DataGridView.CellToolTipTextNeeded Event
Assembly: System.Windows.Forms (in system.windows.forms.dll)
'Declaration Public Event CellToolTipTextNeeded As DataGridViewCellToolTipTextNeededEventHandler 'Usage Dim instance As DataGridView Dim handler As DataGridViewCellToolTipTextNeededEventHandler AddHandler instance.CellToolTipTextNeeded, handler
/** @event */ public void add_CellToolTipTextNeeded (DataGridViewCellToolTipTextNeededEventHandler value) /** @event */ public void remove_CellToolTipTextNeeded (DataGridViewCellToolTipTextNeededEventHandler value)
JScript supports the use of events, but not the declaration of new ones.
The CellToolTipTextNeeded event occurs only when the DataGridView control DataSource property is set or its VirtualMode property is true.
When you handle the CellToolTipTextNeeded event, the ToolTip text you specify in the handler is shown whenever the mouse pointer is over a cell and the control ShowCellToolTips property value is true. The CellToolTipTextNeeded event is useful when you want to display ToolTips determined by the current state or value of a cell.
The CellToolTipTextNeeded event also occurs whenever the value of the DataGridViewCell.ToolTipText property is retrieved, either programmatically or when the mouse pointer enters a cell.
You can use the DataGridViewCellEventArgs.ColumnIndex and RowIndex properties to determine the state or value of a cell, and use this information to change or modify the DataGridViewCellToolTipTextNeededEventArgs.ToolTipText property. This property is initialized with the value of the cell ToolTipText property, which the event value overrides.
Handle the CellToolTipTextNeeded event when working with large amounts of data to avoid the performance penalties of setting the cell ToolTipText value for multiple cells. For more information, see Best Practices for Scaling the Windows Forms DataGridView Control.
For more information about handling events, see Consuming Events.
The following code example demonstrates how to use a CellToolTipTextNeeded event handler to display information from hidden columns in a data-bound DataGridView control.
Public Sub dataGridView1_CellToolTipTextNeeded(ByVal sender As Object, _ ByVal e As DataGridViewCellToolTipTextNeededEventArgs) _ Handles dataGridView1.CellToolTipTextNeeded Dim newLine As String = Environment.NewLine If e.RowIndex > -1 Then Dim dataGridViewRow1 As DataGridViewRow = _ dataGridView1.Rows(e.RowIndex) ' Add the employee's ID to the ToolTipText. e.ToolTipText = String.Format("EmployeeID {0}: {1}", _ dataGridViewRow1.Cells("EmployeeID").Value.ToString(), _ newLine) ' Add the employee's name to the ToolTipText. e.ToolTipText += String.Format("{0} {1} {2} {3}", _ dataGridViewRow1.Cells("TitleOfCourtesy").Value.ToString(), _ dataGridViewRow1.Cells("FirstName").Value.ToString(), _ dataGridViewRow1.Cells("LastName").Value.ToString(), _ newLine) ' Add the employee's title to the ToolTipText. e.ToolTipText += String.Format("{0}{1}{2}", _ dataGridViewRow1.Cells("Title").Value.ToString(), _ newLine, newLine) ' Add the employee's contact information to the ToolTipText. e.ToolTipText += String.Format("{0}{1}{2}, ", _ dataGridViewRow1.Cells("Address").Value.ToString(), newLine, _ dataGridViewRow1.Cells("City").Value.ToString()) If Not String.IsNullOrEmpty( _ dataGridViewRow1.Cells("Region").Value.ToString()) e.ToolTipText += String.Format("{0}, ", _ dataGridViewRow1.Cells("Region").Value.ToString()) End If e.ToolTipText += String.Format("{0}, {1}{2}{3} EXT:{4}{5}{6}", _ dataGridViewRow1.Cells("Country").Value.ToString(), _ dataGridViewRow1.Cells("PostalCode").Value.ToString(), _ newLine, _ dataGridViewRow1.Cells("HomePhone").Value.ToString(), _ dataGridViewRow1.Cells("Extension").Value.ToString(), _ newLine, newLine) ' Add employee information to the ToolTipText. Dim HireDate As DateTime = _ CType(dataGridViewRow1.Cells("HireDate").Value, DateTime) e.ToolTipText += _ String.Format("Employee since: {0}/{1}/{2}{3}Manager: {4}", _ HireDate.Month.ToString(), HireDate.Day.ToString(), _ HireDate.Year.ToString(), newLine, _ dataGridViewRow1.Cells("Manager").Value.ToString()) End If End Sub
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
Reference
DataGridView ClassDataGridView Members
System.Windows.Forms Namespace
DataGridView.DataSource Property
DataGridView.VirtualMode Property
DataGridView.ShowCellToolTips Property
DataGridViewCellToolTipTextNeededEventHandler
DataGridViewCellToolTipTextNeededEventArgs
DataGridViewCellToolTipTextNeededEventArgs.ToolTipText
DataGridViewCell.ToolTipText
OnCellToolTipTextNeeded