DataGridViewCellContextMenuStripNeededEventHandler Delegate
Represents the method that will handle a CellContextMenuStripNeeded event of a DataGridView.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
'Declaration Public Delegate Sub DataGridViewCellContextMenuStripNeededEventHandler ( _ sender As Object, _ e As DataGridViewCellContextMenuStripNeededEventArgs _ ) 'Usage Dim instance As New DataGridViewCellContextMenuStripNeededEventHandler(AddressOf HandlerMethod)
Parameters
- sender
- Type: System.Object
The source of the event.
- e
- Type: System.Windows.Forms.DataGridViewCellContextMenuStripNeededEventArgs
A DataGridViewCellContextMenuStripNeededEventArgs that contains the event data.
The CellContextMenuStripNeeded event occurs only when the DataGridView control DataSource property is set or its VirtualMode property is true.
When you handle the CellContextMenuStripNeeded event, the shortcut menu that you specify in the handler is shown whenever the user right-clicks a cell. This is useful when you want to display shortcut menus determined by the current state or value of a cell.
The CellContextMenuStripNeeded event also occurs whenever the value of the DataGridViewCell.ContextMenuStrip property is retrieved, either programmatically or when the user right-clicks the cell.
You can use the ColumnIndex and RowIndex properties to determine the state or value of a cell, and use this information to set the ContextMenuStrip property. This property is initialized with the value of the cell ContextMenuStrip property, which the event value overrides.
Handle the CellContextMenuStripNeeded event when working with large amounts of data to avoid the performance penalties of setting the cell ContextMenuStrip value for multiple cells. For more information, see Best Practices for Scaling the Windows Forms DataGridView Control.
You can also specify shortcut menus for individual rows rather than individual cells by setting the row ContextMenuStrip property or handling the DataGridView control's RowContextMenuStripNeeded event. The cell ContextMenuStrip property setting overrides the row ContextMenuStrip property setting, and the CellContextMenuStripNeeded event overrides both the RowContextMenuStripNeeded event and the row ContextMenuStrip property setting. You can specify Nothing for a cell shortcut menu, however, to prevent a row shortcut menu from being overridden.
For more information about handling events, see Consuming Events.
When you create a DataGridViewCellContextMenuStripNeededEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.
The following code example uses DataGridViewCellContextMenuStripNeededEventArgs to set the context menu without unsharing the row.
Private WithEvents wholeTable As New ToolStripMenuItem() Private WithEvents lookUp As New ToolStripMenuItem() Private strip As ContextMenuStrip Private cellErrorText As String Private Sub dataGridView1_CellContextMenuStripNeeded(ByVal sender As Object, _ ByVal e As DataGridViewCellContextMenuStripNeededEventArgs) _ Handles dataGridView1.CellContextMenuStripNeeded cellErrorText = String.Empty If strip Is Nothing Then strip = New ContextMenuStrip() lookUp.Text = "Look Up" wholeTable.Text = "See Whole Table" strip.Items.Add(lookUp) strip.Items.Add(wholeTable) End If e.ContextMenuStrip = strip End Sub Private Sub wholeTable_Click(ByVal sender As Object, ByVal e As EventArgs) Handles wholeTable.Click dataGridView1.DataSource = Populate("Select * from employees", True) End Sub Private theCellImHoveringOver As DataGridViewCellEventArgs Private Sub dataGridView1_CellMouseEnter(ByVal sender As Object, _ ByVal e As DataGridViewCellEventArgs) _ Handles dataGridView1.CellMouseEnter theCellImHoveringOver = e End Sub Private cellErrorLocation As DataGridViewCellEventArgs Private Sub lookUp_Click(ByVal sender As Object, ByVal e As EventArgs) Handles lookUp.Click Try dataGridView1.DataSource = Populate("Select * from employees where " & _ dataGridView1.Columns(theCellImHoveringOver.ColumnIndex).Name & " = '" & _ dataGridView1.Rows(theCellImHoveringOver.RowIndex).Cells(theCellImHoveringOver.ColumnIndex).Value.ToString() & _ "'", True) Catch ex As SqlException cellErrorText = "Can't look this cell up" cellErrorLocation = theCellImHoveringOver End Try End Sub Private Sub dataGridView1_CellErrorTextNeeded(ByVal sender As Object, _ ByVal e As DataGridViewCellErrorTextNeededEventArgs) _ Handles dataGridView1.CellErrorTextNeeded If (Not cellErrorLocation Is Nothing) Then If e.ColumnIndex = cellErrorLocation.ColumnIndex AndAlso _ e.RowIndex = cellErrorLocation.RowIndex Then e.ErrorText = cellErrorText End If End If End Sub Private Function Populate(ByVal query As String, ByVal resetUnsharedCounter As Boolean) As DataTable If resetUnsharedCounter Then ResetCounter() End If ' Alter the data source as necessary Dim adapter As New SqlDataAdapter(query, _ New SqlConnection("Integrated Security=SSPI;Persist Security Info=False;" & _ "Initial Catalog=Northwind;Data Source=localhost")) Dim table As New DataTable() table.Locale = System.Globalization.CultureInfo.InvariantCulture adapter.Fill(table) Return table End Function Private count As New Label() Private unsharedRowCounter As Integer Private Sub ResetCounter() unsharedRowCounter = 0 count.Text = unsharedRowCounter.ToString() End Sub
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.