Access main thread control in backgroundworker thread

Question

I have a function ShowPanel(Control ctrl) which required to pass Control as parameter. I need to call this function in background worker thread. I use following code

void bw_DoWork(object sender,DoWorkEventArgs e)
{                      
    ShowPanel(listBox1);           
}

But fails with execption

Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on

How can I pass listBox1 here in background thread ?

Answer 1

serilize the call , since you can not access a control which is created on different thread , you need to seriliaze the call using below

 void bw_DoWork(object sender,DoWorkEventArgs e)
 {                      
   this.Invoke(new MethodInvoker(delegate {

              ShowPanel(listBox1);           
    })); 
 }

Answer 2

I suppose there should be BeginInvoke instead of Invoke.

Otherwise here's more generic solution.

You need to add a reference to WindowsBase.dll.

On the main thread get thread's dispatcher:

public class SomeClass
{
    System.Windows.Threading.Dispatcher mainThreadDispatcher;       

    // assuming class is instantiated in a main thread, otherwise get a dispatcher to the
    // main thread
    public SomeClass()
    {
        Dispatcher mainThreadDispatcher = Dispatcher.CurrentDispatcher;
    }

    public void MethodCalledFromBackgroundThread()
    {
        mainThreadDispatcher.BeginInvoke((Action)({() => ShowPanel(listBox1);}));
    }
}