Why am I getting an exception: InvalidOperationException?

Question

The exception is the code:

private void DownloadProgressCallback(object sender, DownloadProgressChangedEventArgs e)
{
   ActiveDownloadJob adJob = e.UserState as ActiveDownloadJob;
   if (adJob != null && adJob.ProgressBar != null)
   {
      adJob.ProgressBar.Invoke((Action)(() => adJob.ProgressBar.Value = e.ProgressPercentage));
   }
}

In line:

adJob.ProgressBar.Invoke((Action)(() => adJob.ProgressBar.Value = e.ProgressPercentage));

This is the ActiveDownloadJob class in form1:

class ActiveDownloadJob
{
            public DownloadImages.DownloadData DownloadData;
            public ProgressBar ProgressBar;
            public WebClient WebClient;

            public ActiveDownloadJob(DownloadImages.DownloadData downloadData, ProgressBar progressBar, WebClient webClient)
            {
                try
                {
                    this.DownloadData = downloadData;
                    this.ProgressBar = progressBar;
                    this.WebClient = webClient;
                }
                catch (Exception err)
                {
                    MessageBox.Show(err.ToString());
                }
            }
        }

I'm not sure that I need to call this line, since im is not using a flashlight now, but I'm not sure.

This is a complete exception message: Invoke or BeginInvoke cannot be called in a control until a window handle is created

System.InvalidOperationException was unhandled by user code
  HResult=-2146233079
  Message=Invoke or BeginInvoke cannot be called on a control until the window handle has been created.
  Source=System.Windows.Forms
  StackTrace:
       at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
       at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
       at System.Windows.Forms.Control.Invoke(Delegate method)
       at WeatherMaps.Form1.DownloadProgressCallback(Object sender, DownloadProgressChangedEventArgs e) in d:\C-Sharp\WeatherMaps\WeatherMaps\WeatherMaps\Form1.cs:line 290
       at System.Net.WebClient.OnDownloadProgressChanged(DownloadProgressChangedEventArgs e)
       at System.Net.WebClient.ReportDownloadProgressChanged(Object arg)
  InnerException: 

How can I change this line without using Invoke or if Invoke is required, how can I fix the line and the exception?

I know I should handle it in the Form1 Form closing event, but how? What should I do in Form1 closing event?

Answer 1

, , Invoke " " " ", Handle .

InvokeRequired, , Invoke, false, Handle , .

var method = (Action)(() => adJob.ProgressBar.Value = e.ProgressPercentage);
if(adJob.ProgressBar.InvokeRequired)
    adJob.ProgressBar.Invoke(method);
else
    method();

Answer 2

, , Window Handle. :

if (adJob.ProgressBar.Handle != IntPtr.Zero)
{
    adJob.ProgressBar.Invoke((Action)(() =>
        adJob.ProgressBar.Value = e.ProgressPercentage));
}

, , , Form.

Answer 3

:

MethodInvoker mi = () => adJob.ProgressBar.Value = e.ProgressPercentage;
if(InvokeRequired) BeginInvoke(mi);
else mi();