DataGridView.VirtualMode Properti

Definisi

Ruang nama:

System.Windows.Forms

Rakitan:

System.Windows.Forms.dll

Mendapatkan atau menetapkan nilai yang menunjukkan apakah Anda telah menyediakan operasi manajemen data Anda sendiri untuk DataGridView kontrol.

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

Nilai Properti

Boolean

trueDataGridView jika menggunakan operasi manajemen data yang Anda berikan; jika tidak, false. Default adalah false.

Contoh

Kode contoh kode berikut menggunakan mode virtual untuk membuat tabel bilangan bulat positif.

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

Keterangan

Mode virtual dirancang untuk digunakan dengan penyimpanan data yang sangat besar. VirtualMode Saat properti adalah true, Anda membuat DataGridView dengan jumlah baris dan kolom yang ditetapkan lalu menangani CellValueNeeded peristiwa untuk mengisi sel. Mode virtual memerlukan implementasi cache data yang mendasar untuk menangani populasi, pengeditan, dan penghapusan DataGridView sel berdasarkan tindakan pengguna. Untuk informasi selengkapnya tentang menerapkan mode virtual, lihat Cara: Menerapkan Mode Virtual di kontrol Formulir Windows DataGridView.

Anda harus menggunakan mode virtual untuk mempertahankan nilai kolom yang tidak terikat saat DataGridView kontrol dalam mode terikat. Pengurutan menurut kolom yang tidak terikat dalam mode terikat tidak didukung.

Lihat juga

• Kontrol DataGridView (Formulir Windows)