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. 委派所封裝的方法,將項目加入清單方塊中,並擁有表單的基礎控制代碼的執行緒上執行此方法。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,Invoke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
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 'New

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

   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 'AddListItemMethod

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

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


' 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 'New

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

End Class 'MyThreadClass

備註

委派就類似在 C 或 c + + 語言中的函式指標。Delegates are similar to function pointers in C or C++ languages. 委派會封裝內委派物件的方法的參考。Delegates encapsulate a reference to a method inside a delegate object. 委派物件接著傳遞至程式碼呼叫受參考的方法,並在編譯時期,會叫用的方法可以是未知。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. 不同於在 C 或 c + + 中的函式指標,委派是物件導向、 型別安全且更安全。Unlike function pointers in C or C++, delegates are object-oriented, type-safe, and more secure.

Invoke方法會搜尋控制項的父鏈結,直到它找到一個控制項或表單已期間之處理,如果尚不存在目前的控制項基礎視窗控制代碼。The 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. 如果找不到任何適當的控制代碼,Invoke方法會擲回例外狀況。If no appropriate handle can be found, the Invoke method will throw an exception. 在呼叫期間引發的例外狀況會傳播回呼叫端。Exceptions that are raised during the call will be propagated back to the caller.

注意

除了InvokeRequired屬性,在控制項上都是安全執行緒的四種方法: InvokeBeginInvokeEndInvoke,和CreateGraphics如果已經建立控制項的控制代碼。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. 呼叫CreateGraphics背景執行緒上建立控制項的控制代碼之前可能會導致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. 所有其他的方法呼叫中,您應該使用其中一種叫用方法來對控制項的執行緒的呼叫封送處理。For all other method calls, you should use one of the invoke methods to marshal the call to the control's thread.

委派可以是執行個體EventHandler,在此情況下的傳送者參數會包含此控制項中,與事件參數會包含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. 委派也可以是執行個體MethodInvoker,或任何其他委派會使用 void 參數清單。The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. 呼叫EventHandlerMethodInvoker委派的速度會比其他類型的委派呼叫。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為使用中,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, params object[] args);
abstract member Invoke : Delegate * obj[] -> obj
override this.Invoke : Delegate * obj[] -> obj
Public Function Invoke (method As Delegate, ParamArray 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. 委派所封裝的方法,將項目加入清單方塊中,並擁有的表單中,使用指定的引數的基礎控制代碼的執行緒上執行此方法。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,Invoke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
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 'New

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

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

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

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

Public Class MyThreadClass
   Private myFormControl1 As MyFormControl

   Public Sub New(myForm As MyFormControl)
      myFormControl1 = myForm
   End Sub 'New
   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 'Run
End Class 'MyThreadClass

備註

委派就類似在 C 或 c + + 語言中的函式指標。Delegates are similar to function pointers in C or C++ languages. 委派會封裝內委派物件的方法的參考。Delegates encapsulate a reference to a method inside a delegate object. 委派物件接著傳遞至程式碼呼叫受參考的方法,並在編譯時期,會叫用的方法可以是未知。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. 不同於在 C 或 c + + 中的函式指標,委派是物件導向、 型別安全且更安全。Unlike function pointers in C or C++, delegates are object-oriented, type-safe, and more secure.

如果尚不存在的控制項控點,直到它找到的控制項或表單沒有視窗控制代碼,這個方法會搜尋控制項的父鏈結。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. 如果找不到任何適當的控制代碼,這個方法會擲回例外狀況。If no appropriate handle can be found, this method throws an exception. 在呼叫期間引發的例外狀況會傳播回呼叫端。Exceptions that are raised during the call will be propagated back to the caller.

注意

除了InvokeRequired屬性,在控制項上都是安全執行緒的四種方法: InvokeBeginInvokeEndInvoke,和CreateGraphics如果已經建立控制項的控制代碼。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. 呼叫CreateGraphics背景執行緒上建立控制項的控制代碼之前可能會導致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. 所有其他的方法呼叫中,您應該使用其中一種叫用方法來對控制項的執行緒的呼叫封送處理。For all other method calls, you should use one of the invoke methods to marshal the call to the control's thread.

委派可以是執行個體EventHandler,在此情況下的傳送者參數會包含此控制項中,與事件參數會包含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. 委派也可以是執行個體MethodInvoker,或任何其他委派會使用 void 參數清單。The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. 呼叫EventHandlerMethodInvoker委派的速度會比其他類型的委派呼叫。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為使用中,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