TreeView.EndUpdate 方法
定义
重要
一些信息与预发行产品相关,相应产品在发行之前可能会进行重大修改。 对于此处提供的信息,Microsoft 不作任何明示或暗示的担保。
启用树视图的重绘。
public:
void EndUpdate();
public void EndUpdate ();
member this.EndUpdate : unit -> unit
Public Sub EndUpdate ()
示例
下面的代码示例在 控件中 TreeView 显示客户信息。 根树节点显示客户名称,子树节点显示分配给每个客户的订单号。 在此示例中,将显示 1,000 个客户,每个客户有 15 个订单。 使用 和 方法抑制 的TreeView重新粉刷,并在 创建和绘制 TreeNode 对象时TreeView显示等待Cursor。EndUpdateBeginUpdate 此示例要求你有一个 Customer
可以保存对象集合的对象 Order
。 它还要求具有在应用程序目录中命名MyWait.cur
的游标文件,并且已在 上Form创建了控件的TreeView实例。
// The basic Customer class.
ref class Customer: public System::Object
{
private:
String^ custName;
protected:
ArrayList^ custOrders;
public:
Customer( String^ customername )
{
custName = "";
custOrders = gcnew ArrayList;
this->custName = customername;
}
property String^ CustomerName
{
String^ get()
{
return this->custName;
}
void set( String^ value )
{
this->custName = value;
}
}
property ArrayList^ CustomerOrders
{
ArrayList^ get()
{
return this->custOrders;
}
}
};
// End Customer class
// The basic customer Order class.
ref class Order: public System::Object
{
private:
String^ ordID;
public:
Order( String^ orderid )
{
ordID = "";
this->ordID = orderid;
}
property String^ OrderID
{
String^ get()
{
return this->ordID;
}
void set( String^ value )
{
this->ordID = value;
}
}
};
// End Order class
void FillMyTreeView()
{
// Add customers to the ArrayList of Customer objects.
for ( int x = 0; x < 1000; x++ )
{
customerArray->Add( gcnew Customer( "Customer " + x ) );
}
// Add orders to each Customer object in the ArrayList.
IEnumerator^ myEnum = customerArray->GetEnumerator();
while ( myEnum->MoveNext() )
{
Customer^ customer1 = safe_cast<Customer^>(myEnum->Current);
for ( int y = 0; y < 15; y++ )
{
customer1->CustomerOrders->Add( gcnew Order( "Order " + y ) );
}
}
// Display a wait cursor while the TreeNodes are being created.
::Cursor::Current = gcnew System::Windows::Forms::Cursor( "MyWait.cur" );
// Suppress repainting the TreeView until all the objects have been created.
treeView1->BeginUpdate();
// Clear the TreeView each time the method is called.
treeView1->Nodes->Clear();
// Add a root TreeNode for each Customer object in the ArrayList.
myEnum = customerArray->GetEnumerator();
while ( myEnum->MoveNext() )
{
Customer^ customer2 = safe_cast<Customer^>(myEnum->Current);
treeView1->Nodes->Add( gcnew TreeNode( customer2->CustomerName ) );
// Add a child treenode for each Order object in the current Customer object.
IEnumerator^ myEnum = customer2->CustomerOrders->GetEnumerator();
while ( myEnum->MoveNext() )
{
Order^ order1 = safe_cast<Order^>(myEnum->Current);
treeView1->Nodes[ customerArray->IndexOf( customer2 ) ]->Nodes->Add( gcnew TreeNode( customer2->CustomerName + "." + order1->OrderID ) );
}
}
// Reset the cursor to the default for all controls.
::Cursor::Current = Cursors::Default;
// Begin repainting the TreeView.
treeView1->EndUpdate();
}
// The basic Customer class.
public class Customer : System.Object
{
private string custName = "";
protected ArrayList custOrders = new ArrayList();
public Customer(string customername)
{
this.custName = customername;
}
public string CustomerName
{
get{return this.custName;}
set{this.custName = value;}
}
public ArrayList CustomerOrders
{
get{return this.custOrders;}
}
} // End Customer class
// The basic customer Order class.
public class Order : System.Object
{
private string ordID = "";
public Order(string orderid)
{
this.ordID = orderid;
}
public string OrderID
{
get{return this.ordID;}
set{this.ordID = value;}
}
} // End Order class
// Create a new ArrayList to hold the Customer objects.
private ArrayList customerArray = new ArrayList();
private void FillMyTreeView()
{
// Add customers to the ArrayList of Customer objects.
for(int x=0; x<1000; x++)
{
customerArray.Add(new Customer("Customer" + x.ToString()));
}
// Add orders to each Customer object in the ArrayList.
foreach(Customer customer1 in customerArray)
{
for(int y=0; y<15; y++)
{
customer1.CustomerOrders.Add(new Order("Order" + y.ToString()));
}
}
// Display a wait cursor while the TreeNodes are being created.
Cursor.Current = new Cursor("MyWait.cur");
// Suppress repainting the TreeView until all the objects have been created.
treeView1.BeginUpdate();
// Clear the TreeView each time the method is called.
treeView1.Nodes.Clear();
// Add a root TreeNode for each Customer object in the ArrayList.
foreach(Customer customer2 in customerArray)
{
treeView1.Nodes.Add(new TreeNode(customer2.CustomerName));
// Add a child treenode for each Order object in the current Customer object.
foreach(Order order1 in customer2.CustomerOrders)
{
treeView1.Nodes[customerArray.IndexOf(customer2)].Nodes.Add(
new TreeNode(customer2.CustomerName + "." + order1.OrderID));
}
}
// Reset the cursor to the default for all controls.
Cursor.Current = Cursors.Default;
// Begin repainting the TreeView.
treeView1.EndUpdate();
}
Public Class Customer
Inherits [Object]
Private custName As String = ""
Friend custOrders As New ArrayList()
Public Sub New(ByVal customername As String)
Me.custName = customername
End Sub
Public Property CustomerName() As String
Get
Return Me.custName
End Get
Set(ByVal Value As String)
Me.custName = Value
End Set
End Property
Public ReadOnly Property CustomerOrders() As ArrayList
Get
Return Me.custOrders
End Get
End Property
End Class
Public Class Order
Inherits [Object]
Private ordID As String
Public Sub New(ByVal orderid As String)
Me.ordID = orderid
End Sub
Public Property OrderID() As String
Get
Return Me.ordID
End Get
Set(ByVal Value As String)
Me.ordID = Value
End Set
End Property
End Class
' Create a new ArrayList to hold the Customer objects.
Private customerArray As New ArrayList()
Private Sub FillMyTreeView()
' Add customers to the ArrayList of Customer objects.
Dim x As Integer
For x = 0 To 999
customerArray.Add(New Customer("Customer" + x.ToString()))
Next x
' Add orders to each Customer object in the ArrayList.
Dim customer1 As Customer
For Each customer1 In customerArray
Dim y As Integer
For y = 0 To 14
customer1.CustomerOrders.Add(New Order("Order" + y.ToString()))
Next y
Next customer1
' Display a wait cursor while the TreeNodes are being created.
Cursor.Current = New Cursor("MyWait.cur")
' Suppress repainting the TreeView until all the objects have been created.
treeView1.BeginUpdate()
' Clear the TreeView each time the method is called.
treeView1.Nodes.Clear()
' Add a root TreeNode for each Customer object in the ArrayList.
Dim customer2 As Customer
For Each customer2 In customerArray
treeView1.Nodes.Add(New TreeNode(customer2.CustomerName))
' Add a child TreeNode for each Order object in the current Customer object.
Dim order1 As Order
For Each order1 In customer2.CustomerOrders
treeView1.Nodes(customerArray.IndexOf(customer2)).Nodes.Add( _
New TreeNode(customer2.CustomerName + "." + order1.OrderID))
Next order1
Next customer2
' Reset the cursor to the default for all controls.
Cursor.Current = System.Windows.Forms.Cursors.Default
' Begin repainting the TreeView.
treeView1.EndUpdate()
End Sub
注解
若要在一次添加一个项时保持性能, TreeView请调用 BeginUpdate 方法。 方法 BeginUpdate 在调用 方法之前 EndUpdate 阻止控件绘制。
将项添加到树视图控件的首选方法是使用 AddRange 方法将树节点项数组添加到树视图。 但是,如果要一次添加一个项,请使用 BeginUpdate 方法来防止 TreeView 控件在添加操作期间绘制。 若要允许控件恢复绘制,请在将所有树节点添加到树视图中时调用 EndUpdate 方法。
适用于
另请参阅
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