Dispatcher.Invoke Method (DispatcherPriority, Delegate, Object, Object)
Assembly: WindowsBase (in windowsbase.dll)
public Object Invoke ( DispatcherPriority priority, Delegate method, Object arg, params Object args )
public Object Invoke ( DispatcherPriority priority, Delegate method, Object arg, Object args )
public function Invoke ( priority : DispatcherPriority, method : Delegate, arg : Object, ... args : Object ) : Object
The priority, relative to the other pending operations in the Dispatcher event queue, the specified method is invoked.
A delegate to a method that takes multiple arguments, which is pushed onto the Dispatcher event queue.
An object to pass as an argument to the given method.
An array of objects to pass as arguments to the given method.
Return ValueThe return value from the delegate being invoked or a null reference (Nothing in Visual Basic) if the delegate has no return value.
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.