false;
    }

我认为它不起作用,因为项已折叠,其容器未实例化。因此,尝试直接选择TreeViewItem绝对不是最好的方法。

相反,我们使用MVVM方法。每个viewmodel对象都应该具有IsSelected属性。然后将TreeViewItem.IsSelected属性绑定到它。

反恐精英:

public interface INestable : INotifyPropertyChanged
{
  string ID { get; set; }

  // Make sure you invoke PropertyChanged in setter
  bool IsSelected { get; set; } 

  event PropertyChangedEventHandler PropertyChanged;
  ...
}

<TreeView ...>
  <TreeView.ItemContainerStyle>
   <Style TargetType="{x:Type TreeViewItem}">
     <Setter Property="IsSelected" Value="{Binding Path=IsSelected, Mode=TwoWay}" />
   </Style>
  </TreeView.ItemContainerStyle>
</TreeView>

现在,您可以浏览模型并进行设置 IsSelected 那里的财产。

您可能还想跟踪 IsExpanded

要了解更多关于TreeView的信息,请阅读Josh Smith的这篇精彩文章: Simplifying the WPF TreeView by Using the ViewModel Pattern

希望这有帮助。

尽管被接受的答案在大多数情况下都有效。它可能恰好不起作用,因为对象是在另一个线程上创建的,而该线程根本不受调度程序控制。

我个人认为正确的解决方案更复杂。我知道这很糟糕,但我真的认为是这样。无论是否虚拟化,我的代码都应该可以工作。此外,您可以删除任何不需要的引用(我没有验证)。

一切都从SetSelectedTreeViewItem()开始,它激活(+设置焦点并进入视图)新添加的项。

希望它能帮助或启发一些。。。快乐编码!!!

    //  ******************************************************************
    private List<MultiSimBase> SetPathListFromRootToNode(MultiSimBase multiSimBase, List<MultiSimBase> listTopToNode = null)
    {
        if (listTopToNode == null)
        {
            listTopToNode = new List<MultiSimBase>();
        }

        listTopToNode.Insert(0, multiSimBase);
        if (multiSimBase.Parent != null)
        {
            SetPathListFromRootToNode(multiSimBase.Parent, listTopToNode);
        }

        return listTopToNode;
    }

    // ******************************************************************
    private void SetSelectedTreeViewItem(MultiSimBase multiSimBase)
    {
        List<MultiSimBase> listOfMultiSimBasePathFromRootToNode = SetPathListFromRootToNode(multiSimBase);

        TreeViewStudy.SetItemHierarchyVisible(listOfMultiSimBasePathFromRootToNode, (tvi) =>
                                                                                    {
                                                                                        tvi.IsSelected = true;
                                                                                        tvi.Focus();
                                                                                        tvi.BringIntoView();
                                                                                    });
    }

现在是通用代码:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Threading;

namespace HQ.Util.Wpf.WpfUtil
{
    public static class TreeViewExtensions
    {
        public delegate void OnTreeViewVisible(TreeViewItem tvi);

        private static void SetItemHierarchyVisible(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 (listOfRootToNodePath.Count == 0)
                    {
                        if (onTreeViewVisible != null)
                            onTreeViewVisible(tvi);
                    }
                    else
                    {
                        if (!tvi.IsExpanded)
                            tvi.IsExpanded = true;

                        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.
        /// </summary>
        /// <param name="treeView">TreeView where  an item has to be set visible</param>
        /// <param name="collectionOfRootToNodePath">Any of collection that implement ICollection like a generic List.
        /// The collection should have every objet of the path to the targeted item from the top 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, IList listOfRootToNodePath, OnTreeViewVisible onTreeViewVisible = null)
        {
            ItemContainerGenerator icg = treeView.ItemContainerGenerator;
            if (icg == null)
                return; // Is tree loaded and initialized ???

            SetItemHierarchyVisible(icg, listOfRootToNodePath, onTreeViewVisible);
        }

    using System;

namespace HQ.Util.Wpf.WpfUtil
{
    // Requested to unsubscribe into an anonymous method that is a delegate used for a one time execution
    // http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/df2773eb-0cc1-4f3a-a674-e32f2ef2c3f1/
    public class ActionHolder
    {
        public void Execute()
        {
            if (Action != null)
            {
                Action();
            }
        }

        public Action Action { get; set; }
    }
}