DataGridView.CellValueNeeded Événement

Définition

Se produit lorsque la propriété VirtualMode du contrôle DataGridView a la valeur true et que le DataGridView nécessite une valeur pour une cellule pour mettre en forme et afficher la cellule.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 

Exemples

L’exemple de code suivant gère l’événement CellValueNeeded pour remplir des cellules avec des entiers positifs.The following code example handles the CellValueNeeded event to populate cells with positive integers. Cet exemple fait partie d’un plus grand exemple disponible dans la rubrique de référence 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)

Remarques

Utilisez cet événement en mode virtuel pour remplir des cellules avec des données d’un magasin de données personnalisé sans provoquer le partage des lignes.Use this event in virtual mode to populate cells with data from a custom data store without causing rows to become unshared. Pour plus d’informations sur le partage de lignes, consultez meilleures pratiques pour la mise à l’échelle du contrôle DataGridView Windows Forms.For more information about row sharing, see Best Practices for Scaling the Windows Forms DataGridView Control. Pour plus d’informations sur le mode virtuel, consultez mode virtuel dans le Windows Forms contrôle DataGridView.For more information about virtual mode, see Virtual Mode in the Windows Forms DataGridView Control.

Pour ajouter des valeurs spécifiées par l’utilisateur à votre magasin de données personnalisé, gérez l’événement CellValuePushed.To add user-specified values to your custom data store, handle the CellValuePushed event.

Pour plus d’informations sur la façon de gérer les événements, consultez gestion et déclenchement d’événements.For more information about how to handle events, see Handling and Raising Events.

S’applique à

Voir aussi