TreeView拖动

namespace TreeViewConfig
{
    public partial class FormMain : Form
    {
        const int scrollRegion = 25;

        [DllImport("user32.dll")]

        private static extern int SendMessage(IntPtr hWnd, int wMsg, int wParam, int lParam);


        public FormMain()
        {
            InitializeComponent();

        }

        private void btnConnToDB_Click(object sender, EventArgs e)
        {
            treeViewMain.Nodes.Clear();
            tableStation.Clear();

            treeViewMain.Nodes.Add("牵引");
            treeViewMain.Nodes.Add("电力");


            //连接数据库            
            SqlConnection connection = new SqlConnection();
            connection.ConnectionString = "server=" + textBoxServer.Text + ";Initial Catalog=" + textBoxDB.Text + ";Integrated Security=false;uid=" + textBoxUser.Text + ";pwd=" + textBoxPwd.Text;

            SqlDataAdapter command = new SqlDataAdapter("SELECT distinct name, StID, StCode, type FROM stationConfig order by StCode", connection);
            command.Fill(dsStation, "StationConfig");

            connection.Close();

            tableStation = dsStation.Tables["StationConfig"];

            IEnumerable<DataRow> query =
                from name in tableStation.AsEnumerable()
                select name;

            foreach (DataRow dr in query)
            {
                if (dr.Field<byte>("type") <= 3)
                {
                    treeViewMain.Nodes[0].Nodes.Add(string.Format("[{0}] {1}",
                    (dr.Field<Int16>("StCode")).ToString("000"),
                    dr.Field<string>("name")));
                }
                else
                {
                    treeViewMain.Nodes[1].Nodes.Add(string.Format("[{0}] {1}",
                    (dr.Field<Int16>("StCode")).ToString("000"),
                    dr.Field<string>("name")));
                }
            }
        }

        private void treeViewMain_DragDrop(object sender, DragEventArgs e)
        {
            //得到拖放中的节点
            TreeNode moveNode = (TreeNode)e.Data.GetData("System.Windows.Forms.TreeNode");
                        
            //根据鼠标坐标确定要移动到的目标节点
            TreeNode targetNode = new TreeNode();
            Point pt = ((TreeView)(sender)).PointToClient(new Point(e.X, e.Y));

            targetNode = this.treeViewMain.GetNodeAt(pt);

            //如果目标为自己，返回
            if (targetNode.Text == moveNode.Text)
            {
                return;
            }

            //如果目标包含在自己的节点树中，返回            
            if (moveNode.Nodes.Contains(targetNode))
            {
                return;
            }
            else if (targetNode.FullPath.Contains(moveNode.FullPath))
            {
                return;
            }

            //如果目标为父节点，返回
            if (targetNode.Parent == moveNode)
            {
                return;
            }

            //添加节点
            TreeNode newmoveNode = (TreeNode)moveNode.Clone();

            targetNode.Nodes.Insert(targetNode.Nodes.Count, newmoveNode);

            //更新当前拖动的节点选择
            treeViewMain.SelectedNode = newmoveNode;

            targetNode.Expand();

            //移除拖放的节点
            moveNode.Remove();
        }

        private void treeViewMain_DragEnter(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent("System.Windows.Forms.TreeNode"))
            {
                e.Effect = DragDropEffects.Move;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }

        private void treeViewMain_ItemDrag(object sender, ItemDragEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                //((TreeNode)e.Item).Parent.Collapse();
                DoDragDrop(e.Item, DragDropEffects.Move);
            }
        }

        private void treeViewMain_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            if (e.Button == System.Windows.Forms.MouseButtons.Right)
            {
                treeViewMain.SelectedNode = e.Node;
                contextMenuStripTree.Show(treeViewMain, e.X, e.Y);
            }
        }

        private void AddNodeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            AddNodeForm addnodeform = new AddNodeForm();
            addnodeform.Location = new Point(treeViewMain.Location.X + 25, addNodeFormY);
            addnodeform.StartPosition = FormStartPosition.Manual;
            addnodeform.ShowDialog(this);

            if (addnodeform.NewNodeName != "")
            {
                treeViewMain.SelectedNode.Nodes.Insert(treeViewMain.SelectedNode.Nodes.Count, addnodeform.NewNodeName);
                treeViewMain.SelectedNode.Expand();
            }
            addnodeform.Close();
        }

        private void DelNodeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            treeViewMain.SelectedNode.Remove();
        }

        private void treeViewMain_MouseMove(object sender, MouseEventArgs e)
        {
            addNodeFormY = e.Y + 45;
            mouseY = e.Y;

            label1.Text = string.Format("X:{0}   Y:{1}   treeViewMain.VScrollPos:{2}  treeViewMain.Height:{3}   mouseY：{4}", e.X, e.Y, treeViewMain.VScrollPos, treeViewMain.Height, mouseY);
        }
                
        private void treeViewMain_DragOver(object sender, DragEventArgs e)
        {
            //拖动过程中高亮鼠标滑过的节点
            TreeViewHitTestInfo hti = this.treeViewMain.HitTest(this.treeViewMain.PointToClient(new Point(e.X, e.Y)));
            this.treeViewMain.SelectedNode = hti.Node;

            //拖动过程中鼠标达到上下边界时滚动条自动调整            
            if (e.Y > (treeViewMain.Height + scrollRegion*8))
            {
                //向下滚动
                SendMessage(treeViewMain.Handle, (int)277, (int)1, 0);
            }
            else if (e.Y < (treeViewMain.Top + scrollRegion))
            {
                //向上滚动
                SendMessage(treeViewMain.Handle, (int)277, (int)0, 0);
            }

        }
    }
}