教你快速实现TreeView节点拖放(Drag&Drop)

  1using System;
  2using System.Collections.Generic;
  3using System.ComponentModel;
  4using System.Data;
  5using System.Drawing;
  6using System.Linq;
  7using System.Text;
  8using System.Windows.Forms;
  9
 10namespace MyTree
 11{
 12    public partial class Form2 : Form
 13    {
 14        // Node being dragged
 15        private TreeNode dragNode = null;
 16
 17        // Temporary drop node for selection
 18        private TreeNode tempDropNode = null;
 19
 20        // Timer for scrolling
 21        private Timer timer = new Timer();
 22
 23        public Form2()
 24        {
 25            InitializeComponent();
 26            
 27            //bind data to the treeView
 28            BindTreeView mt = new BindTreeView();
 29            mt.SetSqlconnstr("Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\App_Data\\MemuTreeDB.mdf;Integrated Security=True;User Instance=True");
 30            mt.GetDataSet("tbTree");
 31            mt.BindTV(treeView1);
 32
 33            this.treeView1.ExpandAll();
 34
 35            timer.Interval = 200;
 36            timer.Tick += new EventHandler(timer_Tick);
 37        }
 38
 39        private void treeView_ItemDrag(object sender, System.Windows.Forms.ItemDragEventArgs e)
 40        {
 41            // Get drag node and select it
 42            this.dragNode = (TreeNode)e.Item;
 43            this.treeView1.SelectedNode = this.dragNode;
 44/**//**/
 45            // Reset image list used for drag image
 46            this.imageListDrag.Images.Clear();
 47            this.imageListDrag.ImageSize = new Size(this.dragNode.Bounds.Size.Width + this.treeView1.Indent, this.dragNode.Bounds.Height);
 48
 49            // Create new bitmap
 50            // This bitmap will contain the tree node image to be dragged
 51            Bitmap bmp = new Bitmap(this.dragNode.Bounds.Width + this.treeView1.Indent, this.dragNode.Bounds.Height);
 52
 53            // Get graphics from bitmap
 54            Graphics gfx = Graphics.FromImage(bmp);
 55
 56            // Draw node icon into the bitmap
 57            gfx.DrawImage(this.imageListTreeView.Images[0], 0, 0);
 58
 59            // Draw node label into bitmap
 60            gfx.DrawString(this.dragNode.Text,
 61                this.treeView1.Font,
 62                new SolidBrush(this.treeView1.ForeColor),
 63                (float)this.treeView1.Indent, 1.0f);
 64
 65            // Add bitmap to imagelist
 66            this.imageListDrag.Images.Add(bmp);
 67
 68            // Get mouse position in client coordinates
 69            Point p = this.treeView1.PointToClient(Control.MousePosition);
 70
 71            // Compute delta between mouse position and node bounds
 72            int dx = p.X + this.treeView1.Indent - this.dragNode.Bounds.Left;
 73            int dy = p.Y - this.dragNode.Bounds.Top;
 74
 75            // Begin dragging image
 76            if (DragHelper.ImageList_BeginDrag(this.imageListDrag.Handle, 0, dx, dy))
 77            {
 78                // Begin dragging
 79                this.treeView1.DoDragDrop(bmp, DragDropEffects.Move);
 80                // End dragging image
 81                DragHelper.ImageList_EndDrag();
 82            }
 83
 84        }
 85
 86        private void treeView1_DragOver(object sender, System.Windows.Forms.DragEventArgs e)
 87        {
 88            // Compute drag position and move image
 89            Point formP = this.PointToClient(new Point(e.X, e.Y));
 90            DragHelper.ImageList_DragMove(formP.X - this.treeView1.Left, formP.Y - this.treeView1.Top);
 91
 92            // Get actual drop node
 93            TreeNode dropNode = this.treeView1.GetNodeAt(this.treeView1.PointToClient(new Point(e.X, e.Y)));
 94            if (dropNode == null)
 95            {
 96                e.Effect = DragDropEffects.None;
 97                return;
 98            }
 99
100            e.Effect = DragDropEffects.Move;
101
102            // if mouse is on a new node select it
            if (this.tempDropNode != dropNode)
104            {
105                DragHelper.ImageList_DragShowNolock(false);
106                this.treeView1.SelectedNode = dropNode;
107                DragHelper.ImageList_DragShowNolock(true);
108                tempDropNode = dropNode;
109            }
110
111            // Avoid that drop node is child of drag node 
            TreeNode tmpNode = dropNode;
113            while (tmpNode.Parent != null)
114            {
115                if (tmpNode.Parent == this.dragNode) e.Effect = DragDropEffects.None;
116                tmpNode = tmpNode.Parent;
117            }
        }
119
120        private void treeView1_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
121        {
122            // Unlock updates
            DragHelper.ImageList_DragLeave(this.treeView1.Handle);
124
125            // Get drop node
            TreeNode dropNode = this.treeView1.GetNodeAt(this.treeView1.PointToClient(new Point(e.X, e.Y)));
127
128            // If drop node isn't equal to drag node, add drag node as child of drop node
            if (this.dragNode != dropNode)
130            {
131                // Remove drag node from parent
                if (this.dragNode.Parent == null)
133                {
134                    this.treeView1.Nodes.Remove(this.dragNode);
135                }
                else
                {
138                    this.dragNode.Parent.Nodes.Remove(this.dragNode);
139                }
140
141                // Add drag node to drop node
                dropNode.Nodes.Add(this.dragNode);
143                dropNode.ExpandAll();
144
145                // Set drag node to null
                this.dragNode = null;
147
148                // Disable scroll timer
                this.timer.Enabled = false;
150            }
        }
152
153        private void treeView1_DragEnter(object sender, System.Windows.Forms.DragEventArgs e)
154        {
155            DragHelper.ImageList_DragEnter(this.treeView1.Handle, e.X - this.treeView1.Left,
156                e.Y - this.treeView1.Top);
157
158            // Enable timer for scrolling dragged item
            this.timer.Enabled = true;
160        }
161
162        private void treeView1_DragLeave(object sender, System.EventArgs e)
163        {
164            DragHelper.ImageList_DragLeave(this.treeView1.Handle);
165
166            // Disable timer for scrolling dragged item
            this.timer.Enabled = false;
168        }
169
170        private void treeView1_GiveFeedback(object sender, System.Windows.Forms.GiveFeedbackEventArgs e)
171        {
172            if (e.Effect == DragDropEffects.Move)
173            {
174                // Show pointer cursor while dragging
                e.UseDefaultCursors = false;
176                this.treeView1.Cursor = Cursors.Default;
177            }
            else e.UseDefaultCursors = true;
179
180        }
181
182        private void timer_Tick(object sender, EventArgs e)
183        {
184            // get node at mouse position
            Point pt = PointToClient(Control.MousePosition);
186            TreeNode node = this.treeView1.GetNodeAt(pt);
187
188            if (node == null) return;
189
190            // if mouse is near to the top, scroll up
            if (pt.Y < 30)
192            {
193                // set actual node to the upper one
                if (node.PrevVisibleNode != null)
195                {
196                    node = node.PrevVisibleNode;
197
198                    // hide drag image
                    DragHelper.ImageList_DragShowNolock(false);
200                    // scroll and refresh
                    node.EnsureVisible();
202                    this.treeView1.Refresh();
203                    // show drag image
                    DragHelper.ImageList_DragShowNolock(true);
205
206                }
            }
            // if mouse is near to the bottom, scroll down
            else if (pt.Y > this.treeView1.Size.Height - 30)
210            {
211                if (node.NextVisibleNode != null)
212                {
213                    node = node.NextVisibleNode;
214
215                    DragHelper.ImageList_DragShowNolock(false);
216                    node.EnsureVisible();
217                    this.treeView1.Refresh();
218                    DragHelper.ImageList_DragShowNolock(true);
219                }
            }
        }
222
223        private void Form2_Load(object sender, EventArgs e)
224        {
225
226        }
    }
}
229

 1using System;
 2using System.Runtime.InteropServices;
 3
 4namespace MyTree
 5{
 6    public class DragHelper
 7    {
 8        [DllImport("comctl32.dll")]
 9        public static extern bool InitCommonControls();
10
11        [DllImport("comctl32.dll", CharSet=CharSet.Auto)]
12        public static extern bool ImageList_BeginDrag(IntPtr himlTrack, int
            iTrack, int dxHotspot, int dyHotspot);
14
15        [DllImport("comctl32.dll", CharSet=CharSet.Auto)]
16        public static extern bool ImageList_DragMove(int x, int y);
17
18        [DllImport("comctl32.dll", CharSet=CharSet.Auto)]
19        public static extern void ImageList_EndDrag();
20
21        [DllImport("comctl32.dll", CharSet=CharSet.Auto)]
22        public static extern bool ImageList_DragEnter(IntPtr hwndLock, int x, int y);
23
24        [DllImport("comctl32.dll", CharSet=CharSet.Auto)]
25        public static extern bool ImageList_DragLeave(IntPtr hwndLock);
26
27        [DllImport("comctl32.dll", CharSet=CharSet.Auto)]
28        public static extern bool ImageList_DragShowNolock(bool fShow);
29
30        static DragHelper()
31        {
32            InitCommonControls();
33        }
    }
}
36