DataGridView.VirtualMode DataGridView.VirtualMode DataGridView.VirtualMode DataGridView.VirtualMode Property

Definition

Ruft einen Wert ab oder legt einen Wert fest, der angibt, ob für das DataGridView-Steuerelement eigene Operationen zur Datenverwaltung bereitgestellt wurden.Gets or sets a value indicating whether you have provided your own data-management operations for the DataGridView control.

public:
 property bool VirtualMode { bool get(); void set(bool value); };
public bool VirtualMode { get; set; }
member this.VirtualMode : bool with get, set
Public Property VirtualMode As Boolean

Eigenschaftswert

true , wenn die DataGridView Datenverwaltungsvorgänge verwendet, die Sie bereitstellen, andernfalls false.true if the DataGridView uses data-management operations that you provide; otherwise, false. Die Standardeinstellung ist false.The default is false.

Beispiele

Im folgenden Codebeispiel Code wird der virtuelle Modus verwendet, um eine Tabelle mit positiven ganzen Zahlen zu erstellen.The following code example code uses virtual mode to create a table of positive integers.

using System.IO;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Drawing;
using System;

public class VirtualModeDemo : Form
{
    DataGridView dataGridView1 = new DataGridView();

    public VirtualModeDemo()
        : base()
    {
        Text = "DataGridView virtual-mode demo (cell-level commit scope)";
        dataGridView1.NewRowNeeded +=
            new DataGridViewRowEventHandler(dataGridView1_NewRowNeeded);
        dataGridView1.RowsAdded +=
            new DataGridViewRowsAddedEventHandler(dataGridView1_RowsAdded);
        dataGridView1.CellValidating +=
            new DataGridViewCellValidatingEventHandler(dataGridView1_CellValidating);
        dataGridView1.CellValueNeeded +=
            new DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
        dataGridView1.CellValuePushed +=
            new DataGridViewCellValueEventHandler(dataGridView1_CellValuePushed);

        Controls.Add(dataGridView1);
        dataGridView1.VirtualMode = true;
        dataGridView1.AllowUserToDeleteRows = false;
        dataGridView1.Columns.Add("Numbers", "Positive Numbers");
        dataGridView1.Rows.AddCopies(0, initialSize);
    }

    bool newRowNeeded;
    private void dataGridView1_NewRowNeeded(object sender,
        DataGridViewRowEventArgs e)
    {
        newRowNeeded = true;
    }

    const int initialSize = 5000000;
    int numberOfRows = initialSize;

    private void dataGridView1_RowsAdded(object sender,
         DataGridViewRowsAddedEventArgs e)
    {
        if (newRowNeeded)
        {
            newRowNeeded = false;
            numberOfRows = numberOfRows + 1;
        }
    }

    #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>();

    private void dataGridView1_CellValidating(object sender,
        DataGridViewCellValidatingEventArgs e)
    {
        dataGridView1.Rows[e.RowIndex].ErrorText = "";
        int newInteger;

        // Don't try to validate the 'new row' until finished 
        // editing since there
        // is not any point in validating its initial value.
        if (dataGridView1.Rows[e.RowIndex].IsNewRow) { return; }
        if (!int.TryParse(e.FormattedValue.ToString(),
            out newInteger) || newInteger < 0)
        {
            e.Cancel = true;
            dataGridView1.Rows[e.RowIndex].ErrorText = "the value must be a non-negative integer";
        }
    }

    [STAThreadAttribute()]
    public static void Main()
    {
        Application.Run(new VirtualModeDemo());
    }
}
Imports System.IO
Imports System.Collections.Generic
Imports System.Windows.Forms

Public Class VirtualModeDemo
    Inherits System.Windows.Forms.Form

    Dim WithEvents dataGridView1 As New DataGridView

    Public Sub New()

        MyBase.New()

        Text = "DataGridView virtual-mode demo (cell-level commit scope)"

        Controls.Add(dataGridView1)
        dataGridView1.VirtualMode = True
        dataGridView1.AllowUserToDeleteRows = False
        dataGridView1.Columns.Add("Numbers", "Positive Numbers")
        dataGridView1.Rows.AddCopies(0, initialSize)

    End Sub

    Dim newRowNeeded As Boolean

    Private Sub dataGridView1_NewRowNeeded(ByVal sender As Object, _
        ByVal e As DataGridViewRowEventArgs) _
        Handles dataGridView1.NewRowNeeded

        newRowNeeded = True
    End Sub

    Const initialSize As Integer = 5000000
    Dim numberOfRows As Integer = initialSize

    Private Sub dataGridView1_RowsAdded(ByVal sender As Object, _
        ByVal e As DataGridViewRowsAddedEventArgs) _
        Handles dataGridView1.RowsAdded

        If newRowNeeded Then
            newRowNeeded = False
            numberOfRows = numberOfRows + 1
        End If
    End Sub

#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)

    Private Sub dataGridView1_CellValidating(ByVal sender As Object, _
        ByVal e _
        As DataGridViewCellValidatingEventArgs) _
        Handles dataGridView1.CellValidating

        Me.dataGridView1.Rows(e.RowIndex).ErrorText = ""
        Dim newInteger As Integer

        ' Don't try to validate the 'new row' until finished 
        ' editing since there
        ' is not any point in validating its initial value.
        If dataGridView1.Rows(e.RowIndex).IsNewRow Then Return
        If Not Integer.TryParse(e.FormattedValue.ToString(), newInteger) _
            OrElse newInteger < 0 Then

            e.Cancel = True
            Me.dataGridView1.Rows(e.RowIndex).ErrorText = "the value must be a non-negative integer"

        End If
    End Sub

    <STAThreadAttribute()> _
    Public Shared Sub Main()
        Application.Run(New VirtualModeDemo())
    End Sub
End Class

Hinweise

Der virtuelle Modus ist für die Verwendung mit sehr großen Daten speichern konzipiert.Virtual mode is designed for use with very large stores of data. Wenn die VirtualMode -Eigenschaft trueist, erstellen Sie DataGridView eine mit einer festgelegten Anzahl von Zeilen und Spalten, und CellValueNeeded behandeln Sie dann das-Ereignis, um die Zellen aufzufüllen.When the VirtualMode property is true, you create a DataGridView with a set number of rows and columns and then handle the CellValueNeeded event to populate the cells. Der virtuelle Modus erfordert die Implementierung eines zugrunde liegenden Daten Caches, um die Auffüllung, Bearbeitung und DataGridView Löschung von Zellen auf der Grundlage von Aktionen des Benutzers zu bewältigen.Virtual mode requires implementation of an underlying data cache to handle the population, editing, and deletion of DataGridView cells based on actions of the user. Weitere Informationen zum Implementieren des virtuellen Modus finden Sie unter Gewusst wie: Implementieren Sie den virtuellen Modus im Windows Forms DataGridView-Steuerelement.For more information about implementing virtual mode, see How to: Implement Virtual Mode in the Windows Forms DataGridView Control.

Sie müssen den virtuellen Modus verwenden, um die Werte ungebundener Spalten beizubehalten DataGridView , wenn sich das Steuerelement im gebundenen Modus befindet.You must use virtual mode to maintain the values of unbound columns when the DataGridView control is in bound mode. Das Sortieren nach ungebundenen Spalten im gebundenen Modus wird nicht unterstützt.Sorting by unbound columns in bound mode is not supported.

Gilt für:

Siehe auch