Dispatcher.Invoke Method (Delegate, TimeSpan, DispatcherPriority, Object())
Executes the specified delegate within the designated time span at the specified priority with the specified arguments synchronously on the thread the Dispatcher is associated with.
Assembly: WindowsBase (in WindowsBase.dll)
'Declaration Public Function Invoke ( _ method As Delegate, _ timeout As TimeSpan, _ priority As DispatcherPriority, _ ParamArray args As Object() _ ) As Object
- Type: System.Delegate
A delegate to a method that takes parameters specified in args, which is pushed onto the Dispatcher event queue.
- Type: System.TimeSpan
The maximum amount of time to wait for the operation to complete.
- Type: System.Windows.Threading.DispatcherPriority
The priority, relative to the other pending operations in the Dispatcher event queue, the specified method is invoked.
- Type: System.Object()
An array of objects to pass as arguments to the given method. Can be Nothing.
Return ValueType: System.Object
The return value from the delegate being invoked or Nothing if the delegate has no return value.
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.
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.