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Comment : sous-classer un contrôle TreeView à l'aide de rappels natifs

Mise à jour : novembre 2007

Cet exemple explique comment sous-classer un contrôle TreeView pour créer un événement NodeMouseClick, ce qui n'est pas possible dans le .NET Compact Framework.

Le formulaire affiche le contrôle TreeView sous-classé et les informations à propos d'un nœud sur lequel un clic a été effectué. Il affiche le texte d'un nœud et les coordonnées x et y de l'emplacement où le clic a été effectué sur le contrôle TreeView qui change lorsque vous cliquez dans différents endroits sur un nœud.

Cet exemple de programme est décrit en détail dans Sous-classement de contrôles avec une procédure de fenêtre managée.

Pour sous-classer un contrôle TreeView afin de créer un événement NodeMouseClick

  1. Dans Microsoft Visual Studio 2005, créez un projet Smart Device Pocket PC.

  2. Ajoutez la classe d'assistance Win32 à votre projet. Ce code est disponible dans Comment : utiliser une classe d'assistance pour les appels de plates-formes.

  3. Ajoutez la classe WinProcHooker à votre projet. Ce code est disponible dans Comment : utiliser une classe pour raccorder des procédures Windows.

  4. Ajoutez la classe TreeViewBonus à votre projet.

    // Extends the standard TreeView control to add an implementation
    // of the NodeMouseClick event.
    public class TreeViewBonus : TreeView
    {
        // The original parent of this control.
        Control prevParent = null;
    
        // Creates a new instance of the derived TreeView control
        public TreeViewBonus()
        {
        }
    
        // Called when the control's parent is changed. Here we hook into that
        // parent's WndProc and spy on the WM_NOTIFY message. When the parent
        // changes, we unhook the old parent's WndProc and hook into the new one.
        protected override void OnParentChanged(EventArgs e)
        {
            // unhook the old parent
            if (this.prevParent != null)
            {
                WndProcHooker.UnhookWndProc(prevParent, Win32.WM_NOTIFY);
            }
            // update the previous parent
            prevParent = this.Parent;
    
            // hook up the new parent
            if (this.Parent != null)
            {
                WndProcHooker.HookWndProc(this.Parent,
                new WndProcHooker.WndProcCallback(this.WM_Notify_Handler),
                Win32.WM_NOTIFY);
            }
    
            base.OnParentChanged(e);
        }
    
        // Occurs when the user clicks a TreeNode with the mouse.
        public event TreeNodeMouseClickEventHandler NodeMouseClick;
    
        // Occurs when the mouse pointer is over the control and a mouse button is clicked.
        protected void OnNodeMouseClick(TreeNodeMouseClickEventArgs e)
        {
            if (NodeMouseClick != null)
                NodeMouseClick(this, e);
       }
    
        // The method that gets called when a WM_NOTIFY message is received by the
        // TreeView's parent.
        // hwnd - The handle of the window that received the message
        // msg - The message received
        // wParam - The wParam arguments for the message
        // lParam - The lParam arguments for the message
        // handled - Set to true to indicate that this message was handled
        // Returns an appropriate return code for the message handled
        int WM_Notify_Handler(
            IntPtr hwnd, uint msg, uint wParam, int lParam,
            ref bool handled)
        {
            Win32.NMHDR nmHdr = new Win32.NMHDR();
            System.Runtime.InteropServices.Marshal.PtrToStructure((IntPtr)lParam, nmHdr);
            switch (nmHdr.code)
            {
                case Win32.NM_RCLICK:
                case Win32.NM_CLICK:
                    // get the cursor coordinates on the client
                    Point msgPos = Win32.LParamToPoint((int)Win32.GetMessagePos());
                    msgPos = this.PointToClient(msgPos);
    
                    // check to see if the click was on an item
                    Win32.TVHITTESTINFO hti = new Win32.TVHITTESTINFO();
                    hti.pt.X = msgPos.X;
                    hti.pt.Y = msgPos.Y;
                    int hitem = Win32.SendMessage(this.Handle, Win32.TVM_HITTEST, 0, ref hti);
                    uint htMask = (
                        Win32.TVHT_ONITEMICON |
                        Win32.TVHT_ONITEMLABEL |
                        Win32.TVHT_ONITEMINDENT |
                        Win32.TVHT_ONITEMBUTTON |
                        Win32.TVHT_ONITEMRIGHT |
                        Win32.TVHT_ONITEMSTATEICON);
                    if ((hti.flags & htMask) != 0)
                    {
                        bool leftButton = (nmHdr.code == Win32.NM_CLICK);
                        RaiseNodeMouseClickEvent(hti.hItem,
                            leftButton ? MouseButtons.Left : MouseButtons.Right,
                            msgPos);
                        return 0;
                    }
                    break;
                default:
                    break;
            }
            return 0;
        }
    
        // Raises the TreeNodeMouseClick event for the TreeNode with the specified handle.
        // hNode - The handle of the node for which the event is raised
        // button - The [mouse] buttons that were pressed to raise the event
        // coords - The [client] cursor coordinates at the time of the event
        void RaiseNodeMouseClickEvent(IntPtr hNode, MouseButtons button, Point coords)
        {
            TreeNode tn = FindTreeNodeFromHandle(this.Nodes, hNode);
    
            TreeNodeMouseClickEventArgs e = new TreeNodeMouseClickEventArgs(
                tn,
                button,
                1, coords.X, coords.Y);
    
            OnNodeMouseClick(e);
        }
    
        // Finds a TreeNode in the provided TreeNodeCollection that has the handle specified.
        // Warning: recursion!
        // tnc - The TreeNodeCollection to search
        // handle - The handle of the TreeNode to find in the collection
        // Returns tThe TreeNode if found; null otherwise
        TreeNode FindTreeNodeFromHandle(TreeNodeCollection tnc, IntPtr handle)
        {
            foreach (TreeNode tn in tnc)
            {
            if (tn.Handle == handle) return tn;
                // we couldn't have clicked on a child of this node if this node
                // is not expanded!
                if (tn.IsExpanded)
                {
                    TreeNode tn2 = FindTreeNodeFromHandle(tn.Nodes, handle);
                    if (tn2 != null) return tn2;
                }
            }
            return null;
        }
    }
    
  5. Ajoutez la classe TreeNodeMouseClickEventArgs à votre projet.

    // Provides data for the System.Windows.Forms.TreeView.NodeMouseClick event
    public class TreeNodeMouseClickEventArgs : MouseEventArgs
    {
        // Initializes a new instance of the TreeNodeMouseClickEventArgs class.
        // node - The node that was clicked
        // button - One of the System.Windows.Forms.MouseButtons members
        // clicks - The number of clicks that occurred
        // x - The x-coordinate where the click occurred
        // y - The y-coordinate where the click occurred
        public TreeNodeMouseClickEventArgs(TreeNode node, MouseButtons button, int clicks, int x, int y)
            :
            base(button, clicks, x, y, 0)
        {
            nodeValue = node;
        }
    
        //
        // Gets the node that was clicked.
        //
        public TreeNode Node
        {
            get { return nodeValue; }
            set { nodeValue = value; }
        }
        TreeNode nodeValue;
    
        public override string ToString()
        {
            return string.Format(
                "TreeNodeMouseClickEventArgs\r\n\tNode: {0}\r\n\tButton: {1}\r\n\tX: {2}\r\n\tY: {3}",
                nodeValue.Text, Button.ToString(), X, Y);
        }
    }
    
  6. Déclarez une variable de formulaire nommée treeViewB de type TreeViewBonus.

    private TreeViewBonus treeViewB;
    
  7. Ajoutez le code suivant au constructeur de la classe Form1, qui doit suivre l'appel à InitializeComponent. Ce code ajoute également une plage de nœuds d'arbre et réorganise leur hiérarchie.

    InitializeComponent();
    this.treeViewB = new TreeViewBonus();
    this.treeViewB.NodeMouseClick += new TreeNodeMouseClickEventHandler(this.tv_NodeMouseClicked);
    this.treeViewB.Location = new System.Drawing.Point(18, 16);
    this.treeViewB.Size = new System.Drawing.Size(205, 144);
    this.treeViewB.Name = "treeViewB";
    
    
    // Set up the tree nodes.
    System.Windows.Forms.TreeNode treeNode1 = new System.Windows.Forms.TreeNode("Node0");
    System.Windows.Forms.TreeNode treeNode2 = new System.Windows.Forms.TreeNode("Node2");
    System.Windows.Forms.TreeNode treeNode3 = new System.Windows.Forms.TreeNode("Node3");
    System.Windows.Forms.TreeNode treeNode4 = new System.Windows.Forms.TreeNode("Node6");
    System.Windows.Forms.TreeNode treeNode5 = new System.Windows.Forms.TreeNode("Node7");
    System.Windows.Forms.TreeNode treeNode6 = new System.Windows.Forms.TreeNode("Node8");
    System.Windows.Forms.TreeNode treeNode7 = new System.Windows.Forms.TreeNode("Node4");
    System.Windows.Forms.TreeNode treeNode8 = new System.Windows.Forms.TreeNode("Node1");
    System.Windows.Forms.TreeNode treeNode9 = new System.Windows.Forms.TreeNode("Node5");
    System.Windows.Forms.TreeNode treeNode10 = new System.Windows.Forms.TreeNode("Node9");
    System.Windows.Forms.TreeNode treeNode11 = new System.Windows.Forms.TreeNode("Node10");
    System.Windows.Forms.TreeNode treeNode12 = new System.Windows.Forms.TreeNode("Node11");
    
    treeNode2.Text = "Node2";
    treeNode4.Text = "Node6";
    treeNode5.Text = "Node7";
    treeNode6.Text = "Node8";
    treeNode3.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode4,
            treeNode5,
            treeNode6});
    treeNode3.Text = "Node3";
    treeNode7.Text = "Node4";
    treeNode1.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode2,
            treeNode3,
            treeNode7});
    treeNode1.Text = "Node0";
    treeNode12.Text = "Node11";
    treeNode11.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode12});
    treeNode11.Text = "Node10";
    treeNode10.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode11});
    treeNode10.Text = "Node9";
    treeNode9.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode10});
    treeNode9.Text = "Node5";
    treeNode8.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode9});
    treeNode8.Text = "Node1";
    this.treeViewB.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
            treeNode1,
            treeNode8});
    
    this.Controls.Add(treeViewB);
    
    
  8. Ajoutez le délégué et la méthode de gestion d'événements pour l'événement NodeMouseClick dérivé dans la classe Form1.

        // Delegate represents the method that will handle
        // the NodeMouseClick event of a TreeView.
        // Parameters:
        // sender - The source of the event.
        // e - A TreeNodeMouseClickEventArgs that contains the event data.
        public delegate void TreeNodeMouseClickEventHandler(object sender, TreeNodeMouseClickEventArgs e);
    
    private void tv_NodeMouseClicked(object sender, TreeNodeMouseClickEventArgs e)
    {
        // Show the current node and the coordinates
        // in TreeView control where it was clicked.
        // This is just some of the information you
        // can obtain from TreeNodeMouseClickEventArgs.
    
        // Use a StringBuilder for efficient
        // use of device resources.
        StringBuilder sb = new StringBuilder();
        sb.Append(e.Node.Text + " ");
        sb.Append("X: " + e.X.ToString() + ", ");
        sb.Append("Y: " + e.Y.ToString());
    
        label1.Text = sb.ToString();
    
    }
    
  9. Compilez et exécutez l'application.

Voir aussi

Tâches

Comment : utiliser une classe pour raccorder des procédures Windows

Comment : utiliser une classe d'assistance pour les appels de plates-formes

Comment : sous-classer un contrôle TreeView à l'aide de rappels natifs

Comment : afficher un remplissage dégradé

Concepts

.Rubriques Comment relatives au .NET Compact Framework

Autres ressources

Interopérabilité dans le .NET Compact Framework