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Dispatcher.Invoke Method (DispatcherPriority, TimeSpan, Delegate, Object, Object[])

Executes the specified delegate at the specified priority with the specified arguments synchronously on the thread the Dispatcher is associated with.

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

public Object Invoke (
	DispatcherPriority priority,
	TimeSpan timeout,
	Delegate method,
	Object arg,
	params Object[] args
)
public Object Invoke (
	DispatcherPriority priority, 
	TimeSpan timeout, 
	Delegate method, 
	Object arg, 
	Object[] args
)
public function Invoke (
	priority : DispatcherPriority, 
	timeout : TimeSpan, 
	method : Delegate, 
	arg : Object, 
	... args : Object[]
) : Object
You cannot use methods in XAML.

Parameters

priority

The priority, relative to the other pending operations in the Dispatcher event queue, the specified method is invoked.

timeout

The maximum time to wait for the operation to finish.

method

A delegate to a method that takes multiple arguments, which is pushed onto the Dispatcher event queue.

arg

An object to pass as an argument to the specified method.

args

An array of objects to pass as arguments to the specified method.

Return Value

The return value from the delegate being invoked or a null reference (Nothing in Visual Basic) if the delegate has no return value.
Exception typeCondition

ArgumentException

priority is equal to Inactive.

InvalidEnumArgumentException

priority is not a valid DispatcherPriority.

ArgumentNullException

method is a null reference (Nothing in Visual Basic).

Arg can be a null reference (Nothing in Visual Basic) if an argument is not needed.

In WPF, only the thread which created a DispatcherObject may access that object. For example, a background thread which is spun off from the main UI thread cannot update the contents of a Button which 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.

Invoke is a synchronous operation; therefore, control will not return to the calling object until after the callback returns.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0
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