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)

[BrowsableAttribute(false)]
public Object Invoke(
	DispatcherPriority priority,
	TimeSpan timeout,
	Delegate method,
	Object arg,
	params Object[] args
)

Parameters

priority
Type: System.Windows.Threading.DispatcherPriority
The priority, relative to the other pending operations in the Dispatcher event queue, the specified method is invoked.
timeout
Type: System.TimeSpan
The maximum time to wait for the operation to finish.
method
Type: System.Delegate
A delegate to a method that takes multiple arguments, which is pushed onto the Dispatcher event queue.
arg
Type: System.Object
An object to pass as an argument to the specified method.
args
Type: System.Object[]
An array of objects to pass as arguments to the specified method.

Return Value

Type: System.Object
The return value from the delegate being invoked or null if the delegate has no return value.

ExceptionCondition
ArgumentException

priority is equal to Inactive.

InvalidEnumArgumentException

priority is not a valid DispatcherPriority.

ArgumentNullException

method is null.

Arg can be null if an argument is not needed.

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.

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

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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