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Background Worker and Timer in System Tray App C#

This is an incredibly simple task tray app - using ApplicationContext and a few guides I found online.
The purpose of the app is to query a small REST API and show a message box to the user on a given result. I need to essentially have the API query in a background loop, running every 10 seconds or something similar. This is to report on data that I've made accessible via another service.
I've done some reading and it seems a BackgroundWorker and Timer is an appropriate option, but I'm lost on where to go next. How exactly can I achieve this? I initially tried adding a while(true) loop to the TaskTrayApplicationContext but it just created an infinite loop whereby you couldn't do anything else with the app.
namespace TaskTrayApplication
{
public class TaskTrayApplicationContext : ApplicationContext
{
NotifyIcon notifyIcon = new NotifyIcon();
Configuration configWindow = new Configuration();
public TaskTrayApplicationContext()
{
MenuItem configMenuItem = new MenuItem("Configuration", new EventHandler(ShowConfig));
MenuItem exitMenuItem = new MenuItem("Exit", new EventHandler(Exit));
notifyIcon.Icon = TaskTrayApplication.Properties.Resources.AppIcon;
notifyIcon.DoubleClick += new EventHandler(ShowMessage);
notifyIcon.ContextMenu = new ContextMenu(new MenuItem[] { configMenuItem, exitMenuItem });
notifyIcon.Visible = true;
}
void ShowMessage(object sender, EventArgs e)
{
// Only show the message if the settings say we can.
if (TaskTrayApplication.Properties.Settings.Default.ShowMessage)
MessageBox.Show("This is the Serenity TaskTray Agent.");
}
void ShowConfig(object sender, EventArgs e)
{
// If we are already showing the window meerly focus it.
if (configWindow.Visible)
configWindow.Focus();
else
configWindow.ShowDialog();
}
void Exit(object sender, EventArgs e)
{
// We must manually tidy up and remove the icon before we exit.
// Otherwise it will be left behind until the user mouses over.
notifyIcon.Visible = false;
Application.Exit();
}
}
}
And the Program.cs
using System;
using System.Collections.Generic;
using System.Windows.Forms;
namespace TaskTrayApplication
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
// Instead of running a form, we run an ApplicationContext.
Application.Run(new TaskTrayApplicationContext());
}
}
}

Threading is hard, concurrency is hard. Background worker and System.Timers are both constructs that run in their own thread.
winforms won't allow for interaction between threads that own a control (read: that created a control) and threads that don't. This is a whole subject apart i wont get into now - theres good stuff to read out there why this is and how to go about it: https://visualstudiomagazine.com/articles/2010/11/18/multithreading-in-winforms.aspx
There are tools to help, one is the dispatchertimer:
https://learn.microsoft.com/en-us/dotnet/api/system.windows.threading.dispatchertimer?view=netcore-3.1
This is a special timer that instead of its own thread, schedules tasks on the main thread. The main thread in a winforms application handles the drawing of controls, showing of the different windows etc. e.g. this 'owns' all controls.
A sample can be seen on msdn, i adopted it here to show you what you could do:
public class TaskTrayApplicationContext : ApplicationContext
{
...
DispatcherTimer dispatcherTimer;
public TaskTrayApplicationContext()
{
...
dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
dispatcherTimer.Tick += new EventHandler(dispatcherTimer_Tick);
dispatcherTimer.Interval = new TimeSpan(0,0,1);
dispatcherTimer.Start();
}
private void dispatcherTimer_Tick(object sender, EventArgs e)
{
// Fetch your data via a rest api
var myData = MyDataFunction();
// check and show dialog if the data is not okay
if(myData.Result.Value = 'NOT_OKAY!')
ShowMessage(this, myData.Result); // or something.
}
...
Now since this does not utilize a second thread, this means the main ui thread could be blocked from drawing the windows, reacting to user input etc. because its busy doing work in the timer_tick function. This would for example happen if your rest call takes a long time.
This will make your application freeze and irresponsive. This could be a problem but most likely wont, so lets burn that bridge when we get to it.

(WPF) How to ping from a class in c#?

I'm creating a WPF tool to use on my HelpDesk team using XAML and C#, but I'd like to improve upon what I've done. I've got a textbox to enter a hostname, a button to start a ping, and a textbox that will keep pinging that hostname until I press the button again.
I'd like to keep the functionality the same, but I know there's a better way to write this code.
Currently, I have a class that pings the server and returns a response ONE single time. My main form calls this class, the logic is not written in the main form. When I tried to make this loop, it just kills the function after the first run through rather than looping. The way I got it to work was by using a timer to call the function/ping class every 500 MS or so, and stopping the timer by clicking the button again.
Here's my current way of doing this, t stands for "timer":
private void onTick(object sender, EventArgs e)
{
PingClass pingClass = new PingClass();
_richtext.AppendText(pingClass.PingHost(_textBox.Text));
_richtext.ScrollToEnd();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
if ((string)_pingBtn.Content == "Ping")
{
_richtext.Visibility = Visibility.Visible;
_pingBtn.Content = "Stop Ping";
t.Interval = 500;
t.Tick += onTick;
t.Start();
}
else if ((string)_pingBtn.Content == "Stop Ping")
{
_richtext.Visibility = Visibility.Hidden;
_pingBtn.Content = "Ping";
t.Stop();
}
The class itself is pretty simple, it just returns a string of whatever the response from the host is. Unfortunately, it doesn't allow me to loop through inside the class because it stops at the first return. I'd like to gather an "average ping" and some other stats, but can't with the way it's currently set up. I don't want to have a timer, I want to be able to loop in the class itself until the button in the main form is pressed. Is this possible?

C# Console Application with a form on the side displaying live data

I have a console application that takes in live data from a database, and acts upon it in real time, the bulk of my Main method is within a while(true) loop. I need a form in the background which displays one part of the data that available during the loop. I want it refreshing every time the program completes a loop showing the new value. I've added a form to my project, and added the following code to my initialisation section:
DataDisplay dataDisplay = new DataDisplay();
dataDisplay.Show();
above the Main declaration.
This makes the window pop up, but whenever I mouse over it my cursor turns into the Microsoft loading blue circle. The rest of my program runs fine, current functionality remains, just the form isn't happy.
Variants of
Application.Run(dataDisplay);
dataDisplay.ShowDialog();
Cause my program to hang on the above lines without progressing to the while loop as the applications doesn't end.
I haven't started building the functionality for populating my form as it doesn't seem to want to behave.
What am I doing wrong, I am relatively new to C# and Winforms both.

You are blocking your main thread, that's why the gui can't update or react to any user input. I would suggest moving the while(true) loop to a different thread.
Here's a short example:
class MyForm : Form
{
public Label label;
public MyForm()
{
label = new Label();
this.Controls.Add(label);
}
}
class Program
{
static void Main(string[] args)
{
MyForm f = new MyForm();
(new Task(() =>
{
//your loop
while (true)
{
f.Invoke(new Action(() =>
{
f.label.Text = (new Random()).Next().ToString();
}));
Console.WriteLine("working...");
Thread.Sleep(500);
}
})).Start();
f.ShowDialog(); //blocks as long as the form is open
}
}

Multithreading to speed up load times

I made a program that loads a bunch of computer information. In the Form_Load event I have it initialize 3 (that number will grow) panels of information. One that has a bunch of unit information seems to make the program load rather slowly. I've tried to speed it up a bunch by switching from WMI to using Native calls, which helped a bunch. Soon though I'm going to have network information posted as well. I used to load that panel but i disabled it for a little bit till I work out the bugs in my other panels. So while learning how I can use a seperate thread to update my battery information I figured that I might be able to create seperate threads in my unit information panel so that it might could load faster. I dont know that any of my information would cause concurrent issues, but i can work on that.
I want to start small so what if i change this
private void Form1_Load(object sender, EventArgs e)
{
unitInformationPanel1.PopulateUnitInformation();
batteryInformationPanel1.InitializeBatteries();
magStripeReaderPanel1.SetupPointOfSale();
}
to this
private void Form1_Load(object sender, EventArgs e)
{
Thread infoThread = new Thread(new ThreadStart(unitInformationPanel1.PopulateUnitInformation));
infoThread.Start();
batteryInformationPanel1.InitializeBatteries();
magStripeReaderPanel1.SetupPointOfSale();
}
would the info thread be terminated when populate unit info is done? or would it be better to move that thread creation into PopulateUnitInformation? here is what it looks like.
public void PopulateUnitInformation()
{
unitModelLabel.Text = Properties.Settings.Default.UnitModelString;
serialNumberLabel.Text = Properties.Settings.Default.UnitSerialString;
biosVersionLabel.Text = UnitBios.GetBiosNumber();
osLabel.Text = OS.getOSString();
cpuLabel.Text = UnitCpu.GetCpuInfo();
var hdd = HddInfo.GetHddInfo();
diskNameLabel.Text = hdd.Name;
diskCapacityLabel.Text = hdd.Capacity;
diskFirmwareLabel.Text = hdd.Firmware;
memoryLabel.Text = MemoryInformation.GetTotalMemory();
NetworkPresenceInformation.GetAdapatersPresent();
biometricLabel.Text = BiometricInformation.IsPresent ? "Present" : "Not Present";
var networkAdaptersPresense = NetworkPresenceInformation.GetAdapatersPresent();
bluetoothLabel.Text = networkAdaptersPresense[0] ? "Present" : "Not Present";
wifiLabel.Text = networkAdaptersPresense[1] ? "Present" : "Not Present";
cellularLabel.Text = networkAdaptersPresense[2] ? "Present" : "Not Present";
}
--
wow i just ran it with the infothread and it still took some time to load (might be the 12 panels i created in the main thread. but it loaded the 12 frames and the unit information panel populated its information after everything loaded. That was cool, but is it safe? is it somewhat easy to make 12 threads for my panels? or is that dumb?
EDIT
this is what i did for stopwatch.
Stopwatch programTimer;
public Form1()
{
programTimer = Stopwatch.StartNew();
InitializeComponent();
SetupDebugWindow();
TerminateKeymon();
UnitModel.SetModel();
UnitSerialNumber.SetSerialNumber();
}
private void Form1_Shown(object sender, EventArgs e)
{
audioBrightnessPanel1.UpdateBrightnessTrackbar();
applicationLauncherPanel1.LoadApplications();
programTimer.Stop();
Console.WriteLine("Load Time: {0}",programTimer.ElapsedMilliseconds);
timer1.Start();
}
Will this be accurate?
EDIT 2 6/18/2012
Well I took the advice of using backgroundworker. Please let me know if i did this right.
private void Form1_Load(object sender, EventArgs e)
{
backgroundWorker1.RunWorkerAsync();
}
void BackgroundWorker1DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
{
unitInformationPanel1.PopulateUnitInformation();
batteryInformationPanel1.InitializeBatteries();
magStripeReaderPanel1.SetupPointOfSale();
}

You've asked a very broad question, but I'm going to give some general advice. If you want more specific information, you should consider deleting this question and posting more specific individual questions.
First and foremost, you should very strongly consider using something like the System.Threading.Task class for your multithreaded operations. There is a ton of information online about how to get started with it and how you can use Tasks to manage asynchronous operations. The short story is that if you're spinning up your own thread (as you're doing above), you almost certainly should be using something else to do that for you.
Adding multithreading to your code will not, in the strictest sense of the word, make it any "faster"; they will always take the same amount of total processor time. What it can and will do is two things: free up the UI thread to be responsive and allow you to split that "total processor time" across multiple cores or processors, should those be available to the system. So, if you have operation X that takes 10 seconds to complete, then just shifting operation X to another thread will not make it complete any faster than 10 seconds.
No, what you are doing above is not safe. I'm assuming that somewhere you've turned off checking for cross-thread communication errors in your app? Otherwise, that code should throw an exception, assuming this is a WinForms or WPF application. This is one reason to use Tasks, as you can easily separate the part of your process that actually takes a long time (or isn't UI related), then add a task continuation that uses the results and populates the UI elements within a properly synchronized context.

So my final approach this was as follows. I felt that my Main Form was doing more than it should. Sticking with the single responsibility principle I decided that MainForm should only be responsible for one thing, showing and displaying all 12 panels (now down to 11, i turned one into a menu item). So moved all the multithreading out of mainform and into program.cs. I found that this was even a little more difficult. What I did find though was a simple solution that allows me to not even worry about multithreading at all. It was the Idle event. Here is what i chose to do.
[STAThread]
static void Main()
{
DateTime current = DateTime.Now;
DateTime today = new DateTime(2012,7,19);
TimeSpan span = current.Subtract(today);
if (span.Days<0)
{
MessageBox.Show("Please adjust Time then restart Aspects","Adjust Time");
Process.Start("timedate.cpl").WaitForExit();
}
else
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Idle += new EventHandler(Application_Idle);
mainForm = new MainForm();
mainForm.Closing += new CancelEventHandler(mainForm_Closing);
#if !DEBUG
TerminateKeymon();
StartSerial();
SetupDefaultValues();
EmbeddedMessageBox(0);
#endif
Application.Run(mainForm);
}
}
static void Application_Idle(object sender, EventArgs e)
{
Application.Idle -= Application_Idle;
mainForm.toolStripProgressBar1.Increment(1);
UnitInformation.SetupUnitInformation();
mainForm.toolStripProgressBar1.Increment(1);
Aspects.Unit.HddInfo.GetHddInfo();
mainForm.toolStripProgressBar1.Increment(1);
for (int i = 0; i < mainForm.Controls.Count; i++)
{
if (mainForm.Controls[i] is AbstractSuperPanel)
{
try
{
var startMe = mainForm.Controls[i] as AbstractSuperPanel;
startMe.StartWorking();
mainForm.toolStripProgressBar1.Increment(1);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message + mainForm.Controls[i].ToString());
}
}
}
mainForm.toolStripProgressBar1.Value = 0;
}
to sum up what that does is is I add a idle listener event. Once the thead goes idle (basically meaning that Mainform is finished drawing and making all 12 panels and is showing on my desktop) I then kill the idle event listener and tell all my panels and classes to start working one at a time, updating my progress bar as I go. It works great. The load time is still the same as it was before, but there is window visibile after only a few seconds. Maybe not the best use of resources, but i think the solution is simple and straight forward.

I had a question somewhat related to this for Mobile app development a few months back (see How to write a Trigger?), and Marc "the man" Gravell posted back with a simple class that I modified to return data to my main application whenever the thread was complete.
The actual class I put into use has loads of pointless data (for you), so I'm going to paste in a revised version of Mr. Gravell's code using techniques which I used to make them work:
First, I had to create my own EventArgs class:
public class SuperEventArgs : EventArgs {
private object data;
public SuperEventArgs(object data) : base() {
this.data = data;
}
public object Data { get { return data; } }
}
Using that, here is a class I created to pass my data back to the main thread:
public delegate event DataChangedHandler(object sender, SuperEventArgs e);
public class Simple1 {
private object parameter1, parameter2;
private Control parent;
#if PocketPC
public delegate void MethodInvoker(); // include this if it is not defined
#endif
public Simple1(Control frmControl, object param1, object param2) {
parent = frmControl;
parameter1 = param1;
parameter2 = param2;
}
public event DataChangedHandler DataChanged;
public void Start() {
object myData = new object(); // whatever this is. DataTable?
try {
// long routine code goes here
} finally {
if (DataChanged != null) {
SuperEventArgs e = new SuperEventArgs(myData);
MethodInvoker methInvoker = delegate {
DataChanged(this, e);
};
try {
parent.BeginInvoke(methInvoker);
} catch (Exception err) {
Log(err); // something you'd write
}
}
}
}
}
Back in the actual main thread of execution, you'd do something like this:
public partial class Form1 : Form {
private Simple1 simple;
public Form1() {
object query = new object(); // something you want to pass in
simple = new Simple1(this, query, DateTime.Now);
simple.DataChanged += new DataChangedHandler(simple1_DataChanged);
Thread thread = new Thread(simpleStart);
thread.Start();
}
private void simpleStart() {
if (simple != null) {
simple.Start();
}
}
private void simple1_DataChanged(object sender, SuperEventArgs e) {
MyFancyData fancy = e.Data as MyFancyData;
if (fancy != null) {
// populate your form with the data you received.
}
}
}
I know it looks long, but it works really well!
This is not anything I have actually tested, of course, because there isn't any data. If you get to working with it and you experience any issues, let me know and I'll happily help you work through them.
~JoeP

Program hangs after leaving screen saver or locking computer

Our program works fine, until someone locks the computer or the screen-saver pops up (but not ctrl+alt+delete). Once the computer is unlocked/the screen saver is closed, the application stops drawing everything except the title bar, and stops responding to input - it displays a mostly-white window which can't be moved or closed.
(Example of application freezing - the mountains are from my desktop background)
If we let it sit for about 5~10 minutes, it comes back to life, and doesn't hang again (even after locking the computer/screen saver popup) until the application is restarted.
It's difficult to debug, because it doesn't happen when the program is started from Visual Studio, only when the .exe is manually opened.
It only happens when the splash-screen is shown - if I remove the code to show the splash-screen, it stops happening. We need the splash-screen, however.
I've tried every suggestion on this page; the only one this doesn't happen with is using Microsoft.VisualBasic.WindowsFormsApplicationBase, but that causes all sorts of other problems.
Information about this on the Internet appears to be scarce - has anyone run into a similar problem before?
Here is the relevant code:
//Multiple programs use this login form, all have the same issue
public partial class LoginForm<TMainForm>
where TMainForm : Form, new()
{
private readonly Action _showLoadingForm;
public LoginForm(Action showLoadingForm)
{
...
_showLoadingForm = showLoadingForm;
}
private void btnLogin_Click(object sender, EventArgs e)
{
...
this.Hide();
ShowLoadingForm(); //Problem goes away when commenting-out this line
new TMainForm().ShowDialog();
this.Close();
}
private void ShowLoadingForm()
{
Thread loadingFormThread = new Thread(o => _showLoadingForm());
loadingFormThread.IsBackground = true;
loadingFormThread.SetApartmentState(ApartmentState.STA);
loadingFormThread.Start();
}
}
Here is an example of one of the _showLoadingForm actions used in one of the programs:
public static bool _showSplash = true;
public static void ShowSplashScreen()
{
//Ick, DoEvents! But we were having problems with CloseSplashScreen being called
//before ShowSplashScreen - this hack was found at
//https://stackoverflow.com/questions/48916/multi-threaded-splash-screen-in-c/48946#48946
using(SplashForm splashForm = new SplashForm())
{
splashForm.Show();
while(_showSplash)
Application.DoEvents();
splashForm.Close();
}
}
//Called in MainForm_Load()
public static void CloseSplashScreen()
{
_showSplash = false;
}

Splash Screen Issues
The DoEvents thing is very undesirable and doesn't necessarily accomplish what you think it does. DoEvents tell the CLR to attend to the windows message loop (for the splash screen), but doesn't necessarily offer up any processing time to other threads. Thread.Sleep() will offer other threads a chance to process, but won't necessarily allow the windows message loop for your splash screen to continue pumping messages. So you really need both if you must use a loop, but in a minute I'm going to recommend getting away from this loop altogether. In addition to that loop issue, I don't see any explicit way the splash thread is being cleaned up. You need some kind of Thread.Join() or Thread.Abort() happening somewhere.
Instead of using a Application.DoEvents() loop, I like to use a ManualResetEvent to synchronize the splash forms start up with the calling thread. That way the ShowSplash() method doesn't return until the splash is shown. Anytime after that we are obviously ok to close it down as we know it was finished being shown.
Here's a thread with a few good examples:.NET Multi-threaded Splash Screens in C#
Here's how I modified my favorite example, that #AdamNosfinger posted, to include a ManualResetEvent to synchronize the ShowSplash method with the splash screen thread:
public partial class FormSplash : Form
{
private static Thread _splashThread;
private static FormSplash _splashForm;
// This is used to make sure you can't call SplashScreenClose before the SplashScreenOpen has finished showing the splash initially.
static ManualResetEvent SplashScreenLoaded;
public FormSplash()
{
InitializeComponent();
// Signal out ManualResetEvent so we know the Splash form is good to go.
SplashScreenLoaded.Set();
}
/// <summary>
/// Show the Splash Screen (Loading...)
/// </summary>
public static void ShowSplash()
{
if (_splashThread == null)
{
// Setup our manual reset event to syncronize the splash screen thread and our main application thread.
SplashScreenLoaded = new ManualResetEvent(false);
// show the form in a new thread
_splashThread = new Thread(new ThreadStart(DoShowSplash));
_splashThread.IsBackground = true;
_splashThread.Start();
// Wait for the splash screen thread to let us know its ok for the app to keep going.
// This next line will not return until the SplashScreen is loaded.
SplashScreenLoaded.WaitOne();
SplashScreenLoaded.Close();
SplashScreenLoaded = null;
}
}
// called by the thread
private static void DoShowSplash()
{
if (_splashForm == null)
_splashForm = new FormSplash();
// create a new message pump on this thread (started from ShowSplash)
Application.Run(_splashForm);
}
/// <summary>
/// Close the splash (Loading...) screen
/// </summary>
public static void CloseSplash()
{
// need to call on the thread that launched this splash
if (_splashForm.InvokeRequired)
_splashForm.Invoke(new MethodInvoker(CloseSplash));
else
Application.ExitThread();
}
}
Main Form Issues
It looks as though you are launching your mainform from your login window using ShowDialog and then closing the login form. Have I understood correctly? This is not good if so. ShowDialog is intended for child windows of your application and wants to have an owner window, if you don't specify an owner form in the method arguments the currently active window is assumed to be the owner. See MSDN
So your main form is assuming the login form is its parent, but you close the login form shortly after showing the main form. So I'm not sure what state the application is left in at that point. You should consider using a standard Form.Show() method instead and simply adjusting the Form properties to appear like a dialog if this is the desired outcome (ex: BorderStyle, MaximizeBox, MinimizeBox, ControlBox, TopMost).
IMPORTANT EDIT: Ok I'm human, I messed up and forgot ShowDialog was a blocking method. While that does negate the owner handle issue, I still recommend not using ShowDialog for your main application form unless you can provide a significant justification for it that is not appearance or threading related (as those should be fixed with other techniques). The advice is still sound, despite the misstep on my part.
Possible Painting Issues
You did not specify which controls you were using or if you were doing any custom painting in your application. But you need to keep in mind some windows handles will be forcibly closed when you lock the computer. For example if you have some custom painted controls and are caching fonts, brushes or other GDI resources you need to have some try { ... } catch { ... } blocks in your code that dispose of and then rebuild the cached GDI resources when an exception is raised during painting. I've run into this before where I was custom painting a list box and caching some GDI objects. If you have any custom painting code anywhere in your app, including in the splash screen, please double check all GDI objects are nicely disposed/cleaned up.

After adding a few lines of code to the code snippets above, I could compile a working program. However, I could not reproduce the problem (Windows 7 Starter). I tried locking the computer, and starting the screen saver, too. I did this while the splash screen was active, and in other situations, but the main window always remained responsive. I think there must be something else going on here, probably during the initialization of the main window.
Here is the code, maybe it helps the others figure out the problem.
using System;
using System.Threading;
using System.Windows.Forms;
public class MainForm : Form
{
//Here is an example of one of the _showLoadingForm actions used in one of the programs:
public static bool _showSplash = true;
public static void ShowSplashScreen()
{
//Ick, DoEvents! But we were having problems with CloseSplashScreen being called
//before ShowSplashScreen - this hack was found at
//http://stackoverflow.com/questions/48916/multi-threaded-splash-screen-in-c/48946#48946
using(SplashForm splashForm = new SplashForm())
{
splashForm.Show();
while(_showSplash)
Application.DoEvents();
splashForm.Close();
}
}
//Called in MainForm_Load()
public static void CloseSplashScreen()
{
_showSplash = false;
}
public MainForm()
{
Text = "MainForm";
Load += delegate(object sender, EventArgs e)
{
Thread.Sleep(3000);
CloseSplashScreen();
};
}
}
//Multiple programs use this login form, all have the same issue
public class LoginForm<TMainForm> : Form where TMainForm : Form, new()
{
private readonly Action _showLoadingForm;
public LoginForm(Action showLoadingForm)
{
Text = "LoginForm";
Button btnLogin = new Button();
btnLogin.Text = "Login";
btnLogin.Click += btnLogin_Click;
Controls.Add(btnLogin);
//...
_showLoadingForm = showLoadingForm;
}
private void btnLogin_Click(object sender, EventArgs e)
{
//...
this.Hide();
ShowLoadingForm(); //Problem goes away when commenting-out this line
new TMainForm().ShowDialog();
this.Close();
}
private void ShowLoadingForm()
{
Thread loadingFormThread = new Thread(o => _showLoadingForm());
loadingFormThread.IsBackground = true;
loadingFormThread.SetApartmentState(ApartmentState.STA);
loadingFormThread.Start();
}
}
public class SplashForm : Form
{
public SplashForm()
{
Text = "SplashForm";
}
}
public class Program
{
public static void Main()
{
var loginForm = new LoginForm<MainForm>(MainForm.ShowSplashScreen);
loginForm.Visible = true;
Application.Run(loginForm);
}
}

Several years later (with the code no longer in front of me), I'll add an answer for anyone else who experiences this problem.
The issue turned out to be exactly as Hans Passant had guessed. The problem was that, due to some incredibly obscure and innocuous bugs in the .Net framework, InvokeRequired can sometimes return false when it should return true, causing code that should run on the GUI thread to run in the background (which, due to some more obscure and innocuous bugs, causes the behavior I was seeing).
The solution is to not rely on InvokeRequired, using a hack similar to this:
void Main()
{
Thread.Current.Name = "GuiThread";
...
}
bool IsGuiThread()
{
return Thread.Current.Name == "GuiThread";
}
//Later, call IsGuiThread() to determine if GUI code is being run on GUI thread
This solution, as well as an extremely in-depth look at the causes of the issue, was found here.

since there is no working example
can you try removing Application.DoEvents(); and inserting a thread.sleep?
Application.DoEvents(); let say can be very evil.

From the quick scan I did of your code, it looks like the key to your problem might be using
Application.Run(_splashForm);
Ideally you would use that inside a thread, but maybe it would work in conjunction with your DoEvents too. Sorry if you are doing that and I just missed it...

In our application we had some similar problems with the splash screen. We wanted to have a splash screen with an animated gif (don't blame on me, it was a management decision). That only works correctly, when the splashScreen has its own message loop. Because I think the DoEvents is the key to your problem, I show you, how we solved it. Hopefully it will help you to solve your problem!
We're going to show the splash screen in that way:
// AnimatedClockSplashScreen is a special form from us, it can be any other!
// Our form is set to be TopMost
splashScreen = new AnimatedClockSplashScreen();
Task.Factory.StartNew(() => Application.Run(splashScreen));
The splash screen is a simple containing the animated gif of a clock. It doesn't have any loop, so it doesn't steel any time.
When the splash needs to be closed, we do it in that way:
if (splashScreen != null)
{
if (splashScreen.IsHandleCreated)
{
try
{
splashScreen.Invoke(new MethodInvoker(() => splashScreen.Close()));
}
catch (InvalidOperationException)
{
}
}
splashScreen.Dispose();
splashScreen = null;
}

remove this line, you don't need it, You are forcing it to a single thread when the default is mta. Take the default.
loadingFormThread.SetApartmentState(ApartmentState.STA);
change the following:
using(SplashForm splashForm = new SplashForm())
{
splashForm.Show();
while(_showSplash)
Application.DoEvents();
splashForm.Close();
}
to:
SplashForm splashForm = new SplashForm())
splashForm.Show();
Change this:
public static void CloseSplashScreen()
{
_showSplash = false;
}
to this:
public static void CloseSplashScreen()
{
splashForm.Close();
}

Here's a shot in the dark: when we idle, we also ask the thread to go to sleep. I'm not sure that this will help, but it's worth a shot:
while(_showSplash) {
System.Threading.Thread.Sleep(500);
Application.DoEvents();
}

Have you tried using a WaitHandle for showing the form in the thread?
Something like:
EventWaitHandle _waitHandle = new AutoResetEvent(false);
public static void ShowSplashScreen()
{
using(SplashForm splashForm = new SplashForm())
{
splashForm.Show();
_waitHandle.WaitOne();
splashForm.Close();
}
}
//Called in MainForm_Load()
public static void CloseSplashScreen()
{
_waitHandle.Set();
}

I think your problem is because you are using Form.ShowDialog, not Application.Run. ShowDialog runs a restricted message loop that runs on top of the main message loop and ignores some windows messages.
Something like this should work:
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault( false );
Application.Run( new MainForm() );
}
}
public partial class MainForm: Form
{
FormSplash dlg = null;
void ShowSplashScreen()
{
var t = new Thread( () =>
{
using ( dlg = new FormSplash() ) dlg.ShowDialog();
}
);
t.SetApartmentState( ApartmentState.STA );
t.IsBackground = true;
t.Start();
}
void CloseSplashScreen()
{
dlg.Invoke( ( MethodInvoker ) ( () => dlg.Close() ) );
}
public MainForm()
{
ShowSplashScreen();
InitializeComponent();
Thread.Sleep( 3000 ); // simulate big form
CloseSplashScreen();
}
}