【WPF】 實現Treeview 的拖拽

實現方式有兩種。
  方式一：通過重載事件來進行的
     參考項目源碼：http://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
     優點：調用到自己的項目中方式簡單。隨意拖動
     缺點：難以添加限制對於一些節點不能拖動的設置性弱
  方式二：通過寫Treeview的事件來進行拖動

     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;
        }
//檢查是否能夠拖
        private bool IsValidDropTarget(object id)
        {
            bool res = false;
            if (id != null)
            {
                
                //根據各自需求來寫
            }
            return res;
        }
  //Drop 進行保存
 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;
                }
            }

            //進行增加刪除功能
            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:主要有三個方法體  tvRequire_MouseDown(開始記錄坐標) tvRequire_MouseMove(指定拖動效果操作)TheTreeView_CheckDropTarget(用來檢查是否可拖動)  tvRequire_Drop  （用來進行拖動后的保存）

       優點：能夠自定義的限制拖拽條件，比較容易理解
       缺點：代碼量多，復用率低

  轉載請注明出處: http://www.cnblogs.com/ruicky/archive/2013/01/21/2869206.html