Control.Invoke Control.Invoke Control.Invoke Control.Invoke Method

定義

在擁有控制項基礎視窗控制代碼的執行緒上執行委派。Executes a delegate on the thread that owns the control's underlying window handle.

多載

Invoke(Delegate) Invoke(Delegate) Invoke(Delegate) Invoke(Delegate)

在擁有控制項基礎視窗控制代碼的執行緒上執行指定的委派。Executes the specified delegate on the thread that owns the control's underlying window handle.

Invoke(Delegate, Object[]) Invoke(Delegate, Object[]) Invoke(Delegate, Object[]) Invoke(Delegate, Object[])

在擁有控制項基礎視窗控制代碼的執行緒上,以指定的引數清單執行指定的委派。Executes the specified delegate, on the thread that owns the control's underlying window handle, with the specified list of arguments.

Invoke(Delegate) Invoke(Delegate) Invoke(Delegate) Invoke(Delegate)

在擁有控制項基礎視窗控制代碼的執行緒上執行指定的委派。Executes the specified delegate on the thread that owns the control's underlying window handle.

public:
 System::Object ^ Invoke(Delegate ^ method);
public object Invoke (Delegate method);
member this.Invoke : Delegate -> obj
Public Function Invoke (method As Delegate) As Object

參數

method
Delegate Delegate Delegate Delegate

委派,包含要在控制項執行緒內容中呼叫的方法。A delegate that contains a method to be called in the control's thread context.

傳回

來自所叫用的委派的傳回值,或者如果委派沒有任何傳回值,則為 nullThe return value from the delegate being invoked, or null if the delegate has no return value.

範例

下列程式碼範例顯示包含委派的控制項。The following code example shows controls that contain a delegate. 委派會封裝將專案新增至清單方塊的方法,而這個方法會在擁有表單基礎控制碼的執行緒上執行。The delegate encapsulates a method that adds items to the list box, and this method is executed on the thread that owns the underlying handle of the form. 當使用者按一下按鈕時, Invoke會執行委派。When the user clicks on the button, Invoke runs the delegate.

/*
The following example demonstrates the 'Invoke(Delegate*)' method of 'Control class.
A 'ListBox' and a 'Button' control are added to a form, containing a delegate
which encapsulates a method that adds items to the listbox.This function is executed
on the thread that owns the underlying handle of the form. When user clicks on button
the above delegate is executed using 'Invoke' method.
*/

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

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Threading;

public ref class MyFormControl: public Form
{
public:
   delegate void AddListItem();
   AddListItem^ myDelegate;

private:
   Button^ myButton;
   Thread^ myThread;
   ListBox^ myListBox;

public:
   MyFormControl();
   void AddListItemMethod()
   {
      String^ myItem;
      for ( int i = 1; i < 6; i++ )
      {
         myItem = "MyListItem {0}",i;
         myListBox->Items->Add( myItem );
         myListBox->Update();
         Thread::Sleep( 300 );
      }
   }

private:
   void Button_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      myThread = gcnew Thread( gcnew ThreadStart( this, &MyFormControl::ThreadFunction ) );
      myThread->Start();
   }

   void ThreadFunction();
};


// The following code assumes a 'ListBox' and a 'Button' control are added to a form,
// containing a delegate which encapsulates a method that adds items to the listbox.
public ref class MyThreadClass
{
private:
   MyFormControl^ myFormControl1;

public:
   MyThreadClass( MyFormControl^ myForm )
   {
      myFormControl1 = myForm;
   }

   void Run()
   {
      // Execute the specified delegate on the thread that owns
      // 'myFormControl1' control's underlying window handle.
      myFormControl1->Invoke( myFormControl1->myDelegate );
   }
};


MyFormControl::MyFormControl()
{
   myButton = gcnew Button;
   myListBox = gcnew ListBox;
   myButton->Location = Point( 72, 160 );
   myButton->Size = System::Drawing::Size( 152, 32 );
   myButton->TabIndex = 1;
   myButton->Text = "Add items in list box";
   myButton->Click += gcnew EventHandler( this, &MyFormControl::Button_Click );
   myListBox->Location = Point( 48, 32 );
   myListBox->Name = "myListBox";
   myListBox->Size = System::Drawing::Size( 200, 95 );
   myListBox->TabIndex = 2;
   ClientSize = System::Drawing::Size( 292, 273 );
   array<Control^>^ temp0 = {myListBox,myButton};
   Controls->AddRange( temp0 );
   Text = " 'Control_Invoke' example";
   myDelegate = gcnew AddListItem( this, &MyFormControl::AddListItemMethod );
}

void MyFormControl::ThreadFunction()
{
   MyThreadClass^ myThreadClassObject = gcnew MyThreadClass( this );
   myThreadClassObject->Run();
}

int main()
{
   MyFormControl^ myForm = gcnew MyFormControl;
   myForm->ShowDialog();
}
/*
The following example demonstrates the 'Invoke(Delegate)' method of 'Control class.
A 'ListBox' and a 'Button' control are added to a form, containing a delegate
which encapsulates a method that adds items to the listbox.This function is executed
on the thread that owns the underlying handle of the form. When user clicks on button
the above delegate is executed using 'Invoke' method.


*/

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;

   public class MyFormControl : Form
   {
      public delegate void AddListItem();
      public AddListItem myDelegate;
      private Button myButton;
      private Thread myThread;
      private ListBox myListBox;
      public MyFormControl()
      {
         myButton = new Button();
         myListBox = new ListBox();
         myButton.Location = new Point(72, 160);
         myButton.Size = new Size(152, 32);
         myButton.TabIndex = 1;
         myButton.Text = "Add items in list box";
         myButton.Click += new EventHandler(Button_Click);
         myListBox.Location = new Point(48, 32);
         myListBox.Name = "myListBox";
         myListBox.Size = new Size(200, 95);
         myListBox.TabIndex = 2;
         ClientSize = new Size(292, 273);
         Controls.AddRange(new Control[] {myListBox,myButton});
         Text = " 'Control_Invoke' example";
         myDelegate = new AddListItem(AddListItemMethod);
      }
      static void Main()
      {
         MyFormControl myForm = new MyFormControl();
         myForm.ShowDialog();
      }
      public void AddListItemMethod()
      {
         String myItem;
         for(int i=1;i<6;i++)
         {
            myItem = "MyListItem" + i.ToString();
            myListBox.Items.Add(myItem);
            myListBox.Update();
            Thread.Sleep(300);
         }
      }
      private void Button_Click(object sender, EventArgs e)
      {
         myThread = new Thread(new ThreadStart(ThreadFunction));
         myThread.Start();
      }
      private void ThreadFunction()
      {
         MyThreadClass myThreadClassObject  = new MyThreadClass(this);
         myThreadClassObject.Run();
      }
   }

// The following code assumes a 'ListBox' and a 'Button' control are added to a form, 
// containing a delegate which encapsulates a method that adds items to the listbox.

   public class MyThreadClass
   {
      MyFormControl myFormControl1;
      public MyThreadClass(MyFormControl myForm)
      {
         myFormControl1 = myForm;
      }

      public void Run()
      {
         // Execute the specified delegate on the thread that owns
         // 'myFormControl1' control's underlying window handle.
         myFormControl1.Invoke(myFormControl1.myDelegate);
      }
   }
' The following example demonstrates the 'Invoke(Delegate)' method of 'Control class.
' A 'ListBox' and a 'Button' control are added to a form, containing a delegate
' which encapsulates a method that adds items to the listbox.This function is executed
' on the thread that owns the underlying handle of the form. When user clicks on button
' the above delegate is executed using 'Invoke' method.

Imports System.Drawing
Imports System.Windows.Forms
Imports System.Threading

Public Class MyFormControl
   Inherits Form

   Delegate Sub AddListItem()
   Public myDelegate As AddListItem
   Private myButton As Button
   Private myThread As Thread
   Private myListBox As ListBox

   Public Sub New()
      myButton = New Button()
      myListBox = New ListBox()
      myButton.Location = New Point(72, 160)
      myButton.Size = New Size(152, 32)
      myButton.TabIndex = 1
      myButton.Text = "Add items in list box"
      AddHandler myButton.Click, AddressOf Button_Click
      myListBox.Location = New Point(48, 32)
      myListBox.Name = "myListBox"
      myListBox.Size = New Size(200, 95)
      myListBox.TabIndex = 2
      ClientSize = New Size(292, 273)
      Controls.AddRange(New Control() {myListBox, myButton})
      Text = " 'Control_Invoke' example"
      myDelegate = New AddListItem(AddressOf AddListItemMethod)
   End Sub

   Shared Sub Main()
      Dim myForm As New MyFormControl()
      myForm.ShowDialog()
   End Sub

   Public Sub AddListItemMethod()
      Dim myItem As String
      Dim i As Integer
      For i = 1 To 5
         myItem = "MyListItem" + i.ToString()
         myListBox.Items.Add(myItem)
         myListBox.Update()
         Thread.Sleep(300)
      Next i
   End Sub

   Private Sub Button_Click(sender As Object, e As EventArgs)
      myThread = New Thread(New ThreadStart(AddressOf ThreadFunction))
      myThread.Start()
   End Sub

   Private Sub ThreadFunction()
      Dim myThreadClassObject As New MyThreadClass(Me)
      myThreadClassObject.Run()
   End Sub
End Class


' The following code assumes a 'ListBox' and a 'Button' control are added to a form, 
' containing a delegate which encapsulates a method that adds items to the listbox.
Public Class MyThreadClass
   Private myFormControl1 As MyFormControl

   Public Sub New(myForm As MyFormControl)
      myFormControl1 = myForm
   End Sub

   Public Sub Run()
      ' Execute the specified delegate on the thread that owns
      ' 'myFormControl1' control's underlying window handle.
      myFormControl1.Invoke(myFormControl1.myDelegate)
   End Sub

End Class

備註

委派與 C 或C++語言中的函式指標類似。Delegates are similar to function pointers in C or C++ languages. 委派會封裝委派物件內方法的參考。Delegates encapsulate a reference to a method inside a delegate object. 然後,可以將委派物件傳遞至呼叫所參考方法的程式碼,而要叫用的方法在編譯時期可能是未知的。The delegate object can then be passed to code that calls the referenced method, and the method to be invoked can be unknown at compile time. 不同于 C 或C++中的函式指標,委派是物件導向、型別安全,而且更安全。Unlike function pointers in C or C++, delegates are object-oriented, type-safe, and more secure.

如果目前控制項的基礎視窗控制碼尚不存在,方法會搜尋控制項的父鏈,直到找到具有視窗控制碼的控制項或表單為止。InvokeThe Invoke method searches up the control's parent chain until it finds a control or form that has a window handle if the current control's underlying window handle does not exist yet. 如果找不到適當的控制碼, Invoke此方法將會擲回例外狀況。If no appropriate handle can be found, the Invoke method will throw an exception. 呼叫期間引發的例外狀況將會傳播回呼叫端。Exceptions that are raised during the call will be propagated back to the caller.

注意

除了InvokeRequired屬性之外,控制項上還有四個具備執行緒安全的方法: InvokeBeginInvokeEndInvokeCreateGraphics (如果已經建立控制項的控制碼)。In addition to the InvokeRequired property, there are four methods on a control that are thread safe: Invoke, BeginInvoke, EndInvoke, and CreateGraphics if the handle for the control has already been created. CreateGraphics背景執行緒上建立控制項的控制碼之前呼叫,可能會造成不合法的跨執行緒呼叫。Calling CreateGraphics before the control's handle has been created on a background thread can cause illegal cross thread calls. 對於所有其他方法呼叫,您應該使用其中一個 invoke 方法,將呼叫封送處理至控制項的執行緒。For all other method calls, you should use one of the invoke methods to marshal the call to the control's thread.

委派可以是的實例EventHandler,在這種情況下,傳送者參數會包含這個控制項,而事件參數將包含。 EventArgs.EmptyThe delegate can be an instance of EventHandler, in which case the sender parameter will contain this control, and the event parameter will contain EventArgs.Empty. 委派也可以是的MethodInvoker實例,或任何接受 void 參數清單的其他委派。The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. 呼叫EventHandlerMethodInvoker委派的速度會比另一個委派類型的呼叫更快。A call to an EventHandler or MethodInvoker delegate will be faster than a call to another type of delegate.

注意

如果應該處理訊息的執行緒不再使用中,可能會擲回例外狀況。An exception might be thrown if the thread that should process the message is no longer active.

另請參閱

Invoke(Delegate, Object[]) Invoke(Delegate, Object[]) Invoke(Delegate, Object[]) Invoke(Delegate, Object[])

在擁有控制項基礎視窗控制代碼的執行緒上,以指定的引數清單執行指定的委派。Executes the specified delegate, on the thread that owns the control's underlying window handle, with the specified list of arguments.

public:
 virtual System::Object ^ Invoke(Delegate ^ method, cli::array <System::Object ^> ^ args);
public object Invoke (Delegate method, object[] args);
abstract member Invoke : Delegate * obj[] -> obj
override this.Invoke : Delegate * obj[] -> obj
Public Function Invoke (method As Delegate, args As Object()) As Object

參數

method
Delegate Delegate Delegate Delegate

方法的委派,採用和 args 參數中包含者相同的數字和類型的參數。A delegate to a method that takes parameters of the same number and type that are contained in the args parameter.

args
Object[]

做為引數傳遞至指定方法的物件陣列。An array of objects to pass as arguments to the specified method. 如果方法沒有引數,這個參數可能是 nullThis parameter can be null if the method takes no arguments.

傳回

Object,包含所叫用的委派的傳回值,如果委派沒有傳回值,則為 nullAn Object that contains the return value from the delegate being invoked, or null if the delegate has no return value.

實作

範例

下列程式碼範例顯示包含委派的控制項。The following code example shows controls that contain a delegate. 委派會封裝將專案新增至清單方塊的方法,而這個方法會在擁有表單基礎控制碼的執行緒上,使用指定的引數來執行。The delegate encapsulates a method that adds items to the list box, and this method is executed on the thread that owns the underlying handle of the form, using the specified arguments. 當使用者按一下按鈕時, Invoke會執行委派。When the user clicks on the button, Invoke runs the delegate.

using namespace System;
using namespace System::Drawing;
using namespace System::ComponentModel;
using namespace System::Windows::Forms;
using namespace System::Threading;
ref class MyFormControl: public Form
{
public:
   delegate void AddListItem( String^ myString );
   AddListItem^ myDelegate;

private:
   Button^ myButton;
   Thread^ myThread;
   ListBox^ myListBox;

public:
   MyFormControl();
   void AddListItemMethod( String^ myString );

private:
   void Button_Click( Object^ sender, EventArgs^ e );
   void ThreadFunction();
};

ref class MyThreadClass
{
private:
   MyFormControl^ myFormControl1;

public:
   MyThreadClass( MyFormControl^ myForm )
   {
      myFormControl1 = myForm;
   }

   String^ myString;
   void Run()
   {
      for ( int i = 1; i <= 5; i++ )
      {
         myString = String::Concat( "Step number ", i, " executed" );
         Thread::Sleep( 400 );
         
         // Execute the specified delegate on the thread that owns
         // 'myFormControl1' control's underlying window handle with
         // the specified list of arguments.
         array<Object^>^myStringArray = {myString};
         myFormControl1->Invoke( myFormControl1->myDelegate, myStringArray );

      }
   }

};

MyFormControl::MyFormControl()
{
   myButton = gcnew Button;
   myListBox = gcnew ListBox;
   myButton->Location = Point(72,160);
   myButton->Size = System::Drawing::Size( 152, 32 );
   myButton->TabIndex = 1;
   myButton->Text = "Add items in list box";
   myButton->Click += gcnew EventHandler( this, &MyFormControl::Button_Click );
   myListBox->Location = Point(48,32);
   myListBox->Name = "myListBox";
   myListBox->Size = System::Drawing::Size( 200, 95 );
   myListBox->TabIndex = 2;
   ClientSize = System::Drawing::Size( 292, 273 );
   array<Control^>^formControls = {myListBox,myButton};
   Controls->AddRange( formControls );
   Text = " 'Control_Invoke' example ";
   myDelegate = gcnew AddListItem( this, &MyFormControl::AddListItemMethod );
}

void MyFormControl::AddListItemMethod( String^ myString )
{
   myListBox->Items->Add( myString );
}

void MyFormControl::Button_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
   myThread = gcnew Thread( gcnew ThreadStart( this, &MyFormControl::ThreadFunction ) );
   myThread->Start();
}

void MyFormControl::ThreadFunction()
{
   MyThreadClass^ myThreadClassObject = gcnew MyThreadClass( this );
   myThreadClassObject->Run();
}

int main()
{
   MyFormControl^ myForm = gcnew MyFormControl;
   myForm->ShowDialog();
}

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;

   public class MyFormControl : Form
   {
      public delegate void AddListItem(String myString);
      public AddListItem myDelegate;
      private Button myButton;
      private Thread myThread;
      private ListBox myListBox;
      public MyFormControl()
      {
         myButton = new Button();
         myListBox = new ListBox();
         myButton.Location = new Point(72, 160);
         myButton.Size = new Size(152, 32);
         myButton.TabIndex = 1;
         myButton.Text = "Add items in list box";
         myButton.Click += new EventHandler(Button_Click);
         myListBox.Location = new Point(48, 32);
         myListBox.Name = "myListBox";
         myListBox.Size = new Size(200, 95);
         myListBox.TabIndex = 2;
         ClientSize = new Size(292, 273);
         Controls.AddRange(new Control[] {myListBox,myButton});
         Text = " 'Control_Invoke' example ";
         myDelegate = new AddListItem(AddListItemMethod);
      }
      static void Main()
      {
         MyFormControl myForm = new MyFormControl();
         myForm.ShowDialog();
      }
      public void AddListItemMethod(String myString)
      {
            myListBox.Items.Add(myString);
      }
      private void Button_Click(object sender, EventArgs e)
      {
         myThread = new Thread(new ThreadStart(ThreadFunction));
         myThread.Start();
      }
      private void ThreadFunction()
      {
         MyThreadClass myThreadClassObject  = new MyThreadClass(this);
         myThreadClassObject.Run();
      }
   }
   public class MyThreadClass
   {
      MyFormControl myFormControl1;
      public MyThreadClass(MyFormControl myForm)
      {
         myFormControl1 = myForm;
      }
      String myString;

      public void Run()
      {


         for (int i = 1; i <= 5; i++)
         {
            myString = "Step number " + i.ToString() + " executed";
            Thread.Sleep(400);
            // Execute the specified delegate on the thread that owns
            // 'myFormControl1' control's underlying window handle with
            // the specified list of arguments.
            myFormControl1.Invoke(myFormControl1.myDelegate,
                                   new Object[] {myString});
         }
      }
   }
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Threading

Public Class MyFormControl
   Inherits Form

   Delegate Sub AddListItem(myString As String)
   Public myDelegate As AddListItem
   Private myButton As Button
   Private myThread As Thread
   Private myListBox As ListBox

   Public Sub New()
      myButton = New Button()
      myListBox = New ListBox()
      myButton.Location = New Point(72, 160)
      myButton.Size = New Size(152, 32)
      myButton.TabIndex = 1
      myButton.Text = "Add items in list box"
      AddHandler myButton.Click, AddressOf Button_Click
      myListBox.Location = New Point(48, 32)
      myListBox.Name = "myListBox"
      myListBox.Size = New Size(200, 95)
      myListBox.TabIndex = 2
      ClientSize = New Size(292, 273)
      Controls.AddRange(New Control() {myListBox, myButton})
      Text = " 'Control_Invoke' example "
      myDelegate = New AddListItem(AddressOf AddListItemMethod)
   End Sub

   Shared Sub Main()
      Dim myForm As New MyFormControl()
      myForm.ShowDialog()
   End Sub

   Public Sub AddListItemMethod(myString As String)
      myListBox.Items.Add(myString)
   End Sub

   Private Sub Button_Click(sender As Object, e As EventArgs)
      myThread = New Thread(New ThreadStart(AddressOf ThreadFunction))
      myThread.Start()
   End Sub

   Private Sub ThreadFunction()
      Dim myThreadClassObject As New MyThreadClass(Me)
      myThreadClassObject.Run()
   End Sub
End Class

Public Class MyThreadClass
   Private myFormControl1 As MyFormControl

   Public Sub New(myForm As MyFormControl)
      myFormControl1 = myForm
   End Sub
   Private myString As String

   Public Sub Run()

      Dim i As Integer
      For i = 1 To 5
         myString = "Step number " + i.ToString() + " executed"
         Thread.Sleep(400)
         ' Execute the specified delegate on the thread that owns
         ' 'myFormControl1' control's underlying window handle with
         ' the specified list of arguments.
         myFormControl1.Invoke(myFormControl1.myDelegate, New Object() {myString})
      Next i

   End Sub
End Class

備註

委派與 C 或C++語言中的函式指標類似。Delegates are similar to function pointers in C or C++ languages. 委派會封裝委派物件內方法的參考。Delegates encapsulate a reference to a method inside a delegate object. 然後,可以將委派物件傳遞至呼叫所參考方法的程式碼,而要叫用的方法在編譯時期可能是未知的。The delegate object can then be passed to code that calls the referenced method, and the method to be invoked can be unknown at compile time. 不同于 C 或C++中的函式指標,委派是物件導向、型別安全,而且更安全。Unlike function pointers in C or C++, delegates are object-oriented, type-safe, and more secure.

如果控制項的控制碼尚不存在,則這個方法會搜尋控制項的父鏈,直到找到有視窗控制碼的控制項或表單為止。If the control's handle does not exist yet, this method searches up the control's parent chain until it finds a control or form that does have a window handle. 如果找不到適當的控制碼,則這個方法會擲回例外狀況。If no appropriate handle can be found, this method throws an exception. 呼叫期間引發的例外狀況將會傳播回呼叫端。Exceptions that are raised during the call will be propagated back to the caller.

注意

除了InvokeRequired屬性之外,控制項上還有四個具備執行緒安全的方法: InvokeBeginInvokeEndInvokeCreateGraphics (如果已經建立控制項的控制碼)。In addition to the InvokeRequired property, there are four methods on a control that are thread safe: Invoke, BeginInvoke, EndInvoke, and CreateGraphics if the handle for the control has already been created. CreateGraphics背景執行緒上建立控制項的控制碼之前呼叫,可能會造成不合法的跨執行緒呼叫。Calling CreateGraphics before the control's handle has been created on a background thread can cause illegal cross thread calls. 對於所有其他方法呼叫,您應該使用其中一個 invoke 方法,將呼叫封送處理至控制項的執行緒。For all other method calls, you should use one of the invoke methods to marshal the call to the control's thread.

委派可以是的實例EventHandler,在這種情況下,傳送者參數會包含這個控制項,而事件參數將包含。 EventArgs.EmptyThe delegate can be an instance of EventHandler, in which case the sender parameter will contain this control, and the event parameter will contain EventArgs.Empty. 委派也可以是的MethodInvoker實例,或任何接受 void 參數清單的其他委派。The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. 呼叫EventHandlerMethodInvoker委派的速度會比另一個委派類型的呼叫更快。A call to an EventHandler or MethodInvoker delegate will be faster than a call to another type of delegate.

注意

如果應該處理訊息的執行緒不再使用中,可能會擲回例外狀況。An exception might be thrown if the thread that should process the message is no longer active.

另請參閱

適用於