public void MyTaskAsync(string[] files)
{
MyTaskWorkerDelegate worker = new MyTaskWorkerDelegate(MyTaskWorker);
AsyncCallback completedCallback = new AsyncCallback(MyTaskCompletedCallback);
lock (_sync)
{
if (_myTaskIsRunning)
throw new InvalidOperationException("The control is currently busy.");
AsyncOperation async = AsyncOperationManager.CreateOperation(null);
MyAsyncContext context = new MyAsyncContext();
bool cancelled;
worker.BeginInvoke(files, async, context, out cancelled, completedCallback, async);
_myTaskIsRunning = true;
_myTaskContext = context;
}
}
private void MyTaskWorker(string[] files, AsyncOperation async, MyAsyncContext asyncContext, out bool cancelled)
{
cancelled = false;
for (int i = 0; i < files.Length; i++)
{
// a time consuming operation with a file (compression, encryption etc.)
Thread.Sleep(1000);
// compute progress
int progressPercentage = 100 * (i + 1) / files.Length;
// raise the progress changed event
MyTaskProgressChangedEventArgs eArgs = new MyTaskProgressChangedEventArgs(progressPercentage, files[i], Id, null);
async.Post(delegate(object e) { OnMyTaskProgressChanged((MyTaskProgressChangedEventArgs)e); }, eArgs);
if (asyncContext.IsCancelling)
{
cancelled = true;
return;
}
}
}
private void MyTaskCompletedCallback(IAsyncResult ar)
{
// get the original worker delegate and the AsyncOperation instance
MyTaskWorkerDelegate worker = (MyTaskWorkerDelegate)((AsyncResult)ar).AsyncDelegate;
AsyncOperation async = (AsyncOperation)ar.AsyncState;
bool cancelled;
// finish the asynchronous operation
worker.EndInvoke(out cancelled, ar);
// clear the running task flag
lock (_sync)
{
_myTaskIsRunning = false;
_myTaskContext = null;
}
// raise the completed event
MyTaskAsyncCompletedEventArgs completedArgs = new MyTaskAsyncCompletedEventArgs(null, cancelled, null, Id);
async.PostOperationCompleted(delegate(object e) { OnMyTaskCompleted((MyTaskAsyncCompletedEventArgs)e); }, completedArgs);
}