Assembly: System.Windows.Forms (in system.windows.forms.dll)
Public Event AfterCheck As TreeViewEventHandler
Dim instance As TreeView Dim handler As TreeViewEventHandler AddHandler instance.AfterCheck, handler
public event TreeViewEventHandler AfterCheck
public: event TreeViewEventHandler^ AfterCheck { void add (TreeViewEventHandler^ value); void remove (TreeViewEventHandler^ value); }
/** @event */ public void add_AfterCheck (TreeViewEventHandler value) /** @event */ public void remove_AfterCheck (TreeViewEventHandler value)
JScript supporta l'utilizzo di eventi ma non la dichiarazione di nuovi.
Se si imposta la proprietà TreeNode.Checked dall'interno di un gestore eventi BeforeCheck o AfterCheck, l'evento verrà generato più volte e potrebbe verificarsi un comportamento imprevisto. Per impedire che l'evento venga generato più volte, aggiungere al gestore eventi istruzioni in base alle quali il codice venga eseguito ricorsivamente solo se la proprietà Action dell'oggetto TreeViewEventArgs non è impostata su TreeViewAction.Unknown.
Per ulteriori informazioni sulla gestione di eventi, vedere Utilizzo degli eventi.
Nell'esempio di codice riportato di seguito viene eseguito l'aggiornamento di tutti i nodi figlio della struttura di un controllo TreeNode quando l'utente ne modifica lo stato di selezione. È necessario che nel codice sia presente un oggetto Form con un controllo TreeView il cui insieme TreeNodeCollection contiene oggetti TreeNode. Nell'insieme TreeNodeCollection devono essere presenti nodi di struttura dotati di nodi figlio.
' Updates all child tree nodes recursively. Private Sub CheckAllChildNodes(treeNode As TreeNode, nodeChecked As Boolean) Dim node As TreeNode For Each node In treeNode.Nodes node.Checked = nodeChecked If node.Nodes.Count > 0 Then ' If the current node has child nodes, call the CheckAllChildsNodes method recursively. Me.CheckAllChildNodes(node, nodeChecked) End If Next node End Sub ' NOTE This code can be added to the BeforeCheck event handler instead of the AfterCheck event. ' After a tree node's Checked property is changed, all its child nodes are updated to the same value. Private Sub node_AfterCheck(sender As Object, e As TreeViewEventArgs) Handles treeView1.AfterCheck ' The code only executes if the user caused the checked state to change. If e.Action <> TreeViewAction.Unknown Then If e.Node.Nodes.Count > 0 Then ' Calls the CheckAllChildNodes method, passing in the current ' Checked value of the TreeNode whose checked state changed. Me.CheckAllChildNodes(e.Node, e.Node.Checked) End If End If End Sub
// Updates all child tree nodes recursively. private void CheckAllChildNodes(TreeNode treeNode, bool nodeChecked) { foreach(TreeNode node in treeNode.Nodes) { node.Checked = nodeChecked; if(node.Nodes.Count > 0) { // If the current node has child nodes, call the CheckAllChildsNodes method recursively. this.CheckAllChildNodes(node, nodeChecked); } } } // NOTE This code can be added to the BeforeCheck event handler instead of the AfterCheck event. // After a tree node's Checked property is changed, all its child nodes are updated to the same value. private void node_AfterCheck(object sender, TreeViewEventArgs e) { // The code only executes if the user caused the checked state to change. if(e.Action != TreeViewAction.Unknown) { if(e.Node.Nodes.Count > 0) { /* Calls the CheckAllChildNodes method, passing in the current Checked value of the TreeNode whose checked state changed. */ this.CheckAllChildNodes(e.Node, e.Node.Checked); } } }
// Updates all child tree nodes recursively. void CheckAllChildNodes( TreeNode^ treeNode, bool nodeChecked ) { IEnumerator^ myEnum = treeNode->Nodes->GetEnumerator(); while ( myEnum->MoveNext() ) { TreeNode^ node = safe_cast<TreeNode^>(myEnum->Current); node->Checked = nodeChecked; if ( node->Nodes->Count > 0 ) { // If the current node has child nodes, call the CheckAllChildsNodes method recursively. this->CheckAllChildNodes( node, nodeChecked ); } } } // NOTE This code can be added to the BeforeCheck event handler instead of the AfterCheck event. // After a tree node's Checked property is changed, all its child nodes are updated to the same value. void node_AfterCheck( Object^ /*sender*/, TreeViewEventArgs^ e ) { // The code only executes if the user caused the checked state to change. if ( e->Action != TreeViewAction::Unknown ) { if ( e->Node->Nodes->Count > 0 ) { /* Calls the CheckAllChildNodes method, passing in the current Checked value of the TreeNode whose checked state changed. */ this->CheckAllChildNodes( e->Node, e->Node->Checked ); } } }
// Updates all child tree nodes recursively.
private void CheckAllChildNodes(TreeNode treeNode, boolean nodeChecked)
{
for (int iCtr = 0; iCtr < treeNode.get_Nodes().get_Count(); iCtr++) {
TreeNode node = treeNode.get_Nodes().get_Item(iCtr);
node.set_Checked(nodeChecked);
if (node.get_Nodes().get_Count() > 0) {
// If the current node has child nodes, call the
// CheckAllChildsNodes method recursively.
this.CheckAllChildNodes(node, nodeChecked);
}
}
} //CheckAllChildNodes
// NOTE This code can be added to the BeforeCheck event handler instead
// of the AfterCheck event. After a tree node's Checked property is
// changed, all its child nodes are updated to the same value.
private void Node_AfterCheck(Object sender, TreeViewEventArgs e)
{
// The code only executes if the user caused the checked state to change.
if (!(e.get_Action().Equals(TreeViewAction.Unknown))) {
if (e.get_Node().get_Nodes().get_Count() > 0) {
/* Calls the CheckAllChildNodes method, passing in the current
Checked value of the TreeNode whose checked state changed. */
this.CheckAllChildNodes(e.get_Node(), e.get_Node().get_Checked());
}
}
} //Node_AfterCheck
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile per Pocket PC, Windows Mobile per Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework non supporta tutte le versioni di ciascuna piattaforma. Per un elenco delle versioni supportate, vedere Requisiti di sistema.