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Panduan: Menerapkan Mode Virtual di Kontrol Windows Forms DataGridView

Saat Anda ingin menampilkan data tabular dalam jumlah yang sangat besar dalam kontrol DataGridView, Anda dapat mengatur properti VirtualMode ke true dan secara eksplisit mengelola interaksi kontrol dengan penyimpanan datanya. Ini memungkinkan Anda menyempurnakan performa kontrol dalam situasi ini.

Kontrol DataGridView menyediakan beberapa peristiwa yang dapat Anda tangani untuk berinteraksi dengan penyimpanan data kustom. Panduan ini memandu Anda melalui proses penerapan penanganan aktivitas ini. Contoh kode dalam topik ini menggunakan sumber data yang sangat sederhana untuk tujuan ilustrasi. Dalam lingkungan produksi, Anda biasanya hanya akan memuat baris yang perlu Anda tampilkan ke dalam cache, dan menangani peristiwa DataGridView untuk berinteraksi dan memperbarui cache. Untuk informasi selengkapnya, lihat Menerapkan Mode Virtual dengan Pemuatan Data Just-In-Time di Kontrol Windows Forms DataGridView

Untuk menyalin kode dalam topik ini sebagai daftar tunggal, lihat Cara: Menerapkan Mode Virtual di Kontrol Windows Forms DataGridView.

Membuat Formulir

Untuk menerapkan mode virtual

  1. Buat kelas yang berasal dari Form dan berisi kontrol DataGridView.

    Kode berikut berisi beberapa inisialisasi dasar. Ini mendeklarasikan beberapa variabel yang akan digunakan dalam langkah-langkah selanjutnya, menyediakan metode Main, dan menyediakan tata letak formulir sederhana di konstruktor kelas.

    #using <System.Drawing.dll>
#using <System.dll>
#using <System.Windows.Forms.dll>

using namespace System;
using namespace System::Windows::Forms;

public ref class Customer
{
private:
   String^ companyNameValue;
   String^ contactNameValue;

public:
   Customer()
   {
      
      // Leave fields empty.
   }

   Customer( String^ companyName, String^ contactName )
   {
      companyNameValue = companyName;
      contactNameValue = contactName;
   }


   property String^ CompanyName 
   {
      String^ get()
      {
         return companyNameValue;
      }

      void set( String^ value )
      {
         companyNameValue = value;
      }

   }

   property String^ ContactName 
   {
      String^ get()
      {
         return contactNameValue;
      }

      void set( String^ value )
      {
         contactNameValue = value;
      }

   }

};

public ref class Form1: public Form
{
private:
   DataGridView^ dataGridView1;

   // Declare an ArrayList to serve as the data store. 
   System::Collections::ArrayList^ customers;

   // Declare a Customer object to store data for a row being edited.
   Customer^ customerInEdit;

   // Declare a variable to store the index of a row being edited. 
   // A value of -1 indicates that there is no row currently in edit. 
   int rowInEdit;

   // Declare a variable to indicate the commit scope. 
   // Set this value to false to use cell-level commit scope. 
   bool rowScopeCommit;

public:
   static void Main()
   {
      Application::Run( gcnew Form1 );
   }

   Form1()
   {
      dataGridView1 = gcnew DataGridView;
      customers = gcnew System::Collections::ArrayList;
      rowInEdit = -1;
      rowScopeCommit = true;
      
      // Initialize the form.
      this->dataGridView1->Dock = DockStyle::Fill;
      this->Controls->Add( this->dataGridView1 );
      this->Load += gcnew EventHandler( this, &Form1::Form1_Load );
   }

private:

    using System;
using System.Windows.Forms;

public class Form1 : Form
{
    private DataGridView dataGridView1 = new DataGridView();

    // Declare an ArrayList to serve as the data store.
    private System.Collections.ArrayList customers =
        new System.Collections.ArrayList();

    // Declare a Customer object to store data for a row being edited.
    private Customer customerInEdit;

    // Declare a variable to store the index of a row being edited.
    // A value of -1 indicates that there is no row currently in edit.
    private int rowInEdit = -1;

    // Declare a variable to indicate the commit scope.
    // Set this value to false to use cell-level commit scope.
    private bool rowScopeCommit = true;

    [STAThreadAttribute()]
    public static void Main()
    {
        Application.Run(new Form1());
    }

    public Form1()
    {
        // Initialize the form.
        this.dataGridView1.Dock = DockStyle.Fill;
        this.Controls.Add(this.dataGridView1);
        this.Load += new EventHandler(Form1_Load);
        this.Text = "DataGridView virtual-mode demo (row-level commit scope)";
    }

    Imports System.Windows.Forms

Public Class Form1
    Inherits Form

    Private WithEvents dataGridView1 As New DataGridView()

    ' Declare an ArrayList to serve as the data store. 
    Private customers As New System.Collections.ArrayList()

    ' Declare a Customer object to store data for a row being edited.
    Private customerInEdit As Customer

    ' Declare a variable to store the index of a row being edited. 
    ' A value of -1 indicates that there is no row currently in edit. 
    Private rowInEdit As Integer = -1

    ' Declare a variable to indicate the commit scope. 
    ' Set this value to false to use cell-level commit scope. 
    Private rowScopeCommit As Boolean = True

    <STAThreadAttribute()> _
    Public Shared Sub Main()
        Application.Run(New Form1())
    End Sub

    Public Sub New()
        ' Initialize the form.
        Me.dataGridView1.Dock = DockStyle.Fill
        Me.Controls.Add(Me.dataGridView1)
        Me.Text = "DataGridView virtual-mode demo (row-level commit scope)"
    End Sub

    };

int main()
{
   Form1::Main();
}

    }

    
End Class

  2. Terapkan handler untuk peristiwa Load formulir Anda yang menginisialisasi kontrol DataGridView dan mengisi penyimpanan data dengan nilai sampel.

    void Form1_Load( Object^ /*sender*/, EventArgs^ /*e*/ )
{
   
   // Enable virtual mode.
   this->dataGridView1->VirtualMode = true;
   
   // Connect the virtual-mode events to event handlers. 
   this->dataGridView1->CellValueNeeded += gcnew
       DataGridViewCellValueEventHandler( this, &Form1::dataGridView1_CellValueNeeded );
   this->dataGridView1->CellValuePushed += gcnew
       DataGridViewCellValueEventHandler( this, &Form1::dataGridView1_CellValuePushed );
   this->dataGridView1->NewRowNeeded += gcnew
       DataGridViewRowEventHandler( this, &Form1::dataGridView1_NewRowNeeded );
   this->dataGridView1->RowValidated += gcnew
       DataGridViewCellEventHandler( this, &Form1::dataGridView1_RowValidated );
   this->dataGridView1->RowDirtyStateNeeded += gcnew
       QuestionEventHandler( this, &Form1::dataGridView1_RowDirtyStateNeeded );
   this->dataGridView1->CancelRowEdit += gcnew
       QuestionEventHandler( this, &Form1::dataGridView1_CancelRowEdit );
   this->dataGridView1->UserDeletingRow += gcnew
       DataGridViewRowCancelEventHandler( this, &Form1::dataGridView1_UserDeletingRow );
   
   // Add columns to the DataGridView.
   DataGridViewTextBoxColumn^ companyNameColumn = gcnew DataGridViewTextBoxColumn;
   companyNameColumn->HeaderText = L"Company Name";
   companyNameColumn->Name = L"Company Name";
   DataGridViewTextBoxColumn^ contactNameColumn = gcnew DataGridViewTextBoxColumn;
   contactNameColumn->HeaderText = L"Contact Name";
   contactNameColumn->Name = L"Contact Name";
   this->dataGridView1->Columns->Add( companyNameColumn );
   this->dataGridView1->Columns->Add( contactNameColumn );
   this->dataGridView1->AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode::DisplayedCells;
   
   // Add some sample entries to the data store. 
   this->customers->Add( gcnew Customer( L"Bon app'",L"Laurence Lebihan" ) );
   this->customers->Add( gcnew Customer( L"Bottom-Dollar Markets",L"Elizabeth Lincoln" ) );
   this->customers->Add( gcnew Customer( L"B's Beverages",L"Victoria Ashworth" ) );
   
   // Set the row count, including the row for new records.
   this->dataGridView1->RowCount = 4;
}

    private void Form1_Load(object sender, EventArgs e)
{
    // Enable virtual mode.
    this.dataGridView1.VirtualMode = true;

    // Connect the virtual-mode events to event handlers.
    this.dataGridView1.CellValueNeeded += new
        DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
    this.dataGridView1.CellValuePushed += new
        DataGridViewCellValueEventHandler(dataGridView1_CellValuePushed);
    this.dataGridView1.NewRowNeeded += new
        DataGridViewRowEventHandler(dataGridView1_NewRowNeeded);
    this.dataGridView1.RowValidated += new
        DataGridViewCellEventHandler(dataGridView1_RowValidated);
    this.dataGridView1.RowDirtyStateNeeded += new
        QuestionEventHandler(dataGridView1_RowDirtyStateNeeded);
    this.dataGridView1.CancelRowEdit += new
        QuestionEventHandler(dataGridView1_CancelRowEdit);
    this.dataGridView1.UserDeletingRow += new
        DataGridViewRowCancelEventHandler(dataGridView1_UserDeletingRow);

    // Add columns to the DataGridView.
    DataGridViewTextBoxColumn companyNameColumn = new
        DataGridViewTextBoxColumn();
    companyNameColumn.HeaderText = "Company Name";
    companyNameColumn.Name = "Company Name";
    DataGridViewTextBoxColumn contactNameColumn = new
        DataGridViewTextBoxColumn();
    contactNameColumn.HeaderText = "Contact Name";
    contactNameColumn.Name = "Contact Name";
    this.dataGridView1.Columns.Add(companyNameColumn);
    this.dataGridView1.Columns.Add(contactNameColumn);
    this.dataGridView1.AutoSizeColumnsMode =
        DataGridViewAutoSizeColumnsMode.DisplayedCells;

    // Add some sample entries to the data store.
    this.customers.Add(new Customer(
        "Bon app'", "Laurence Lebihan"));
    this.customers.Add(new Customer(
        "Bottom-Dollar Markets", "Elizabeth Lincoln"));
    this.customers.Add(new Customer(
        "B's Beverages", "Victoria Ashworth"));

    // Set the row count, including the row for new records.
    this.dataGridView1.RowCount = 4;
}

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) _
    Handles Me.Load

    ' Enable virtual mode.
    Me.dataGridView1.VirtualMode = True

    ' Add columns to the DataGridView.
    Dim companyNameColumn As New DataGridViewTextBoxColumn()
    With companyNameColumn
        .HeaderText = "Company Name"
        .Name = "Company Name"
    End With
    Dim contactNameColumn As New DataGridViewTextBoxColumn()
    With contactNameColumn
        .HeaderText = "Contact Name"
        .Name = "Contact Name"
    End With
    Me.dataGridView1.Columns.Add(companyNameColumn)
    Me.dataGridView1.Columns.Add(contactNameColumn)
    Me.dataGridView1.AutoSizeColumnsMode = _
    DataGridViewAutoSizeColumnsMode.DisplayedCells

    ' Add some sample entries to the data store. 
    Me.customers.Add(New Customer("Bon app'", "Laurence Lebihan"))
    Me.customers.Add(New Customer("Bottom-Dollar Markets", _
        "Elizabeth Lincoln"))
    Me.customers.Add(New Customer("B's Beverages", "Victoria Ashworth"))

    ' Set the row count, including the row for new records.
    Me.dataGridView1.RowCount = 4

End Sub

  3. Terapkan handler untuk peristiwa CellValueNeeded yang mengambil nilai sel yang diminta dari penyimpanan data atau objek Customer yang saat ini sedang diedit.

    Peristiwa ini terjadi setiap kali kontrol DataGridView perlu menggambar sel.

    void dataGridView1_CellValueNeeded( Object^ /*sender*/,
    System::Windows::Forms::DataGridViewCellValueEventArgs^ e )
{
   Customer^ customerTmp = nullptr;
   
   // Store a reference to the Customer object for the row being painted.
   if ( e->RowIndex == rowInEdit )
   {
      customerTmp = this->customerInEdit;
   }
   else
   {
      customerTmp = dynamic_cast<Customer^>(this->customers[ e->RowIndex ]);
   }
   
   // Set the cell value to paint using the Customer object retrieved.
   int switchcase = 0;
   if ( (this->dataGridView1->Columns[ e->ColumnIndex ]->Name)->Equals( L"Company Name" ) )
         switchcase = 1;
   else
   if ( (this->dataGridView1->Columns[ e->ColumnIndex ]->Name)->Equals( L"Contact Name" ) )
         switchcase = 2;


   switch ( switchcase )
   {
      case 1:
         e->Value = customerTmp->CompanyName;
         break;

      case 2:
         e->Value = customerTmp->ContactName;
         break;
   }
}



    private void dataGridView1_CellValueNeeded(object sender,
    System.Windows.Forms.DataGridViewCellValueEventArgs e)
{
    // If this is the row for new records, no values are needed.
    if (e.RowIndex == this.dataGridView1.RowCount - 1) return;

    Customer customerTmp = null;

    // Store a reference to the Customer object for the row being painted.
    if (e.RowIndex == rowInEdit)
    {
        customerTmp = this.customerInEdit;
    }
    else
    {
        customerTmp = (Customer)this.customers[e.RowIndex];
    }

    // Set the cell value to paint using the Customer object retrieved.
    switch (this.dataGridView1.Columns[e.ColumnIndex].Name)
    {
        case "Company Name":
            e.Value = customerTmp.CompanyName;
            break;

        case "Contact Name":
            e.Value = customerTmp.ContactName;
            break;
    }
}

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

    ' If this is the row for new records, no values are needed.
    If e.RowIndex = Me.dataGridView1.RowCount - 1 Then
        Return
    End If

    Dim customerTmp As Customer = Nothing

    ' Store a reference to the Customer object for the row being painted.
    If e.RowIndex = rowInEdit Then
        customerTmp = Me.customerInEdit
    Else
        customerTmp = CType(Me.customers(e.RowIndex), Customer)
    End If

    ' Set the cell value to paint using the Customer object retrieved.
    Select Case Me.dataGridView1.Columns(e.ColumnIndex).Name
        Case "Company Name"
            e.Value = customerTmp.CompanyName

        Case "Contact Name"
            e.Value = customerTmp.ContactName
    End Select

End Sub

  4. Terapkan handler untuk peristiwa CellValuePushed yang menyimpan nilai sel yang diedit di objek Customer yang mewakili baris yang diedit. Kejadian ini terjadi setiap kali pengguna menerapkan perubahan nilai sel.

    void dataGridView1_CellValuePushed( Object^ /*sender*/,
    System::Windows::Forms::DataGridViewCellValueEventArgs^ e )
{
   Customer^ customerTmp = nullptr;
   
   // Store a reference to the Customer object for the row being edited.
   if ( e->RowIndex < this->customers->Count )
   {
      
      // If the user is editing a new row, create a new Customer object.
      if ( this->customerInEdit == nullptr )
      {
         this->customerInEdit = gcnew Customer(
             (dynamic_cast<Customer^>(this->customers[ e->RowIndex ]))->CompanyName,
             (dynamic_cast<Customer^>(this->customers[ e->RowIndex ])->ContactName) );
      }

      customerTmp = this->customerInEdit;
      this->rowInEdit = e->RowIndex;
   }
   else
   {
      customerTmp = this->customerInEdit;
   }

   
   // Set the appropriate Customer property to the cell value entered.
   int switchcase = 0;
   if ( (this->dataGridView1->Columns[ e->ColumnIndex ]->Name)->Equals( L"Company Name" ) )
         switchcase = 1;
   else
   if ( (this->dataGridView1->Columns[ e->ColumnIndex ]->Name)->Equals( L"Contact Name" ) )
         switchcase = 2;


   switch ( switchcase )
   {
      case 1:
         customerTmp->CompanyName = dynamic_cast<String^>(e->Value);
         break;

      case 2:
         customerTmp->ContactName = dynamic_cast<String^>(e->Value);
         break;
   }
}



    private void dataGridView1_CellValuePushed(object sender,
    System.Windows.Forms.DataGridViewCellValueEventArgs e)
{
    Customer customerTmp = null;

    // Store a reference to the Customer object for the row being edited.
    if (e.RowIndex < this.customers.Count)
    {
        // If the user is editing a new row, create a new Customer object.
        this.customerInEdit ??= new Customer(
            ((Customer)this.customers[e.RowIndex]).CompanyName,
            ((Customer)this.customers[e.RowIndex]).ContactName);
        customerTmp = this.customerInEdit;
        this.rowInEdit = e.RowIndex;
    }
    else
    {
        customerTmp = this.customerInEdit;
    }

    // Set the appropriate Customer property to the cell value entered.
    String newValue = e.Value as String;
    switch (this.dataGridView1.Columns[e.ColumnIndex].Name)
    {
        case "Company Name":
            customerTmp.CompanyName = newValue;
            break;

        case "Contact Name":
            customerTmp.ContactName = newValue;
            break;
    }
}

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

    Dim customerTmp As Customer = Nothing

    ' Store a reference to the Customer object for the row being edited.
    If e.RowIndex < Me.customers.Count Then

        ' If the user is editing a new row, create a new Customer object.
        If Me.customerInEdit Is Nothing Then
            Me.customerInEdit = New Customer( _
                CType(Me.customers(e.RowIndex), Customer).CompanyName, _
                CType(Me.customers(e.RowIndex), Customer).ContactName)
        End If
        customerTmp = Me.customerInEdit
        Me.rowInEdit = e.RowIndex

    Else
        customerTmp = Me.customerInEdit
    End If

    ' Set the appropriate Customer property to the cell value entered.
    Dim newValue As String = TryCast(e.Value, String)
    Select Case Me.dataGridView1.Columns(e.ColumnIndex).Name
        Case "Company Name"
            customerTmp.CompanyName = newValue
        Case "Contact Name"
            customerTmp.ContactName = newValue
    End Select

End Sub

  5. Terapkan handler untuk peristiwa NewRowNeeded yang membuat objek Customer baru yang mewakili baris yang baru dibuat.

    Peristiwa ini terjadi setiap kali pengguna memasuki baris untuk rekaman baru.

    void dataGridView1_NewRowNeeded( Object^ /*sender*/,
    System::Windows::Forms::DataGridViewRowEventArgs^ /*e*/ )
{
   
   // Create a new Customer object when the user edits
   // the row for new records.
   this->customerInEdit = gcnew Customer;
   this->rowInEdit = this->dataGridView1->Rows->Count - 1;
}



    private void dataGridView1_NewRowNeeded(object sender,
    System.Windows.Forms.DataGridViewRowEventArgs e)
{
    // Create a new Customer object when the user edits
    // the row for new records.
    this.customerInEdit = new Customer();
    this.rowInEdit = this.dataGridView1.Rows.Count - 1;
}

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

    ' Create a new Customer object when the user edits
    ' the row for new records.
    Me.customerInEdit = New Customer()
    Me.rowInEdit = Me.dataGridView1.Rows.Count - 1

End Sub

  6. Terapkan handler untuk peristiwa RowValidated yang menyimpan baris baru atau yang dimodifikasi ke penyimpanan data.

    Kejadian ini terjadi setiap kali pengguna mengubah baris saat ini.

    void dataGridView1_RowValidated( Object^ /*sender*/,
    System::Windows::Forms::DataGridViewCellEventArgs^ e )
{
   
   // Save row changes if any were made and release the edited 
   // Customer object if there is one.
   if ( e->RowIndex >= this->customers->Count && e->RowIndex != this->dataGridView1->Rows->Count - 1 )
   {
      
      // Add the new Customer object to the data store.
      this->customers->Add( this->customerInEdit );
      this->customerInEdit = nullptr;
      this->rowInEdit = -1;
   }
   else
   if ( this->customerInEdit != nullptr && e->RowIndex < this->customers->Count )
   {
      
      // Save the modified Customer object in the data store.
      this->customers[ e->RowIndex ] = this->customerInEdit;
      this->customerInEdit = nullptr;
      this->rowInEdit = -1;
   }
   else
   if ( this->dataGridView1->ContainsFocus )
   {
      this->customerInEdit = nullptr;
      this->rowInEdit = -1;
   }
}



    private void dataGridView1_RowValidated(object sender,
    System.Windows.Forms.DataGridViewCellEventArgs e)
{
    // Save row changes if any were made and release the edited
    // Customer object if there is one.
    if (e.RowIndex >= this.customers.Count &&
        e.RowIndex != this.dataGridView1.Rows.Count - 1)
    {
        // Add the new Customer object to the data store.
        this.customers.Add(this.customerInEdit);
        this.customerInEdit = null;
        this.rowInEdit = -1;
    }
    else if (this.customerInEdit != null &&
        e.RowIndex < this.customers.Count)
    {
        // Save the modified Customer object in the data store.
        this.customers[e.RowIndex] = this.customerInEdit;
        this.customerInEdit = null;
        this.rowInEdit = -1;
    }
    else if (this.dataGridView1.ContainsFocus)
    {
        this.customerInEdit = null;
        this.rowInEdit = -1;
    }
}

    Private Sub dataGridView1_RowValidated(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) _
    Handles dataGridView1.RowValidated

    ' Save row changes if any were made and release the edited 
    ' Customer object if there is one.
    If e.RowIndex >= Me.customers.Count AndAlso _
        e.RowIndex <> Me.dataGridView1.Rows.Count - 1 Then

        ' Add the new Customer object to the data store.
        Me.customers.Add(Me.customerInEdit)
        Me.customerInEdit = Nothing
        Me.rowInEdit = -1

    ElseIf (Me.customerInEdit IsNot Nothing) AndAlso _
        e.RowIndex < Me.customers.Count Then

        ' Save the modified Customer object in the data store.
        Me.customers(e.RowIndex) = Me.customerInEdit
        Me.customerInEdit = Nothing
        Me.rowInEdit = -1

    ElseIf Me.dataGridView1.ContainsFocus Then

        Me.customerInEdit = Nothing
        Me.rowInEdit = -1

    End If

End Sub

  7. Terapkan handler untuk peristiwa RowDirtyStateNeeded yang menunjukkan apakah peristiwa CancelRowEdit akan terjadi ketika pengguna memberi sinyal pembalikan baris dengan menekan ESC dua kali dalam mode edit atau sekali di luar mode edit.

    Secara default, CancelRowEdit terjadi pada pembalikan baris ketika sel apa pun di baris saat ini telah dimodifikasi kecuali properti QuestionEventArgs.Response diatur ke true di penanganan aktivitas RowDirtyStateNeeded. Kejadian ini berguna ketika cakupan komit ditentukan pada waktu run-time.

    void dataGridView1_RowDirtyStateNeeded( Object^ /*sender*/,
    System::Windows::Forms::QuestionEventArgs^ e )
{
   if (  !rowScopeCommit )
   {
      
      // In cell-level commit scope, indicate whether the value
      // of the current cell has been modified.
      e->Response = this->dataGridView1->IsCurrentCellDirty;
   }
}



    private void dataGridView1_RowDirtyStateNeeded(object sender,
    System.Windows.Forms.QuestionEventArgs e)
{
    if (!rowScopeCommit)
    {
        // In cell-level commit scope, indicate whether the value
        // of the current cell has been modified.
        e.Response = this.dataGridView1.IsCurrentCellDirty;
    }
}

    Private Sub dataGridView1_RowDirtyStateNeeded(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.QuestionEventArgs) _
    Handles dataGridView1.RowDirtyStateNeeded

    If Not rowScopeCommit Then

        ' In cell-level commit scope, indicate whether the value
        ' of the current cell has been modified.
        e.Response = Me.dataGridView1.IsCurrentCellDirty

    End If

End Sub

  8. Terapkan handler untuk peristiwa CancelRowEdit yang membuang nilai objek Customer yang mewakili baris saat ini.

    Peristiwa ini terjadi ketika pengguna memberi sinyal pembalikan baris dengan menekan ESC dua kali dalam mode edit atau sekali di luar mode edit. Kejadian ini tidak terjadi jika tidak ada sel dalam baris saat ini yang telah dimodifikasi atau jika nilai properti QuestionEventArgs.Response telah diatur ke false dalam penanganan aktivitas RowDirtyStateNeeded.

    void dataGridView1_CancelRowEdit( Object^ /*sender*/,
    System::Windows::Forms::QuestionEventArgs^ /*e*/ )
{
   if ( this->rowInEdit == this->dataGridView1->Rows->Count - 2 &&
        this->rowInEdit == this->customers->Count )
   {
      
      // If the user has canceled the edit of a newly created row, 
      // replace the corresponding Customer object with a new, empty one.
      this->customerInEdit = gcnew Customer;
   }
   else
   {
      
      // If the user has canceled the edit of an existing row, 
      // release the corresponding Customer object.
      this->customerInEdit = nullptr;
      this->rowInEdit = -1;
   }
}



    private void dataGridView1_CancelRowEdit(object sender,
    System.Windows.Forms.QuestionEventArgs e)
{
    if (this.rowInEdit == this.dataGridView1.Rows.Count - 2 &&
        this.rowInEdit == this.customers.Count)
    {
        // If the user has canceled the edit of a newly created row,
        // replace the corresponding Customer object with a new, empty one.
        this.customerInEdit = new Customer();
    }
    else
    {
        // If the user has canceled the edit of an existing row,
        // release the corresponding Customer object.
        this.customerInEdit = null;
        this.rowInEdit = -1;
    }
}

    Private Sub dataGridView1_CancelRowEdit(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.QuestionEventArgs) _
    Handles dataGridView1.CancelRowEdit

    If Me.rowInEdit = Me.dataGridView1.Rows.Count - 2 AndAlso _
        Me.rowInEdit = Me.customers.Count Then

        ' If the user has canceled the edit of a newly created row, 
        ' replace the corresponding Customer object with a new, empty one.
        Me.customerInEdit = New Customer()

    Else

        ' If the user has canceled the edit of an existing row, 
        ' release the corresponding Customer object.
        Me.customerInEdit = Nothing
        Me.rowInEdit = -1

    End If

End Sub

  9. Terapkan handler untuk peristiwa UserDeletingRow yang menghapus objek Customer yang ada dari penyimpanan data atau membuang objek Customer yang belum disimpan yang mewakili baris yang baru dibuat.

    Kejadian ini terjadi setiap kali pengguna menghapus baris dengan mengklik header baris dan menekan tombol DELETE.

    void dataGridView1_UserDeletingRow( Object^ /*sender*/,
    System::Windows::Forms::DataGridViewRowCancelEventArgs^ e )
{
   if ( e->Row->Index < this->customers->Count )
   {
      
      // If the user has deleted an existing row, remove the 
      // corresponding Customer object from the data store.
      this->customers->RemoveAt( e->Row->Index );
   }

   if ( e->Row->Index == this->rowInEdit )
   {
      
      // If the user has deleted a newly created row, release
      // the corresponding Customer object. 
      this->rowInEdit = -1;
      this->customerInEdit = nullptr;
   }
}

    private void dataGridView1_UserDeletingRow(object sender,
    System.Windows.Forms.DataGridViewRowCancelEventArgs e)
{
    if (e.Row.Index < this.customers.Count)
    {
        // If the user has deleted an existing row, remove the
        // corresponding Customer object from the data store.
        this.customers.RemoveAt(e.Row.Index);
    }

    if (e.Row.Index == this.rowInEdit)
    {
        // If the user has deleted a newly created row, release
        // the corresponding Customer object.
        this.rowInEdit = -1;
        this.customerInEdit = null;
    }
}

    Private Sub dataGridView1_UserDeletingRow(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.DataGridViewRowCancelEventArgs) _
    Handles dataGridView1.UserDeletingRow

    If e.Row.Index < Me.customers.Count Then

        ' If the user has deleted an existing row, remove the 
        ' corresponding Customer object from the data store.
        Me.customers.RemoveAt(e.Row.Index)

    End If

    If e.Row.Index = Me.rowInEdit Then

        ' If the user has deleted a newly created row, release
        ' the corresponding Customer object. 
        Me.rowInEdit = -1
        Me.customerInEdit = Nothing

    End If

End Sub

  10. Terapkan kelas Customers sederhana untuk mewakili item data yang digunakan oleh contoh kode ini.

    public ref class Customer
{
private:
   String^ companyNameValue;
   String^ contactNameValue;

public:
   Customer()
   {
      
      // Leave fields empty.
   }

   Customer( String^ companyName, String^ contactName )
   {
      companyNameValue = companyName;
      contactNameValue = contactName;
   }


   property String^ CompanyName 
   {
      String^ get()
      {
         return companyNameValue;
      }

      void set( String^ value )
      {
         companyNameValue = value;
      }

   }

   property String^ ContactName 
   {
      String^ get()
      {
         return contactNameValue;
      }

      void set( String^ value )
      {
         contactNameValue = value;
      }

   }

};

    public class Customer
{
    private String companyNameValue;
    private String contactNameValue;

    public Customer()
    {
        // Leave fields empty.
    }

    public Customer(String companyName, String contactName)
    {
        companyNameValue = companyName;
        contactNameValue = contactName;
    }

    public String CompanyName
    {
        get
        {
            return companyNameValue;
        }
        set
        {
            companyNameValue = value;
        }
    }

    public String ContactName
    {
        get
        {
            return contactNameValue;
        }
        set
        {
            contactNameValue = value;
        }
    }
}

    Public Class Customer

    Private companyNameValue As String
    Private contactNameValue As String

    Public Sub New()
        ' Leave fields empty.
    End Sub

    Public Sub New(ByVal companyName As String, ByVal contactName As String)
        companyNameValue = companyName
        contactNameValue = contactName
    End Sub

    Public Property CompanyName() As String
        Get
            Return companyNameValue
        End Get
        Set(ByVal value As String)
            companyNameValue = value
        End Set
    End Property

    Public Property ContactName() As String
        Get
            Return contactNameValue
        End Get
        Set(ByVal value As String)
            contactNameValue = value
        End Set
    End Property

End Class

Menguji Aplikasi

Anda sekarang dapat menguji formulir untuk memastikan formulir tersebut berulah seperti yang diharapkan.

Untuk menguji formulir

  • Kompilasi dan jalankan aplikasi.

    Anda akan melihat kontrol DataGridView yang terisi dengan tiga data pelanggan. Anda dapat mengubah nilai beberapa sel dalam baris dan menekan ESC dua kali dalam mode edit dan sekali di luar mode edit untuk mengembalikan seluruh baris ke nilai aslinya. Saat Anda memodifikasi, menambahkan, atau menghapus baris dalam kontrol, Customer objek di penyimpanan data juga dimodifikasi, ditambahkan, atau dihapus.

Langkah Selanjutnya

Aplikasi ini memberi Anda pemahaman dasar tentang peristiwa yang harus Anda tangani untuk menerapkan mode virtual dalam kontrol DataGridView. Anda dapat meningkatkan aplikasi dasar ini dengan sejumlah cara:

  • Terapkan penyimpanan data yang menyimpan nilai dari database eksternal. Cache harus mengambil dan membuang nilai seperlunya sehingga hanya berisi apa yang diperlukan untuk ditampilkan saat mengonsumsi sejumlah kecil memori di komputer klien.

  • Menyempurnakan performa penyimpanan data tergantung pada kebutuhan Anda. Misalnya, Anda mungkin ingin mengkompensasi koneksi jaringan yang lambat daripada batasan memori komputer klien dengan menggunakan ukuran cache yang lebih besar dan meminimalkan jumlah kueri database.

Untuk informasi selengkapnya tentang penyimpanan nilai dari database eksternal, lihat Cara: Menerapkan Mode Virtual hanya dengan Pemuatan DataIn-Time di Kontrol Windows Forms DataGridView.

Lihat juga