TreeNodeEventHandler Delegat

Definition

Stellt die Methode zur Behandlung der folgenden Ereignisse des TreeNodeCollapsed-Steuerelements dar: TreeNodeDataBound, TreeNodeExpanded, TreeNodePopulate oder TreeView.Represents the method that will handle the TreeNodeCollapsed, TreeNodeDataBound, TreeNodeExpanded, or TreeNodePopulate event of the TreeView control.

public delegate void TreeNodeEventHandler(System::Object ^ sender, TreeNodeEventArgs ^ e);
public delegate void TreeNodeEventHandler(object sender, TreeNodeEventArgs e);
type TreeNodeEventHandler = delegate of obj * TreeNodeEventArgs -> unit
Public Delegate Sub TreeNodeEventHandler(sender As Object, e As TreeNodeEventArgs)

Parameter

sender
Object

Die Quelle des Ereignisses.The source of the event.

e
TreeNodeEventArgs

Ein TreeNodeEventArgs, das die Ereignisdaten enthält.A TreeNodeEventArgs that contains the event data.

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie der-Delegat verwendet wird TreeNodeEventHandler , um eine Ereignis Behandlungsmethode Programm gesteuert zu registrieren.The following code example demonstrates how to use the TreeNodeEventHandler delegate to register an event-handling method programmatically.


<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  void Page_Load(Object sender, EventArgs e)
  {

    // Create a new TreeView control.
    TreeView NewTree = new TreeView();

    // Set the properties of the TreeView control.
    NewTree.ID = "BookTreeView";
    NewTree.DataSourceID = "BookXmlDataSource";

    // Create the tree node binding relationship.

    // Create the root node binding.
    TreeNodeBinding RootBinding = new TreeNodeBinding();
    RootBinding.DataMember = "Book";
    RootBinding.TextField = "Title";

    // Create the parent node binding.
    TreeNodeBinding ParentBinding = new TreeNodeBinding();
    ParentBinding.DataMember = "Chapter";
    ParentBinding.TextField = "Heading";

    // Create the leaf node binding.
    TreeNodeBinding LeafBinding = new TreeNodeBinding();
    LeafBinding.DataMember = "Section";
    LeafBinding.TextField = "Heading";

    // Add bindings to the DataBindings collection.
    NewTree.DataBindings.Add(RootBinding);
    NewTree.DataBindings.Add(ParentBinding); 
    NewTree.DataBindings.Add(LeafBinding);

    // Manually register the event handler for the TreeNodeExpanded event.
    NewTree.TreeNodeExpanded += new TreeNodeEventHandler(this.Node_Expand);

    // Add the TreeView control to the Controls collection of the PlaceHolder control.
    ControlPlaceHolder.Controls.Add(NewTree);

  }

  void Node_Expand(Object sender, TreeNodeEventArgs e)
  {

    // Display the expanded node.
    Message.Text = "You expanded: " + e.Node.Text;

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>TreeView TreeNodeEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
    
      <h3>TreeView TreeNodeEventHandler Example</h3>
      
      <asp:PlaceHolder id="ControlPlaceHolder" runat="server">
      </asp:PlaceHolder>
   
      <asp:XmlDataSource id="BookXmlDataSource"  
        DataFile="book.xml"
        runat="server">
      </asp:XmlDataSource>
      
      <br /><br />
      
      <asp:Label id="Message" runat="server"/>
    
    </form>
  </body>
</html>


<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

    ' Create a new TreeView control.
    Dim NewTree As TreeView = New TreeView

    ' Set the properties of the TreeView control.
    NewTree.ID = "BookTreeView"
    NewTree.DataSourceID = "BookXmlDataSource"

    ' Create the tree node binding relationship.

    ' Create the root node binding.
    Dim RootBinding As TreeNodeBinding = New TreeNodeBinding
    RootBinding.DataMember = "Book"
    RootBinding.TextField = "Title"

    ' Create the parent node binding.
    Dim ParentBinding As TreeNodeBinding = New TreeNodeBinding
    ParentBinding.DataMember = "Chapter"
    ParentBinding.TextField = "Heading"

    ' Create the leaf node binding.
    Dim LeafBinding As TreeNodeBinding = New TreeNodeBinding
    LeafBinding.DataMember = "Section"
    LeafBinding.TextField = "Heading"

    ' Add bindings to the DataBindings collection.
    NewTree.DataBindings.Add(RootBinding)
    NewTree.DataBindings.Add(ParentBinding)
    NewTree.DataBindings.Add(LeafBinding)

    ' Manually register the event handler for the TreeNodeExpanded event.
    AddHandler NewTree.TreeNodeExpanded, AddressOf Node_Expand

    ' Add the TreeView control to the Controls collection of the PlaceHolder control.
    ControlPlaceHolder.Controls.Add(NewTree)

  End Sub

  Sub Node_Expand(ByVal sender As Object, ByVal e As TreeNodeEventArgs)

    ' Display the expanded node.
    Message.Text = "You expanded: " & e.Node.Text

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>TreeView TreeNodeEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
    
      <h3>TreeView TreeNodeEventHandler Example</h3>
      
      <asp:PlaceHolder id="ControlPlaceHolder" runat="server">
      </asp:PlaceHolder>
   
      <asp:XmlDataSource id="BookXmlDataSource"  
        DataFile="book.xml"
        runat="server">
      </asp:XmlDataSource>
      
      <br /><br />
      
      <asp:Label id="Message" runat="server"/>
    
    </form>
  </body>
</html>

Hinweise

Beim Erstellen eines TreeNodeEventHandler-Delegaten bestimmen Sie die Methode für die Ereignisbehandlung.When you create a TreeNodeEventHandler delegate, you identify the method that will handle the event. Um dem Ereignishandler das Ereignis zuzuordnen, fügen Sie dem Ereignis eine Instanz des Delegaten hinzu.To associate the event with your event handler, add an instance of the delegate to the event. Der Ereignishandler wird bei jedem Eintreten des Ereignisses aufgerufen, sofern der Delegat nicht entfernt wird.The event handler is called whenever the event occurs, unless you remove the delegate. Weitere Informationen zu Ereignishandlerdelegaten finden Sie unter behandeln und Auswerfen von Ereignissen.For more information about event-handler delegates, see Handling and Raising Events.

Erweiterungsmethoden

GetMethodInfo(Delegate)

Ruft ein Objekt ab, das die Methode darstellt, die vom angegebenen Delegaten dargestellt wird.Gets an object that represents the method represented by the specified delegate.

Gilt für:

Siehe auch