Control.Invoke Méthode

Définition

Exécute un délégué sur le thread qui détient le handle de fenêtre sous-jacent du contrôle.Executes a delegate on the thread that owns the control's underlying window handle.

Surcharges

Invoke(Delegate)

Exécute le délégué spécifié sur le thread qui détient le handle de fenêtre sous-jacent du contrôle.Executes the specified delegate on the thread that owns the control's underlying window handle.

Invoke(Delegate, Object[])

Exécute le délégué spécifié sur le thread qui détient le handle de fenêtre sous-jacent du contrôle, avec la liste d’arguments spécifiée.Executes the specified delegate, on the thread that owns the control's underlying window handle, with the specified list of arguments.

Invoke(Delegate)

Exécute le délégué spécifié sur le thread qui détient le handle de fenêtre sous-jacent du contrôle.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

Paramètres

method
Delegate

Délégué qui contient une méthode à appeler dans le contexte du thread du contrôle.A delegate that contains a method to be called in the control's thread context.

Retours

Valeur de retour du délégué appelé ou null si le délégué n'a pas de valeur de retour.The return value from the delegate being invoked, or null if the delegate has no return value.

Exemples

L’exemple de code suivant affiche des contrôles qui contiennent un délégué.The following code example shows controls that contain a delegate. Le délégué encapsule une méthode qui ajoute des éléments à la zone de liste, et cette méthode est exécutée sur le thread qui possède le handle sous-jacent du formulaire.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. Quand l’utilisateur clique sur le bouton, Invoke exécute le délégué.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

Remarques

Les délégués sont semblables aux pointeurs de fonction en C++ C ou en langages.Delegates are similar to function pointers in C or C++ languages. Les délégués encapsulent une référence à une méthode à l’intérieur d’un objet délégué.Delegates encapsulate a reference to a method inside a delegate object. L’objet délégué peut ensuite être passé au code qui appelle la méthode référencée, et la méthode à appeler peut être inconnue au moment de la compilation.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. Contrairement aux pointeurs de fonction en C++C ou, les délégués sont orientés objet, de type sécurisé et plus sécurisés.Unlike function pointers in C or C++, delegates are object-oriented, type-safe, and more secure.

La méthode Invoke effectue une recherche dans la chaîne parente du contrôle jusqu’à ce qu’elle trouve un contrôle ou un formulaire ayant un handle de fenêtre si le handle de fenêtre sous-jacent du contrôle actuel n’existe pas encore.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. Si aucun handle approprié n’est trouvé, la méthode Invoke lèvera une exception.If no appropriate handle can be found, the Invoke method will throw an exception. Les exceptions levées pendant l’appel sont propagées à l’appelant.Exceptions that are raised during the call will be propagated back to the caller.

Notes

En plus de la propriété InvokeRequired, il existe quatre méthodes sur un contrôle thread-safe : Invoke, BeginInvoke, EndInvoke et CreateGraphics Si le handle du contrôle a déjà été créé.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. L’appel de CreateGraphics avant la création du handle du contrôle sur un thread d’arrière-plan peut entraîner des appels inter-threads non conformes.Calling CreateGraphics before the control's handle has been created on a background thread can cause illegal cross thread calls. Pour tous les autres appels de méthode, vous devez utiliser l’une des méthodes Invoke pour marshaler l’appel au thread du contrôle.For all other method calls, you should use one of the invoke methods to marshal the call to the control's thread.

Le délégué peut être une instance de EventHandler, auquel cas le paramètre sender contient ce contrôle, et le paramètre Event contient EventArgs.Empty.The 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. Le délégué peut également être une instance de MethodInvoker, ou tout autre délégué qui accepte une liste de paramètres void.The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. Un appel à un délégué EventHandler ou MethodInvoker est plus rapide qu’un appel à un autre type de délégué.A call to an EventHandler or MethodInvoker delegate will be faster than a call to another type of delegate.

Notes

Une exception peut être levée si le thread qui doit traiter le message n’est plus actif.An exception might be thrown if the thread that should process the message is no longer active.

Voir aussi

Invoke(Delegate, Object[])

Exécute le délégué spécifié sur le thread qui détient le handle de fenêtre sous-jacent du contrôle, avec la liste d’arguments spécifiée.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

Paramètres

method
Delegate

Délégué vers une méthode qui accepte des paramètres du même nombre et du même type que ceux contenus dans le paramètre args.A delegate to a method that takes parameters of the same number and type that are contained in the args parameter.

args
Object[]

Tableau d'objets à passer comme arguments à la méthode spécifiée.An array of objects to pass as arguments to the specified method. Ce paramètre peut être null si la méthode n'accepte aucun argument.This parameter can be null if the method takes no arguments.

Retours

Object qui contient la valeur de retour du délégué appelé ou null si le délégué n'a pas de valeur de retour.An Object that contains the return value from the delegate being invoked, or null if the delegate has no return value.

Implémente

Exemples

L’exemple de code suivant affiche des contrôles qui contiennent un délégué.The following code example shows controls that contain a delegate. Le délégué encapsule une méthode qui ajoute des éléments à la zone de liste, et cette méthode est exécutée sur le thread qui possède le handle sous-jacent du formulaire, à l’aide des arguments spécifiés.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. Quand l’utilisateur clique sur le bouton, Invoke exécute le délégué.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

Remarques

Les délégués sont semblables aux pointeurs de fonction en C++ C ou en langages.Delegates are similar to function pointers in C or C++ languages. Les délégués encapsulent une référence à une méthode à l’intérieur d’un objet délégué.Delegates encapsulate a reference to a method inside a delegate object. L’objet délégué peut ensuite être passé au code qui appelle la méthode référencée, et la méthode à appeler peut être inconnue au moment de la compilation.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. Contrairement aux pointeurs de fonction en C++C ou, les délégués sont orientés objet, de type sécurisé et plus sécurisés.Unlike function pointers in C or C++, delegates are object-oriented, type-safe, and more secure.

Si le handle du contrôle n’existe pas encore, cette méthode effectue une recherche dans la chaîne parente du contrôle jusqu’à ce qu’il trouve un contrôle ou un formulaire qui a un handle de fenêtre.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. Si aucun handle approprié n’est trouvé, cette méthode lève une exception.If no appropriate handle can be found, this method throws an exception. Les exceptions levées pendant l’appel sont propagées à l’appelant.Exceptions that are raised during the call will be propagated back to the caller.

Notes

En plus de la propriété InvokeRequired, il existe quatre méthodes sur un contrôle thread-safe : Invoke, BeginInvoke, EndInvoke et CreateGraphics Si le handle du contrôle a déjà été créé.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. L’appel de CreateGraphics avant la création du handle du contrôle sur un thread d’arrière-plan peut entraîner des appels inter-threads non conformes.Calling CreateGraphics before the control's handle has been created on a background thread can cause illegal cross thread calls. Pour tous les autres appels de méthode, vous devez utiliser l’une des méthodes Invoke pour marshaler l’appel au thread du contrôle.For all other method calls, you should use one of the invoke methods to marshal the call to the control's thread.

Le délégué peut être une instance de EventHandler, auquel cas le paramètre sender contient ce contrôle, et le paramètre Event contient EventArgs.Empty.The 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. Le délégué peut également être une instance de MethodInvoker, ou tout autre délégué qui accepte une liste de paramètres void.The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. Un appel à un délégué EventHandler ou MethodInvoker est plus rapide qu’un appel à un autre type de délégué.A call to an EventHandler or MethodInvoker delegate will be faster than a call to another type of delegate.

Notes

Une exception peut être levée si le thread qui doit traiter le message n’est plus actif.An exception might be thrown if the thread that should process the message is no longer active.

Voir aussi

S’applique à