Wskazówki: implementowanie trybu wirtualnego w formancie DataGridView formularzy systemu Windows
Jeśli chcesz wyświetlić bardzo duże ilości danych tabelarycznych w kontrolce DataGridView , możesz ustawić VirtualMode właściwość na true
i jawnie zarządzać interakcją kontrolki z jej magazynem danych. Pozwala to dostosować wydajność kontrolki w tej sytuacji.
Kontrolka DataGridView udostępnia kilka zdarzeń, które można obsługiwać w celu interakcji z niestandardowym magazynem danych. Ten przewodnik przeprowadzi Cię przez proces implementowania tych procedur obsługi zdarzeń. Przykładowy kod w tym temacie używa bardzo prostego źródła danych do celów ilustracyjnych. W ustawieniu produkcyjnym zwykle ładowane są tylko wiersze potrzebne do wyświetlenia w pamięci podręcznej oraz obsługa DataGridView zdarzeń w celu interakcji i aktualizowania pamięci podręcznej. Aby uzyskać więcej informacji, zobacz Implementowanie trybu wirtualnego za pomocą ładowania danych just in time w kontrolce DataGridView formularzy systemu Windows
Aby skopiować kod w tym temacie jako pojedynczą listę, zobacz Instrukcje: implementowanie trybu wirtualnego w kontrolce DataGridView formularzy systemu Windows.
Tworzenie formularza
Aby zaimplementować tryb wirtualny
Utwórz klasę pochodzącą z Form kontrolki i zawierającą kontrolkę DataGridView .
Poniższy kod zawiera pewne podstawowe inicjowanie. Deklaruje niektóre zmienne, które będą używane w kolejnych krokach, udostępnia metodę
Main
i udostępnia prosty układ formularza w konstruktorze klasy.#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
Zaimplementuj program obsługi zdarzenia formularza Load , który inicjuje kontrolkę DataGridView i wypełnia magazyn danych przykładowymi wartościami.
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
Zaimplementuj procedurę obsługi dla CellValueNeeded zdarzenia, które pobiera żądaną wartość komórki z magazynu danych lub
Customer
obiektu aktualnie edytowanego.To zdarzenie występuje za każdym razem, gdy kontrolka DataGridView musi malować komórkę.
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
Zaimplementuj program obsługi zdarzenia CellValuePushed , który przechowuje edytowaną wartość komórki w
Customer
obiekcie reprezentującym edytowany wiersz. To zdarzenie występuje za każdym razem, gdy użytkownik zatwierdzi zmianę wartości komórki.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
Zaimplementuj program obsługi dla NewRowNeeded zdarzenia, który tworzy nowy
Customer
obiekt reprezentujący nowo utworzony wiersz.To zdarzenie występuje za każdym razem, gdy użytkownik wprowadza wiersz dla nowych rekordów.
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
Zaimplementuj program obsługi zdarzenia RowValidated , który zapisuje nowe lub zmodyfikowane wiersze w magazynie danych.
To zdarzenie występuje za każdym razem, gdy użytkownik zmieni bieżący wiersz.
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
Zaimplementuj program obsługi zdarzenia RowDirtyStateNeeded , który wskazuje, czy CancelRowEdit zdarzenie będzie miało miejsce, gdy użytkownik sygnalizuje zmianę wiersza, naciskając dwukrotnie klawisz ESC w trybie edycji lub raz poza trybem edycji.
Domyślnie następuje przekierowanie wierszy, CancelRowEdit gdy wszystkie komórki w bieżącym wierszu zostały zmodyfikowane, chyba że QuestionEventArgs.Response właściwość jest ustawiona na
true
wartość w procedurze RowDirtyStateNeeded obsługi zdarzeń. To zdarzenie jest przydatne, gdy zakres zatwierdzenia jest określany w czasie wykonywania.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
Zaimplementuj program obsługi zdarzenia CancelRowEdit , który odrzuca wartości
Customer
obiektu reprezentującego bieżący wiersz.To zdarzenie występuje, gdy użytkownik sygnalizuje zmianę wiersza przez dwukrotne naciśnięcie klawisza ESC w trybie edycji lub raz poza trybem edycji. To zdarzenie nie występuje, jeśli w bieżącym wierszu nie zmodyfikowano żadnych komórek lub jeśli wartość QuestionEventArgs.Response właściwości została ustawiona na
false
w procedurze obsługi zdarzeń 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
Zaimplementuj program obsługi zdarzenia UserDeletingRow , który usuwa istniejący
Customer
obiekt z magazynu danych lub odrzuca niezapisanyCustomer
obiekt reprezentujący nowo utworzony wiersz.To zdarzenie występuje za każdym razem, gdy użytkownik usunie wiersz, klikając nagłówek wiersza i naciskając klawisz 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
Zaimplementuj prostą
Customers
klasę do reprezentowania elementów danych używanych w tym przykładzie kodu.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
Testowanie aplikacji
Teraz możesz przetestować formularz, aby upewnić się, że działa zgodnie z oczekiwaniami.
Aby przetestować formularz
Skompiluj i uruchom aplikację.
Zostanie wyświetlona kontrolka DataGridView wypełniona trzema rekordami klienta. Możesz zmodyfikować wartości wielu komórek w wierszu i dwukrotnie nacisnąć klawisz ESC w trybie edycji, a raz poza trybem edycji, aby przywrócić cały wiersz do jego oryginalnych wartości. Podczas modyfikowania, dodawania lub usuwania wierszy w kontrolce
Customer
obiekty w magazynie danych również są modyfikowane, dodawane lub usuwane.
Następne kroki
Ta aplikacja zapewnia podstawową wiedzę na temat zdarzeń, które należy obsługiwać w celu zaimplementowania trybu wirtualnego w kontrolce DataGridView . Tę podstawową aplikację można ulepszyć na wiele sposobów:
Zaimplementuj magazyn danych, który buforuje wartości z zewnętrznej bazy danych. Pamięć podręczna powinna pobierać i odrzucać wartości zgodnie z potrzebami, tak aby zawierała tylko to, co jest niezbędne do wyświetlania, jednocześnie zużywając niewielką ilość pamięci na komputerze klienckim.
Dostosuj wydajność magazynu danych w zależności od wymagań. Na przykład możesz chcieć zrekompensować wolne połączenia sieciowe, a nie ograniczenia pamięci komputera klienckiego przy użyciu większego rozmiaru pamięci podręcznej i zminimalizować liczbę zapytań bazy danych.
Aby uzyskać więcej informacji na temat buforowania wartości z zewnętrznej bazy danych, zobacz Instrukcje: implementowanie trybu wirtualnego przy użyciu ładowania danych just in time w kontrolce DataGridView formularzy systemu Windows.
Zobacz też
- DataGridView
- VirtualMode
- CellValueNeeded
- CellValuePushed
- NewRowNeeded
- RowValidated
- RowDirtyStateNeeded
- CancelRowEdit
- UserDeletingRow
- Dostrajanie wydajności w kontrolce DataGridView formularzy Windows Forms
- Najlepsze praktyki dotyczące skalowania kontrolki DataGridView formularzy Windows Forms
- Implementowanie trybu wirtualnego przy użyciu ładowania danych Just-In-Time w kontrolce DataGridView formularzy Windows Forms
- Instrukcje: implementowanie trybu wirtualnego w kontrolce DataGridView formularzy Windows Forms
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