DataGridView.CellValueNeeded Evento

Definición

Se produce cuando el valor de la propiedad VirtualMode del control DataGridView es true y DataGridView requiere un valor para una celda para dar formato a la celda y mostrarla.Occurs when the VirtualMode property of the DataGridView control is true and the DataGridView requires a value for a cell in order to format and display the cell.

public:
 event System::Windows::Forms::DataGridViewCellValueEventHandler ^ CellValueNeeded;
public event System.Windows.Forms.DataGridViewCellValueEventHandler CellValueNeeded;
member this.CellValueNeeded : System.Windows.Forms.DataGridViewCellValueEventHandler 
Public Custom Event CellValueNeeded As DataGridViewCellValueEventHandler 

Ejemplos

En el ejemplo de código siguiente se controla el evento CellValueNeeded para rellenar las celdas con enteros positivos.The following code example handles the CellValueNeeded event to populate cells with positive integers. Este ejemplo forma parte de un ejemplo más grande disponible en el tema de referencia VirtualMode.This example is part of a larger example available in the VirtualMode reference topic.

#pragma region Data store maintance

    void VirtualConnector::dataGridView1_CellValueNeeded
        (Object^ sender, DataGridViewCellValueEventArgs^ e)
    {
        if (store->ContainsKey(e->RowIndex))
        {
            // Use the store if the e value has been modified 
            // and stored.            
            e->Value = gcnew Int32(store->default[e->RowIndex]); 
        }
        else if (newRowNeeded && e->RowIndex == numberOfRows)
        {
            if (dataGridView1->IsCurrentCellInEditMode)
            {
                e->Value = initialValue;
            }
            else
            {
                // Show a blank e if the cursor is just loitering
                // over(the) last row.
                e->Value = String::Empty;
            }
        }
        else
        {
            e->Value = e->RowIndex;
        }
    }

    void VirtualConnector::dataGridView1_CellValuePushed
        (Object^ sender, DataGridViewCellValueEventArgs^ e)
    {
        String^ value = e->Value->ToString();
        store[e->RowIndex] = Int32::Parse(value, 
            CultureInfo::CurrentCulture);
    }
#pragma endregion
#region "data store maintance"
const int initialValue = -1;

private void dataGridView1_CellValueNeeded(object sender,
    DataGridViewCellValueEventArgs e)
{
    if (store.ContainsKey(e.RowIndex))
    {
        // Use the store if the e value has been modified 
        // and stored.            
        e.Value = store[e.RowIndex];
    }
    else if (newRowNeeded && e.RowIndex == numberOfRows)
    {
        if (dataGridView1.IsCurrentCellInEditMode)
        {
            e.Value = initialValue;
        }
        else
        {
            // Show a blank value if the cursor is just resting
            // on the last row.
            e.Value = String.Empty;
        }
    }
    else
    {
        e.Value = e.RowIndex;
    }
}

private void dataGridView1_CellValuePushed(object sender,
    DataGridViewCellValueEventArgs e)
{
    store.Add(e.RowIndex, int.Parse(e.Value.ToString()));
}
#endregion

private Dictionary<int, int> store = new Dictionary<int, int>();
#Region "data store maintance"
    Const initialValue As Integer = -1

    Private Sub dataGridView1_CellValueNeeded(ByVal sender As Object, _
        ByVal e As DataGridViewCellValueEventArgs) _
        Handles dataGridView1.CellValueNeeded

        If store.ContainsKey(e.RowIndex) Then
            ' Use the store if the e value has been modified 
            ' and stored.
            e.Value = store(e.RowIndex)
        ElseIf newRowNeeded AndAlso e.RowIndex = numberOfRows Then
            If dataGridView1.IsCurrentCellInEditMode Then
                e.Value = initialValue
            Else
                ' Show a blank value if the cursor is just resting
                ' on the last row.
                e.Value = String.Empty
            End If
        Else
            e.Value = e.RowIndex
        End If
    End Sub

    Private Sub dataGridView1_CellValuePushed(ByVal sender As Object, _
        ByVal e As DataGridViewCellValueEventArgs) _
        Handles dataGridView1.CellValuePushed

        store.Add(e.RowIndex, CInt(e.Value))

    End Sub
#End Region

    Dim store As System.Collections.Generic.Dictionary(Of Integer, Integer) = _
        New Dictionary(Of Integer, Integer)

Comentarios

Utilice este evento en modo virtual para rellenar las celdas con datos de un almacén de datos personalizado sin que las filas dejen de estar compartidas.Use this event in virtual mode to populate cells with data from a custom data store without causing rows to become unshared. Para obtener más información sobre el uso compartido de filas, vea prácticas recomendadas para escalar el control DataGridView Windows Forms.For more information about row sharing, see Best Practices for Scaling the Windows Forms DataGridView Control. Para obtener más información sobre el modo virtual, vea modo virtual en el control DataGridView de Windows Forms.For more information about virtual mode, see Virtual Mode in the Windows Forms DataGridView Control.

Para agregar los valores especificados por el usuario al almacén de datos personalizado, controle el evento CellValuePushed.To add user-specified values to your custom data store, handle the CellValuePushed event.

Para obtener más información acerca de cómo controlar eventos, vea controlar y provocar eventos.For more information about how to handle events, see Handling and Raising Events.

Se aplica a

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