Free-ebooks-library - Bahar Ali Khan

class Program
{
static BackgroundWorker _bw = new BackgroundWorker();
static void Main()
{
_bw.DoWork += bw_DoWork;
_bw.RunWorkerAsync ("Message to worker");
Console.ReadLine();
}
static void bw_DoWork (object sender, DoWorkEventArgs e)
{
// This is called on the worker thread
Console.WriteLine (e.Argument); // writes "Message to worker"
// Perform time-consuming task...
}
}
BackgroundWorker has a RunWorkerCompleted event that fires after the DoWork event
handler has done its job. Handling RunWorkerCompleted is not mandatory, but you
usually do so in order to query any exception that was thrown in DoWork. Further,
code within a RunWorkerCompleted event handler is able to update user interface
controls without explicit marshaling; code within the DoWork event handler cannot.
To add support for progress reporting:
1. Set the WorkerReportsProgress property to true.
2. Periodically call ReportProgress from within the DoWork event handler with a
“percentage complete” value, and optionally, a user-state object.
3. Handle the ProgressChanged event, querying its event argument’s ProgressPer
centage property.
4. Code in the ProgressChanged event handler is free to interact with UI controls
just as with RunWorkerCompleted. This is typically where you will update a progress
bar.
To add support for cancellation:
1. Set the WorkerSupportsCancellation property to true.
2. Periodically check the CancellationPending property from within the DoWork
event handler. If it’s true, set the event argument’s Cancel property to true, and
return. (The worker can also set Cancel and exit without CancellationPending
being true if it decides that the job is too difficult and it can’t go on.)
3. Call CancelAsync to request cancellation.
Here’s an example that implements all the preceding features:
using System;
using System.Threading;
using System.ComponentModel;
BackgroundWorker | 853
Threading