Tutorial: Implementar el modo virtual en el control DataGridView de formularios Windows FormsWalkthrough: Implementing Virtual Mode in the Windows Forms DataGridView Control

Cuando desea mostrar grandes cantidades de datos tabulares en una DataGridView control, puede establecer el VirtualMode propiedad true y administrar explícitamente la interacción del control con su almacén de datos.When you want to display very large quantities of tabular data in a DataGridView control, you can set the VirtualMode property to true and explicitly manage the control's interaction with its data store. Esto le permite ajustar el rendimiento del control en esta situación.This lets you fine-tune the performance of the control in this situation.

El DataGridView control proporciona varios eventos que puede controlar para interactuar con un almacén de datos personalizado.The DataGridView control provides several events that you can handle to interact with a custom data store. En este tutorial le guiará a través del proceso de implementación de estos controladores de eventos.This walkthrough guides you through the process of implementing these event handlers. El ejemplo de código en este tema usa un origen de datos muy sencillo con fines meramente ilustrativos.The code example in this topic uses a very simple data source for illustration purposes. En una configuración de producción, normalmente se cargará solo las filas que se debe mostrar en una memoria caché y controlar DataGridView eventos e interactuar con actualizar la memoria caché.In a production setting, you will typically load only the rows you need to display into a cache, and handle DataGridView events to interact with and update the cache. Para obtener más información, consulte implementar el modo Virtual con la carga de datos Just In Time en el DataGridView Control de formularios de WindowsFor more information, see Implementing Virtual Mode with Just-In-Time Data Loading in the Windows Forms DataGridView Control

Para copiar el código de este tema como una sola lista, vea Cómo: Implementar el modo Virtual en el Windows Forms DataGridView Control.To copy the code in this topic as a single listing, see How to: Implement Virtual Mode in the Windows Forms DataGridView Control.

Crear el formularioCreating the Form

Para implementar el modo virtualTo implement virtual mode

  1. Cree una clase que deriva de Form y contiene un DataGridView control.Create a class that derives from Form and contains a DataGridView control.

    El siguiente código contiene alguna inicialización básica.The following code contains some basic initialization. Declara algunas variables que se usará en pasos posteriores, se proporciona un Main método y proporciona un diseño de forma sencilla en el constructor de clase.It declares some variables that will be used in later steps, provides a Main method, and provides a simple form layout in the class constructor.

    #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. Implementar un controlador para el formulario Load eventos que inicializa el DataGridView controlar y rellena el almacén de datos con valores de ejemplo.Implement a handler for your form's Load event that initializes the DataGridView control and populates the data store with sample values.

    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::AllCells;
       
       // 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.AllCells;
    
        // 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.AllCells
    
        ' 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. Implementar un controlador para el CellValueNeeded eventos que recupera el valor de celda solicitado desde el almacén de datos o el Customer objeto actualmente en la edición.Implement a handler for the CellValueNeeded event that retrieves the requested cell value from the data store or the Customer object currently in edit.

    Este evento se produce siempre que el DataGridView control necesita dibujar una celda.This event occurs whenever the DataGridView control needs to paint a cell.

    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. Implementar un controlador para el CellValuePushed eventos que almacena un valor de celda modificada en el Customer objeto que representa la fila editada.Implement a handler for the CellValuePushed event that stores an edited cell value in the Customer object representing the edited row. Este evento se produce cada vez que el usuario confirma un cambio del valor de celda.This event occurs whenever the user commits a cell value change.

    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. Implementar un controlador para el NewRowNeeded eventos que crea un nuevo Customer objeto que representa una fila recién creada.Implement a handler for the NewRowNeeded event that creates a new Customer object representing a newly created row.

    Este evento se produce cada vez que el usuario escribe la fila para los nuevos registros.This event occurs whenever the user enters the row for new records.

    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. Implementar un controlador para el RowValidated eventos que guarda filas nuevas o modificadas en el almacén de datos.Implement a handler for the RowValidated event that saves new or modified rows to the data store.

    Este evento se produce cuando el usuario cambia la fila actual.This event occurs whenever the user changes the current row.

    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. Implementar un controlador para el RowDirtyStateNeeded evento que indica si el CancelRowEdit se producirá un evento cuando el usuario señala la reversión de la fila, presione ESC dos veces en modo de edición o una vez fuera del modo de edición.Implement a handler for the RowDirtyStateNeeded event that indicates whether the CancelRowEdit event will occur when the user signals row reversion by pressing ESC twice in edit mode or once outside of edit mode.

    De forma predeterminada, CancelRowEdit se produce al crear una nueva versión de fila cuando se han modificado las celdas de la fila actual a menos que el QuestionEventArgs.Response propiedad está establecida en true en el RowDirtyStateNeeded controlador de eventos.By default, CancelRowEdit occurs upon row reversion when any cells in the current row have been modified unless the QuestionEventArgs.Response property is set to true in the RowDirtyStateNeeded event handler. Este evento es útil cuando el ámbito de confirmación se determina en tiempo de ejecución.This event is useful when the commit scope is determined at 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. Implementar un controlador para el CancelRowEdit eventos que descartan los valores de la Customer objeto que representa la fila actual.Implement a handler for the CancelRowEdit event that discards the values of the Customer object representing the current row.

    Este evento se produce cuando el usuario señala la reversión de la fila, presione ESC dos veces en modo de edición o una vez fuera del modo de edición.This event occurs when the user signals row reversion by pressing ESC twice in edit mode or once outside of edit mode. Este evento no se produce si no hay ninguna celda en la fila actual se han modificado o si el valor de la QuestionEventArgs.Response se ha establecido la propiedad en false en un RowDirtyStateNeeded controlador de eventos.This event does not occur if no cells in the current row have been modified or if the value of the QuestionEventArgs.Response property has been set to false in a RowDirtyStateNeeded event handler.

    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. Implementar un controlador para el UserDeletingRow eventos que se eliminan una existente Customer objeto desde el almacén de datos o un no guardados se perderán Customer objeto que representa una fila recién creada.Implement a handler for the UserDeletingRow event that deletes an existing Customer object from the data store or discards an unsaved Customer object representing a newly created row.

    Este evento se produce cada vez que el usuario elimina una fila haciendo clic en un encabezado de fila y presione la tecla SUPR.This event occurs whenever the user deletes a row by clicking a row header and pressing the DELETE key.

    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. Implementar una sencilla Customers clase para representar los elementos de datos utilizados en este ejemplo de código.Implement a simple Customers class to represent the data items used by this code example.

    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
    

Probar la aplicaciónTesting the Application

Puede comprobar el formulario para asegurarse de que se comporta de la forma prevista.You can now test the form to make sure it behaves as expected.

Para comprobar el formularioTo test the form

  • Compile y ejecute la aplicación.Compile and run the application.

    Verá un DataGridView rellenado con tres registros de cliente del control.You will see a DataGridView control populated with three customer records. Puede modificar los valores de varias celdas en una fila y presione ESC dos veces en modo de edición y una vez fuera del modo de edición para revertir toda la fila a sus valores originales.You can modify the values of multiple cells in a row and press ESC twice in edit mode and once outside of edit mode to revert the entire row to its original values. Al modificar, agregar o eliminar filas en el control, Customer objetos en el almacén de datos se puede modificar, se agregan o se eliminan también.When you modify, add, or delete rows in the control, Customer objects in the data store are modified, added, or deleted as well.

Pasos siguientesNext Steps

Esta aplicación le ofrece un conocimiento básico de los eventos que se debe controlar para implementar el modo virtual en el DataGridView control.This application gives you a basic understanding of the events you must handle to implement virtual mode in the DataGridView control. Puede mejorar esta aplicación básica de varias maneras:You can improve this basic application in a number of ways:

  • Implementar un almacén de datos que almacena en caché los valores de una base de datos externo.Implement a data store that caches values from an external database. La memoria caché debe recuperar y descartar los valores según sea necesario para que solo contiene lo que es necesario para su presentación y consume una pequeña cantidad de memoria en el equipo cliente.The cache should retrieve and discard values as necessary so that it only contains what is necessary for display while consuming a small amount of memory on the client computer.

  • Ajustar el rendimiento del almacén de datos según sus requisitos.Fine-tune the performance of the data store depending on your requirements. Por ejemplo, podría desea compensar para conexiones de red lentas, en lugar de las limitaciones de memoria del equipo cliente utilizando un tamaño de caché mayor y minimizar el número de consultas de base de datos.For example, you might want to compensate for slow network connections rather than client-computer memory limitations by using a larger cache size and minimizing the number of database queries.

Para obtener más información sobre almacenamiento en caché los valores de una base de datos externo, vea Cómo: Implementar el modo Virtual con la carga de datos Just-In-Time en el Windows Forms DataGridView Control.For more information about caching values from an external database, see How to: Implement Virtual Mode with Just-In-Time Data Loading in the Windows Forms DataGridView Control.

Vea tambiénSee also