Gewusst wie: Behandeln des Opening-Ereignisses von ContextMenuStrip
Aktualisiert: November 2007
Sie können das Verhalten des ContextMenuStrip-Steuerelements anpassen, indem Sie das Opening-Ereignis behandeln.
Beispiel
Das folgende Codebeispiel veranschaulicht, wie das Opening-Ereignis behandelt wird. Der Ereignishandler fügt einem ContextMenuStrip-Steuerelement dynamisch Elemente hinzu. Das vollständige Codebeispiel finden Sie unter Gewusst wie: Dynamisches Hinzufügen von ToolStrip-Elementen.
' This event handler is invoked when the ContextMenuStrip
' control's Opening event is raised. It demonstrates
' dynamic item addition and dynamic SourceControl
' determination with reuse.
Sub cms_Opening(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs)
' Acquire references to the owning control and item.
Dim c As Control = fruitContextMenuStrip.SourceControl
Dim tsi As ToolStripDropDownItem = fruitContextMenuStrip.OwnerItem
' Clear the ContextMenuStrip control's
' Items collection.
fruitContextMenuStrip.Items.Clear()
' Check the source control first.
If (c IsNot Nothing) Then
' Add custom item (Form)
fruitContextMenuStrip.Items.Add(("Source: " + c.GetType().ToString()))
ElseIf (tsi IsNot Nothing) Then
' Add custom item (ToolStripDropDownButton or ToolStripMenuItem)
fruitContextMenuStrip.Items.Add(("Source: " + tsi.GetType().ToString()))
End If
' Populate the ContextMenuStrip control with its default items.
fruitContextMenuStrip.Items.Add("-")
fruitContextMenuStrip.Items.Add("Apples")
fruitContextMenuStrip.Items.Add("Oranges")
fruitContextMenuStrip.Items.Add("Pears")
' Set Cancel to false.
' It is optimized to true based on empty entry.
e.Cancel = False
End Sub
// This event handler is invoked when the ContextMenuStrip
// control's Opening event is raised. It demonstrates
// dynamic item addition and dynamic SourceControl
// determination with reuse.
void cms_Opening(object sender, System.ComponentModel.CancelEventArgs e)
{
// Acquire references to the owning control and item.
Control c = fruitContextMenuStrip.SourceControl as Control;
ToolStripDropDownItem tsi = fruitContextMenuStrip.OwnerItem as ToolStripDropDownItem;
// Clear the ContextMenuStrip control's Items collection.
fruitContextMenuStrip.Items.Clear();
// Check the source control first.
if (c != null)
{
// Add custom item (Form)
fruitContextMenuStrip.Items.Add("Source: " + c.GetType().ToString());
}
else if (tsi != null)
{
// Add custom item (ToolStripDropDownButton or ToolStripMenuItem)
fruitContextMenuStrip.Items.Add("Source: " + tsi.GetType().ToString());
}
// Populate the ContextMenuStrip control with its default items.
fruitContextMenuStrip.Items.Add("-");
fruitContextMenuStrip.Items.Add("Apples");
fruitContextMenuStrip.Items.Add("Oranges");
fruitContextMenuStrip.Items.Add("Pears");
// Set Cancel to false.
// It is optimized to true based on empty entry.
e.Cancel = false;
}
Legen Sie die CancelEventArgs.Cancel-Eigenschaft auf true fest, um das Öffnen des Menüs zu verhindern.