Dispatcher.BeginInvoke Method (Delegate, Object[]) (System.Windows.Threading)

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.NET Framework Class Library

Dispatcher.BeginInvoke Method (Delegate, Object[])

Updated: July 2008

Executes the specified delegate asynchronously with the specified arguments on the thread that the Dispatcher was created on.

Namespace: System.Windows.Threading
Assembly: WindowsBase (in WindowsBase.dll)

Syntax

Visual Basic (Declaration)

Public Function BeginInvoke ( _
	method As Delegate, _
	ParamArray args As Object() _
) As DispatcherOperation

Visual Basic (Usage)

Dim instance As Dispatcher
Dim method As [Delegate]
Dim args As Object()
Dim returnValue As DispatcherOperation

returnValue = instance.BeginInvoke(method, _
	args)

public DispatcherOperation BeginInvoke(
	Delegate method,
	params Object[] args
)

Visual C++

public:
DispatcherOperation^ BeginInvoke(
	Delegate^ method, 
	... array<Object^>^ args
)

JScript

public function BeginInvoke(
	method : Delegate, 
	... args : Object[]
) : DispatcherOperation

XAML

You cannot use methods in XAML.

Parameters

method: Type: System.Delegate
The delegate to a method that takes parameters specified in args, which is pushed onto the Dispatcher event queue.

args: Type: System.Object[]
An array of objects to pass as arguments to the given method. Can be null.

Return Value

Type: System.Windows.Threading.DispatcherOperation
An object, which is returned immediately after BeginInvoke is called, that can be used to interact with the delegate as it is pending execution in the event queue.

Remarks

The DispatcherOperation object returned by BeginInvoke can be used in several ways to interact with the specified delegate, such as:

Changing the DispatcherPriority of the delegate as it is pending execution in the event queue.
Removing the delegate from the event queue.
Waiting for the delegate to return.
Obtaining the value that the delegate returns after it is executed.

BeginInvoke is asynchronous; therefore, control returns immediately to the calling object after it is called.

In WPF, only the thread that created a DispatcherObject may access that object. For example, a background thread that is spun off from the main UI thread cannot update the contents of a Button that was created on the UI thread. In order for the background thread to access the Content property of the Button, the background thread must delegate the work to the Dispatcher associated with the UI thread. This is accomplished by using either Invoke or BeginInvoke. Invoke is synchronous and BeginInvoke is asynchronous. The operation is added to the event queue of the Dispatcher at the specified DispatcherPriority.

If BeginInvoke is called on a Dispatcher that has shut down, the status property of the returned DispatcherOperation is set to Aborted.

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information