Making a function call on another thread using the C# Dispatcher class

There may be a situation when you need to execute a function on a different thread, such as ensuring that calls across the interface between a multi-threaded dll and its single-threaded user are made on the same, single thread. To achive this, you can use the target thread's Dispatcher object as follows:

  1. Create a delegate of the function you wish to be able to call:
    public delegate void MyDelegate(int i, string str);
    public class TargetThreadClass 
        public TargetThreadClass() 
            MyDelegate del = new MyDelegate(this.FuncToExec); 
        public void FuncToExec(int i, string str) 
           // Do something 
  2. Within the target thread, create an instance of a Dispatcher object and set it to the thread's current dispatcher:
    Dispatcher UserDispatcher = Dispatcher.CurrentDispatcher;

    Then pass this dispatcher, along with the delegate into the source thread.

  3. Then to call FuncToExec on the target thread, use:
    UserDispatcher.Invoke(del, new object[] { 123, "arg string"});

    Where the first parameter of Invoke is the delegate itself and the second an array of the delegate's parameters (if any), in this example the delegate takes an int and a string.

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