具有多个选择的WPF TreeView [英] WPF TreeView with Multiple Selection

问题描述

标准WPF 树视图可以不支持多项选择.

The standard WPF tree view does not support multiple selections.

如何向WPF应用程序添加支持多重选择的树形视图?商业产品很好(我目前知道一种商业实现方式- http://www.telerik .com/products/wpf/treeview.aspx )

How can I add a tree view that supports multiple selection to my WPF application? Commercial products are fine (I am currently aware of one commercial implementation - http://www.telerik.com/products/wpf/treeview.aspx)

推荐答案

下面的代码可以正常工作，并且更简单.但是，缺点是要使用treeview类的非公共属性IsSelectionChangeActive.下面的代码:

The code below works fine and is much simpler. However the draw back is the use of the non public property, IsSelectionChangeActive, of the treeview class. Code below:

private static readonly PropertyInfo IsSelectionChangeActiveProperty 
  = typeof (TreeView).GetProperty
    (
      "IsSelectionChangeActive",
      BindingFlags.NonPublic | BindingFlags.Instance
    );

public static void AllowMultiSelection(TreeView treeView)
{
  if (IsSelectionChangeActiveProperty==null) return;

  var selectedItems = new List<TreeViewItem>();
  treeView.SelectedItemChanged += (a, b) =>
  {
    var treeViewItem = treeView.SelectedItem as TreeViewItem;
    if (treeViewItem == null) return;

    // allow multiple selection
    // when control key is pressed
    if (Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl))
    {
      // suppress selection change notification
      // select all selected items
      // then restore selection change notifications
      var isSelectionChangeActive = 
        IsSelectionChangeActiveProperty.GetValue(treeView, null);

      IsSelectionChangeActiveProperty.SetValue(treeView, true, null);
      selectedItems.ForEach(item => item.IsSelected = true);

      IsSelectionChangeActiveProperty.SetValue
      (
        treeView, 
        isSelectionChangeActive, 
        null
      );
    }
    else
    {
      // deselect all selected items except the current one
      selectedItems.ForEach(item => item.IsSelected = (item == treeViewItem) );
      selectedItems.Clear();
    }

    if (!selectedItems.Contains(treeViewItem))
    {
      selectedItems.Add(treeViewItem);
    }
    else
    {
      // deselect if already selected
      treeViewItem.IsSelected = false;
      selectedItems.Remove(treeViewItem);
    }
  };

}

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