ListView.BeginUpdate Method
Definition
Important
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Prevents the control from drawing until the EndUpdate() method is called.
public:
void BeginUpdate();public void BeginUpdate ();member this.BeginUpdate : unit -> unitPublic Sub BeginUpdate ()Examples
The following code example demonstrates initializing a ListView control to contain check boxes. It also demonstrates how to use the BeginUpdate and EndUpdate methods. To run this example, paste the following code into a form that contains a ListView named ListView1. Call the InitializeListView method from the form's constructor or Load method.
void InitializeListView()
{
this->ListView1 = gcnew System::Windows::Forms::ListView;
// Set properties such as BackColor and DockStyle and Location.
this->ListView1->BackColor = System::Drawing::SystemColors::Control;
this->ListView1->Dock = System::Windows::Forms::DockStyle::Top;
this->ListView1->Location = System::Drawing::Point( 0, 0 );
this->ListView1->Size = System::Drawing::Size( 292, 130 );
this->ListView1->View = System::Windows::Forms::View::Details;
this->ListView1->HideSelection = false;
// Allow the user to select multiple items.
this->ListView1->MultiSelect = true;
// Show CheckBoxes in the ListView.
this->ListView1->CheckBoxes = true;
//Set the column headers and populate the columns.
ListView1->HeaderStyle = ColumnHeaderStyle::Nonclickable;
ColumnHeader^ columnHeader1 = gcnew ColumnHeader;
columnHeader1->Text = "Breakfast Choices";
columnHeader1->TextAlign = HorizontalAlignment::Left;
columnHeader1->Width = 146;
ColumnHeader^ columnHeader2 = gcnew ColumnHeader;
columnHeader2->Text = "Price Each";
columnHeader2->TextAlign = HorizontalAlignment::Center;
columnHeader2->Width = 142;
this->ListView1->Columns->Add( columnHeader1 );
this->ListView1->Columns->Add( columnHeader2 );
array<String^>^foodList = {"Juice","Coffee","Cereal & Milk","Fruit Plate","Toast & Jelly","Bagel & Cream Cheese"};
array<String^>^foodPrice = {"1.09","1.09","2.19","2.79","2.09","2.69"};
int count;
// Members are added one at a time, so call BeginUpdate to ensure
// the list is painted only once, rather than as each list item is added.
ListView1->BeginUpdate();
for ( count = 0; count < foodList->Length; count++ )
{
ListViewItem^ listItem = gcnew ListViewItem( foodList[ count ] );
listItem->SubItems->Add( foodPrice[ count ] );
ListView1->Items->Add( listItem );
}
//Call EndUpdate when you finish adding items to the ListView.
ListView1->EndUpdate();
this->Controls->Add( this->ListView1 );
}
private void InitializeListView()
{
this.ListView1 = new System.Windows.Forms.ListView();
// Set properties such as BackColor and DockStyle and Location.
this.ListView1.BackColor = System.Drawing.SystemColors.Control;
this.ListView1.Dock = System.Windows.Forms.DockStyle.Top;
this.ListView1.Location = new System.Drawing.Point(0, 0);
this.ListView1.Size = new System.Drawing.Size(292, 130);
this.ListView1.View = System.Windows.Forms.View.Details;
this.ListView1.HideSelection = false;
// Allow the user to select multiple items.
this.ListView1.MultiSelect = true;
// Show CheckBoxes in the ListView.
this.ListView1.CheckBoxes = true;
//Set the column headers and populate the columns.
ListView1.HeaderStyle = ColumnHeaderStyle.Nonclickable;
ColumnHeader columnHeader1 = new ColumnHeader();
columnHeader1.Text = "Breakfast Choices";
columnHeader1.TextAlign = HorizontalAlignment.Left;
columnHeader1.Width = 146;
ColumnHeader columnHeader2 = new ColumnHeader();
columnHeader2.Text = "Price Each";
columnHeader2.TextAlign = HorizontalAlignment.Center;
columnHeader2.Width = 142;
this.ListView1.Columns.Add(columnHeader1);
this.ListView1.Columns.Add(columnHeader2);
string[] foodList = new string[]{"Juice", "Coffee",
"Cereal & Milk", "Fruit Plate", "Toast & Jelly",
"Bagel & Cream Cheese"};
string[] foodPrice = new string[]{"1.09", "1.09", "2.19",
"2.79", "2.09", "2.69"};
int count;
// Members are added one at a time, so call BeginUpdate to ensure
// the list is painted only once, rather than as each list item is added.
ListView1.BeginUpdate();
for(count = 0; count < foodList.Length; count++)
{
ListViewItem listItem = new ListViewItem(foodList[count]);
listItem.SubItems.Add(foodPrice[count]);
ListView1.Items.Add(listItem);
}
//Call EndUpdate when you finish adding items to the ListView.
ListView1.EndUpdate();
this.Controls.Add(this.ListView1);
}
Private Sub InitializeListView()
Me.ListView1 = New System.Windows.Forms.ListView
' Set properties such as BackColor, Location and Size
Me.ListView1.BackColor = System.Drawing.SystemColors.Control
Me.ListView1.Dock = System.Windows.Forms.DockStyle.Top
Me.ListView1.Location = New System.Drawing.Point(0, 0)
Me.ListView1.Size = New System.Drawing.Size(292, 130)
Me.ListView1.View = System.Windows.Forms.View.Details
Me.ListView1.HideSelection = False
' Allow user to select multiple items.
Me.ListView1.MultiSelect = True
' Show check boxes in the ListView.
Me.ListView1.CheckBoxes = True
'Set the column headers and populate the columns.
ListView1.HeaderStyle = ColumnHeaderStyle.Nonclickable
Dim columnHeader1 As New ColumnHeader
With columnHeader1
.Text = "Breakfast Choices"
.TextAlign = HorizontalAlignment.Left
.Width = 146
End With
Dim columnHeader2 As New ColumnHeader
With columnHeader2
.Text = "Price Each"
.TextAlign = HorizontalAlignment.Center
.Width = 142
End With
Me.ListView1.Columns.Add(columnHeader1)
Me.ListView1.Columns.Add(columnHeader2)
Dim foodList() As String = New String() {"Juice", "Coffee", _
"Cereal & Milk", "Fruit Plate", "Toast & Jelly", _
"Bagel & Cream Cheese"}
Dim foodPrice() As String = New String() {"1.09", "1.09", "2.19", _
"2.79", "2.09", "2.69"}
Dim count As Integer
' Members are added one at a time, so call BeginUpdate to ensure
' the list is painted only once, rather than as each list item is added.
ListView1.BeginUpdate()
For count = 0 To foodList.Length - 1
Dim listItem As New ListViewItem(foodList(count))
listItem.SubItems.Add(foodPrice(count))
ListView1.Items.Add(listItem)
Next
'Call EndUpdate when you finish adding items to the ListView.
ListView1.EndUpdate()
Me.Controls.Add(Me.ListView1)
End Sub
Remarks
The preferred way to add multiple items to a ListView is to use the AddRange method of the ListView.ListViewItemCollection (accessed through the Items property of the ListView). This enables you to add an array of items to the list in a single operation. However, if you want to add items one at a time using the Add method of the ListView.ListViewItemCollection class, you can use the BeginUpdate method to prevent the control from repainting the ListView every time that an item is added. When you have completed the task of adding items to the control, call the EndUpdate method to enable the ListView to repaint. This way of adding items can prevent flickered drawing of the ListView when lots of items are being added to the control.
If BeginUpdate is called more than once, EndUpdate must be called an equivalent number of times. Until the last call to EndUpdate the ListView will not repaint. Other than this, multiple calls to BeginUpdate have no effect.
