I created a simple Windows Forms project using C# while taking advantage of BackgroundWorker object to run task at backward thread.
You just have to change/alter only one method: "CallMeBackward" which is called at backward thread in the demo project.
BackgroundWorker cannot intercept main thread for UI elements. You've to use main thread instead.
You just have to change/alter only one method: "CallMeBackward" which is called at backward thread in the demo project.
using System;
using System.ComponentModel;
using System.Threading;
namespace BackgroundWorkerInWindowsFormsApp
{
public partial class Form1 : System.Windows.Forms.Form
{
BackgroundWorker _backgroundWorker = new BackgroundWorker();
/*============================================================================*/
public Form1()
{
InitializeComponent();
/*============================================================================*/
_backgroundWorker.DoWork += new DoWorkEventHandler(BackgroundWorkerDoWorkEvent);
_backgroundWorker.WorkerSupportsCancellation = true;
ThreadPool.QueueUserWorkItem(_backgroundWorker.RunWorkerAsync);
/*============================================================================*/
}
/*============================================================================*/
void BackgroundWorkerDoWorkEvent(object sender, DoWorkEventArgs e)
{
BackgroundWorker backgroundWorker = sender as BackgroundWorker;
string argument = (string)e.Argument;
e.Result = OnTimeConsumingOperation(backgroundWorker, argument);
}
/*============================================================================*/
string OnTimeConsumingOperation(BackgroundWorker bw, string arg)
{
ThreadPool.QueueUserWorkItem(_ =>
{
CallMeBackward();
});
return string.Empty;
}
/*============================================================================*/
void CallMeBackward()
{
for (var i = 0; i < 2000; i++)
{
counterLabel.Text = i.ToString();
timerLabel.Text = DateTime.Now.ToLongTimeString();
}
}
/*============================================================================*/
protected override void Dispose(bool disposing)
{
_backgroundWorker.CancelAsync();
_backgroundWorker.Dispose();
/*============================================================================*/
var timer = new System.Windows.Forms.Timer();
timer.Tick += (obj, evt) =>
{
if (!_backgroundWorker.IsBusy)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
};
timer.Start();
}
/*============================================================================*/
}
}
UI elements are not thread-safe and should be accessed only on the thread that created them. Otherwise you'll get following error message:
Cross-thread operation not valid: Control 'richTextBox1' accessed from a thread other than the thread it was created on.
