Assembly: System.Windows.Forms (in system.windows.forms.dll)
Public Class TreeViewEventArgs Inherits EventArgs
Dim instance As TreeViewEventArgs
public class TreeViewEventArgs : EventArgs
public ref class TreeViewEventArgs : public EventArgs
public class TreeViewEventArgs extends EventArgs
public class TreeViewEventArgs extends EventArgs
Per ulteriori informazioni sulla gestione di eventi, vedere Utilizzo degli eventi.
Nell'esempio riportato di seguito viene illustrato un oggetto TreeView personalizzato. Ereditando la classe TreeView, questa versione personalizzata dispone di tutta la funzionalità di un oggetto TreeView normale. La modifica di alcuni valori di proprietà nel costruttore fornisce un aspetto univoco. Poiché la proprietà ShowPlusMinus è impostata su false, il controllo personalizzato esegue anche l'override del metodo OnAfterSelect in modo da non consentire l'espansione e la compressione dei nodi quando si fa clic su di essi.
Un controllo personalizzato in questo modo può essere utilizzato in tutta un'organizzazione per fornire agevolmente un'interfaccia coerente senza dover specificare le proprietà del controllo in ogni singolo progetto.
Public Class CustomizedTreeView Inherits TreeView Public Sub New() ' Customize the TreeView control by setting various properties. BackColor = System.Drawing.Color.CadetBlue FullRowSelect = True HotTracking = True Indent = 34 ShowPlusMinus = False ' The ShowLines property must be false for the FullRowSelect ' property to work. ShowLines = False End Sub 'New Protected Overrides Sub OnAfterSelect(ByVal e As TreeViewEventArgs) ' Confirm that the user initiated the selection. ' This prevents the first node from expanding when it is ' automatically selected during the initialization of ' the TreeView control. If e.Action <> TreeViewAction.Unknown Then If e.Node.IsExpanded Then e.Node.Collapse() Else e.Node.Expand() End If End If ' Remove the selection. This allows the same node to be ' clicked twice in succession to toggle the expansion state. SelectedNode = Nothing End Sub 'OnAfterSelect End Class 'CustomizedTreeView
public class CustomizedTreeView : TreeView { public CustomizedTreeView() { // Customize the TreeView control by setting various properties. BackColor = System.Drawing.Color.CadetBlue; FullRowSelect = true; HotTracking = true; Indent = 34; ShowPlusMinus = false; // The ShowLines property must be false for the FullRowSelect // property to work. ShowLines = false; } protected override void OnAfterSelect(TreeViewEventArgs e) { // Confirm that the user initiated the selection. // This prevents the first node from expanding when it is // automatically selected during the initialization of // the TreeView control. if (e.Action != TreeViewAction.Unknown) { if (e.Node.IsExpanded) { e.Node.Collapse(); } else { e.Node.Expand(); } } // Remove the selection. This allows the same node to be // clicked twice in succession to toggle the expansion state. SelectedNode = null; } }
public ref class CustomizedTreeView: public TreeView { public: CustomizedTreeView() { // Customize the TreeView control by setting various properties. BackColor = System::Drawing::Color::CadetBlue; FullRowSelect = true; HotTracking = true; Indent = 34; ShowPlusMinus = false; // The ShowLines property must be false for the FullRowSelect // property to work. ShowLines = false; } protected: virtual void OnAfterSelect( TreeViewEventArgs^ e ) override { // Confirm that the user initiated the selection. // This prevents the first node from expanding when it is // automatically selected during the initialization of // the TreeView control. if ( e->Action != TreeViewAction::Unknown ) { if ( e->Node->IsExpanded ) { e->Node->Collapse(); } else { e->Node->Expand(); } } // Remove the selection. This allows the same node to be // clicked twice in succession to toggle the expansion state. SelectedNode = nullptr; } };
public class CustomizedTreeView extends TreeView
{
public CustomizedTreeView()
{
// Customize the TreeView control by setting various properties.
set_BackColor(System.Drawing.Color.get_CadetBlue());
set_FullRowSelect(true);
set_HotTracking(true);
set_Indent(34);
set_ShowPlusMinus(false);
// The ShowLines property must be false for the FullRowSelect
// property to work.
set_ShowLines(false);
} //CustomizedTreeView
protected void OnAfterSelect(TreeViewEventArgs e)
{
// Confirm that the user initiated the selection.
// This prevents the first node from expanding when it is
// automatically selected during the initialization of
// the TreeView control.
if (!(e.get_Action().Equals(TreeViewAction.Unknown))) {
if (e.get_Node().get_IsExpanded()) {
e.get_Node().Collapse();
}
else {
e.get_Node().Expand();
}
}
// Remove the selection. This allows the same node to be
// clicked twice in succession to toggle the expansion state.
set_SelectedNode(null);
} //OnAfterSelect
}//CustomizedTreeView
System.EventArgs
System.Windows.Forms.TreeViewEventArgs
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.