Question

My application has a restricted access. I have a user/password box in a small dialog, and when logged-in, I’m loading a very big form with a tons of controls and several big grids. The whole InitializeComponent() take almost 10 secs to load without any data.

The issue is : how I could pre-run the Form constructor() while users are filling the two login fields ? If user is very slow and need >10 secs to complete authentification, it will be as quick as a wink to show application.

I think it is possible because it is two seperates top level windows, but I have no idea how to implement it. BackgroundWorker, new Thread, … ? Any clue ?

SOLUTION :

Following Eamonn McEvoy’s example, I added some fixes about my prerequesites : I wanted to show only login dialog, and if logged successful, I show the big form.

[STAThread]
static void Main()
{
    Launcher context = new Launcher();
    Application.Run(context);
}


public class Launcher : ApplicationContext
{
    private BigForm _bigForm;
    private Thread _loginThread;
    private SynchronizeLogin _sharedLogin;

    public class SynchronizeLogin
    {
        private bool _waited = false;
        public bool IsInitialized
        {
            get // loginform should wait before closing until return true
            {
                lock (this)
                {
                    return _waited;
                }
            }
            set // must be set when bigform is initialized
            {
                lock (this)
                {
                    _waited = value;
                }
            }
        }

        private DialogResult _logged = DialogResult.None;
        public DialogResult loginResult
        {
            get // wait until loginform close
            {
                lock (this)
                {
                    if (_logged != DialogResult.None)
                        return _logged;
                    else
                    {
                        Monitor.Wait(this);
                        return _logged;
                    }
                }
            }
            set // set from loginform when closing
            {
                lock (this)
                {
                    _logged = value;
                    Monitor.Pulse(this);
                }
            }
        }
    }

    public Launcher()
    {
        // sync obj between forms
        _sharedLogin = new SynchronizeLogin();
        _loginThread = new Thread(new ThreadStart(LaunchLogin));
        _loginThread.Start();

        // first form
        _bigForm= new BigForm(_sharedLogin);
        _bigForm.Closed += new EventHandler(OnFormClosed);

        // notify login thread that the main one is ready
        // from now, the login form should be near closing
        _sharedLogin.IsInitialized = true;

        WaitLogon();
    }

    private void WaitLogon()
    {
        if (_sharedLogin.loginResult == DialogResult.OK)
        {
            _bigForm.LoginSuccessful(); // read and use auth session
            _bigForm.Show();
        }
        else
        {
            // escape on user login form
            // (other exit calls are not working in ctor)
            Environment.Exit(42);
        }
    }

    private void LaunchLogin()
    {
        // ask user
        LoginDialog _loginForm = new LoginDialog (_sharedLogin);
        _sharedLogin.loginResult = _loginForm.ShowDialog();

        // userlogin form closed
        // end only current thread
        Application.ExitThread();
    }

    private void OnFormClosed(object sender, EventArgs e)
    {
        // big form closed
        // end ApplicationContext globally
        base.ExitThread();
    }
}

Answer 1

You could create your login window in a new thread from your main windows constructor

using System.Threading;

private AuthSession _authSession;

public MainWindowConstructor()
{ 
    Thread loginThread = new Thread(new ThreadStart(Login());
    loginThread.Start();
    //Continue initializing
}

private void Login()
{
    LoginWindow loginWindow = new LoginWindow();
    _authSession = loginWindow.GetAuthSession();
    loginWindow.Close();
}