Detect when a form has been closed c#

Question

I have a WinForm that I create that shows a prompt with a button. This is a custom WinForm view, as a message box dialog was not sufficient.

I have a background worker started and running. I also want to exit the while(aBackgroundWorker.IsBusy) loop if the button on myForm was clicked.

//MyProgram.cs

using(CustomForm myForm = new CustomForm())
{
    myForm.Show(theFormOwner);
    myForm.Refresh();

    while(aBackgroundWorker.IsBusy)
    {
        Thread.Sleep(1);
        Application.DoEvents();
    }
}

Right now, in the CustomForm the Button_clicked event, I have

//CustomForm.cs

private void theButton_Click(object sender, EventArgs e)
{
  this.Close();
}

Do I need to add more code to the CustomForm class, or the location where I declare and initialize the form in order to be able to detect a closure?

Answer 1

To detect when the form is actually closed, you need to hook the FormClosed event:

    this.FormClosed += new FormClosedEventHandler(Form1_FormClosed);

    void Form1_FormClosed(object sender, FormClosedEventArgs e)
    {
        // Do something
    }

Alternatively:

using(CustomForm myForm = new CustomForm())
{
    myForm.FormClosed += new FormClosedEventHandler(MyForm_FormClosed);
    ...
}

void MyForm_FormClosed(object sender, FormClosedEventArgs e)
{
    // Do something
}

Answer 2

You might be going overkill. To show a form like a dialog window and wait for it to exit before returning control back to the calling form, just use:

mySubForm.ShowDialog();

This will "block" the main form until the child is closed.