Assigning value to a control in using Multi Threading

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I am new to multi Threadding, From google search I got so many examples and all are explaining with console applications, but when I work with windows forms it is not accepting to assign a value to any control. it is showing error

Cross-thread operation not valid: Control 'lblInfo' accessed from a thread other than the thread it was created on

Please help me. and provide any useful links (multi threading with winforms)

Thanks in advance

Posted 23-Mar-11 21:15pm

Sridhar Patnayak

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Sergey Alexandrovich Kryukov 24-Mar-11 3:27am

Correct tag, please: AS.net?
--SA

4 solutions

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Prerak Patel · Answer 1 · 2011-03-23T21:28:00

Solution 1

Prevent 'cross-thread operation not allowed' exception through reflection[^] would help you.

Posted 23-Mar-11 21:28pm

Prerak Patel

Micha3ldg · Answer 2 · 2011-03-23T23:11:00

Solution 2

Take a look on this example. Executing the method using Invoke and BeginInvoke with delegates's aid.

Make Thread-Safe Calls to Windows Forms Controls[^]

Posted 23-Mar-11 23:11pm

Micha3ldg

Jefis · Answer 3 · 2011-03-24T02:35:00

Solution 3

I usually do something like this in UI code:

private void MoveMyCoolButton(){<br />
 if (this.InvokeRequired){<br />
   this.Invoke(new Action(MoveMyCoolButton));<br />
 }<br />
 <...> Continue on your UI code <...><br />
}

Posted 24-Mar-11 2:35am

Jefis

Nick Reshetinsky · Answer 4 · 2011-03-24T02:59:00

Yes..you cannot update controls on non-UI thread so if you want other threads
to do something with your controls you must marshal it to UI thread...
How??
Well, each control has methods Invoke( ) and BeginInvoke( ). They accept
a delegate ( a pointer to some function) and arguments to be called on
UI-thread.

 delegate void UpdateUIDelegate(int value);

// another thread method
private void DoLongCalculation( ) {
  int progress = 0;
  while( true) {
  // blah-blah-blah
  // invoking from other thread
  m_progressBar.Invoke( new UpdateUIDelegate(UpdateUI), progress);
 }
}

private void UpdateUI(int value) {
 m_progressBar.Value = value;
}