Wait window in a windows application

Question

I basically need to show a wait window to the user. For this i have put two seperate window forms in the application. the first form is the main form with a button. The second one is a empty one with just a label text. On click of the button in Form1 i do the below

Form2 f = new Form2();
f.Show();
Thread.Sleep(2000);
f.Close();

My idea here is to show the wait window to the user for 2 second. But when i do this the Form 2 is not completely loaded because of which the label in it is blank. Please let me know your inputs on this.

Answer 1

That's because you probably do some lengthy operation in the same thread (UI thread). You should execute your code in a new thread (see Thread class) or at least call Application.DoEvents periodically from inside your lengthy operation to update the UI.

Answer 2

You're basically blocking the UI thread.

I suggest that instead, you make your Form2 constructor (or possibly Load event handler) start a timer which will fire two seconds later. When the timer fires, close the form. During those two seconds, the UI thread will be free, so everything will display properly and the user will be able to move the window etc.

Answer 3

When yo use Thread.Sleep you will disable the windows message loop and prevent the window from painting itself.

You could force a repaint:

f.Refresh();

Or better yet use a timer with a callback.

Timer t = new Timer();
t.Interval = 2000;
t.Tick += delegate { Close(); t.Stop();};
t.Start();

To prevent users from clicking in the original window you can open the new form as a dialog:

f.ShowDialog();

Answer 4

You can (an always should for UI threads) use Thread.Current.Join(2000) instead of Thread.Sleep(2000).

Answer 5

I think you should just use

f.ShowDialog(this);

Then control is returned when f is closed.

By using the sleep, you are blocking the UI thread from updating for 2 seconds. (The thread is asleep).