【WPF】 实现Treeview 的拖拽

实现方式有两种。
  方式一：通过重载事件来进行的
     参考项目源码：https://files.cnblogs.com/ruicky/Wpf-TreeView-%E5%85%A8%E8%83%BD%E5%AE%9E%E7%8E%B0%E6%8B%96%E6%8B%BD.zip
     优点：调用到自己的项目中方式简单。随意拖动
     缺点：难以添加限制对于一些节点不能拖动的设置性弱
  方式二：通过写Treeview的事件来进行拖动

     前台：

<TreeView Name="tvRequire"  BorderThickness="1"   

MouseDown="tvRequire_MouseDown" MouseMove="tvRequire_MouseMove" 

DragEnter="TheTreeView_CheckDropTarget" 

DragLeave="TheTreeView_CheckDropTarget" 

DragOver="TheTreeView_CheckDropTarget" Drop="tvRequire_Drop" >
   </TreeView>

    后台：

private Point _lastMouseDown;
        private void tvRequire_MouseDown(object sender, 

MouseButtonEventArgs e)
        {
            if (e.ChangedButton == MouseButton.Left)
            {
                _lastMouseDown = e.GetPosition(tvRequire);
            }
        }

 private void tvRequire_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                Point currentPosition = e.GetPosition(tvRequire);
                if ((Math.Abs(currentPosition.X - 

_lastMouseDown.X) > 2.0) || (Math.Abs(currentPosition.Y - 

_lastMouseDown.Y) > 2.0))
                {
                    if ((tvRequire.SelectedItem as TreeViewItem) 

!= null)
                    {
                        DragDropEffects finalDropEffect = 

DragDrop.DoDragDrop(tvRequire.SelectedItem as TreeViewItem, 

sender, DragDropEffects.Move);

                    }
                }
            }
        }

private void TheTreeView_CheckDropTarget(object sender, 

DragEventArgs e)
        {
            
            if (e.Source as TreeViewItem != null)
            {
                if (!IsValidDropTarget((e.Source as 

TreeViewItem).Tag))
                {
                    e.Effects = DragDropEffects.None;
                }
            }
            e.Handled = true;
        }
//检查是否能够拖
        private bool IsValidDropTarget(object id)
        {
            bool res = false;
            if (id != null)
            {
                
                //根据各自需求来写
            }
            return res;
        }
  //Drop 进行保存
 private void tvRequire_Drop(object sender, DragEventArgs e)
        {
            TreeViewItem treeViewItemParent = new TreeViewItem();
            if (e.Source as EditableTextBlock != null)
            {
                treeViewItemParent = (e.Source as 

EditableTextBlock).Parent as TreeViewItem;//().Parent as 

TreeViewItem
                if (tvRequire.SelectedItem as TreeViewItem == 

(e.Source as EditableTextBlock).Parent as TreeViewItem)
                {
                    return;
                }
            }
            else
            {
                treeViewItemParent = e.Source as TreeViewItem;
                if (tvRequire.SelectedItem as TreeViewItem == 

e.Source as TreeViewItem)
                {
                    return;
                }
            }

            //进行增加删除功能
            TreeViewItem itemRemoved = tvRequire.SelectedItem as 

TreeViewItem;
            CusRequireInfo cusRequireInfo = 

BLLCusRequire.GetModel(Convert.ToInt32(itemRemoved.Tag));
            if (cusRequireInfo.ParentId == 0)
            {
                tvRequire.Items.Remove(itemRemoved);
            }
            else
            {
                (itemRemoved.Parent as TreeViewItem).Items.Remove

(itemRemoved);
            }
            (treeViewItemParent).Items.Add(itemRemoved);

            cusRequireInfo.ParentId = Convert.ToInt32

(treeViewItemParent.Tag);
            BLLCusRequire.Update(cusRequireInfo);
        }

   PS:主要有三个方法体  tvRequire_MouseDown(开始记录坐标) tvRequire_MouseMove(指定拖动效果操作)TheTreeView_CheckDropTarget(用来检查是否可拖动)  tvRequire_Drop  （用来进行拖动后的保存）

       优点：能够自定义的限制拖拽条件，比较容易理解
       缺点：代码量多，复用率低

  转载请注明出处: http://www.cnblogs.com/ruicky/archive/2013/01/21/2869206.html