TreeView.BeforeLabelEdit-Ereignis
Tritt ein, bevor der Text der Strukturknotenbezeichnung bearbeitet wird.
Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)
Syntax
'Declaration
Public Event BeforeLabelEdit As NodeLabelEditEventHandler
'Usage
Dim instance As TreeView
Dim handler As NodeLabelEditEventHandler
AddHandler instance.BeforeLabelEdit, handler
public event NodeLabelEditEventHandler BeforeLabelEdit
public:
event NodeLabelEditEventHandler^ BeforeLabelEdit {
void add (NodeLabelEditEventHandler^ value);
void remove (NodeLabelEditEventHandler^ value);
}
/** @event */
public void add_BeforeLabelEdit (NodeLabelEditEventHandler value)
/** @event */
public void remove_BeforeLabelEdit (NodeLabelEditEventHandler value)
JScript unterstützt die Verwendung von Ereignissen, aber nicht die Deklaration von neuen Ereignissen.
Hinweise
Weitere Informationen zum Behandeln von Ereignissen finden Sie unter Behandeln von Ereignissen.
Beispiel
Im folgenden Codebeispiel wird die Verwendung der Member BeforeLabelEdit, AfterSelect und TopNode veranschaulicht. Fügen Sie zum Ausführen dieses Beispiels den folgenden Code in ein Formular ein, das ein TreeView-Steuerelement mit dem Namen TreeView1 enthält. Rufen Sie die InitializeTreeView-Methode im Konstruktor oder in der Load-Methode des Formulars auf.
Private Sub InitializeTreeView()
' Construct the TreeView object.
Me.TreeView1 = New System.Windows.Forms.TreeView
' Set dock, location, size name, and tab order
' values for the TreeView object.
With TreeView1
.Dock = System.Windows.Forms.DockStyle.Left
.Location = New System.Drawing.Point(0, 0)
.Name = "TreeView1"
.Size = New System.Drawing.Size(152, 266)
.TabIndex = 1
End With
' Set the LabelEdit property to true to allow the
' user to edit the TreeNode text.
Me.TreeView1.LabelEdit = True
' Declare and create objects needed to populate
' the TreeView.
Dim file, files(), filePath As String
files = New String() {"bigPresentation.ppt", "myFinances.xls", _
"myResume.doc"}
filePath = "c:\myFiles"
Dim nodes As New System.Collections.ArrayList
' Create a node for each file, setting the Text property to the
' file's name and the Tag property to file's fully-qualified name.
For Each file In files
Dim node As New TreeNode(file)
node.Tag = filePath & "\" & file
nodes.Add(node)
Next
' Create a new node named topNode and add the ArrayList of
' nodes to topNode.
Dim topNode As New TreeNode("myFiles", _
nodes.ToArray(GetType(TreeNode)))
topNode.Tag = filePath
' Add topNode to the TreeView.
TreeView1.Nodes.Add(topNode)
' Add the TreeView to the form.
Me.Controls.Add(TreeView1)
End Sub
Private Sub TreeView1_BeforeLabelEdit(ByVal sender As Object, _
ByVal e As NodeLabelEditEventArgs) Handles TreeView1.BeforeLabelEdit
' Determine whether the user has selected the top node. If so,
' change the LabelEdit property to false so the user cannot
' edit this label.
If (e.Node Is TreeView1.TopNode) Then
TreeView1.LabelEdit = False
MessageBox.Show("You are not allowed to edit the top node")
End If
' Set the LabelEdit property to true again.
TreeView1.LabelEdit = True
End Sub
...
' Handle the After_Select event.
Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, _
ByVal e As System.Windows.Forms.TreeViewEventArgs) _
Handles TreeView1.AfterSelect
' Vary the response depending on which TreeViewAction
' triggered the event.
Select Case (e.Action)
Case TreeViewAction.ByKeyboard
MessageBox.Show("You like the keyboard!")
Case TreeViewAction.ByMouse
MessageBox.Show("You like the mouse!")
End Select
End Sub
private void InitializeTreeView()
{
// Construct the TreeView object.
this.TreeView1 = new System.Windows.Forms.TreeView();
// Set dock, location, size name, and tab order
// values for the TreeView object.
TreeView1.Dock = System.Windows.Forms.DockStyle.Left;
TreeView1.Location = new System.Drawing.Point(0, 0);
TreeView1.Name = "TreeView1";
TreeView1.Size = new System.Drawing.Size(152, 266);
TreeView1.TabIndex = 1;
// Associate the event-handling methods with the
// BeforeLabeEdit and the AfterSelect events.
TreeView1.BeforeLabelEdit +=
new NodeLabelEditEventHandler(TreeView1_BeforeLabelEdit);
TreeView1.AfterSelect +=
new TreeViewEventHandler(TreeView1_AfterSelect);
// Set the LabelEdit property to true to allow the
// user to edit the TreeNode text.
this.TreeView1.LabelEdit = true;
// Declare and create objects needed to populate
// the TreeView.
string[] files = new string[]{"bigPresentation.ppt",
"myFinances.xls", "myResume.doc"};;
string filePath = "c:\\myFiles";
System.Collections.ArrayList nodes =
new System.Collections.ArrayList();
// Create a node for each file, setting the Text property to the
// file's name and the Tag property to file's fully-qualified name.
foreach ( string file in files )
{
TreeNode node = new TreeNode(file);
node.Tag = filePath+"\\"+file;
nodes.Add(node);
}
TreeNode[] treeNodes = new TreeNode[nodes.Count];
nodes.CopyTo(treeNodes);
// Create a new node named topNode and add the ArrayList of
// nodes to topNode.
TreeNode topNode = new TreeNode("myFiles", treeNodes);
topNode.Tag = filePath;
// Add topNode to the TreeView.
TreeView1.Nodes.Add(topNode);
// Add the TreeView to the form.
this.Controls.Add(TreeView1);
}
private void TreeView1_BeforeLabelEdit(object sender,
NodeLabelEditEventArgs e)
{
// Determine whether the user has selected the top node. If so,
// change the LabelEdit property to false so the user cannot
// edit this label.
if (e.Node == TreeView1.TopNode)
{
TreeView1.LabelEdit = false;
MessageBox.Show("You are not allowed to edit the top node");
}
// Set the LabelEdit property to true again.
TreeView1.LabelEdit = true;
}
...
// Handle the After_Select event.
private void TreeView1_AfterSelect(System.Object sender,
System.Windows.Forms.TreeViewEventArgs e)
{
// Vary the response depending on which TreeViewAction
// triggered the event.
switch((e.Action))
{
case TreeViewAction.ByKeyboard:
MessageBox.Show("You like the keyboard!");
break;
case TreeViewAction.ByMouse:
MessageBox.Show("You like the mouse!");
break;
}
}
private:
void InitializeTreeView()
{
// Construct the TreeView object.
this->TreeView1 = gcnew System::Windows::Forms::TreeView;
// Set dock, location, size name, and tab order
// values for the TreeView object.
TreeView1->Dock = System::Windows::Forms::DockStyle::Left;
TreeView1->Location = System::Drawing::Point( 0, 0 );
TreeView1->Name = "TreeView1";
TreeView1->Size = System::Drawing::Size( 152, 266 );
TreeView1->TabIndex = 1;
// Associate the event-handling methods with the
// BeforeLabeEdit and the AfterSelect events.
TreeView1->BeforeLabelEdit += gcnew NodeLabelEditEventHandler( this, &Form1::TreeView1_BeforeLabelEdit );
TreeView1->AfterSelect += gcnew TreeViewEventHandler( this, &Form1::TreeView1_AfterSelect );
// Set the LabelEdit property to true to allow the
// user to edit the TreeNode text.
this->TreeView1->LabelEdit = true;
// Declare and create objects needed to populate
// the TreeView.
array<String^>^files = {"bigPresentation.ppt","myFinances.xls","myResume.doc"};
;
String^ filePath = "c:\\myFiles";
System::Collections::ArrayList^ nodes = gcnew System::Collections::ArrayList;
// Create a node for each file, setting the Text property to the
// file's name and the Tag property to file's fully-qualified name.
System::Collections::IEnumerator^ myEnum = files->GetEnumerator();
while ( myEnum->MoveNext() )
{
String^ file = safe_cast<String^>(myEnum->Current);
TreeNode^ node = gcnew TreeNode( file );
node->Tag = String::Concat( filePath, "\\", file );
nodes->Add( node );
}
array<TreeNode^>^treeNodes = gcnew array<TreeNode^>(nodes->Count);
nodes->CopyTo( treeNodes );
// Create a new node named topNode and add the ArrayList of
// nodes to topNode.
TreeNode^ topNode = gcnew TreeNode( "myFiles",treeNodes );
topNode->Tag = filePath;
// Add topNode to the TreeView.
TreeView1->Nodes->Add( topNode );
// Add the TreeView to the form.
this->Controls->Add( TreeView1 );
}
void TreeView1_BeforeLabelEdit( Object^ /*sender*/, NodeLabelEditEventArgs^ e )
{
// Determine whether the user has selected the top node. If so,
// change the LabelEdit property to false so the user cannot
// edit this label.
if ( e->Node == TreeView1->TopNode )
{
TreeView1->LabelEdit = false;
MessageBox::Show( "You are not allowed to edit the top node" );
}
// Set the LabelEdit property to true again.
TreeView1->LabelEdit = true;
}
...
private:
// Handle the After_Select event.
void TreeView1_AfterSelect( System::Object^ /*sender*/, System::Windows::Forms::TreeViewEventArgs^ e )
{
// Vary the response depending on which TreeViewAction
// triggered the event.
switch ( (e->Action) )
{
case TreeViewAction::ByKeyboard:
MessageBox::Show( "You like the keyboard!" );
break;
case TreeViewAction::ByMouse:
MessageBox::Show( "You like the mouse!" );
break;
}
}
private void InitializeTreeView()
{
// Construct the TreeView object.
this.treeView1 = new System.Windows.Forms.TreeView();
// Set dock, location, size name, and tab order
// values for the TreeView object.
treeView1.set_Dock(System.Windows.Forms.DockStyle.Left);
treeView1.set_Location(new System.Drawing.Point(0, 0));
treeView1.set_Name("TreeView1");
treeView1.set_Size(new System.Drawing.Size(152, 266));
treeView1.set_TabIndex(1);
// Associate the event-handling methods with the
// BeforeLabeEdit and the AfterSelect events.
treeView1.add_BeforeLabelEdit(
new NodeLabelEditEventHandler(treeView1_BeforeLabelEdit));
treeView1.add_AfterSelect(new TreeViewEventHandler(
treeView1_AfterSelect));
// Set the LabelEdit property to true to allow the
// user to edit the TreeNode text.
this.treeView1.set_LabelEdit(true);
// Declare and create objects needed to populate
// the TreeView.
String files[] = new String[] { "bigPresentation.ppt", "myFinances.xls",
"myResume.doc" };
String filePath = "c:\\myFiles";
System.Collections.ArrayList nodes = new System.Collections.ArrayList();
// Create a node for each file, setting the Text property to the
// file's name and the Tag property to file's fully-qualified name.
for (int iCtr = 0; iCtr < files.length; iCtr++) {
String file = files[iCtr];
TreeNode node = new TreeNode(file);
node.set_Tag(filePath + "\\" + file);
nodes.Add(node);
}
TreeNode treeNodes[] = new TreeNode[nodes.get_Count()];
nodes.CopyTo(treeNodes);
// Create a new node named topNode and add the ArrayList of
// nodes to topNode.
TreeNode topNode = new TreeNode("myFiles", treeNodes);
topNode.set_Tag(filePath);
// Add topNode to the TreeView.
treeView1.get_Nodes().Add(topNode);
// Add the TreeView to the form.
this.get_Controls().Add(treeView1);
} //InitializeTreeView
private void treeView1_BeforeLabelEdit(Object sender,
NodeLabelEditEventArgs e)
{
// Determine whether the user has selected the top node. If so,
// change the LabelEdit property to false so the user cannot
// edit this label.
if (e.get_Node().Equals(treeView1.get_TopNode())) {
treeView1.set_LabelEdit(false);
MessageBox.Show("You are not allowed to edit the top node");
}
// Set the LabelEdit property to true again.
treeView1.set_LabelEdit(true);
} //treeView1_BeforeLabelEdit
...
// Handle the After_Select event.
private void treeView1_AfterSelect(Object sender,
System.Windows.Forms.TreeViewEventArgs e)
{
// Vary the response depending on which TreeViewAction
// triggered the event.
switch (e.get_Action()) {
case TreeViewAction.ByKeyboard:
MessageBox.Show("You like the keyboard!");
break;
case TreeViewAction.ByMouse:
MessageBox.Show("You like the mouse!");
break;
}
} //treeView1_AfterSelect
Plattformen
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
Siehe auch
Referenz
TreeView-Klasse
TreeView-Member
System.Windows.Forms-Namespace
OnBeforeLabelEdit
TreeView.AfterLabelEdit-Ereignis
OnAfterLabelEdit