Question

I have a Thread that starts in my main form

    private void changePasswordbutton_Click_1(object sender, EventArgs e)
    {
        waitForm.Show();
        Thread thread = new Thread(ProcessInkPresenter);
        thread.SetApartmentState(ApartmentState.STA);
        thread.Start();
        thread.Join();
        waitForm.Hide();
        waitForm.Dispose();
    }

I want to close the waitForm inside the ProcessInkPresenter method (which is running on a thread) instead of waiting for the thread to complete.

How do I do this?

Thanks

Method signatures

private void ProcessInkPresenter()

Defined in the class header

Wait waitForm;

Answer 1

Your original code doesn’t make sense. It shows a form, then starts a thread, then waits for that thread to complete. If you want the form to be run on it’s own UI thread, have ProcessInkPresenter run on the same UI thread (which it should if it interacts with the UI) and have the form closed and be disposed of when ProcessInkPresenter completes, try this:

private void changePasswordbutton_Click_1(object sender, EventArgs e)
{
    Thread thread = new Thread(state => {
            using (var waitForm = new WaitForm()) {
                waitForm.Activated += (s, e) => {
                    ProcessInkPresenter();
                    waitForm.Hide();
                }
                Application.Run(waitForm);
            }
        }
    );
    thread.SetApartmentState(ApartmentState.STA);
    thread.Start();
}

If the worker thread does not have to interact with the GUI, then what you want is something like the following. Note that I make use of Invoke to make sure that the interaction with the UI is done on the UI thread. There is no need to check InvokeRequired here, since I already know for sure that I am on a background thread.

If you want to keep the same waitForm instance:

private void changePasswordbutton_Click_1(object sender, EventArgs e)
{
    Thread thread = new Thread(state => {
            try {
                ProcessInkPresenter();

                // If ProcessInkPresenter fails, this line will never execute
                waitForm.Invoke(new Action(()=>waitForm.Hide()));
            }
            catch (Exception ex) {
                // You probably want to do something with ex here,
                // rather than just swallowing it.
            }
        });
    thread.SetApartmentState(ApartmentState.STA);
    thread.Start();
    waitForm.Show();
}

NOTE: It doesn’t make sense to dispose your WaitForm if you have a single instance of it (your Wait instance). Either construct an instance each time you use it, or never dispose it and use .Hide() instead.