DataGridViewCellToolTipTextNeededEventArgs Class

Provides data for the CellToolTipTextNeeded event.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in

public class DataGridViewCellToolTipTextNeededEventArgs : DataGridViewCellEventArgs
public class DataGridViewCellToolTipTextNeededEventArgs extends DataGridViewCellEventArgs
public class DataGridViewCellToolTipTextNeededEventArgs extends DataGridViewCellEventArgs
Not applicable.

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 ColumnIndex and RowIndex properties to determine the state or value of a cell, and use this information to set the 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 fills the ToolTipText with information from hidden cells in the DataGridView.

void dataGridView1_CellToolTipTextNeeded(object sender,
    DataGridViewCellToolTipTextNeededEventArgs e)
    string newLine = Environment.NewLine;
    if (e.RowIndex > -1)
        DataGridViewRow dataGridViewRow1 = dataGridView1.Rows[e.RowIndex];

        // Add the employee's ID to the ToolTipText.
        e.ToolTipText = String.Format("EmployeeID {0}:{1}",
            dataGridViewRow1.Cells["EmployeeID"].Value, newLine);

        // Add the employee's name to the ToolTipText.
        e.ToolTipText += String.Format("{0} {1} {2}{3}",

        // Add the employee's title to the ToolTipText.
        e.ToolTipText += String.Format("{0}{1}{2}",
            newLine, newLine);

        // Add the employee's contact information to the ToolTipText.
        e.ToolTipText += String.Format("{0}{1}{2}, ",
            dataGridViewRow1.Cells["Address"].Value.ToString(), newLine,
        if (!String.IsNullOrEmpty(
            e.ToolTipText += String.Format("{0}, ",
        e.ToolTipText += String.Format("{0}, {1}{2}{3} EXT:{4}{5}{6}",
            newLine, dataGridViewRow1.Cells["HomePhone"].Value.ToString(),
            newLine, newLine);

        // Add employee information to the ToolTipText.
        DateTime HireDate =
        e.ToolTipText +=
            String.Format("Employee since: {0}/{1}/{2}{3}Manager: {4}",
            HireDate.Month.ToString(), HireDate.Day.ToString(),
            HireDate.Year.ToString(), newLine,


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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