ProgressBar and Background Controller in C#
ProgressBar indicates visually the progress of an operation. It is best used on a long-running computation or task. And the BackgroundWorker is often used to perform that task—it does not block the interface. Let's see how to create a progress bar.
Please add a ProgressBar control to your Windows Forms program by double-clicking on the ProgressBar entry in the Toolbox.
For this example, we also need a BackgroundWorker—add one and then create the event handlers required. We need the Load event handler, the DoWork event handler, and the ProgressChanged event handler.
using System.ComponentModel;
using System.Threading;
using System.Windows.Forms;
Namespace WindowsFormsApplication1
{
publicpartialclassForm1 : Form
{
Public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, System.EventArgs e)
{
// Start the BackgroundWorker.
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 1; i <= 100; i++)
{
// Wait 100 milliseconds.
Thread.Sleep(100);
// Report progress.
backgroundWorker1.ReportProgress(i);
}
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
// Change the value of the ProgressBar to the BackgroundWorker progress.
progressBar1.Value = e.ProgressPercentage;
// Set the text.
this.Text = e.ProgressPercentage.ToString();
}
}
}
Starting the background task. In the Form Load event handler, please add a method call to the RunWorkerAsync method on the BackgroundWorker instance. This will create a thread and the DoWork method will begin.
Inside the DoWork event handler, we loop over the numbers. At each iteration, wait for one-tenth of a second. Then, we call the ReportProgress method on the BackgroundWorker instance.
In the ProgressChanged event handler, we set the value of the ProgressBar to the ProgressPercentage property of the ProgressChangedEventArgs argument. This will be the values 1 through 100. We also update the title text.
One of the useful properties on the ProgressBar is the ForeColor property. This can be set to a Color value to change the color of the bar itself that is drawn on the screen.
As a visual indication of progress, the ProgressBar control is often used in conjunction with a threading mechanism such as BackgroundWorker. With options to adjust its visual aspects, the ProgressBar makes a suitable widget for letting your users know the application is still active.
