Run a progressbar in a thread

Question

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.NET3.5

Visual-Studio

C#3.5

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Hi there, i want to run a progressbar in a thread. i did this code but it didn't work
could you helpe me please .thanks

C#

 private void button2_Click(object sender, EventArgs e)
        {
            Thread th = new Thread(st);
            th.Start();

           
        }
        void st()
        {

            for (int i = 0; i < 101; i++)
            {
                progressBar1.Value=i;
Thread.Sleep(10);

            }
        }

i get this error

C#

Control.Invoke must be used to interact with controls created on a separate thread.

What I have tried:

private void button2_Click(object sender, EventArgs e)
{
Thread th = new Thread(st);
th.Start();

}
void st()
{

for (int i = 0; i < 100; i++)
{
progressBar1.Value = 100;

}
}

Posted 12-Jun-16 22:34pm

Jammes_Ca

Updated 13-Jun-16 14:55pm

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2 solutions

Solution 2

All you need to do is to marshall the update of the ProgressBar back to the UI thread. This is very easy:

C#

private void button2_Click(object sender, EventArgs e)
{
    Thread th = new Thread(st);
    th.Start();
}
void st()
{
    Function update = (i) => { progressBar1.Value = i; };
    object[] upi = new object[1];
    for (int i = 0; i < 101; i++)
    {
        upi[0] = i;
        progressBar1.Invoke(update, upi);
        Thread.Sleep(10);
    }
}

This will have the started thread running and updating the ProgressBar every 10ms, while the rest of the application runs unimpeded. (You probably want a longer delay to verify that this is running without blocking the UI thread...)

See MSDN: Control.Invoke Method (Delegate, Object[]) (System.Windows.Forms)[^]

Posted 13-Jun-16 14:55pm

Matt T Heffron

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Shahin Khorshidnia · Accepted Answer · 2016-06-12T22:42:00

Solution 1

Do this:

C#

private delegate void ProgressHandler();
private void DoProgress()
{
   for (int i = 0; i < 101; i++)
   {
       progressBar1.Value=i;
       Thread.Sleep(10);
 
   }
}

then:

C#

void st()
{
    if (progressBar1.InvokeRequired)
        progressBar1.Invoke(new ProgressHandler(DoProgress));
    else
        DoProgress();
}

However, this kind of ProgressBar is meaningless because ProgressBass has to show some progress in your application.

Posted 12-Jun-16 22:42pm

Shahin Khorshidnia

Updated 12-Jun-16 22:46pm

v2

Comments

Jammes_Ca 13-Jun-16 5:06am

big thanks :)

Shahin Khorshidnia 13-Jun-16 5:19am

Cheers

Jammes_Ca 13-Jun-16 5:25am

i have an other problem, in my button2_Click program there are several thread.slepp(); and i recognize that the thread.slepp() in my main block the progressbar :( why ?. it's doenst start simultaneously

Shahin Khorshidnia 13-Jun-16 5:40am

Actually, we need to see the code. Maybe a "Thread.Sleep()" is blocking an important part of a sequential progress. However, we cannot help you unless you provide us with the code.

Jammes_Ca 13-Jun-16 5:53am

private delegate void ProgressHandler();
private void DoProgress()
{
for (int i = 0; i < 101; i++)
{
progressBar1.Value = i;
Thread.Sleep(1000);

}
}

private void button2_Click(object sender, EventArgs e)
{
Thread th = new Thread(st);
th.Start();
Thread.Sleep(1000);
textBox1.Text = "a";
Thread.Sleep(1000);
textBox1.Text = "b";
Thread.Sleep(1000);
textBox1.Text = "c";
Thread.Sleep(1000);
textBox1.Text = "d";
Thread.Sleep(1000);

}
void st()
{
if (progressBar1.InvokeRequired)
progressBar1.Invoke(new ProgressHandler(DoProgress));
else
DoProgress();
}
the progressbar start after the ending of the code of button2

Shahin Khorshidnia 13-Jun-16 6:44am

You can't do it this way. Because Thread.Sleep makes the UI Thread busy. If you want TextBoxes to wait before text changing, you can use Timer

Jammes_Ca 13-Jun-16 8:30am

Thanks :)

Shahin Khorshidnia 13-Jun-16 8:36am

Sure