DataGridViewCellContextMenuStripNeededEventHandler Delegado

Definición

Representa el método que controlará un evento CellContextMenuStripNeeded de un control DataGridView.Represents the method that will handle a CellContextMenuStripNeeded event of a DataGridView.

public delegate void DataGridViewCellContextMenuStripNeededEventHandler(System::Object ^ sender, DataGridViewCellContextMenuStripNeededEventArgs ^ e);
public delegate void DataGridViewCellContextMenuStripNeededEventHandler(object sender, DataGridViewCellContextMenuStripNeededEventArgs e);
type DataGridViewCellContextMenuStripNeededEventHandler = delegate of obj * DataGridViewCellContextMenuStripNeededEventArgs -> unit
Public Delegate Sub DataGridViewCellContextMenuStripNeededEventHandler(sender As Object, e As DataGridViewCellContextMenuStripNeededEventArgs)

Parámetros

sender
Object

Origen del evento.The source of the event.

Herencia
DataGridViewCellContextMenuStripNeededEventHandler

Ejemplos

En el ejemplo de código DataGridViewCellContextMenuStripNeededEventArgs siguiente se usa para establecer el menú contextual sin dejar de compartir la fila.The following code example uses DataGridViewCellContextMenuStripNeededEventArgs to set the context menu without unsharing the row.

ToolStripMenuItem^ wholeTable;
ToolStripMenuItem^ lookUp;
System::Windows::Forms::ContextMenuStrip^ strip;
String^ cellErrorText;

void dataGridView1_CellContextMenuStripNeeded( Object^ /*sender*/,
    DataGridViewCellContextMenuStripNeededEventArgs^ e )
{
    cellErrorText = String::Empty;
    if ( strip == nullptr )
    {
        strip = gcnew System::Windows::Forms::ContextMenuStrip;
        lookUp->Text = L"Look Up";
        wholeTable->Text = L"See Whole Table";
        strip->Items->Add( lookUp );
        strip->Items->Add( wholeTable );
    }

    e->ContextMenuStrip = strip;
}

void wholeTable_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
    dataGridView1->DataSource = Populate( L"Select * from employees", true );
}

DataGridViewCellEventArgs^ theCellImHoveringOver;
void dataGridView1_CellMouseEnter( Object^ /*sender*/, DataGridViewCellEventArgs^ e )
{
    theCellImHoveringOver = e;
}

DataGridViewCellEventArgs^ cellErrorLocation;
void lookUp_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
    try
    {
        dataGridView1->DataSource = Populate( String::Format( L"Select * from employees where {0} = '{1}'", dataGridView1->Columns[ theCellImHoveringOver->ColumnIndex ]->Name, dataGridView1->Rows[ theCellImHoveringOver->RowIndex ]->Cells[ theCellImHoveringOver->ColumnIndex ]->Value ), true );
    }
    catch ( ... ) 
    {
        cellErrorText = L"Can't look this cell up";
        cellErrorLocation = theCellImHoveringOver;
    }

}

void dataGridView1_CellErrorTextNeeded( Object^ /*sender*/, DataGridViewCellErrorTextNeededEventArgs^ e )
{
    if ( cellErrorLocation != nullptr )
    {
        if ( e->ColumnIndex == cellErrorLocation->ColumnIndex && e->RowIndex == cellErrorLocation->RowIndex )
        {
            e->ErrorText = cellErrorText;
        }
    }
}

DataTable^ Populate( String^ query, bool resetUnsharedCounter )
{
    if ( resetUnsharedCounter )
    {
        ResetCounter();
    }


    // Alter the data source as necessary
    SqlDataAdapter^ adapter = gcnew SqlDataAdapter( query,
        gcnew SqlConnection( L"Integrated Security=SSPI;Persist Security Info=False;"
        L"Initial Catalog=Northwind;Data Source= localhost" ) );
    DataTable^ table = gcnew DataTable;
    adapter->Fill( table );
    return table;
}

Label^ count;
int unsharedRowCounter;
void ResetCounter()
{
    unsharedRowCounter = 0;
    count->Text = unsharedRowCounter.ToString();
}
private ToolStripMenuItem wholeTable = new ToolStripMenuItem();
private ToolStripMenuItem lookUp = new ToolStripMenuItem();
private ContextMenuStrip strip;
private string cellErrorText;

private void dataGridView1_CellContextMenuStripNeeded(object sender,
    DataGridViewCellContextMenuStripNeededEventArgs e)
{
    cellErrorText = String.Empty;

    if (strip == null)
    {
        strip = new ContextMenuStrip();
        lookUp.Text = "Look Up";
        wholeTable.Text = "See Whole Table";
        strip.Items.Add(lookUp);
        strip.Items.Add(wholeTable);
    }
    e.ContextMenuStrip = strip;
}

private void wholeTable_Click(object sender, EventArgs e)
{
    dataGridView1.DataSource = Populate("Select * from employees", true);
}

private DataGridViewCellEventArgs theCellImHoveringOver;

private void dataGridView1_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
{
    theCellImHoveringOver = e;
}

private DataGridViewCellEventArgs cellErrorLocation;

private void lookUp_Click(object sender, EventArgs e)
{
    try
    {
        dataGridView1.DataSource = Populate("Select * from employees where " +
            dataGridView1.Columns[theCellImHoveringOver.ColumnIndex].Name + " = '" +
            dataGridView1.Rows[theCellImHoveringOver.RowIndex].
            Cells[theCellImHoveringOver.ColumnIndex].Value + "'",
            true);
    }
    catch (SqlException)
    {
        cellErrorText = "Can't look this cell up";
        cellErrorLocation = theCellImHoveringOver;
    }
}

private void dataGridView1_CellErrorTextNeeded(object sender,
    DataGridViewCellErrorTextNeededEventArgs e)
{
    if (cellErrorLocation != null)
    {
        if (e.ColumnIndex == cellErrorLocation.ColumnIndex &&
            e.RowIndex == cellErrorLocation.RowIndex)
        {
            e.ErrorText = cellErrorText;
        }
    }
}

private DataTable Populate(string query, bool resetUnsharedCounter)
{
    if (resetUnsharedCounter)
    {
        ResetCounter();
    }

    // Alter the data source as necessary
    SqlDataAdapter adapter = new SqlDataAdapter(query,
        new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;" +
        "Initial Catalog=Northwind;Data Source=localhost"));

    DataTable table = new DataTable();
    table.Locale = System.Globalization.CultureInfo.InvariantCulture;
    adapter.Fill(table);
    return table;
}

private Label count = new Label();
private int unsharedRowCounter;

private void ResetCounter()
{
    unsharedRowCounter = 0;
    count.Text = unsharedRowCounter.ToString();
}
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

Comentarios

El CellContextMenuStripNeeded evento solo se produce cuando DataGridView se DataSource establece la propiedad del control VirtualMode o su truepropiedad es.The CellContextMenuStripNeeded event occurs only when the DataGridView control DataSource property is set or its VirtualMode property is true.

Al controlar el CellContextMenuStripNeeded evento, el menú contextual que se especifica en el controlador se muestra cada vez que el usuario hace clic con el botón secundario en una celda.When you handle the CellContextMenuStripNeeded event, the shortcut menu that you specify in the handler is shown whenever the user right-clicks a cell. Esto resulta útil si desea mostrar los menús contextuales determinados por el estado actual o el valor de una celda.This is useful when you want to display shortcut menus determined by the current state or value of a cell.

El CellContextMenuStripNeeded evento también se produce siempre que se recupera DataGridViewCell.ContextMenuStrip el valor de la propiedad, ya sea mediante programación o cuando el usuario hace clic con el botón secundario en la celda.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.

Puede utilizar las ColumnIndex propiedades y RowIndex para determinar el estado o el valor de una celda y utilizar esta información para establecer la ContextMenuStrip propiedad.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. Esta propiedad se inicializa con el valor de la propiedad de ContextMenuStrip celda, que reemplaza el valor de evento.This property is initialized with the value of the cell ContextMenuStrip property, which the event value overrides.

Controle CellContextMenuStripNeeded el evento al trabajar con grandes cantidades de datos para evitar las penalizaciones en el rendimiento de ContextMenuStrip establecer el valor de la celda para varias celdas.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. Para obtener más información, consulte Procedimientos recomendados para ajustar la escala del control DataGridView en Windows Forms.For more information, see Best Practices for Scaling the Windows Forms DataGridView Control.

También puede especificar menús contextuales para filas individuales en lugar de celdas individuales estableciendo la ContextMenuStrip propiedad Row o controlando el RowContextMenuStripNeeded DataGridView evento del 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. El valor ContextMenuStrip de la propiedad de celda invalida el ContextMenuStrip valor de la propiedad Row CellContextMenuStripNeeded , y el evento invalida el RowContextMenuStripNeeded valor de la propiedad ContextMenuStrip Event y de Row.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. Sin embargo, null puede especificar para un menú contextual de celda para evitar que se invalide un menú contextual de fila.You can specify null for a cell shortcut menu, however, to prevent a row shortcut menu from being overridden.

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.

Cuando se crea un delegado DataGridViewCellContextMenuStripNeededEventHandler, se identifica el método que controlará el evento.When you create a DataGridViewCellContextMenuStripNeededEventHandler delegate, you identify the method that will handle the event. Para asociar el evento al controlador, se debe agregar una instancia del delegado al evento.To associate the event with your event handler, add an instance of the delegate to the event. Siempre que se produce el evento, se llama a su controlador, a menos que se quite el delegado.The event handler is called whenever the event occurs, unless you remove the delegate. Para obtener más información sobre los delegados de controladores de eventos, vea controlar y provocar eventos.For more information about event-handler delegates, see Handling and Raising Events.

Métodos de extensión

GetMethodInfo(Delegate)

Obtiene un objeto que representa el método representado por el delegado especificado.Gets an object that represents the method represented by the specified delegate.

Se aplica a

Consulte también: